[collectd.git] / src / network.c

/**
 * collectd - src/network.c
 * Copyright (C) 2005-2009  Florian octo Forster
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; only version 2 of the License is applicable.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 *
 * Authors:
 *   Florian octo Forster <octo at verplant.org>
 **/

#include "collectd.h"
#include "plugin.h"
#include "common.h"
#include "configfile.h"
#include "utils_avltree.h"

#include "network.h"

#if HAVE_PTHREAD_H
# include <pthread.h>
#endif
#if HAVE_SYS_SOCKET_H
# include <sys/socket.h>
#endif
#if HAVE_NETDB_H
# include <netdb.h>
#endif
#if HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#if HAVE_ARPA_INET_H
# include <arpa/inet.h>
#endif
#if HAVE_POLL_H
# include <poll.h>
#endif

#if HAVE_GCRYPT_H
# include <gcrypt.h>
#endif

/* 1500 - 40 - 8  =  Ethernet packet - IPv6 header - UDP header */
/* #define BUFF_SIZE 1452 */

#ifndef IPV6_ADD_MEMBERSHIP
# ifdef IPV6_JOIN_GROUP
#  define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
# else
#  error "Neither IP_ADD_MEMBERSHIP nor IPV6_JOIN_GROUP is defined"
# endif
#endif /* !IP_ADD_MEMBERSHIP */

/* Buffer size to allocate. */
#define BUFF_SIZE 1024

/*
 * Maximum size required for encryption / signing:
 * Type/length:       4
 * Hash/orig length: 22
 * Padding (up to):  15
 * --------------------
 *                   41
 */
#define BUFF_SIG_SIZE 41

/*
 * Private data types
 */
typedef struct sockent
{
        int                      fd;
        struct sockaddr_storage *addr;
        socklen_t                addrlen;

#define SECURITY_LEVEL_NONE     0
#if HAVE_GCRYPT_H
# define SECURITY_LEVEL_SIGN    1
# define SECURITY_LEVEL_ENCRYPT 2
        int security_level;
        char *shared_secret;
        gcry_cipher_hd_t cypher;
#endif /* HAVE_GCRYPT_H */

        struct sockent          *next;
} sockent_t;

/*                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-------+-----------------------+-------------------------------+
 * ! Ver.  !                       ! Length                        !
 * +-------+-----------------------+-------------------------------+
 */
struct part_header_s
{
        uint16_t type;
        uint16_t length;
};
typedef struct part_header_s part_header_t;

/*                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-------------------------------+-------------------------------+
 * ! Type                          ! Length                        !
 * +-------------------------------+-------------------------------+
 * : (Length - 4) Bytes                                            :
 * +---------------------------------------------------------------+
 */
struct part_string_s
{
        part_header_t *head;
        char *value;
};
typedef struct part_string_s part_string_t;

/*                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-------------------------------+-------------------------------+
 * ! Type                          ! Length                        !
 * +-------------------------------+-------------------------------+
 * : (Length - 4 == 2 || 4 || 8) Bytes                             :
 * +---------------------------------------------------------------+
 */
struct part_number_s
{
        part_header_t *head;
        uint64_t *value;
};
typedef struct part_number_s part_number_t;

/*                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-------------------------------+-------------------------------+
 * ! Type                          ! Length                        !
 * +-------------------------------+---------------+---------------+
 * ! Num of values                 ! Type0         ! Type1         !
 * +-------------------------------+---------------+---------------+
 * ! Value0                                                        !
 * !                                                               !
 * +---------------------------------------------------------------+
 * ! Value1                                                        !
 * !                                                               !
 * +---------------------------------------------------------------+
 */
struct part_values_s
{
        part_header_t *head;
        uint16_t *num_values;
        uint8_t  *values_types;
        value_t  *values;
};
typedef struct part_values_s part_values_t;

/*                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-------------------------------+-------------------------------+
 * ! Type                          ! Length                        !
 * +-------------------------------+-------------------------------+
 * ! Hash (Bits   0 -  31)                                         !
 * : :                                                             :
 * ! Hash (Bits 224 - 255)                                         !
 * +---------------------------------------------------------------+
 */
struct part_signature_sha256_s
{
  part_header_t head;
  char hash[32];
};
typedef struct part_signature_sha256_s part_signature_sha256_t;

/*                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-------------------------------+-------------------------------+
 * ! Type                          ! Length                        !
 * +-------------------------------+-------------------------------+
 * ! Original length               ! Padding (0 - 15 bytes)        !
 * +-------------------------------+-------------------------------+
 * ! Hash (Bits   0 -  31)                                         !
 * : :                                                             :
 * ! Hash (Bits 128 - 159)                                         !
 * +---------------------------------------------------------------+
 */
struct part_encryption_aes256_s
{
  part_header_t head;
  uint16_t orig_length;
  char padding[15];
  char hash[20];
};
typedef struct part_encryption_aes256_s part_encryption_aes256_t;

struct receive_list_entry_s
{
  char data[BUFF_SIZE];
  int  data_len;
  int  fd;
  struct receive_list_entry_s *next;
};
typedef struct receive_list_entry_s receive_list_entry_t;

/*
 * Private variables
 */
static int network_config_ttl = 0;
static int network_config_forward = 0;

static sockent_t *sending_sockets = NULL;

static receive_list_entry_t *receive_list_head = NULL;
static receive_list_entry_t *receive_list_tail = NULL;
static pthread_mutex_t       receive_list_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t        receive_list_cond = PTHREAD_COND_INITIALIZER;

static sockent_t     *listen_sockets = NULL;
static struct pollfd *listen_sockets_pollfd = NULL;
static int            listen_sockets_num = 0;

/* The receive and dispatch threads will run as long as `listen_loop' is set to
 * zero. */
static int       listen_loop = 0;
static int       receive_thread_running = 0;
static pthread_t receive_thread_id;
static int       dispatch_thread_running = 0;
static pthread_t dispatch_thread_id;

/* Buffer in which to-be-sent network packets are constructed. */
static char             send_buffer[BUFF_SIZE];
static char            *send_buffer_ptr;
static int              send_buffer_fill;
static value_list_t     send_buffer_vl = VALUE_LIST_STATIC;
static pthread_mutex_t  send_buffer_lock = PTHREAD_MUTEX_INITIALIZER;

/* In this cache we store all the values we received, so we can send out only
 * those values which were *not* received via the network plugin, too. This is
 * used for the `Forward false' option. */
static c_avl_tree_t    *cache_tree = NULL;
static pthread_mutex_t  cache_lock = PTHREAD_MUTEX_INITIALIZER;
static time_t           cache_flush_last = 0;
static int              cache_flush_interval = 1800;

/*
 * Private functions
 */
static int cache_flush (void)
{
        char **keys = NULL;
        int    keys_num = 0;

        char **tmp;
        int    i;

        char   *key;
        time_t *value;
        c_avl_iterator_t *iter;

        time_t curtime = time (NULL);

        iter = c_avl_get_iterator (cache_tree);
        while (c_avl_iterator_next (iter, (void *) &key, (void *) &value) == 0)
        {
                if ((curtime - *value) <= cache_flush_interval)
                        continue;
                tmp = (char **) realloc (keys,
                                (keys_num + 1) * sizeof (char *));
                if (tmp == NULL)
                {
                        sfree (keys);
                        c_avl_iterator_destroy (iter);
                        ERROR ("network plugin: cache_flush: realloc"
                                        " failed.");
                        return (-1);
                }
                keys = tmp;
                keys[keys_num] = key;
                keys_num++;
        } /* while (c_avl_iterator_next) */
        c_avl_iterator_destroy (iter);

        for (i = 0; i < keys_num; i++)
        {
                if (c_avl_remove (cache_tree, keys[i], (void *) &key,
                                        (void *) &value) != 0)
                {
                        WARNING ("network plugin: cache_flush: c_avl_remove"
                                        " (%s) failed.", keys[i]);
                        continue;
                }

                sfree (key);
                sfree (value);
        }

        sfree (keys);

        DEBUG ("network plugin: cache_flush: Removed %i %s",
                        keys_num, (keys_num == 1) ? "entry" : "entries");
        cache_flush_last = curtime;
        return (0);
} /* int cache_flush */

static int cache_check (const value_list_t *vl)
{
        char key[1024];
        time_t *value = NULL;
        int retval = -1;

        if (cache_tree == NULL)
                return (-1);

        if (format_name (key, sizeof (key), vl->host, vl->plugin,
                                vl->plugin_instance, vl->type, vl->type_instance))
                return (-1);

        pthread_mutex_lock (&cache_lock);

        if (c_avl_get (cache_tree, key, (void *) &value) == 0)
        {
                if (*value < vl->time)
                {
                        *value = vl->time;
                        retval = 0;
                }
                else
                {
                        DEBUG ("network plugin: cache_check: *value = %i >= vl->time = %i",
                                        (int) *value, (int) vl->time);
                        retval = 1;
                }
        }
        else
        {
                char *key_copy = strdup (key);
                value = malloc (sizeof (time_t));
                if ((key_copy != NULL) && (value != NULL))
                {
                        *value = vl->time;
                        c_avl_insert (cache_tree, key_copy, value);
                        retval = 0;
                }
                else
                {
                        sfree (key_copy);
                        sfree (value);
                }
        }

        if ((time (NULL) - cache_flush_last) > cache_flush_interval)
                cache_flush ();

        pthread_mutex_unlock (&cache_lock);

        return (retval);
} /* int cache_check */

static int write_part_values (char **ret_buffer, int *ret_buffer_len,
                const data_set_t *ds, const value_list_t *vl)
{
        char *packet_ptr;
        int packet_len;
        int num_values;

        part_header_t pkg_ph;
        uint16_t      pkg_num_values;
        uint8_t      *pkg_values_types;
        value_t      *pkg_values;

        int offset;
        int i;

        num_values = vl->values_len;
        packet_len = sizeof (part_header_t) + sizeof (uint16_t)
                + (num_values * sizeof (uint8_t))
                + (num_values * sizeof (value_t));

        if (*ret_buffer_len < packet_len)
                return (-1);

        pkg_values_types = (uint8_t *) malloc (num_values * sizeof (uint8_t));
        if (pkg_values_types == NULL)
        {
                ERROR ("network plugin: write_part_values: malloc failed.");
                return (-1);
        }

        pkg_values = (value_t *) malloc (num_values * sizeof (value_t));
        if (pkg_values == NULL)
        {
                free (pkg_values_types);
                ERROR ("network plugin: write_part_values: malloc failed.");
                return (-1);
        }

        pkg_ph.type = htons (TYPE_VALUES);
        pkg_ph.length = htons (packet_len);

        pkg_num_values = htons ((uint16_t) vl->values_len);

        for (i = 0; i < num_values; i++)
        {
                if (ds->ds[i].type == DS_TYPE_COUNTER)
                {
                        pkg_values_types[i] = DS_TYPE_COUNTER;
                        pkg_values[i].counter = htonll (vl->values[i].counter);
                }
                else
                {
                        pkg_values_types[i] = DS_TYPE_GAUGE;
                        pkg_values[i].gauge = htond (vl->values[i].gauge);
                }
        }

