src/utils_avltree.[ch]: Rename all types and functions to use the prefix `c_avl_'.
[collectd.git] / src / network.c
index 914235a..a426214 100644 (file)
@@ -1,11 +1,10 @@
 /**
  * collectd - src/network.c
- * Copyright (C) 2006  Florian octo Forster
+ * Copyright (C) 2005-2007  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; either version 2 of the License, or (at your
- * option) any later version.
+ * 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
  *   Florian octo Forster <octo at verplant.org>
  **/
 
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <netdb.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-#include <syslog.h>
-#include <errno.h>
+#include "collectd.h"
+#include "plugin.h"
+#include "common.h"
+#include "configfile.h"
+#include "utils_avltree.h"
 
 #include "network.h"
-#include "common.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
+
+/* 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 */
+
+#define BUFF_SIZE 1024
 
 /*
- * From RFC2365:
- *
- * The IPv4 Organization Local Scope -- 239.192.0.0/14
- *
- * 239.192.0.0/14 is defined to be the IPv4 Organization Local Scope, and is
- * the space from which an organization should allocate sub-ranges when
- * defining scopes for private use.
- *
- * Port 25826 is not assigned as of 2005-09-12
+ * Private data types
  */
+typedef struct sockent
+{
+       int                      fd;
+       struct sockaddr_storage *addr;
+       socklen_t                addrlen;
+       struct sockent          *next;
+} sockent_t;
 
-#define IPV4_MCAST_GROUP "239.192.74.66"
-#define UDP_PORT 25826
+/*                      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;
 
-/* 1500 - 40 - 8  =  Ethernet packet - IPv6 header - UDP header */
-#define BUFF_SIZE 1452
+/*                      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;
 
-typedef struct socklist
+/*                      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
 {
-       int              fd;
-       struct socklist *next;
-} socklist_t;
+       part_header_t *head;
+       uint64_t *value;
+};
+typedef struct part_number_s part_number_t;
 
-static socklist_t *listen_socks_head = NULL;
+/*                      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;
 
-uint16_t get_port (void)
+/*
+ * Private variables
+ */
+static const char *config_keys[] =
 {
-       char *port_str;
-       int   port_int;
-       uint16_t ret;
+       "CacheFlush",
+       "Listen",
+       "Server",
+       "TimeToLive",
+       "Forward"
+};
+static int config_keys_num = STATIC_ARRAY_SIZE (config_keys);
 
-       port_str = cf_get_option ("Port", NULL);
-       port_int = 0;
+static int network_config_ttl = 0;
+static int network_config_forward = 0;
 
-       if (port_str != NULL)
-               port_int = atoi (port_str);
+static sockent_t *sending_sockets = NULL;
 
-       if (port_int == 0)
-               port_int = UDP_PORT;
+static struct pollfd *listen_sockets = NULL;
+static int listen_sockets_num = 0;
+static pthread_t listen_thread = 0;
+static int listen_loop = 0;
 
