diff options
Diffstat (limited to 'daemon.c')
| -rw-r--r-- | daemon.c | 297 |
1 files changed, 101 insertions, 196 deletions
@@ -16,12 +16,11 @@ static int log_syslog; static int verbose; static int reuseaddr; -static int child_handler_pipe[2]; static const char daemon_usage[] = "git daemon [--verbose] [--syslog] [--export-all]\n" -" [--timeout=n] [--init-timeout=n] [--strict-paths]\n" -" [--base-path=path] [--base-path-relaxed]\n" +" [--timeout=n] [--init-timeout=n] [--max-connections=n]\n" +" [--strict-paths] [--base-path=path] [--base-path-relaxed]\n" " [--user-path | --user-path=path]\n" " [--interpolated-path=path]\n" " [--reuseaddr] [--detach] [--pid-file=file]\n" @@ -78,38 +77,19 @@ static struct interp interp_table[] = { static void logreport(int priority, const char *err, va_list params) { - /* We should do a single write so that it is atomic and output - * of several processes do not get intermingled. */ - char buf[1024]; - int buflen; - int maxlen, msglen; - - /* sizeof(buf) should be big enough for "[pid] \n" */ - buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid()); - - maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */ - msglen = vsnprintf(buf + buflen, maxlen, err, params); - if (log_syslog) { + char buf[1024]; + vsnprintf(buf, sizeof(buf), err, params); syslog(priority, "%s", buf); - return; + } else { + /* + * Since stderr is set to linebuffered mode, the + * logging of different processes will not overlap + */ + fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid()); + vfprintf(stderr, err, params); + fputc('\n', stderr); } - - /* maxlen counted our own LF but also counts space given to - * vsnprintf for the terminating NUL. We want to make sure that - * we have space for our own LF and NUL after the "meat" of the - * message, so truncate it at maxlen - 1. - */ - if (msglen > maxlen - 1) - msglen = maxlen - 1; - else if (msglen < 0) - msglen = 0; /* Protect against weird return values. */ - buflen += msglen; - - buf[buflen++] = '\n'; - buf[buflen] = '\0'; - - write_in_full(2, buf, buflen); } static void logerror(const char *err, ...) @@ -604,169 +584,107 @@ static int execute(struct sockaddr *addr) return -1; } +static int max_connections = 32; -/* - * 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; -static pid_t dead_child[MAX_CHILDREN]; - -/* These are updated by the main loop */ -static unsigned int children_spawned; -static unsigned int children_deleted; +static unsigned int live_children; static struct child { + struct child *next; pid_t pid; - int addrlen; struct sockaddr_storage address; -} live_child[MAX_CHILDREN]; +} *firstborn; -static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen) +static void add_child(pid_t pid, struct sockaddr *addr, int addrlen) { - live_child[idx].pid = pid; - live_child[idx].addrlen = addrlen; - memcpy(&live_child[idx].address, addr, addrlen); + struct child *newborn, **cradle; + + /* + * This must be xcalloc() -- we'll compare the whole sockaddr_storage + * but individual address may be shorter. + */ + newborn = xcalloc(1, sizeof(*newborn)); + live_children++; + newborn->pid = pid; + memcpy(&newborn->address, addr, addrlen); + for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next) + if (!memcmp(&(*cradle)->address, &newborn->address, + sizeof(newborn->address))) + break; + newborn->next = *cradle; + *cradle = newborn; } -/* - * 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) +static void remove_child(pid_t pid) { - struct child n; + struct child **cradle, *blanket; - 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; - } + for (cradle = &firstborn; (blanket = *cradle); cradle = &blanket->next) + if (blanket->pid == pid) { + *cradle = blanket->next; + live_children--; + free(blanket); + break; + } } /* * 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. + * We kill the newest connection from a duplicate IP. */ -static void kill_some_children(int signo, unsigned start, unsigned stop) +static void kill_some_child(void) { - 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_dead_children(void) -{ - unsigned spawned, reaped, deleted; - - spawned = children_spawned; - reaped = children_reaped; - deleted = children_deleted; + const struct child *blanket, *next; - while (deleted < reaped) { - pid_t pid = dead_child[deleted % MAX_CHILDREN]; - const char *dead = pid < 0 ? " (with error)" : ""; - - if (pid < 0) - pid = -pid; + if (!