        /*
         * Use `memcpy' to write everything to the buffer, because the pointer
         * may be unaligned and some architectures, such as SPARC, can't handle
         * that.
         */
        packet_ptr = *ret_buffer;
        offset = 0;
        memcpy (packet_ptr + offset, &pkg_ph, sizeof (pkg_ph));
        offset += sizeof (pkg_ph);
        memcpy (packet_ptr + offset, &pkg_num_values, sizeof (pkg_num_values));
        offset += sizeof (pkg_num_values);
        memcpy (packet_ptr + offset, pkg_values_types, num_values * sizeof (uint8_t));
        offset += num_values * sizeof (uint8_t);
        memcpy (packet_ptr + offset, pkg_values, num_values * sizeof (value_t));
        offset += num_values * sizeof (value_t);

        assert (offset == packet_len);

        *ret_buffer = packet_ptr + packet_len;
        *ret_buffer_len -= packet_len;

        free (pkg_values_types);
        free (pkg_values);

        return (0);
} /* int write_part_values */

static int write_part_number (char **ret_buffer, int *ret_buffer_len,
                int type, uint64_t value)
{
        char *packet_ptr;
        int packet_len;

        part_header_t pkg_head;
        uint64_t pkg_value;
        
        int offset;

        packet_len = sizeof (pkg_head) + sizeof (pkg_value);

        if (*ret_buffer_len < packet_len)
                return (-1);

        pkg_head.type = htons (type);
        pkg_head.length = htons (packet_len);
        pkg_value = htonll (value);

        packet_ptr = *ret_buffer;
        offset = 0;
        memcpy (packet_ptr + offset, &pkg_head, sizeof (pkg_head));
        offset += sizeof (pkg_head);
        memcpy (packet_ptr + offset, &pkg_value, sizeof (pkg_value));
        offset += sizeof (pkg_value);

        assert (offset == packet_len);

        *ret_buffer = packet_ptr + packet_len;
        *ret_buffer_len -= packet_len;

        return (0);
} /* int write_part_number */

static int write_part_string (char **ret_buffer, int *ret_buffer_len,
                int type, const char *str, int str_len)
{
        char *buffer;
        int buffer_len;

        uint16_t pkg_type;
        uint16_t pkg_length;

        int offset;

        buffer_len = 2 * sizeof (uint16_t) + str_len + 1;
        if (*ret_buffer_len < buffer_len)
                return (-1);

        pkg_type = htons (type);
        pkg_length = htons (buffer_len);

        buffer = *ret_buffer;
        offset = 0;
        memcpy (buffer + offset, (void *) &pkg_type, sizeof (pkg_type));
        offset += sizeof (pkg_type);
        memcpy (buffer + offset, (void *) &pkg_length, sizeof (pkg_length));
        offset += sizeof (pkg_length);
        memcpy (buffer + offset, str, str_len);
        offset += str_len;
        memset (buffer + offset, '\0', 1);
        offset += 1;

        assert (offset == buffer_len);

        *ret_buffer = buffer + buffer_len;
        *ret_buffer_len -= buffer_len;

        return (0);
} /* int write_part_string */

static int parse_part_values (void **ret_buffer, int *ret_buffer_len,
                value_t **ret_values, int *ret_num_values)
{
        char *buffer = *ret_buffer;
        int   buffer_len = *ret_buffer_len;

        uint16_t tmp16;
        size_t exp_size;
        int   i;

        uint16_t pkg_length;
        uint16_t pkg_type;
        uint16_t pkg_numval;

        uint8_t *pkg_types;
        value_t *pkg_values;

        if (buffer_len < (15))
        {
                DEBUG ("network plugin: packet is too short: buffer_len = %i",
                                buffer_len);
                return (-1);
        }

        memcpy ((void *) &tmp16, buffer, sizeof (tmp16));
        buffer += sizeof (tmp16);
        pkg_type = ntohs (tmp16);

        memcpy ((void *) &tmp16, buffer, sizeof (tmp16));
        buffer += sizeof (tmp16);
        pkg_length = ntohs (tmp16);

        memcpy ((void *) &tmp16, buffer, sizeof (tmp16));
        buffer += sizeof (tmp16);
        pkg_numval = ntohs (tmp16);

        assert (pkg_type == TYPE_VALUES);

        exp_size = 3 * sizeof (uint16_t)
                + pkg_numval * (sizeof (uint8_t) + sizeof (value_t));
        if ((buffer_len < 0) || ((size_t) buffer_len < exp_size))
        {
                WARNING ("network plugin: parse_part_values: "
                                "Packet too short: "
                                "Chunk of size %u expected, "
                                "but buffer has only %i bytes left.",
                                (unsigned int) exp_size, buffer_len);
                return (-1);
        }

        if (pkg_length != exp_size)
        {
                WARNING ("network plugin: parse_part_values: "
                                "Length and number of values "
                                "in the packet don't match.");
                return (-1);
        }

        pkg_types = (uint8_t *) malloc (pkg_numval * sizeof (uint8_t));
        pkg_values = (value_t *) malloc (pkg_numval * sizeof (value_t));
        if ((pkg_types == NULL) || (pkg_values == NULL))
        {
                sfree (pkg_types);
                sfree (pkg_values);
                ERROR ("network plugin: parse_part_values: malloc failed.");
                return (-1);
        }

        memcpy ((void *) pkg_types, (void *) buffer, pkg_numval * sizeof (uint8_t));
        buffer += pkg_numval * sizeof (uint8_t);
        memcpy ((void *) pkg_values, (void *) buffer, pkg_numval * sizeof (value_t));
        buffer += pkg_numval * sizeof (value_t);

        for (i = 0; i < pkg_numval; i++)
        {
                if (pkg_types[i] == DS_TYPE_COUNTER)
                        pkg_values[i].counter = ntohll (pkg_values[i].counter);
                else if (pkg_types[i] == DS_TYPE_GAUGE)
                        pkg_values[i].gauge = ntohd (pkg_values[i].gauge);
        }

        *ret_buffer     = buffer;
        *ret_buffer_len = buffer_len - pkg_length;
        *ret_num_values = pkg_numval;
        *ret_values     = pkg_values;

        sfree (pkg_types);

        return (0);
} /* int parse_part_values */

static int parse_part_number (void **ret_buffer, int *ret_buffer_len,
                uint64_t *value)
{
        char *buffer = *ret_buffer;
        int buffer_len = *ret_buffer_len;

        uint16_t tmp16;
        uint64_t tmp64;
        size_t exp_size = 2 * sizeof (uint16_t) + sizeof (uint64_t);

        uint16_t pkg_length;
        uint16_t pkg_type;

        if ((buffer_len < 0) || ((size_t) buffer_len < exp_size))
        {
                WARNING ("network plugin: parse_part_number: "
                                "Packet too short: "
                                "Chunk of size %u expected, "
                                "but buffer has only %i bytes left.",
                                (unsigned int) exp_size, buffer_len);
                return (-1);
        }

        memcpy ((void *) &tmp16, buffer, sizeof (tmp16));
        buffer += sizeof (tmp16);
        pkg_type = ntohs (tmp16);

        memcpy ((void *) &tmp16, buffer, sizeof (tmp16));
        buffer += sizeof (tmp16);
        pkg_length = ntohs (tmp16);

        memcpy ((void *) &tmp64, buffer, sizeof (tmp64));
        buffer += sizeof (tmp64);
        *value = ntohll (tmp64);

        *ret_buffer = buffer;
        *ret_buffer_len = buffer_len - pkg_length;

        return (0);
} /* int parse_part_number */

static int parse_part_string (void **ret_buffer, int *ret_buffer_len,
                char *output, int output_len)
{
        char *buffer = *ret_buffer;
        int   buffer_len = *ret_buffer_len;

        uint16_t tmp16;
        size_t header_size = 2 * sizeof (uint16_t);

        uint16_t pkg_length;
        uint16_t pkg_type;

        if ((buffer_len < 0) || ((size_t) buffer_len < header_size))
        {
                WARNING ("network plugin: parse_part_string: "
                                "Packet too short: "
                                "Chunk of at least size %u expected, "
                                "but buffer has only %i bytes left.",
                                (unsigned int) header_size, buffer_len);
                return (-1);
        }

        memcpy ((void *) &tmp16, buffer, sizeof (tmp16));
        buffer += sizeof (tmp16);
        pkg_type = ntohs (tmp16);

        memcpy ((void *) &tmp16, buffer, sizeof (tmp16));
        buffer += sizeof (tmp16);
        pkg_length = ntohs (tmp16);

        /* Check that packet fits in the input buffer */
        if (pkg_length > buffer_len)
        {
                WARNING ("network plugin: parse_part_string: "
                                "Packet too big: "
                                "Chunk of size %hu received, "
                                "but buffer has only %i bytes left.",
                                pkg_length, buffer_len);
                return (-1);
        }

        /* Check that pkg_length is in the valid range */
        if (pkg_length <= header_size)
        {
                WARNING ("network plugin: parse_part_string: "
                                "Packet too short: "
                                "Header claims this packet is only %hu "
                                "bytes long.", pkg_length);
                return (-1);
        }