-       ret = htons (port_int);
-       return (ret);
-}
+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 char         send_buffer_type[DATA_MAX_NAME_LEN];
+static pthread_mutex_t send_buffer_lock = PTHREAD_MUTEX_INITIALIZER;
+
+static c_avl_tree_t      *cache_tree = NULL;
+static pthread_mutex_t  cache_lock = PTHREAD_MUTEX_INITIALIZER;
+static time_t           cache_flush_last;
+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 char *type, 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, 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);
+
+       DEBUG ("network plugin: cache_check: key = %s; time = %i; retval = %i",
+                       key, (int) vl->time, retval);
+
+       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)
+{
+       part_values_t pv;
+       int i;
+
+       i = 6 + (9 * vl->values_len);
+       if (*ret_buffer_len < i)
+               return (-1);
+       *ret_buffer_len -= i;
+
+       pv.head = (part_header_t *) *ret_buffer;
+       pv.num_values = (uint16_t *) (pv.head + 1);
+       pv.values_types = (uint8_t *) (pv.num_values + 1);
+       pv.values = (value_t *) (pv.values_types + vl->values_len);
+       *ret_buffer = (void *) (pv.values + vl->values_len);
+
+       pv.head->type = htons (TYPE_VALUES);
+       pv.head->length = htons (6 + (9 * vl->values_len));
+       *pv.num_values = htons ((uint16_t) vl->values_len);
+       
+       for (i = 0; i < vl->values_len; i++)
+       {
+               if (ds->ds[i].type == DS_TYPE_COUNTER)
+               {
+                       pv.values_types[i] = DS_TYPE_COUNTER;
+                       pv.values[i].counter = htonll (vl->values[i].counter);
+               }
+               else
+               {
+                       pv.values_types[i] = DS_TYPE_GAUGE;
+                       pv.values[i].gauge = vl->values[i].gauge;
+               }
+       } /* for (values) */
+
+       return (0);
+} /* int write_part_values */
+
+static int write_part_number (char **ret_buffer, int *ret_buffer_len,
+               int type, uint64_t value)
+{
+       part_number_t pn;
+
+       if (*ret_buffer_len < 12)
+               return (-1);
+
+       pn.head = (part_header_t *) *ret_buffer;
+       pn.value = (uint64_t *) (pn.head + 1);
+
+       pn.head->type = htons (type);
+       pn.head->length = htons (12);
+       *pn.value = htonll (value);
+
+       *ret_buffer = (char *) (pn.value + 1);
+       *ret_buffer_len -= 12;
+
+       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)
+{
+       part_string_t ps;
+       int len;
+
+       len = 4 + str_len + 1;
+       if (*ret_buffer_len < len)
+               return (-1);
+       *ret_buffer_len -= len;
+
+       ps.head = (part_header_t *) *ret_buffer;
+       ps.value = (char *) (ps.head + 1);
+
+       ps.head->type = htons ((uint16_t) type);
+       ps.head->length = htons ((uint16_t) str_len + 5);
+       if (str_len > 0)
+               memcpy (ps.value, str, str_len);
+       ps.value[str_len] = '\0';
+       *ret_buffer = (void *) (ps.value + (str_len + 1));
+
+       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;
+       part_values_t pv;
+       int   i;
+
+       uint16_t h_length;
+       uint16_t h_type;
+       uint16_t h_num;
+
+       if (buffer_len < (15))
+       {
+               DEBUG ("network plugin: packet is too short: buffer_len = %i",
+                               buffer_len);
+               return (-1);
+       }
+
+       pv.head = (part_header_t *) buffer;
+       h_length = ntohs (pv.head->length);
+       h_type = ntohs (pv.head->type);
+
+       assert (h_type == TYPE_VALUES);
+
+       pv.num_values = (uint16_t *) (pv.head + 1);
+       h_num = ntohs (*pv.num_values);
+
+       if (h_num != ((h_length - 6) / 9))
+       {
+               DEBUG ("`length' and `num of values' don't match");
+               return (-1);
+       }
+
+       pv.values_types = (uint8_t *) (pv.num_values + 1);
+       pv.values = (value_t *) (pv.values_types + h_num);
+
+       for (i = 0; i < h_num; i++)
+               if (pv.values_types[i] == DS_TYPE_COUNTER)
+                       pv.values[i].counter = ntohll (pv.values[i].counter);
+
+       *ret_buffer     = (void *) (pv.values + h_num);
+       *ret_buffer_len = buffer_len - h_length;
+       *ret_num_values = h_num;
+       *ret_values     = pv.values;
+
+       return (0);
+} /* int parse_part_values */
+
+static int parse_part_number (void **ret_buffer, int *ret_buffer_len,
+               uint64_t *value)
+{
+       part_number_t pn;
+       uint16_t len;
+
+       pn.head = (part_header_t *) *ret_buffer;
+       pn.value = (uint64_t *) (pn.head + 1);
+
+       len = ntohs (pn.head->length);
+       if (len != 12)
+               return (-1);
+       if (len > *ret_buffer_len)
+               return (-1);
+       *value = ntohll (*pn.value);
+
+       *ret_buffer = (void *) (pn.value + 1);
+       *ret_buffer_len -= len;
+
+       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;
+       part_string_t ps;
+
+       uint16_t h_length;
+       uint16_t h_type;
+
+       DEBUG ("network plugin: parse_part_string: ret_buffer = %p;"
+                       " ret_buffer_len = %i; output = %p; output_len = %i;",
+                       *ret_buffer, *ret_buffer_len,
+                       (void *) output, output_len);
+
+       ps.head = (part_header_t *) buffer;
+
+       h_length = ntohs (ps.head->length);
+       h_type = ntohs (ps.head->type);
+
+       DEBUG ("network plugin: parse_part_string: length = %hu; type = %hu;",
+                       h_length, h_type);
+
+       if (buffer_len < h_length)
+       {
+               DEBUG ("packet is too short");
+               return (-1);
+       }
+       assert ((h_type == TYPE_HOST)
+                       || (h_type == TYPE_PLUGIN)
+                       || (h_type == TYPE_PLUGIN_INSTANCE)
+                       || (h_type == TYPE_TYPE)