(blanket = firstborn)) + return; - /* XXX: Custom logging, since we don't wanna getpid() */ - if (verbose) { - if (log_syslog) - syslog(LOG_INFO, "[%d] Disconnected%s", - pid, dead); - else - fprintf(stderr, "[%d] Disconnected%s\n", - pid, dead); + for (; (next = blanket->next); blanket = next) + if (!memcmp(&blanket->address, &next->address, + sizeof(next->address))) { + kill(blanket->pid, SIGTERM); + break; } - remove_child(pid, deleted, spawned); - deleted++; - } - children_deleted = deleted; } -static void check_max_connections(void) +static void check_dead_children(void) { - for (;;) { - int active; - unsigned spawned, deleted; - - check_dead_children(); - - spawned = children_spawned; - deleted = children_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; + int status; + pid_t pid; - /* If the SIGTERM thing isn't helping use SIGKILL */ - kill_some_children(SIGKILL, deleted, spawned); - sleep(1); + while ((pid = waitpid(-1, &status, WNOHANG)) > 0) { + const char *dead = ""; + remove_child(pid); + if (!WIFEXITED(status) || (WEXITSTATUS(status) > 0)) + dead = " (with error)"; + loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead); } } static void handle(int incoming, struct sockaddr *addr, int addrlen) { - pid_t pid = fork(); + pid_t pid; - if (pid) { - unsigned idx; + if (max_connections && live_children >= max_connections) { + kill_some_child(); + sleep(1); /* give it some time to die */ + check_dead_children(); + if (live_children >= max_connections) { + close(incoming); + logerror("Too many children, dropping connection"); + return; + } + } + if ((pid = fork())) { close(incoming); - if (pid < 0) + if (pid < 0) { + logerror("Couldn't fork %s", strerror(errno)); return; + } - idx = children_spawned % MAX_CHILDREN; - children_spawned++; - add_child(idx, pid, addr, addrlen); - - check_max_connections(); + add_child(pid, addr, addrlen); return; } @@ -779,21 +697,11 @@ static void handle(int incoming, struct sockaddr *addr, int addrlen) static void child_handler(int signo) { - for (;;) { - int status; - pid_t pid = waitpid(-1, &status, WNOHANG); - - if (pid > 0) { - unsigned reaped = children_reaped; - if (!WIFEXITED(status) || WEXITSTATUS(status) > 0) - pid = -pid; - dead_child[reaped % MAX_CHILDREN] = pid; - children_reaped = reaped + 1; - write(child_handler_pipe[1], &status, 1); - continue; - } - break; - } + /* + * Otherwise empty handler because systemcalls will get interrupted + * upon signal receipt + * SysV needs the handler to be rearmed + */ signal(SIGCHLD, child_handler); } @@ -836,7 +744,7 @@ static int socksetup(char *listen_addr, int listen_port, int **socklist_p) if (sockfd < 0) continue; if (sockfd >= FD_SETSIZE) { - error("too large socket descriptor."); + logerror("Socket descriptor too large"); close(sockfd); continue; } @@ -936,35 +844,28 @@ static int service_loop(int socknum, int *socklist) struct pollfd *pfd; int i; - if (pipe(child_handler_pipe) < 0) - die ("Could not set up pipe for child handler"); - - pfd = xcalloc(socknum + 1, sizeof(struct pollfd)); + pfd = xcalloc(socknum, sizeof(struct pollfd)); for (i = 0; i < socknum; i++) { pfd[i].fd = socklist[i]; pfd[i].events = POLLIN; } - pfd[socknum].fd = child_handler_pipe[0]; - pfd[socknum].events = POLLIN; signal(SIGCHLD, child_handler); for (;;) { int i; - if (poll(pfd, socknum + 1, -1) < 0) { + check_dead_children(); + + if (poll(pfd, socknum, -1) < 0) { if (errno != EINTR) { - error("poll failed, resuming: %s", + logerror("Poll failed, resuming: %s", strerror(errno)); sleep(1); } continue; } - if (pfd[socknum].revents & POLLIN) { - read(child_handler_pipe[0], &i, 1); - check_dead_children(); - } for (i = 0; i < socknum; i++) { if (pfd[i].revents & POLLIN) { @@ -1022,7 +923,7 @@ static void store_pid(const char *path) FILE *f = fopen(path, "w"); if (!f) die("cannot open pid file %s: %s", path, strerror(errno)); - if (fprintf(f, "%d\n", getpid()) < 0 || fclose(f) != 0) + if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0) die("failed to write pid file %s: %s", path, strerror(errno)); } @@ -1055,11 +956,6 @@ int main(int argc, char **argv) gid_t gid = 0; int i; - /* Without this we cannot rely on waitpid() to tell - * what happened to our children. - */ - signal(SIGCHLD, SIG_DFL); - for (i = 1; i < argc; i++) { char *arg = argv[i]; @@ -1105,6 +1001,12 @@ int main(int argc, char **argv) init_timeout = atoi(arg+15); continue; } + if (!prefixcmp(arg, "--max-connections=")) { + max_connections = atoi(arg+18); + if (max_connections < 0) + max_connections = 0; /* unlimited */ + continue; + } if (!strcmp(arg, "--strict-paths")) { strict_paths = 1; continue; @@ -1178,9 +1080,10 @@ int main(int argc, char **argv) } if (log_syslog) { - openlog("git-daemon", 0, LOG_DAEMON); + openlog("git-daemon", LOG_PID, LOG_DAEMON); set_die_routine(daemon_die); - } + } else + setlinebuf(stderr); /* avoid splitting a message in the middle */ if (inetd_mode && (group_name || user_name)) die("--user and --group are incompatible with --inetd"); @@ -1233,8 +1136,10 @@ int main(int argc, char **argv) return execute(peer); } - if (detach) + if (detach) { daemonize(); + loginfo("Ready to rumble"); + } else sanitize_stdfds(); |