        /* Check that the package data fits into the output buffer.
         * The previous if-statement ensures that:
         * `pkg_length > header_size' */
        if ((output_len < 0)
                        || ((size_t) output_len < ((size_t) pkg_length - header_size)))
        {
                WARNING ("network plugin: parse_part_string: "
                                "Output buffer too small.");
                return (-1);
        }

        /* All sanity checks successfull, let's copy the data over */
        output_len = pkg_length - header_size;
        memcpy ((void *) output, (void *) buffer, output_len);
        buffer += output_len;

        /* For some very weird reason '\0' doesn't do the trick on SPARC in
         * this statement. */
        if (output[output_len - 1] != 0)
        {
                WARNING ("network plugin: parse_part_string: "
                                "Received string does not end "
                                "with a NULL-byte.");
                return (-1);
        }

        *ret_buffer = buffer;
        *ret_buffer_len = buffer_len - pkg_length;

        return (0);
} /* int parse_part_string */

#if HAVE_GCRYPT_H
static int parse_part_sign_sha256 (sockent_t *se, /* {{{ */
    void **ret_buffer, int *ret_buffer_len)
{
  char *buffer = *ret_buffer;
  size_t buffer_len = (size_t) *ret_buffer_len;

  part_signature_sha256_t ps_received;
  char hash[sizeof (ps_received.hash)];

  gcry_md_hd_t hd;
  gcry_error_t err;
  unsigned char *hash_ptr;

  if (se->shared_secret == NULL)
  {
    NOTICE ("network plugin: Received signed network packet but can't verify "
        "it because no shared secret has been configured. Will accept it.");
    return (0);
  }

  if (buffer_len < sizeof (ps_received))
    return (-ENOMEM);

  hd = NULL;
  err = gcry_md_open (&hd, GCRY_MD_SHA256, GCRY_MD_FLAG_HMAC);
  if (err != 0)
  {
    ERROR ("network plugin: Creating HMAC object failed: %s",
        gcry_strerror (err));
    return (-1);
  }

  err = gcry_md_setkey (hd, se->shared_secret,
      strlen (se->shared_secret));
  if (err != 0)
  {
    ERROR ("network plugin: gcry_md_setkey failed: %s",
        gcry_strerror (err));
    gcry_md_close (hd);
    return (-1);
  }

  memcpy (&ps_received, buffer, sizeof (ps_received));
  /* TODO: Check ps_received.head.length! */

  buffer += sizeof (ps_received);
  buffer_len -= sizeof (ps_received);

  gcry_md_write (hd, buffer, buffer_len);
  hash_ptr = gcry_md_read (hd, GCRY_MD_SHA256);
  if (hash_ptr == NULL)
  {
    ERROR ("network plugin: gcry_md_read failed.");
    gcry_md_close (hd);
    return (-1);
  }
  memcpy (hash, hash_ptr, sizeof (hash));

  gcry_md_close (hd);
  hd = NULL;

  *ret_buffer += sizeof (ps_received);
  *ret_buffer_len -= sizeof (ps_received);

  if (memcmp (ps_received.hash, hash,
        sizeof (ps_received.hash)) == 0)
    return (0);
  else /* hashes do not match. */
    return (1);
} /* }}} int parse_part_sign_sha256 */
/* #endif HAVE_GCRYPT_H */

#else /* if !HAVE_GCRYPT_H */
static int parse_part_sign_sha256 (sockent_t *se, /* {{{ */
    void **ret_buffer, int *ret_buffer_len)
{
  INFO ("network plugin: Received signed packet, but the network "
      "plugin was not linked with libgcrypt, so I cannot "
      "verify the signature. The packet will be accepted.");
  return (0);
} /* }}} int parse_part_sign_sha256 */
#endif /* !HAVE_GCRYPT_H */

#if HAVE_GCRYPT_H
static int parse_part_encr_aes256 (sockent_t *se, /* {{{ */
                void **ret_buffer, int *ret_buffer_len)
{
  char  *buffer = *ret_buffer;
  size_t buffer_len = (size_t) *ret_buffer_len;
  size_t orig_buffer_len;
  size_t part_size;
  size_t buffer_offset = 0;
  size_t padding_size;
  part_encryption_aes256_t pea;
  size_t pea_size;
  char hash[sizeof (pea.hash)];
  gcry_error_t err;

  /* Make sure at least the header if available. */
  if (buffer_len < sizeof (pea))
  {
    NOTICE ("network plugin: parse_part_encr_aes256: "
        "Discarding short packet.");
    return (-1);
  }

  if (se->cypher == NULL)
  {
    NOTICE ("network plugin: Unable to decrypt packet, because no cypher "
        "instance is present.");
    return (-1);
  }

  /* Size of `pea' without padding. */
  pea_size = sizeof (pea.head.type) + sizeof (pea.head.length)
    + sizeof (pea.orig_length) + sizeof (pea.hash);

  /* Copy the header information to `pea' */
  memcpy (&pea.head, buffer, sizeof (pea.head));
  buffer_offset += sizeof (pea.head);
  
  /* Check the `part size'. */
  part_size = ntohs (pea.head.length);
  if (part_size > buffer_len)
  {
    NOTICE ("network plugin: parse_part_encr_aes256: "
        "Discarding large part.");
    return (-1);
  }

  /* Decrypt the packet in-place */
  err = gcry_cipher_decrypt (se->cypher,
      buffer + sizeof (pea.head), part_size - sizeof (pea.head),
      /* in = */ NULL, /* in len = */ 0);
  gcry_cipher_reset (se->cypher);
  if (err != 0)
  {
    ERROR ("network plugin: gcry_cipher_decrypt returned: %s",
        gcry_strerror (err));
    return (-1);
  }

  /* Figure out the length of the payload and the length of the padding. */
  memcpy (&pea.orig_length, buffer + buffer_offset, sizeof (pea.orig_length));
  buffer_offset += sizeof (pea.orig_length);
  orig_buffer_len = ntohs (pea.orig_length);
  if (orig_buffer_len > (part_size - pea_size))
  {
    ERROR ("network plugin: Decryption failed: Invalid original length.");
    return (-1);
  }

  /* Calculate the size of the `padding' field. */
  padding_size = part_size - (orig_buffer_len + pea_size);
  if (padding_size > sizeof (pea.padding))
  {
    ERROR ("network plugin: Part- and original length "
        "differ more than %zu bytes.", sizeof (pea.padding));
    return (-1);
  }
  buffer_offset += padding_size;

  memcpy (pea.hash, buffer + buffer_offset, sizeof (pea.hash));
  buffer_offset += sizeof (pea.hash);

  /* Check hash sum */
  memset (hash, 0, sizeof (hash));
  gcry_md_hash_buffer (GCRY_MD_SHA1, hash,
      buffer + buffer_offset, orig_buffer_len);
  
  if (memcmp (hash, pea.hash, sizeof (hash)) != 0)
  {
    ERROR ("network plugin: Decryption failed: Checksum mismatch.");
    return (-1);
  }

  assert ((buffer_offset + orig_buffer_len) <= buffer_len);
  if ((buffer_offset + orig_buffer_len) < buffer_len)
  {
    NOTICE ("network plugin: Trailing, potentially unencrypted data "
        "(%zu bytes) will be ignored.",
        buffer_len - (buffer_offset + orig_buffer_len));
  }

  /* Update return values */
  *ret_buffer = buffer + buffer_offset;
  *ret_buffer_len = (int) orig_buffer_len;

  return (0);
} /* }}} int parse_part_encr_aes256 */
/* #endif HAVE_GCRYPT_H */

#else /* if !HAVE_GCRYPT_H */
static int parse_part_encr_aes256 (sockent_t *se, /* {{{ */
    void **ret_buffer, int *ret_buffer_len)
{
  INFO ("network plugin: Received encrypted packet, but the network "
      "plugin was not linked with libgcrypt, so I cannot "
      "decrypt it. The packet will be discarded.");
  return (-1);
} /* }}} int parse_part_encr_aes256 */
#endif /* !HAVE_GCRYPT_H */

static int parse_packet (receive_list_entry_t *rle) /* {{{ */
{
        int status;

        void *buffer;
        int buffer_len;
        sockent_t *se;

        value_list_t vl = VALUE_LIST_INIT;
        notification_t n;

        int packet_was_encrypted = 0;
        int packet_was_signed = 0;
#if HAVE_GCRYPT_H
        int printed_ignore_warning = 0;
#endif /* HAVE_GCRYPT_H */

        buffer = rle->data;
        buffer_len = rle->data_len;

        /* Look for the correct `sockent_t' */
        se = listen_sockets;
        while ((se != NULL) && (se->fd != rle->fd))
                se = se->next;

        if (se == NULL)
        {
                ERROR ("network plugin: Got packet from FD %i, but can't "
                                "find an appropriate socket entry.",
                                rle->fd);
                return (-1);
        }

        memset (&vl, '\0', sizeof (vl));
        memset (&n, '\0', sizeof (n));
        status = 0;

        while ((status == 0) && (0 < buffer_len)
                        && ((unsigned int) buffer_len > sizeof (part_header_t)))
        {
                uint16_t pkg_length;
                uint16_t pkg_type;

                memcpy ((void *) &pkg_type,
                                (void *) buffer,
                                sizeof (pkg_type));
                memcpy ((void *) &pkg_length,
                                (void *) (buffer + sizeof (pkg_type)),
                                sizeof (pkg_length));

                pkg_length = ntohs (pkg_length);
                pkg_type = ntohs (pkg_type);

                if (pkg_length > buffer_len)
                        break;
                /* Ensure that this loop terminates eventually */
                if (pkg_length < (2 * sizeof (uint16_t)))
                        break;