+                       || (h_type == TYPE_TYPE_INSTANCE));
+
+       ps.value = buffer + 4;
+       if (ps.value[h_length - 5] != '\0')
+       {
+               DEBUG ("String does not end with a nullbyte");
+               return (-1);
+       }
+
+       if (output_len < (h_length - 4))
+       {
+               DEBUG ("output buffer is too small");
+               return (-1);
+       }
+       strcpy (output, ps.value);
+
+       DEBUG ("network plugin: parse_part_string: output = %s", output);
+
+       *ret_buffer = (void *) (buffer + h_length);
+       *ret_buffer_len = buffer_len - h_length;
+
+       return (0);
+} /* int parse_part_string */
+
+static int parse_packet (void *buffer, int buffer_len)
+{
+       part_header_t *header;
+       int status;
+
+       value_list_t vl = VALUE_LIST_INIT;
+       char type[DATA_MAX_NAME_LEN];
+
+       DEBUG ("network plugin: parse_packet: buffer = %p; buffer_len = %i;",
+                       buffer, buffer_len);
+
+       memset (&vl, '\0', sizeof (vl));
+       memset (&type, '\0', sizeof (type));
+       status = 0;
+
+       while ((status == 0) && (buffer_len > sizeof (part_header_t)))
+       {
+               header = (part_header_t *) buffer;
+
+               if (ntohs (header->length) > buffer_len)
+                       break;
+               /* Assure that this loop terminates eventually */
+               if (ntohs (header->length) < 4)
+                       break;
+
+               if (ntohs (header->type) == TYPE_VALUES)
+               {
+                       status = parse_part_values (&buffer, &buffer_len,
+                                       &vl.values, &vl.values_len);
+
+                       if (status != 0)
+                       {
+                               DEBUG ("parse_part_values failed.");
+                               break;
+                       }
+
+                       if ((vl.time > 0)
+                                       && (strlen (vl.host) > 0)
+                                       && (strlen (vl.plugin) > 0)
+                                       && (strlen (type) > 0)
+                                       && (cache_check (type, &vl) == 0))
+                       {
+                               DEBUG ("network plugin: parse_packet:"
+                                               " dispatching values");
+                               plugin_dispatch_values (type, &vl);
+                       }
+                       else
+                       {
+                               DEBUG ("network plugin: parse_packet:"
+                                               " NOT dispatching values");
+                       }
+               }
+               else if (ntohs (header->type) == TYPE_TIME)
+               {
+                       uint64_t tmp = 0;
+                       status = parse_part_number (&buffer, &buffer_len, &tmp);
+                       if (status == 0)
+                               vl.time = (time_t) tmp;
+               }
+               else if (ntohs (header->type) == TYPE_INTERVAL)
+               {
+                       uint64_t tmp = 0;
+                       status = parse_part_number (&buffer, &buffer_len, &tmp);
+                       if (status == 0)
+                               vl.interval = (int) tmp;
+               }
+               else if (ntohs (header->type) == TYPE_HOST)
+               {
+                       status = parse_part_string (&buffer, &buffer_len,
+                                       vl.host, sizeof (vl.host));
+                       DEBUG ("network plugin: parse_packet: vl.host = %s", vl.host);
+               }
+               else if (ntohs (header->type) == TYPE_PLUGIN)
+               {
+                       status = parse_part_string (&buffer, &buffer_len,
+                                       vl.plugin, sizeof (vl.plugin));
+                       DEBUG ("network plugin: parse_packet: vl.plugin = %s", vl.plugin);
+               }
+               else if (ntohs (header->type) == TYPE_PLUGIN_INSTANCE)
+               {
+                       status = parse_part_string (&buffer, &buffer_len,
+                                       vl.plugin_instance, sizeof (vl.plugin_instance));
+                       DEBUG ("network plugin: parse_packet: vl.plugin_instance = %s", vl.plugin_instance);
+               }
+               else if (ntohs (header->type) == TYPE_TYPE)
+               {
+                       status = parse_part_string (&buffer, &buffer_len,
+                                       type, sizeof (type));
+                       DEBUG ("network plugin: parse_packet: type = %s", type);
+               }
+               else if (ntohs (header->type) == TYPE_TYPE_INSTANCE)
+               {
+                       status = parse_part_string (&buffer, &buffer_len,
+                                       vl.type_instance, sizeof (vl.type_instance));
+                       DEBUG ("network plugin: parse_packet: vl.type_instance = %s", vl.type_instance);
+               }
+               else
+               {
+                       DEBUG ("network plugin: parse_packet: Unknown part"
+                                       " type: 0x%0hx", ntohs (header->type));
+                       buffer = ((char *) buffer) + ntohs (header->length);
+               }
+       } /* while (buffer_len > sizeof (part_header_t)) */
+
+       return (0);
+} /* int parse_packet */
+
+static void free_sockent (sockent_t *se)
+{
+       sockent_t *next;
+       while (se != NULL)
+       {
+               next = se->next;
+               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)
+{
+       if ((network_config_ttl < 1) || (network_config_ttl > 255))
+               return (-1);
+
+       DEBUG ("ttl = %i", network_config_ttl);
+
+       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 */
 
