#include "cache.h"
#include "pkt-line.h"
+#include <signal.h>
+#include <sys/wait.h>
#include <sys/socket.h>
#include <netinet/in.h>
+#include <arpa/inet.h>
-static const char daemon_usage[] = "git-daemon [--port=n]";
+static const char daemon_usage[] = "git-daemon [--inetd | --port=n]";
static int upload(char *dir, int dirlen)
{
access("HEAD", R_OK))
return -1;
+ /*
+ * We'll ignore SIGTERM from now on, we have a
+ * good client.
+ */
+ signal(SIGTERM, SIG_IGN);
+
/* git-upload-pack only ever reads stuff, so this is safe */
execlp("git-upload-pack", "git-upload-pack", ".", NULL);
return -1;
}
-static int execute(char *line, int len)
+static int execute(void)
{
+ static char line[1000];
+ int len;
+
+ len = packet_read_line(0, line, sizeof(line));
+
+ if (len && line[len-1] == '\n')
+ line[--len] = 0;
+
if (!strncmp("git-upload-pack /", line, 17))
return upload(line + 16, len - 16);
return -1;
}
+
+/*
+ * We count spawned/reaped separately, just to avoid any
+ * races when updating them from signals. The SIGCHLD handler
+ * will only update children_reaped, and the fork logic will
+ * only update children_spawned.
+ *
+ * MAX_CHILDREN should be a power-of-two to make the modulus
+ * operation cheap. It should also be at least twice
+ * the maximum number of connections we will ever allow.
+ */
+#define MAX_CHILDREN 128
+
+static int max_connections = 25;
+
+/* These are updated by the signal handler */
+static volatile unsigned int children_reaped = 0;
+pid_t dead_child[MAX_CHILDREN];
+
+/* These are updated by the main loop */
+static unsigned int children_spawned = 0;
+static unsigned int children_deleted = 0;
+
+struct child {
+ pid_t pid;
+ int addrlen;
+ struct sockaddr_in address;
+} live_child[MAX_CHILDREN];
+
+static void add_child(int idx, pid_t pid, struct sockaddr_in *addr, int addrlen)
+{
+ live_child[idx].pid = pid;
+ live_child[idx].addrlen = addrlen;
+ live_child[idx].address = *addr;
+}
+
+/*
+ * Walk from "deleted" to "spawned", and remove child "pid".
+ *
+ * We move everything up by one, since the new "deleted" will
+ * be one higher.
+ */
+static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
+{
+ struct child n;
+
+ deleted %= MAX_CHILDREN;
+ spawned %= MAX_CHILDREN;
+ if (live_child[deleted].pid == pid) {
+ live_child[deleted].pid = -1;
+ return;
+ }
+ n = live_child[deleted];
+ for (;;) {
+ struct child m;
+ deleted = (deleted + 1) % MAX_CHILDREN;
+ if (deleted == spawned)
+ die("could not find dead child %d\n", pid);
+ m = live_child[deleted];
+ live_child[deleted] = n;
+ if (m.pid == pid)
+ return;
+ n = m;
+ }
+}
+
+/*
+ * This gets called if the number of connections grows
+ * past "max_connections".
+ *
+ * We _should_ start off by searching for connections
+ * from the same IP, and if there is some address wth
+ * multiple connections, we should kill that first.
+ *
+ * As it is, we just "randomly" kill 25% of the connections,
+ * and our pseudo-random generator sucks too. I have no
+ * shame.
+ *
+ * Really, this is just a place-holder for a _real_ algorithm.
+ */
+static void kill_some_children(int signo, unsigned start, unsigned stop)
+{
+ start %= MAX_CHILDREN;
+ stop %= MAX_CHILDREN;
+ while (start != stop) {
+ if (!(start & 3))
+ kill(live_child[start].pid, signo);
+ start = (start + 1) % MAX_CHILDREN;
+ }
+}
+
+static void check_max_connections(void)
+{
+ for (;;) {
+ int active;
+ unsigned spawned, reaped, deleted;
+
+ spawned = children_spawned;
+ reaped = children_reaped;
+ deleted = children_deleted;
+
+ while (deleted < reaped) {
+ pid_t pid = dead_child[deleted % MAX_CHILDREN];
+ remove_child(pid, deleted, spawned);
+ deleted++;
+ }
+ children_deleted = deleted;
+
+ active = spawned - deleted;
+ if (active <= max_connections)
+ break;
+
+ /* Kill some unstarted connections with SIGTERM */
+ kill_some_children(SIGTERM, deleted, spawned);
+ if (active <= max_connections << 1)
+ break;
+
+ /* If the SIGTERM thing isn't helping use SIGKILL */
+ kill_some_children(SIGKILL, deleted, spawned);
+ sleep(1);
+ }
+}
+
static void handle(int incoming, struct sockaddr_in *addr, int addrlen)
{
- static char line[1000];
- int len;
+ pid_t pid = fork();
+
+ if (pid) {
+ unsigned idx;
- if (fork()) {
close(incoming);
+ if (pid < 0)
+ return;
+
+ idx = children_spawned % MAX_CHILDREN;
+ children_spawned++;
+ add_child(idx, pid, addr, addrlen);
+
+ check_max_connections();
return;
}
dup2(incoming, 0);
dup2(incoming, 1);
close(incoming);
- len = packet_read_line(0, line, sizeof(line));
+ exit(execute());
+}
- if (len && line[len-1] == '\n')
- line[--len] = 0;
+static void child_handler(int signo)
+{
+ for (;;) {
+ pid_t pid = waitpid(-1, NULL, WNOHANG);
- exit(execute(line, len));
+ if (pid > 0) {
+ unsigned reaped = children_reaped;
+ dead_child[reaped % MAX_CHILDREN] = pid;
+ children_reaped = reaped + 1;
+ continue;
+ }
+ break;
+ }
}
static int serve(int port)
int sockfd;
struct sockaddr_in addr;
+ signal(SIGCHLD, child_handler);
sockfd = socket(PF_INET, SOCK_STREAM, IPPROTO_IP);
if (sockfd < 0)
die("unable to open socket (%s)", strerror(errno));
int main(int argc, char **argv)
{
int port = DEFAULT_GIT_PORT;
+ int inetd_mode = 0;
int i;
for (i = 1; i < argc; i++) {
continue;
}
}
+
+ if (!strcmp(arg, "--inetd")) {
+ inetd_mode = 1;
+ continue;
+ }
+
usage(daemon_usage);
}
+ if (inetd_mode)
+ return execute();
+
return serve(port);
}
projects / git.git / blobdiff