                if (pkg_type == TYPE_ENCR_AES256)
                {
                        status = parse_part_encr_aes256 (se, &buffer, &buffer_len);
                        if (status != 0)
                        {
                                ERROR ("network plugin: Decrypting AES256 "
                                                "part failed "
                                                "with status %i.", status);
                                break;
                        }
                        else
                        {
                                packet_was_encrypted = 1;
                        }
                }
#if HAVE_GCRYPT_H
                else if ((se->security_level == SECURITY_LEVEL_ENCRYPT)
                                && (packet_was_encrypted == 0))
                {
                        if (printed_ignore_warning == 0)
                        {
                                INFO ("network plugin: Unencrypted packet or "
                                                "part has been ignored.");
                                printed_ignore_warning = 1;
                        }
                        buffer = ((char *) buffer) + pkg_length;
                        continue;
                }
#endif /* HAVE_GCRYPT_H */
                else if (pkg_type == TYPE_SIGN_SHA256)
                {
                        status = parse_part_sign_sha256 (se, &buffer, &buffer_len);
                        if (status < 0)
                        {
                                ERROR ("network plugin: Verifying SHA-256 "
                                                "signature failed "
                                                "with status %i.", status);
                                break;
                        }
                        else if (status > 0)
                        {
                                ERROR ("network plugin: Ignoring packet with "
                                                "invalid SHA-256 signature.");
                                break;
                        }
                        else
                        {
                                packet_was_signed = 1;
                        }
                }
#if HAVE_GCRYPT_H
                else if ((se->security_level == SECURITY_LEVEL_SIGN)
                                && (packet_was_encrypted == 0)
                                && (packet_was_signed == 0))
                {
                        if (printed_ignore_warning == 0)
                        {
                                INFO ("network plugin: Unsigned packet or "
                                                "part has been ignored.");
                                printed_ignore_warning = 1;
                        }
                        buffer = ((char *) buffer) + pkg_length;
                        continue;
                }
#endif /* HAVE_GCRYPT_H */
                else if (pkg_type == TYPE_VALUES)
                {
                        status = parse_part_values (&buffer, &buffer_len,
                                        &vl.values, &vl.values_len);

                        if (status != 0)
                                break;

                        if ((vl.time > 0)
                                        && (strlen (vl.host) > 0)
                                        && (strlen (vl.plugin) > 0)
                                        && (strlen (vl.type) > 0)
                                        && (cache_check (&vl) == 0))
                        {
                                plugin_dispatch_values (&vl);
                        }
                        else
                        {
                                DEBUG ("network plugin: parse_packet:"
                                                " NOT dispatching values");
                        }

                        sfree (vl.values);
                }
                else if (pkg_type == TYPE_TIME)
                {
                        uint64_t tmp = 0;
                        status = parse_part_number (&buffer, &buffer_len,
                                        &tmp);
                        if (status == 0)
                        {
                                vl.time = (time_t) tmp;
                                n.time = (time_t) tmp;
                        }
                }
                else if (pkg_type == TYPE_INTERVAL)
                {
                        uint64_t tmp = 0;
                        status = parse_part_number (&buffer, &buffer_len,
                                        &tmp);
                        if (status == 0)
                                vl.interval = (int) tmp;
                }
                else if (pkg_type == TYPE_HOST)
                {
                        status = parse_part_string (&buffer, &buffer_len,
                                        vl.host, sizeof (vl.host));
                        if (status == 0)
                                sstrncpy (n.host, vl.host, sizeof (n.host));
                }
                else if (pkg_type == TYPE_PLUGIN)
                {
                        status = parse_part_string (&buffer, &buffer_len,
                                        vl.plugin, sizeof (vl.plugin));
                        if (status == 0)
                                sstrncpy (n.plugin, vl.plugin,
                                                sizeof (n.plugin));
                }
                else if (pkg_type == TYPE_PLUGIN_INSTANCE)
                {
                        status = parse_part_string (&buffer, &buffer_len,
                                        vl.plugin_instance,
                                        sizeof (vl.plugin_instance));
                        if (status == 0)
                                sstrncpy (n.plugin_instance,
                                                vl.plugin_instance,
                                                sizeof (n.plugin_instance));
                }
                else if (pkg_type == TYPE_TYPE)
                {
                        status = parse_part_string (&buffer, &buffer_len,
                                        vl.type, sizeof (vl.type));
                        if (status == 0)
                                sstrncpy (n.type, vl.type, sizeof (n.type));
                }
                else if (pkg_type == TYPE_TYPE_INSTANCE)
                {
                        status = parse_part_string (&buffer, &buffer_len,
                                        vl.type_instance,
                                        sizeof (vl.type_instance));
                        if (status == 0)
                                sstrncpy (n.type_instance, vl.type_instance,
                                                sizeof (n.type_instance));
                }
                else if (pkg_type == TYPE_MESSAGE)
                {
                        status = parse_part_string (&buffer, &buffer_len,
                                        n.message, sizeof (n.message));

                        if (status != 0)
                        {
                                /* do nothing */
                        }
                        else if ((n.severity != NOTIF_FAILURE)
                                        && (n.severity != NOTIF_WARNING)
                                        && (n.severity != NOTIF_OKAY))
                        {
                                INFO ("network plugin: "
                                                "Ignoring notification with "
                                                "unknown severity %i.",
                                                n.severity);
                        }
                        else if (n.time <= 0)
                        {
                                INFO ("network plugin: "
                                                "Ignoring notification with "
                                                "time == 0.");
                        }
                        else if (strlen (n.message) <= 0)
                        {
                                INFO ("network plugin: "
                                                "Ignoring notification with "
                                                "an empty message.");
                        }
                        else
                        {
                                plugin_dispatch_notification (&n);
                        }
                }
                else if (pkg_type == TYPE_SEVERITY)
                {
                        uint64_t tmp = 0;
                        status = parse_part_number (&buffer, &buffer_len,
                                        &tmp);
                        if (status == 0)
                                n.severity = (int) tmp;
                }
                else
                {
                        DEBUG ("network plugin: parse_packet: Unknown part"
                                        " type: 0x%04hx", pkg_type);
                        buffer = ((char *) buffer) + pkg_length;
                }
        } /* while (buffer_len > sizeof (part_header_t)) */

        return (status);
} /* }}} int parse_packet */

static void free_sockent (sockent_t *se) /* {{{ */
{
        sockent_t *next;
        while (se != NULL)
        {
                next = se->next;

#if HAVE_GCRYPT_H
                if (se->cypher != NULL)
                {
                        gcry_cipher_close (se->cypher);
                        se->cypher = NULL;
                }
                free (se->shared_secret);
#endif /* HAVE_GCRYPT_H */

                free (se->addr);
                free (se);

                se = next;
        }
} /* }}} void free_sockent */

/*
 * int network_set_ttl
 *
 * Set the `IP_MULTICAST_TTL', `IP_TTL', `IPV6_MULTICAST_HOPS' or
 * `IPV6_UNICAST_HOPS', depending on which option is applicable.
 *
 * The `struct addrinfo' is used to destinguish between unicast and multicast
 * sockets.
 */
static int network_set_ttl (const sockent_t *se, const struct addrinfo *ai)
{
        DEBUG ("network plugin: network_set_ttl: network_config_ttl = %i;",
                        network_config_ttl);

        if ((network_config_ttl < 1) || (network_config_ttl > 255))
                return (-1);

        if (ai->ai_family == AF_INET)
        {
                struct sockaddr_in *addr = (struct sockaddr_in *) ai->ai_addr;
                int optname;

                if (IN_MULTICAST (ntohl (addr->sin_addr.s_addr)))
                        optname = IP_MULTICAST_TTL;
                else
                        optname = IP_TTL;

                if (setsockopt (se->fd, IPPROTO_IP, optname,
                                        &network_config_ttl,
                                        sizeof (network_config_ttl)) == -1)
                {
                        char errbuf[1024];
                        ERROR ("setsockopt: %s",
                                        sstrerror (errno, errbuf, sizeof (errbuf)));
                        return (-1);
                }
        }
        else if (ai->ai_family == AF_INET6)
        {
                /* Useful example: http://gsyc.escet.urjc.es/~eva/IPv6-web/examples/mcast.html */
                struct sockaddr_in6 *addr = (struct sockaddr_in6 *) ai->ai_addr;
                int optname;

                if (IN6_IS_ADDR_MULTICAST (&addr->sin6_addr))
                        optname = IPV6_MULTICAST_HOPS;
                else
                        optname = IPV6_UNICAST_HOPS;

                if (setsockopt (se->fd, IPPROTO_IPV6, optname,
                                        &network_config_ttl,
                                        sizeof (network_config_ttl)) == -1)
                {
                        char errbuf[1024];
                        ERROR ("setsockopt: %s",
                                        sstrerror (errno, errbuf,
                                                sizeof (errbuf)));
                        return (-1);
                }
        }

        return (0);
} /* int network_set_ttl */

#if HAVE_GCRYPT_H
static int network_set_encryption (sockent_t *se, /* {{{ */
                const char *shared_secret)
{
  char hash[32];
  gcry_error_t err;

  se->shared_secret = sstrdup (shared_secret);

  /*
   * We use CBC *without* an initialization vector: The cipher is reset after
   * each packet and we would have to re-set the IV each time. The first
   * encrypted block will contain the SHA-224 checksum anyway, so this should
   * be quite unpredictable. Also, there's a 2 byte field in the header that's
   * being filled with random numbers. So we only use CBC so the blocks
   * *within* one packet are chained.
   */
  err = gcry_cipher_open (&se->cypher,
      GCRY_CIPHER_AES256, GCRY_CIPHER_MODE_CBC, /* flags = */ 0);
  if (err != 0)
  {
    ERROR ("network plugin: gcry_cipher_open returned: %s",
        gcry_strerror (err));
    return (-1);
  }

  assert (se->shared_secret != NULL);
  gcry_md_hash_buffer (GCRY_MD_SHA256, hash,
      se->shared_secret, strlen (se->shared_secret));

  err = gcry_cipher_setkey (se->cypher, hash, sizeof (hash));
  if (err != 0)
  {
    DEBUG ("network plugin: gcry_cipher_setkey returned: %s",
        gcry_strerror (err));
    gcry_cipher_close (se->cypher);
    se->cypher = NULL;
    return (-1);
  }

  return (0);
} /* }}} int network_set_encryption */
#endif /* HAVE_GCRYPT_H */

static int network_bind_socket (const sockent_t *se, const struct addrinfo *ai)
{
        int loop = 0;
        int yes  = 1;