-int network_create_listen_socket (const char *node, const char *service)
+static int network_bind_socket (const sockent_t *se, const struct addrinfo *ai)
 {
-       socklist_t *socklist_tail;
+       int loop = 0;
+
+       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 */
+
+static sockent_t *network_create_socket (const char *node,
+               const char *service,
+               int listen)
+{
        struct addrinfo  ai_hints;
        struct addrinfo *ai_list, *ai_ptr;
        int              ai_return;
 
-       int num_added = 0;
+       sockent_t *se_head = NULL;
+       sockent_t *se_tail = NULL;
 
-       socklist_tail = listen_socks_head;
-       while ((socklist_tail != NULL) && (socklist_tail->next != NULL))
-               socklist_tail = socklist_tail->next;
+       DEBUG ("node = %s, service = %s", node, service);
 
        memset (&ai_hints, '\0', sizeof (ai_hints));
-       ai_hints.ai_flags    = AI_PASSIVE | AI_ADDRCONFIG;
+       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;
 
-       if ((ai_return = getaddrinfo (node, service, &ai_hints, &ai_list)) != 0)
+       ai_return = getaddrinfo (node, service, &ai_hints, &ai_list);
+       if (ai_return != 0)
        {
-               syslog (LOG_ERR, "getaddrinfo (%s, %s): %s",
-                               node == NULL ? "(null)" : node,
-                               service == NULL ? "(null)" : service,
-                               ai_return == EAI_SYSTEM ? strerror (errno) : gai_strerror (ai_return));
-               return (-1);
+               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)
        {
-               socklist_t *socklist_ent;
+               sockent_t *se;
 
-               if ((socklist_ent = (socklist_t *) malloc (sizeof (socklist_t))) == NULL)
+               if ((se = (sockent_t *) malloc (sizeof (sockent_t))) == NULL)
                {
-                       syslog (LOG_EMERG, "malloc: %s", strerror (errno));
+                       char errbuf[1024];
+                       ERROR ("malloc: %s",
+                                       sstrerror (errno, errbuf,
+                                               sizeof (errbuf)));
                        continue;
                }
 
-               socklist_ent->fd   = socket (ai_ptr->ai_family, ai_ptr->ai_socktype, ai_ptr->ai_protocol);
-               socklist_ent->next = NULL;
-
-               if (socklist_ent->fd == -1)
+               if ((se->addr = (struct sockaddr_storage *) malloc (sizeof (struct sockaddr_storage))) == NULL)
                {
-                       syslog (LOG_ERR, "socket: %s", strerror (errno));
-                       free (socklist_ent);
+                       char errbuf[1024];
+                       ERROR ("malloc: %s",
+                                       sstrerror (errno, errbuf,
+                                               sizeof (errbuf)));
+                       free (se);
                        continue;
                }
 
-               if (bind (socklist_ent->fd, ai_ptr->ai_addr, ai_ptr->ai_addrlen) == -1)
+               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)
                {
-                       syslog (LOG_ERR, "bind: %s", strerror (errno));
-                       close (socklist_ent->fd);
-                       free (socklist_ent);
+                       char errbuf[1024];
+                       ERROR ("socket: %s",
+                                       sstrerror (errno, errbuf,
+                                               sizeof (errbuf)));
+                       free (se->addr);
+                       free (se);
                        continue;
                }
 
-               if (ai_ptr->ai_family == AF_INET)
+               if (listen != 0)
                {
-                       struct sockaddr_in *addr = (struct sockaddr_in *) ai_ptr->ai_addr;
-                       if (IN_MULTICAST (ntohl (addr->sin_addr.s_addr)))
+                       if (network_bind_socket (se, ai_ptr) != 0)
                        {
-                               struct ip_mreq mreq;
-
-                               mreq.imr_multiaddr.s_addr = addr->sin_addr.s_addr;
-                               mreq.imr_interface.s_addr = htonl (INADDR_ANY);
-
-                               if (setsockopt (socklist_ent->fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
-                                                       &mreq, sizeof (mreq)) == -1)
-                               {
-                                       syslog (LOG_ERR, "setsockopt: %s", strerror (errno));
-                                       close (socklist_ent->fd);
-                                       free (socklist_ent);
-                                       continue;
-                               }
+                               close (se->fd);
+                               free (se->addr);
+                               free (se);
+                               continue;
                        }
                }
-               else if (ai_ptr->ai_family == AF_INET6)
+               else /* listen == 0 */
                {
-                       /* Useful example: http://gsyc.escet.urjc.es/~eva/IPv6-web/examples/mcast.html */
-                       struct sockaddr_in6 *addr = (struct sockaddr_in6 *) ai_ptr->ai_addr;
-                       if (IN6_IS_ADDR_MULTICAST (&addr->sin6_addr))
-                       {
-                               struct ipv6_mreq mreq;
-
-                               memcpy (&mreq.ipv6mr_multiaddr,
-                                               &addr->sin6_addr,
-                                               sizeof (addr->sin6_addr));
-
-                               /* FIXME What do I need here? `netdevice(7)'
-                                * doesn't tell me either.. */
-                               mreq6.ipv6mr_interface = 0;
-
-                               if (setsockopt (socklist_ent->fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP,
-                                                       &mreq, sizeof (mreq)) == -1)
-                               {
-                                       syslog (LOG_ERR, "setsockopt: %s", strerror (errno));
-                                       close (socklist_ent->fd);
-                                       free (socklist_ent);
-                                       continue;
-                               }
-                       }
+                       network_set_ttl (se, ai_ptr);
                }
 
-               if (socklist_tail == NULL)
+               if (se_tail == NULL)
                {
-                       listen_socks_head = socklist_tail = socklist_ent;
+                       se_head = se;
+                       se_tail = se;
                }
                else
                {
-                       socklist_tail->next = socklist_ent;
-                       socklist_tail = socklist_ent;
+                       se_tail->next = se;
+                       se_tail = se;
                }
-               num_added++;
+
+               /* We don't open more than one write-socket per node/service pair.. */
+               if (listen == 0)
+                       break;
        }
 
        freeaddrinfo (ai_list);
 