        /* allow multiple sockets to use the same PORT number */
        if (setsockopt(se->fd, SOL_SOCKET, SO_REUSEADDR,
                                &yes, sizeof(yes)) == -1) {
                char errbuf[1024];
                ERROR ("setsockopt: %s", 
                                sstrerror (errno, errbuf, sizeof (errbuf)));
                return (-1);
        }

        DEBUG ("fd = %i; calling `bind'", se->fd);

        if (bind (se->fd, ai->ai_addr, ai->ai_addrlen) == -1)
        {
                char errbuf[1024];
                ERROR ("bind: %s",
                                sstrerror (errno, errbuf, sizeof (errbuf)));
                return (-1);
        }

        if (ai->ai_family == AF_INET)
        {
                struct sockaddr_in *addr = (struct sockaddr_in *) ai->ai_addr;
                if (IN_MULTICAST (ntohl (addr->sin_addr.s_addr)))
                {
                        struct ip_mreq mreq;

                        DEBUG ("fd = %i; IPv4 multicast address found", se->fd);

                        mreq.imr_multiaddr.s_addr = addr->sin_addr.s_addr;
                        mreq.imr_interface.s_addr = htonl (INADDR_ANY);

                        if (setsockopt (se->fd, IPPROTO_IP, IP_MULTICAST_LOOP,
                                                &loop, sizeof (loop)) == -1)
                        {
                                char errbuf[1024];
                                ERROR ("setsockopt: %s",
                                                sstrerror (errno, errbuf,
                                                        sizeof (errbuf)));
                                return (-1);
                        }

                        if (setsockopt (se->fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                                                &mreq, sizeof (mreq)) == -1)
                        {
                                char errbuf[1024];
                                ERROR ("setsockopt: %s",
                                                sstrerror (errno, errbuf,
                                                        sizeof (errbuf)));
                                return (-1);
                        }
                }
        }
        else if (ai->ai_family == AF_INET6)
        {
                /* Useful example: http://gsyc.escet.urjc.es/~eva/IPv6-web/examples/mcast.html */
                struct sockaddr_in6 *addr = (struct sockaddr_in6 *) ai->ai_addr;
                if (IN6_IS_ADDR_MULTICAST (&addr->sin6_addr))
                {
                        struct ipv6_mreq mreq;

                        DEBUG ("fd = %i; IPv6 multicast address found", se->fd);

                        memcpy (&mreq.ipv6mr_multiaddr,
                                        &addr->sin6_addr,
                                        sizeof (addr->sin6_addr));

                        /* http://developer.apple.com/documentation/Darwin/Reference/ManPages/man4/ip6.4.html
                         * ipv6mr_interface may be set to zeroes to
                         * choose the default multicast interface or to
                         * the index of a particular multicast-capable
                         * interface if the host is multihomed.
                         * Membership is associ-associated with a
                         * single interface; programs running on
                         * multihomed hosts may need to join the same
                         * group on more than one interface.*/
                        mreq.ipv6mr_interface = 0;

                        if (setsockopt (se->fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP,
                                                &loop, sizeof (loop)) == -1)
                        {
                                char errbuf[1024];
                                ERROR ("setsockopt: %s",
                                                sstrerror (errno, errbuf,
                                                        sizeof (errbuf)));
                                return (-1);
                        }

                        if (setsockopt (se->fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP,
                                                &mreq, sizeof (mreq)) == -1)
                        {
                                char errbuf[1024];
                                ERROR ("setsockopt: %s",
                                                sstrerror (errno, errbuf,
                                                        sizeof (errbuf)));
                                return (-1);
                        }
                }
        }

        return (0);
} /* int network_bind_socket */

#define CREATE_SOCKET_FLAGS_LISTEN    0x0001
static sockent_t *network_create_socket (const char *node, /* {{{ */
                const char *service,
                const char *shared_secret,
                int security_level,
                int flags)
{
        struct addrinfo  ai_hints;
        struct addrinfo *ai_list, *ai_ptr;
        int              ai_return;

        sockent_t *se_head = NULL;
        sockent_t *se_tail = NULL;

        DEBUG ("node = %s, service = %s", node, service);

        memset (&ai_hints, '\0', sizeof (ai_hints));
        ai_hints.ai_flags    = 0;
#ifdef AI_PASSIVE
        ai_hints.ai_flags |= AI_PASSIVE;
#endif
#ifdef AI_ADDRCONFIG
        ai_hints.ai_flags |= AI_ADDRCONFIG;
#endif
        ai_hints.ai_family   = AF_UNSPEC;
        ai_hints.ai_socktype = SOCK_DGRAM;
        ai_hints.ai_protocol = IPPROTO_UDP;

        ai_return = getaddrinfo (node, service, &ai_hints, &ai_list);
        if (ai_return != 0)
        {
                char errbuf[1024];
                ERROR ("getaddrinfo (%s, %s): %s",
                                (node == NULL) ? "(null)" : node,
                                (service == NULL) ? "(null)" : service,
                                (ai_return == EAI_SYSTEM)
                                ? sstrerror (errno, errbuf, sizeof (errbuf))
                                : gai_strerror (ai_return));
                return (NULL);
        }

        for (ai_ptr = ai_list; ai_ptr != NULL; ai_ptr = ai_ptr->ai_next)
        {
                sockent_t *se;
                int status;

                if ((se = (sockent_t *) malloc (sizeof (sockent_t))) == NULL)
                {
                        char errbuf[1024];
                        ERROR ("malloc: %s",
                                        sstrerror (errno, errbuf,
                                                sizeof (errbuf)));
                        continue;
                }

                if ((se->addr = (struct sockaddr_storage *) malloc (sizeof (struct sockaddr_storage))) == NULL)
                {
                        char errbuf[1024];
                        ERROR ("malloc: %s",
                                        sstrerror (errno, errbuf,
                                                sizeof (errbuf)));
                        free (se);
                        continue;
                }

                assert (sizeof (struct sockaddr_storage) >= ai_ptr->ai_addrlen);
                memset (se->addr, '\0', sizeof (struct sockaddr_storage));
                memcpy (se->addr, ai_ptr->ai_addr, ai_ptr->ai_addrlen);
                se->addrlen = ai_ptr->ai_addrlen;

                se->fd   = socket (ai_ptr->ai_family,
                                ai_ptr->ai_socktype,
                                ai_ptr->ai_protocol);
                se->next = NULL;

                if (se->fd == -1)
                {
                        char errbuf[1024];
                        ERROR ("socket: %s",
                                        sstrerror (errno, errbuf,
                                                sizeof (errbuf)));
                        free (se->addr);
                        free (se);
                        continue;
                }

                if ((flags & CREATE_SOCKET_FLAGS_LISTEN) != 0)
                {
                        status = network_bind_socket (se, ai_ptr);
                        if (status != 0)
                        {
                                close (se->fd);
                                free (se->addr);
                                free (se);
                                continue;
                        }
                }
                else /* sending socket */
                {
                        network_set_ttl (se, ai_ptr);
                }

#if HAVE_GCRYPT_H
                se->security_level = security_level;
                se->shared_secret = NULL;
                se->cypher = NULL;
                if (shared_secret != NULL)
                {
                        status = network_set_encryption (se, shared_secret);
                        if ((status != 0) && (security_level <= SECURITY_LEVEL_SIGN))
                        {
                                WARNING ("network plugin: Starting cryptograp"
                                                "hic subsystem failed. Since "
                                                "security level `Sign' or "
                                                "`None' is configured I will "
                                                "continue.");
                        }
                        else if (status != 0)
                        {
                                ERROR ("network plugin: Starting cryptograp"
                                                "hic subsystem failed. "
                                                "Because the security level "
                                                "is set to `Encrypt' I will "
                                                "not continue!");
                                close (se->fd);
                                free (se->addr);
                                free (se);
                                continue;
                        }
                } /* if (shared_secret != NULL) */
#else
                /* Make compiler happy */
                security_level = 0;
                shared_secret = NULL;
#endif /* HAVE_GCRYPT_H */

                if (se_tail == NULL)
                {
                        se_head = se;
                        se_tail = se;
                }
                else
                {
                        se_tail->next = se;
                        se_tail = se;
                }

                /* We don't open more than one write-socket per node/service pair.. */
                if ((flags & CREATE_SOCKET_FLAGS_LISTEN) == 0)
                        break;
        }

        freeaddrinfo (ai_list);

        return (se_head);
} /* }}} sockent_t *network_create_socket */

static sockent_t *network_create_default_socket (int flags) /* {{{ */
{
        sockent_t *se_ptr  = NULL;
        sockent_t *se_head = NULL;
        sockent_t *se_tail = NULL;

        se_ptr = network_create_socket (NET_DEFAULT_V6_ADDR, NET_DEFAULT_PORT,
                        /* shared secret = */ NULL, SECURITY_LEVEL_NONE,
                        flags);