-       return (num_added);
-}
+       return (se_head);
+} /* sockent_t *network_create_socket */
 
-int get_write_socket (void)
+static sockent_t *network_create_default_socket (int listen)
 {
-       static int sd = -1;
+       sockent_t *se_ptr  = NULL;
+       sockent_t *se_head = NULL;
+       sockent_t *se_tail = NULL;
 
-       if (sd != -1)
-               return (sd);
+       se_ptr = network_create_socket (NET_DEFAULT_V6_ADDR,
+                       NET_DEFAULT_PORT, listen);
 
-       if ((sd = socket (AF_INET, SOCK_DGRAM, 0)) == -1)
+       /* Don't send to the same machine in IPv6 and IPv4 if both are available. */
+       if ((listen == 0) && (se_ptr != NULL))
+               return (se_ptr);
+
+       if (se_ptr != NULL)
        {
-               syslog (LOG_ERR, "socket: %s", strerror (errno));
-               return (-1);
+               se_head = se_ptr;
+               se_tail = se_ptr;
+               while (se_tail->next != NULL)
+                       se_tail = se_tail->next;
        }
 
-       return (sd);
-}
+       se_ptr = network_create_socket (NET_DEFAULT_V4_ADDR, NET_DEFAULT_PORT, listen);
 
-char *addr_to_host (struct sockaddr_in *addr)
+       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)
 {
-       char *host;
-       struct hostent *he;
+       sockent_t *se;
+       sockent_t *se_ptr;
+       int se_num = 0;
+
+       if (service == NULL)
+               service = NET_DEFAULT_PORT;
+
+       if (node == NULL)
+               se = network_create_default_socket (1 /* listen == true */);
+       else
+               se = network_create_socket (node, service, 1 /* listen == true */);
+
+       if (se == NULL)
+               return (-1);
 
-       if ((he = gethostbyaddr ((char *) &addr->sin_addr, sizeof (addr->sin_addr), AF_INET)) != NULL)
+       for (se_ptr = se; se_ptr != NULL; se_ptr = se_ptr->next)
+               se_num++;
+
+       listen_sockets = (struct pollfd *) realloc (listen_sockets,
+                       (listen_sockets_num + se_num)
+                       * sizeof (struct pollfd));
+
+       for (se_ptr = se; se_ptr != NULL; se_ptr = se_ptr->next)
        {
-               host = strdup (he->h_name);
-       }
+               listen_sockets[listen_sockets_num].fd = se_ptr->fd;
+               listen_sockets[listen_sockets_num].events = POLLIN | POLLPRI;
+               listen_sockets[listen_sockets_num].revents = 0;
+               listen_sockets_num++;
+       } /* for (se) */
+
+       free_sockent (se);
+       return (0);
+} /* int network_add_listen_socket */
+
+static int network_add_sending_socket (const char *node, const char *service)
+{
+       sockent_t *se;
+       sockent_t *se_ptr;
+
+       if (service == NULL)
+               service = NET_DEFAULT_PORT;
+
+       if (node == NULL)
+               se = network_create_default_socket (0 /* listen == false */);
        else
+               se = network_create_socket (node, service, 0 /* listen == false */);
+
+       if (se == NULL)
+               return (-1);
+
+       if (sending_sockets == NULL)
        {
-               char *tmp = inet_ntoa (addr->sin_addr);
-               host = strdup (tmp);
+               sending_sockets = se;
+               return (0);
        }
 
-       return (host);
+       for (se_ptr = sending_sockets; se_ptr->next != NULL; se_ptr = se_ptr->next)
+               /* seek end */;
+
+       se_ptr->next = se;
+       return (0);
+} /* int network_get_listen_socket */
+
+int network_receive (void)
+{
+       char buffer[BUFF_SIZE];
+       int  buffer_len;
+
+       int i;
+       int status;
+
+       if (listen_sockets_num == 0)
+               network_add_listen_socket (NULL, NULL);
+
+       if (listen_sockets_num == 0)
+       {
+               ERROR ("network: Failed to open a listening socket.");
+               return (-1);
+       }
+
+       while (listen_loop == 0)
+       {
+               status = poll (listen_sockets, 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++)
+               {
+                       if ((listen_sockets[i].revents & (POLLIN | POLLPRI)) == 0)
+                               continue;
+                       status--;
+
+                       buffer_len = recv (listen_sockets[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);
+                       }
+
+                       parse_packet (buffer, buffer_len);
+               } /* for (listen_sockets) */
+       } /* while (listen_loop == 0) */
+
+       return (0);
 }
 