        /* Don't send to the same machine in IPv6 and IPv4 if both are available. */
        if (((flags & CREATE_SOCKET_FLAGS_LISTEN) == 0) && (se_ptr != NULL))
                return (se_ptr);

        if (se_ptr != NULL)
        {
                se_head = se_ptr;
                se_tail = se_ptr;
                while (se_tail->next != NULL)
                        se_tail = se_tail->next;
        }

        se_ptr = network_create_socket (NET_DEFAULT_V4_ADDR, NET_DEFAULT_PORT,
                        /* shared secret = */ NULL, SECURITY_LEVEL_NONE,
                        flags);

        if (se_tail == NULL)
                return (se_ptr);

        se_tail->next = se_ptr;
        return (se_head);
} /* }}} sockent_t *network_create_default_socket */

static int network_add_listen_socket (const char *node, /* {{{ */
    const char *service, const char *shared_secret, int security_level)
{
        sockent_t *se;
        sockent_t *se_ptr;
        int se_num = 0;

        int flags;

        flags = CREATE_SOCKET_FLAGS_LISTEN;

        if (service == NULL)
                service = NET_DEFAULT_PORT;

        if (node == NULL)
                se = network_create_default_socket (flags);
        else
                se = network_create_socket (node, service,
                    shared_secret, security_level, flags);

        if (se == NULL)
                return (-1);

        for (se_ptr = se; se_ptr != NULL; se_ptr = se_ptr->next)
                se_num++;

        listen_sockets_pollfd = realloc (listen_sockets_pollfd,
                        (listen_sockets_num + se_num)
                        * sizeof (struct pollfd));

        for (se_ptr = se; se_ptr != NULL; se_ptr = se_ptr->next)
        {
                listen_sockets_pollfd[listen_sockets_num].fd = se_ptr->fd;
                listen_sockets_pollfd[listen_sockets_num].events = POLLIN | POLLPRI;
                listen_sockets_pollfd[listen_sockets_num].revents = 0;
                listen_sockets_num++;
        } /* for (se) */

        se_ptr = listen_sockets;
        while ((se_ptr != NULL) && (se_ptr->next != NULL))
                se_ptr = se_ptr->next;

        if (se_ptr == NULL)
                listen_sockets = se;
        else
                se_ptr->next = se;

        return (0);
} /* }}} int network_add_listen_socket */

static int network_add_sending_socket (const char *node, /* {{{ */
    const char *service, const char *shared_secret, int security_level)
{
        sockent_t *se;
        sockent_t *se_ptr;

        if (service == NULL)
                service = NET_DEFAULT_PORT;

        if (node == NULL)
                se = network_create_default_socket (/* flags = */ 0);
        else
                se = network_create_socket (node, service,
                                shared_secret, security_level,
                                /* flags = */ 0);

        if (se == NULL)
                return (-1);

        if (sending_sockets == NULL)
        {
                sending_sockets = se;
                return (0);
        }

        for (se_ptr = sending_sockets; se_ptr->next != NULL; se_ptr = se_ptr->next)
                /* seek end */;

        se_ptr->next = se;
        return (0);
} /* }}} int network_add_sending_socket */

static void *dispatch_thread (void __attribute__((unused)) *arg)
{
  while (42)
  {
    receive_list_entry_t *ent;

    /* Lock and wait for more data to come in */
    pthread_mutex_lock (&receive_list_lock);
    while ((listen_loop == 0)
        && (receive_list_head == NULL))
      pthread_cond_wait (&receive_list_cond, &receive_list_lock);

    /* Remove the head entry and unlock */
    ent = receive_list_head;
    if (ent != NULL)
      receive_list_head = ent->next;
    pthread_mutex_unlock (&receive_list_lock);

    /* Check whether we are supposed to exit. We do NOT check `listen_loop'
     * because we dispatch all missing packets before shutting down. */
    if (ent == NULL)
      break;

    parse_packet (ent);

    sfree (ent);
  } /* while (42) */

  return (NULL);
} /* void *dispatch_thread */

static int network_receive (void)
{
        char buffer[BUFF_SIZE];
        int  buffer_len;

        int i;
        int status;

        receive_list_entry_t *private_list_head;
        receive_list_entry_t *private_list_tail;

        if (listen_sockets_num == 0)
                network_add_listen_socket (/* node = */ NULL,
                                /* service = */ NULL,
                                /* shared secret = */ NULL,
                                /* encryption = */ 0);

        if (listen_sockets_num == 0)
        {
                ERROR ("network: Failed to open a listening socket.");
                return (-1);
        }

        private_list_head = NULL;
        private_list_tail = NULL;

        while (listen_loop == 0)
        {
                status = poll (listen_sockets_pollfd, listen_sockets_num, -1);

                if (status <= 0)
                {
                        char errbuf[1024];
                        if (errno == EINTR)
                                continue;
                        ERROR ("poll failed: %s",
                                        sstrerror (errno, errbuf, sizeof (errbuf)));
                        return (-1);
                }

                for (i = 0; (i < listen_sockets_num) && (status > 0); i++)
                {
                        receive_list_entry_t *ent;

                        if ((listen_sockets_pollfd[i].revents
                                                & (POLLIN | POLLPRI)) == 0)
                                continue;
                        status--;

                        buffer_len = recv (listen_sockets_pollfd[i].fd,
                                        buffer, sizeof (buffer),
                                        0 /* no flags */);
                        if (buffer_len < 0)
                        {
                                char errbuf[1024];
                                ERROR ("recv failed: %s",
                                                sstrerror (errno, errbuf,
                                                        sizeof (errbuf)));
                                return (-1);
                        }

                        /* TODO: Possible performance enhancement: Do not free
                         * these entries in the dispatch thread but put them in
                         * another list, so we don't have to allocate more and
                         * more of these structures. */
                        ent = malloc (sizeof (receive_list_entry_t));
                        if (ent == NULL)
                        {
                                ERROR ("network plugin: malloc failed.");
                                return (-1);
                        }
                        memset (ent, 0, sizeof (receive_list_entry_t));
                        ent->fd = listen_sockets_pollfd[i].fd;
                        ent->next = NULL;

                        /* Hopefully this be optimized out by the compiler. It
                         * might help prevent stupid bugs in the future though.
                         */
                        assert (sizeof (ent->data) == sizeof (buffer));

                        memcpy (ent->data, buffer, buffer_len);
                        ent->data_len = buffer_len;

                        if (private_list_head == NULL)
                                private_list_head = ent;
                        else
                                private_list_tail->next = ent;
                        private_list_tail = ent;

                        /* Do not block here. Blocking here has led to
                         * insufficient performance in the past. */
                        if (pthread_mutex_trylock (&receive_list_lock) == 0)
                        {
                                if (receive_list_head == NULL)
                                        receive_list_head = private_list_head;
                                else
                                        receive_list_tail->next = private_list_head;
                                receive_list_tail = private_list_tail;

                                private_list_head = NULL;
                                private_list_tail = NULL;

                                pthread_cond_signal (&receive_list_cond);
                                pthread_mutex_unlock (&receive_list_lock);
                        }
                } /* for (listen_sockets_pollfd) */
        } /* while (listen_loop == 0) */

        /* Make sure everything is dispatched before exiting. */
        if (private_list_head != NULL)
        {
                pthread_mutex_lock (&receive_list_lock);

                if (receive_list_head == NULL)
                        receive_list_head = private_list_head;
                else
                        receive_list_tail->next = private_list_head;
                receive_list_tail = private_list_tail;

                private_list_head = NULL;
                private_list_tail = NULL;

                pthread_cond_signal (&receive_list_cond);
                pthread_mutex_unlock (&receive_list_lock);
        }

        return (0);
} /* int network_receive */

static void *receive_thread (void __attribute__((unused)) *arg)
{
        return (network_receive () ? (void *) 1 : (void *) 0);
} /* void *receive_thread */

static void network_init_buffer (void)
{
        memset (send_buffer, 0, sizeof (send_buffer));
        send_buffer_ptr = send_buffer;
        send_buffer_fill = 0;

        memset (&send_buffer_vl, 0, sizeof (send_buffer_vl));
} /* int network_init_buffer */

static void networt_send_buffer_plain (const sockent_t *se, /* {{{ */
                const char *buffer, size_t buffer_size)
{
        int status;

        while (42)
        {
                status = sendto (se->fd, buffer, buffer_size, 0 /* no flags */,
                                (struct sockaddr *) se->addr, se->addrlen);
                if (status < 0)
                {
                        char errbuf[1024];
                        if (errno == EINTR)
                                continue;
                        ERROR ("network plugin: sendto failed: %s",
                                        sstrerror (errno, errbuf,
                                                sizeof (errbuf)));
                        break;
                }

                break;
        } /* while (42) */
} /* }}} void networt_send_buffer_plain */

#if HAVE_GCRYPT_H
static void networt_send_buffer_signed (const sockent_t *se, /* {{{ */
                const char *in_buffer, size_t in_buffer_size)
{
        part_signature_sha256_t ps;
        char buffer[sizeof (ps) + in_buffer_size];

        gcry_md_hd_t hd;
        gcry_error_t err;
        unsigned char *hash;

        hd = NULL;
        err = gcry_md_open (&hd, GCRY_MD_SHA256, GCRY_MD_FLAG_HMAC);
        if (err != 0)
        {
                ERROR ("network plugin: Creating HMAC object failed: %s",
                                gcry_strerror (err));
                return;
        }

        err = gcry_md_setkey (hd, se->shared_secret,
                        strlen (se->shared_secret));
        if (err != 0)
        {
                ERROR ("network plugin: gcry_md_setkey failed: %s",
                                gcry_strerror (err));
                gcry_md_close (hd);
                return;
        }

        /* Initialize the `ps' structure. */
        memset (&ps, 0, sizeof (ps));
        ps.head.type = htons (TYPE_SIGN_SHA256);
        ps.head.length = htons ((uint16_t) sizeof (ps));

        /* Calculate the hash value. */
        gcry_md_write (hd, in_buffer, in_buffer_size);
        hash = gcry_md_read (hd, GCRY_MD_SHA256);
        if (hash == NULL)
        {
                ERROR ("network plugin: gcry_md_read failed.");
                gcry_md_close (hd);
                return;
        }

        /* Add the signature and fill the rest of the buffer. */
        memcpy (ps.hash, hash, sizeof (ps.hash));
        memcpy (buffer, &ps, sizeof (ps));
        memcpy (buffer + sizeof (ps), in_buffer, in_buffer_size);

        gcry_md_close (hd);
        hd = NULL;

        networt_send_buffer_plain (se, buffer, sizeof (buffer));
} /* }}} void networt_send_buffer_signed */

static void networt_send_buffer_encrypted (const sockent_t *se, /* {{{ */
                const char *in_buffer, size_t in_buffer_size)
{
  part_encryption_aes256_t pea;
  char buffer[sizeof (pea) + in_buffer_size];
  size_t buffer_size;
  size_t buffer_offset;
  size_t padding_size;
  gcry_error_t err;

  /* Round to the next multiple of 16, because AES has a block size of 128 bit.
   * the first four bytes of `pea' are not encrypted and must be subtracted. */
  buffer_size = sizeof (pea.orig_length) + sizeof (pea.hash) + in_buffer_size;
  padding_size = buffer_size;
  buffer_size = (buffer_size + 15) / 16;
  buffer_size = buffer_size * 16;
  padding_size = buffer_size - padding_size;
  assert (padding_size <= sizeof (pea.padding));
  buffer_size += sizeof (pea.head);

  DEBUG ("network plugin: networt_send_buffer_encrypted: "
      "buffer_size = %zu;", buffer_size);

  /* Initialize the header fields */
  memset (&pea, 0, sizeof (pea));
  pea.head.type = htons (TYPE_ENCR_AES256);
  pea.head.length = htons ((uint16_t) buffer_size);
  pea.orig_length = htons ((uint16_t) in_buffer_size);

  /* Fill the extra field with random values. Some entropy in the encrypted
   * data is usually not a bad thing, I hope. */
  if (padding_size > 0)
    gcry_randomize (&pea.padding, padding_size, GCRY_STRONG_RANDOM);

  /* Create hash of the payload */
  gcry_md_hash_buffer (GCRY_MD_SHA1, pea.hash, in_buffer, in_buffer_size);

  /* Initialize the buffer */
  buffer_offset = 0;
  memset (buffer, 0, sizeof (buffer));

  memcpy (buffer + buffer_offset, &pea.head, sizeof (pea.head));
  buffer_offset += sizeof (pea.head);

  memcpy (buffer + buffer_offset, &pea.orig_length, sizeof (pea.orig_length));
  buffer_offset += sizeof (pea.orig_length);

  if (padding_size > 0)
  {
    memcpy (buffer + buffer_offset, &pea.padding, padding_size);
    buffer_offset += padding_size;
  }

  memcpy (buffer + buffer_offset, &pea.hash, sizeof (pea.hash));
  buffer_offset += sizeof (pea.hash);

  memcpy (buffer + buffer_offset, in_buffer, in_buffer_size);
  buffer_offset += in_buffer_size;

  assert (buffer_offset == buffer_size);

  /* Encrypt the buffer in-place */
  err = gcry_cipher_encrypt (se->cypher,
      buffer + sizeof (pea.head), buffer_size - sizeof (pea.head),
      /* in = */ NULL, /* in len = */ 0);
  gcry_cipher_reset (se->cypher);
  if (err != 0)
  {
    ERROR ("network plugin: gcry_cipher_encrypt returned: %s",
        gcry_strerror (err));
    return;
  }

  /* Send it out without further modifications */
  networt_send_buffer_plain (se, buffer, buffer_size);
} /* }}} void networt_send_buffer_encrypted */
#endif /* HAVE_GCRYPT_H */

static void network_send_buffer (char *buffer, size_t buffer_len) /* {{{ */
{
  sockent_t *se;

  DEBUG ("network plugin: network_send_buffer: buffer_len = %zu", buffer_len);

  for (se = sending_sockets; se != NULL; se = se->next)
  {
#if HAVE_GCRYPT_H
    if (se->security_level == SECURITY_LEVEL_ENCRYPT)
      networt_send_buffer_encrypted (se, buffer, buffer_len);
    else if (se->security_level == SECURITY_LEVEL_SIGN)
      networt_send_buffer_signed (se, buffer, buffer_len);
    else /* if (se->security_level == SECURITY_LEVEL_NONE) */
#endif /* HAVE_GCRYPT_H */
      networt_send_buffer_plain (se, buffer, buffer_len);
  } /* for (sending_sockets) */
} /* }}} void network_send_buffer */

static int add_to_buffer (char *buffer, int buffer_size, /* {{{ */
                value_list_t *vl_def,
                const data_set_t *ds, const value_list_t *vl)
{
        char *buffer_orig = buffer;

        if (strcmp (vl_def->host, vl->host) != 0)
        {
                if (write_part_string (&buffer, &buffer_size, TYPE_HOST,
                                        vl->host, strlen (vl->host)) != 0)
                        return (-1);
                sstrncpy (vl_def->host, vl->host, sizeof (vl_def->host));
        }

        if (vl_def->time != vl->time)
        {
                if (write_part_number (&buffer, &buffer_size, TYPE_TIME,
                                        (uint64_t) vl->time))
                        return (-1);
                vl_def->time = vl->time;
        }

        if (vl_def->interval != vl->interval)
        {
                if (write_part_number (&buffer, &buffer_size, TYPE_INTERVAL,
                                        (uint64_t) vl->interval))
                        return (-1);
                vl_def->interval = vl->interval;
        }

        if (strcmp (vl_def->plugin, vl->plugin) != 0)
        {
                if (write_part_string (&buffer, &buffer_size, TYPE_PLUGIN,
                                        vl->plugin, strlen (vl->plugin)) != 0)
                        return (-1);
                sstrncpy (vl_def->plugin, vl->plugin, sizeof (vl_def->plugin));
        }

        if (strcmp (vl_def->plugin_instance, vl->plugin_instance) != 0)
        {
                if (write_part_string (&buffer, &buffer_size, TYPE_PLUGIN_INSTANCE,
                                        vl->plugin_instance,
                                        strlen (vl->plugin_instance)) != 0)
                        return (-1);
                sstrncpy (vl_def->plugin_instance, vl->plugin_instance, sizeof (vl_def->plugin_instance));
        }

        if (strcmp (vl_def->type, vl->type) != 0)
        {
                if (write_part_string (&buffer, &buffer_size, TYPE_TYPE,
                                        vl->type, strlen (vl->type)) != 0)
                        return (-1);
                sstrncpy (vl_def->type, ds->type, sizeof (vl_def->type));
        }

        if (strcmp (vl_def->type_instance, vl->type_instance) != 0)
        {
                if (write_part_string (&buffer, &buffer_size, TYPE_TYPE_INSTANCE,
                                        vl->type_instance,
                                        strlen (vl->type_instance)) != 0)
                        return (-1);
                sstrncpy (vl_def->type_instance, vl->type_instance, sizeof (vl_def->type_instance));
        }
        
        if (write_part_values (&buffer, &buffer_size, ds, vl) != 0)
                return (-1);

        return (buffer - buffer_orig);
} /* }}} int add_to_buffer */

static void flush_buffer (void)
{
        DEBUG ("network plugin: flush_buffer: send_buffer_fill = %i",
                        send_buffer_fill);

        network_send_buffer (send_buffer, (size_t) send_buffer_fill);
        network_init_buffer ();
}

static int network_write (const data_set_t *ds, const value_list_t *vl,
                user_data_t __attribute__((unused)) *user_data)
{
        int status;

        /* If the value is already in the cache, we have received it via the
         * network. We write it again if forwarding is activated. It's then in
         * the cache and should we receive it again we will ignore it. */
        status = cache_check (vl);
        if ((network_config_forward == 0)
                        && (status != 0))
                return (0);

        pthread_mutex_lock (&send_buffer_lock);

        status = add_to_buffer (send_buffer_ptr,
                        sizeof (send_buffer) - (send_buffer_fill + BUFF_SIG_SIZE),
                        &send_buffer_vl,
                        ds, vl);
        if (status >= 0)
        {
                /* status == bytes added to the buffer */
                send_buffer_fill += status;
                send_buffer_ptr  += status;
        }
        else
        {
                flush_buffer ();

                status = add_to_buffer (send_buffer_ptr,
                                sizeof (send_buffer) - (send_buffer_fill + BUFF_SIG_SIZE),
                                &send_buffer_vl,
                                ds, vl);

                if (status >= 0)
                {
                        send_buffer_fill += status;
                        send_buffer_ptr  += status;
                }
        }

        if (status < 0)
        {
                ERROR ("network plugin: Unable to append to the "
                                "buffer for some weird reason");
        }
        else if ((sizeof (send_buffer) - send_buffer_fill) < 15)
        {
                flush_buffer ();
        }

        pthread_mutex_unlock (&send_buffer_lock);

        return ((status < 0) ? -1 : 0);
} /* int network_write */

static int network_config_set_boolean (const oconfig_item_t *ci, /* {{{ */
    int *retval)
{
  if ((ci->values_num != 1)
      || ((ci->values[0].type != OCONFIG_TYPE_BOOLEAN)
        && (ci->values[0].type != OCONFIG_TYPE_STRING)))
  {
    ERROR ("network plugin: The `%s' config option needs "
        "exactly one boolean argument.", ci->key);
    return (-1);
  }

  if (ci->values[0].type == OCONFIG_TYPE_BOOLEAN)
  {
    if (ci->values[0].value.boolean)
      *retval = 1;
    else
      *retval = 0;
  }
  else
  {
    char *str = ci->values[0].value.string;

    if ((strcasecmp ("true", str) == 0)
        || (strcasecmp ("yes", str) == 0)
        || (strcasecmp ("on", str) == 0))
      *retval = 1;
    else if ((strcasecmp ("false", str) == 0)
        || (strcasecmp ("no", str) == 0)
        || (strcasecmp ("off", str) == 0))
      *retval = 0;
    else
    {
      ERROR ("network plugin: Cannot parse string value `%s' of the `%s' "
          "option as boolean value.",
          str, ci->key);
      return (-1);
    }
  }

  return (0);
} /* }}} int network_config_set_boolean */

static int network_config_set_ttl (const oconfig_item_t *ci) /* {{{ */
{
  int tmp;
  if ((ci->values_num != 1)
      || (ci->values[0].type != OCONFIG_TYPE_NUMBER))
  {
    WARNING ("network plugin: The `TimeToLive' config option needs exactly "
        "one numeric argument.");
    return (-1);
  }

  tmp = (int) ci->values[0].value.number;
  if ((tmp > 0) && (tmp <= 255))
    network_config_ttl = tmp;

  return (0);
} /* }}} int network_config_set_ttl */

#if HAVE_GCRYPT_H
static int network_config_set_security_level (oconfig_item_t *ci, /* {{{ */
    int *retval)
{
  char *str;
  if ((ci->values_num != 1)
      || (ci->values[0].type != OCONFIG_TYPE_STRING))
  {
    WARNING ("network plugin: The `SecurityLevel' config option needs exactly "
        "one string argument.");
    return (-1);
  }

  str = ci->values[0].value.string;
  if (strcasecmp ("Encrypt", str) == 0)
    *retval = SECURITY_LEVEL_ENCRYPT;
  else if (strcasecmp ("Sign", str) == 0)
    *retval = SECURITY_LEVEL_SIGN;
  else if (strcasecmp ("None", str) == 0)
    *retval = SECURITY_LEVEL_NONE;
  else
  {
    WARNING ("network plugin: Unknown security level: %s.", str);
    return (-1);
  }

  return (0);
} /* }}} int network_config_set_security_level */
#endif /* HAVE_GCRYPT_H */

static int network_config_listen_server (const oconfig_item_t *ci) /* {{{ */
{
  char *node;
  char *service;
  char *shared_secret = NULL;
  int security_level = SECURITY_LEVEL_NONE;
  int i;

  if ((ci->values_num < 1) || (ci->values_num > 2)
      || (ci->values[0].type != OCONFIG_TYPE_STRING)
      || ((ci->values_num > 1) && (ci->values[1].type != OCONFIG_TYPE_STRING)))
  {
    ERROR ("network plugin: The `%s' config option needs "
        "one or two string arguments.", ci->key);
    return (-1);
  }

  node = ci->values[0].value.string;
  if (ci->values_num >= 2)
    service = ci->values[1].value.string;
  else
    service = NULL;

  for (i = 0; i < ci->children_num; i++)
  {
    oconfig_item_t *child = ci->children + i;