-int network_receive (char **host, char **type, char **instance, char **value)
+static void *receive_thread (void *arg)
 {
-       int sd = get_read_socket ();
+       return (network_receive () ? (void *) 1 : (void *) 0);
+} /* void *receive_thread */
 
-       char buffer[BUFF_SIZE];
+static void network_send_buffer (const char *buffer, int buffer_len)
+{
+       sockent_t *se;
+       int status;
 
-       struct sockaddr_in addr;
-       socklen_t addr_size;
+       DEBUG ("network plugin: network_send_buffer: buffer_len = %i", buffer_len);
 
-       char *fields[4];
+       for (se = sending_sockets; se != NULL; se = se->next)
+       {
+               while (42)
+               {
+                       status = sendto (se->fd, buffer, buffer_len, 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;
+                       }
 
-       *host     = NULL;
-       *type     = NULL;
-       *instance = NULL;
-       *value    = NULL;
+                       break;
+               } /* while (42) */
+       } /* for (sending_sockets) */
+} /* void network_send_buffer */
 
-       if (sd == -1)
-               return (-1);
+static int add_to_buffer (char *buffer, int buffer_size,
+               value_list_t *vl_def, char *type_def,
+               const data_set_t *ds, const value_list_t *vl)
+{
+       char *buffer_orig = buffer;
 
-       addr_size = sizeof (addr);
+       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);
+               strcpy (vl_def->host, vl->host);
+       }
 
-       if (recvfrom (sd, buffer, BUFF_SIZE, 0, (struct sockaddr *) &addr, &addr_size) == -1)
+       if (vl_def->time != vl->time)
        {
-               syslog (LOG_ERR, "recvfrom: %s", strerror (errno));
-               return (-1);
+               if (write_part_number (&buffer, &buffer_size, TYPE_TIME,
+                                       (uint64_t) vl->time))
+                       return (-1);
+               vl_def->time = vl->time;
        }
 
-       if (strsplit (buffer, fields, 4) != 3)
-               return (-1);
+       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;
+       }
 
-       *host     = addr_to_host (&addr);
-       *type     = strdup (fields[0]);
-       *instance = strdup (fields[1]);
-       *value    = strdup (fields[2]);
+       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);
+               strcpy (vl_def->plugin, vl->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);
+               strcpy (vl_def->plugin_instance, vl->plugin_instance);
+       }
 
-       if (*host == NULL || *type == NULL || *instance == NULL || *value == NULL)
+       if (strcmp (type_def, ds->type) != 0)
+       {
+               if (write_part_string (&buffer, &buffer_size, TYPE_TYPE,
+                                       ds->type, strlen (ds->type)) != 0)
+                       return (-1);
+               strcpy (type_def, ds->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);
+               strcpy (vl_def->type_instance, vl->type_instance);
+       }
+       
+       if (write_part_values (&buffer, &buffer_size, ds, vl) != 0)
                return (-1);
 
-       return (0);
+       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, send_buffer_fill);
+       send_buffer_ptr  = send_buffer;
+       send_buffer_fill = 0;
+       memset (&send_buffer_vl, '\0', sizeof (send_buffer_vl));
+       memset (send_buffer_type, '\0', sizeof (send_buffer_type));
 }
 
-int network_send (char *type, char *instance, char *value)
+static int network_write (const data_set_t *ds, const value_list_t *vl)
 {
-       int sd = get_write_socket ();
-       struct sockaddr_in addr;
+       int status;
 
-       char buf[BUFF_SIZE];
-       int buflen;
+       /* 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 (ds->type, vl);
+       if ((network_config_forward == 0)
+                       && (status != 0))
+               return (0);
 