#if HAVE_GCRYPT_H
    if (strcasecmp ("Secret", child->key) == 0)
    {
      if ((child->values_num == 1)
          && (child->values[0].type == OCONFIG_TYPE_STRING))
        shared_secret = child->values[0].value.string;
      else
        ERROR ("network plugin: The `Secret' option needs exactly one string "
            "argument.");
    }
    else if (strcasecmp ("SecurityLevel", child->key) == 0)
      network_config_set_security_level (child, &security_level);
    else
#endif /* HAVE_GCRYPT_H */
    {
      WARNING ("network plugin: Option `%s' is not allowed here.",
          child->key);
    }
  }

  if ((security_level > SECURITY_LEVEL_NONE) && (shared_secret == NULL))
  {
    ERROR ("network plugin: A security level higher than `none' was "
        "requested, but no shared key was given. Cowardly refusing to open "
        "this socket!");
    return (-1);
  }

  if (strcasecmp ("Listen", ci->key) == 0)
    network_add_listen_socket (node, service, shared_secret, security_level);
  else
    network_add_sending_socket (node, service, shared_secret, security_level);

  return (0);
} /* }}} int network_config_listen_server */

static int network_config_set_cache_flush (const oconfig_item_t *ci) /* {{{ */
{
  int tmp;
  if ((ci->values_num != 1)
      || (ci->values[0].type != OCONFIG_TYPE_NUMBER))
  {
    WARNING ("network plugin: The `CacheFlush' config option needs exactly "
        "one numeric argument.");
    return (-1);
  }

  tmp = (int) ci->values[0].value.number;
  if (tmp > 0)
    network_config_ttl = tmp;

  return (0);
} /* }}} int network_config_set_cache_flush */

static int network_config (oconfig_item_t *ci) /* {{{ */
{
  int i;

  for (i = 0; i < ci->children_num; i++)
  {
    oconfig_item_t *child = ci->children + i;

    if ((strcasecmp ("Listen", child->key) == 0)
        || (strcasecmp ("Server", child->key) == 0))
      network_config_listen_server (child);
    else if (strcasecmp ("TimeToLive", child->key) == 0)
      network_config_set_ttl (child);
    else if (strcasecmp ("Forward", child->key) == 0)
      network_config_set_boolean (child, &network_config_forward);
    else if (strcasecmp ("CacheFlush", child->key) == 0)
      network_config_set_cache_flush (child);
    else
    {
      WARNING ("network plugin: Option `%s' is not allowed here.",
          child->key);
    }
  }

  return (0);
} /* }}} int network_config */

static int network_notification (const notification_t *n,
                user_data_t __attribute__((unused)) *user_data)
{
  char  buffer[BUFF_SIZE];
  char *buffer_ptr = buffer;
  int   buffer_free = sizeof (buffer);
  int   status;

  memset (buffer, '\0', sizeof (buffer));


  status = write_part_number (&buffer_ptr, &buffer_free, TYPE_TIME,
      (uint64_t) n->time);
  if (status != 0)
    return (-1);

  status = write_part_number (&buffer_ptr, &buffer_free, TYPE_SEVERITY,
      (uint64_t) n->severity);
  if (status != 0)
    return (-1);

  if (strlen (n->host) > 0)
  {
    status = write_part_string (&buffer_ptr, &buffer_free, TYPE_HOST,
        n->host, strlen (n->host));
    if (status != 0)
      return (-1);
  }

  if (strlen (n->plugin) > 0)
  {
    status = write_part_string (&buffer_ptr, &buffer_free, TYPE_PLUGIN,
        n->plugin, strlen (n->plugin));
    if (status != 0)
      return (-1);
  }

  if (strlen (n->plugin_instance) > 0)
  {
    status = write_part_string (&buffer_ptr, &buffer_free,
        TYPE_PLUGIN_INSTANCE,
        n->plugin_instance, strlen (n->plugin_instance));
    if (status != 0)
      return (-1);
  }

  if (strlen (n->type) > 0)
  {
    status = write_part_string (&buffer_ptr, &buffer_free, TYPE_TYPE,
        n->type, strlen (n->type));
    if (status != 0)
      return (-1);
  }

  if (strlen (n->type_instance) > 0)
  {
    status = write_part_string (&buffer_ptr, &buffer_free, TYPE_TYPE_INSTANCE,
        n->type_instance, strlen (n->type_instance));
    if (status != 0)
      return (-1);
  }

  status = write_part_string (&buffer_ptr, &buffer_free, TYPE_MESSAGE,
      n->message, strlen (n->message));
  if (status != 0)
    return (-1);

  network_send_buffer (buffer, sizeof (buffer) - buffer_free);

  return (0);
} /* int network_notification */

static int network_shutdown (void)
{
        listen_loop++;

        /* Kill the listening thread */
        if (receive_thread_running != 0)
        {
                INFO ("network plugin: Stopping receive thread.");
                pthread_kill (receive_thread_id, SIGTERM);
                pthread_join (receive_thread_id, NULL /* no return value */);
                memset (&receive_thread_id, 0, sizeof (receive_thread_id));
                receive_thread_running = 0;
        }

        /* Shutdown the dispatching thread */
        if (dispatch_thread_running != 0)
        {
                INFO ("network plugin: Stopping dispatch thread.");
                pthread_mutex_lock (&receive_list_lock);
                pthread_cond_broadcast (&receive_list_cond);
                pthread_mutex_unlock (&receive_list_lock);
                pthread_join (dispatch_thread_id, /* ret = */ NULL);
                dispatch_thread_running = 0;
        }

        free_sockent (listen_sockets);

        if (send_buffer_fill > 0)
                flush_buffer ();

        if (cache_tree != NULL)
        {
                void *key;
                void *value;

                while (c_avl_pick (cache_tree, &key, &value) == 0)
                {
                        sfree (key);
                        sfree (value);
                }
                c_avl_destroy (cache_tree);
                cache_tree = NULL;
        }

        /* TODO: Close `sending_sockets' */

        plugin_unregister_config ("network");
        plugin_unregister_init ("network");
        plugin_unregister_write ("network");
        plugin_unregister_shutdown ("network");

        /* Let the init function do it's move again ;) */
        cache_flush_last = 0;

        return (0);
} /* int network_shutdown */

static int network_init (void)
{
        /* Check if we were already initialized. If so, just return - there's
         * nothing more to do (for now, that is). */
        if (cache_flush_last != 0)
                return (0);

        plugin_register_shutdown ("network", network_shutdown);

        network_init_buffer ();

        cache_tree = c_avl_create ((int (*) (const void *, const void *)) strcmp);
        cache_flush_last = time (NULL);

        /* setup socket(s) and so on */
        if (sending_sockets != NULL)
        {
                plugin_register_write ("network", network_write,
                                /* user_data = */ NULL);
                plugin_register_notification ("network", network_notification,
                                /* user_data = */ NULL);
        }

        /* If no threads need to be started, return here. */
        if ((listen_sockets_num == 0)
                        || ((dispatch_thread_running != 0)
                                && (receive_thread_running != 0)))
                return (0);

        if (dispatch_thread_running == 0)
        {
                int status;
                status = pthread_create (&dispatch_thread_id,
                                NULL /* no attributes */,
                                dispatch_thread,
                                NULL /* no argument */);
                if (status != 0)
                {
                        char errbuf[1024];
                        ERROR ("network: pthread_create failed: %s",
                                        sstrerror (errno, errbuf,
                                                sizeof (errbuf)));
                }
                else
                {
                        dispatch_thread_running = 1;
                }
        }

        if (receive_thread_running == 0)
        {
                int status;
                status = pthread_create (&receive_thread_id,
                                NULL /* no attributes */,
                                receive_thread,
                                NULL /* no argument */);
                if (status != 0)
                {
                        char errbuf[1024];
                        ERROR ("network: pthread_create failed: %s",
                                        sstrerror (errno, errbuf,
                                                sizeof (errbuf)));
                }
                else
                {
                        receive_thread_running = 1;
                }
        }

        return (0);
} /* int network_init */

/* 
 * The flush option of the network plugin cannot flush individual identifiers.
 * All the values are added to a buffer and sent when the buffer is full, the
 * requested value may or may not be in there, it's not worth finding out. We
 * just send the buffer if `flush'  is called - if the requested value was in
 * there, good. If not, well, then there is nothing to flush.. -octo
 */
static int network_flush (int timeout,
                const char __attribute__((unused)) *identifier,
                user_data_t __attribute__((unused)) *user_data)
{
        pthread_mutex_lock (&send_buffer_lock);

        if (((time (NULL) - cache_flush_last) >= timeout)
                        && (send_buffer_fill > 0))
        {
                flush_buffer ();
        }

        pthread_mutex_unlock (&send_buffer_lock);

        return (0);
} /* int network_flush */

void module_register (void)
{
        plugin_register_complex_config ("network", network_config);
        plugin_register_init   ("network", network_init);
        plugin_register_flush   ("network", network_flush,
                        /* user_data = */ NULL);
} /* void module_register */

/* vim: set fdm=marker : */