-       if (sd == -1)
-               return (-1);
+       pthread_mutex_lock (&send_buffer_lock);
+
+       status = add_to_buffer (send_buffer_ptr,
+                       sizeof (send_buffer) - send_buffer_fill,
+                       &send_buffer_vl, send_buffer_type,
+                       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,
+                               &send_buffer_vl, send_buffer_type,
+                               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);
 
-       if ((buflen = snprintf (buf, BUFF_SIZE, "%s %s %s", type, instance, value)) >= BUFF_SIZE)
+       return ((status < 0) ? -1 : 0);
+} /* int network_write */
+
+static int network_config (const char *key, const char *val)
+{
+       char *node;
+       char *service;
+
+       char *fields[3];
+       int   fields_num;
+
+       if ((strcasecmp ("Listen", key) == 0)
+                       || (strcasecmp ("Server", key) == 0))
+       {
+               char *val_cpy = strdup (val);
+               if (val_cpy == NULL)
+                       return (1);
+
+               service = NET_DEFAULT_PORT;
+               fields_num = strsplit (val_cpy, fields, 3);
+               if ((fields_num != 1)
+                               && (fields_num != 2))
+                       return (1);
+               else if (fields_num == 2)
+               {
+                       if ((service = strchr (fields[1], '.')) != NULL)
+                               *service = '\0';
+                       service = fields[1];
+               }
+               node = fields[0];
+
+               if (strcasecmp ("Listen", key) == 0)
+                       network_add_listen_socket (node, service);
+               else
+                       network_add_sending_socket (node, service);
+       }
+       else if (strcasecmp ("TimeToLive", key) == 0)
+       {
+               int tmp = atoi (val);
+               if ((tmp > 0) && (tmp < 256))
+                       network_config_ttl = tmp;
+               else
+                       return (1);
+       }
+       else if (strcasecmp ("Forward", key) == 0)
+       {
+               if ((strcasecmp ("true", val) == 0)
+                               || (strcasecmp ("yes", val) == 0)
+                               || (strcasecmp ("on", val) == 0))
+                       network_config_forward = 1;
+               else
+                       network_config_forward = 0;
+       }
+       else if (strcasecmp ("CacheFlush", key) == 0)
+       {
+               int tmp = atoi (val);
+               if (tmp > 0)
+                       cache_flush_interval = tmp;
+               else return (1);
+       }
+       else
        {
-               syslog (LOG_WARNING, "network_send: Output truncated..");
                return (-1);
        }
-       buf[buflen++] = '\0';
+       return (0);
+} /* int network_config */
 
-       memset(&addr, '\0', sizeof (addr));
-       addr.sin_family = AF_INET;
-       addr.sin_addr.s_addr = inet_addr (IPV4_MCAST_GROUP);
-       addr.sin_port = get_port ();
+static int network_shutdown (void)
+{
+       listen_loop++;
 
-       return (sendto (sd, buf, buflen, 0, (struct sockaddr *) &addr, sizeof (addr)));
-}
+       if (listen_thread != (pthread_t) 0)
+       {
+               pthread_kill (listen_thread, SIGTERM);
+               pthread_join (listen_thread, NULL /* no return value */);
+               listen_thread = (pthread_t) 0;
+       }
+
+       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");
+
+       return (0);
+} /* int network_shutdown */
+
+static int network_init (void)
+{
+       plugin_register_shutdown ("network", network_shutdown);
+
+       send_buffer_ptr  = send_buffer;
+       send_buffer_fill = 0;
+       memset (&send_buffer_vl, '\0', sizeof (send_buffer_vl));
+       memset (send_buffer_type, '\0', sizeof (send_buffer_type));
+
+       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);
+
+       if ((listen_sockets_num != 0) && (listen_thread == 0))
+       {
+               int status;
+
+               status = pthread_create (&listen_thread, 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)));
+               }
+       }
+       return (0);
+} /* int network_init */
+
+void module_register (void)
+{
+       plugin_register_config ("network", network_config,
+                       config_keys, config_keys_num);
+       plugin_register_init   ("network", network_init);
+} /* void module_register */