diff options
Diffstat (limited to '')
| -rw-r--r-- | sbusd.c | 572 |
1 files changed, 572 insertions, 0 deletions
@@ -0,0 +1,572 @@ +/* See LICENSE file for copyright and license details. */ +#include <sys/epoll.h> +#include <sys/ioctl.h> +#include <sys/socket.h> +#include <sys/stat.h> +#include <sys/un.h> +#include <sys/wait.h> +#include <alloca.h> +#include <ctype.h> +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <pwd.h> +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <stropts.h> +#include <time.h> +#include <unistd.h> + +#include "arg.h" + +#define STYPE_MAX(T) (long long int)((1ULL << (8 * sizeof(T) - 1)) - 1) +#define eprintf(...) (weprintf(__VA_ARGS__), exit(1)) + +struct client { + int fd; + char **subs; + size_t nsubs; + size_t subs_siz; + struct client *prev; + struct client *next; +}; + +char *argv0; +static struct client head; +static struct client tail; +static int epfd; +static int had_client = 0; +static struct sockaddr_un addr; +static uid_t *users; +static size_t nusers; + +static void +usage(void) +{ + fprintf(stderr, "usage: %s [-a address] [-f | -p pidfile] [-u user] ... [-cgor]\n", argv0); + exit(1); +} + +static void +weprintf(const char *fmt, ...) +{ + va_list args; + va_start(args, fmt); + vfprintf(stderr, fmt, args); + if (strchr(fmt, '\0')[-1] == ':') { + fputc(' ', stderr); + perror(NULL); + } + va_end(args); +} + +static void +sigexit(int signo) +{ + if (*addr.sun_path) + unlink(addr.sun_path); + exit(0); + (void) signo; +} + +static struct client * +add_client(int fd) +{ + struct client *cl; + cl = malloc(sizeof(*cl)); + if (!cl) + return NULL; + cl->fd = fd; + cl->subs = NULL; + cl->nsubs = 0; + cl->subs_siz = 0; + cl->next = &tail; + cl->prev = tail.prev; + tail.prev->next = cl; + tail.prev = cl; + return cl; +} + +static void +remove_client(struct client *cl) +{ + close(cl->fd); + cl->prev->next = cl->next; + cl->next->prev = cl->prev; + while (cl->nsubs--) + free(cl->subs[cl->nsubs]); + free(cl->subs); + free(cl); +} + +static void +accept_client(int fd) +{ + struct ucred cred; + struct epoll_event ev; + size_t i; + if (fd < 0) { + weprintf("accept <server>:"); + return; + } + if (nusers) { + if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &(socklen_t){sizeof(cred)}) < 0) { + weprintf("getsockopt <client> SOL_SOCKET SO_PEERCRED:"); + close(fd); + return; + } + for (i = nusers; i--;) + if (users[i] == cred.uid) + goto cred_ok; + weprintf("rejected connection from user %li\n", (long int)cred.uid); + close(fd); + return; + } +cred_ok: + ev.events = EPOLLIN | EPOLLRDHUP; + ev.data.ptr = add_client(fd); + if (!ev.data.ptr) { + close(fd); + } else if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &ev)) { + weprintf("epoll_ctl EPOLL_CTL_ADD <client>:"); + remove_client((void *)ev.data.ptr); + } else { + had_client = 1; + } +} + +static int +is_subscription_match(const char *sub, const char *key) +{ + const char *sub_start = sub; + for (;;) { + while (*sub && *sub == *key) { + sub++; + key++; + } + if (!*key) + return !*sub; + if (!*sub) + return sub == sub_start || sub[-1] == '.'; + if (*sub == '*') { + sub++; + while (*key && *key != '.') + key++; + continue; + } + return 0; + } +} + +static int +is_subscribed(const struct client *cl, const char *key) +{ + size_t i = cl->nsubs; + while (i--) + if (is_subscription_match(cl->subs[i], key)) + return 1; + return 0; +} + +static void +add_subscription(struct client *cl, const char *key) +{ + size_t n; + char **new, *k; + if (cl->subs_siz == cl->nsubs) { + n = cl->subs_siz ? (cl->subs_siz << 1) : 1; + new = realloc(cl->subs, n * sizeof(char *)); + if (!new) { + weprintf("realloc:"); + remove_client(cl); + return; + } + cl->subs = new; + cl->subs_siz = n; + } + k = strdup(key); + if (!k) { + weprintf("strdup:"); + remove_client(cl); + return; + } + cl->subs[cl->nsubs++] = k; +} + +static void +remove_subscription(struct client *cl, const char *key) +{ + size_t i = cl->nsubs; + char **new; + while (i--) { + if (!strcmp(key, cl->subs[i])) { + free(cl->subs[i]); + memmove(&cl->subs[i], &cl->subs[i + 1], --(cl->nsubs) - i); + if (cl->subs_siz >= 4 * cl->nsubs) { + new = realloc(cl->subs, cl->nsubs * sizeof(char *)); + if (new) { + cl->subs_siz = cl->nsubs; + cl->subs = new; + } + } + break; + } + } +} + +static void +broadcast(const char *msg, size_t n) +{ + struct client *cl = head.next, *tmp; + for (; cl->next; cl = cl->next) { + if (!is_subscribed(cl, &msg[4])) + continue; + if (send(cl->fd, msg, n, 0) < 0) { /* TODO queue instead of block */ + cl = (tmp = cl)->prev; + weprintf("send <client>:"); + remove_client(tmp); + } + } +} + +static void +handle_message(struct client *cl) +{ + static char buf[3 << 17]; + int fd = cl->fd; + ssize_t r; + + r = recv(fd, buf, sizeof(buf) - 1, 0); + if (r < 0) { + weprintf("recv <client>:"); + remove_client(cl); + return; + } + buf[r] = '\0'; + + if (!strncmp(buf, "MSG ", 4)) { + broadcast(buf, r); + } else if (!strncmp(buf, "UNSUB ", 6)) { + remove_subscription(cl, &buf[6]); + } else if (!strncmp(buf, "SUB ", 4)) { + add_subscription(cl, &buf[4]); + } else { + weprintf("received bad message\n"); + remove_client(cl); + } +} + +static void +randomise(void *buf, size_t n) +{ + char *p = buf; + while (n--) + *p++ = rand(); +} + +static void +print_address(void) +{ + char buf[2 * sizeof(addr.sun_path) + 1]; + char *p = buf; + const unsigned char *a = (const unsigned char *)addr.sun_path; + size_t n = sizeof(addr.sun_path); + + for (; n--; p += 2, a += 1) { + p[0] = "0123456789abcdef"[(int)*a >> 4]; + p[1] = "0123456789abcdef"[(int)*a & 15]; + } + *p = '\0'; + + printf("/dev/unix/abstract/%s\n", buf); + if (ferror(stderr)) + eprintf("failed print generated address:"); +} + +static int +make_socket(const char *address, int reuse, mode_t mode) +{ + int fd = -1, randaddr = 0, hi, lo, listening = 0; + long int tmp; + size_t n; + const char *p, *q; + char *a; + + memset(&addr, 0, sizeof(addr)); + addr.sun_family = AF_UNIX; + + if (strstr(address, "/dev/fd/") == address) { + p = &address[sizeof("/dev/fd/") - 1]; + if (isdigit(*p)) + goto def; + errno = 0; + tmp = strtol(p, &a, 10); + if (errno || *a || tmp < 0) { + errno = 0; + goto def; + } + if (tmp > INT_MAX) { + errno = EBADF; + goto bad_address; + } + fd = (int)tmp; + reuse = 0; + } else if (!strcmp(address, "/dev/unix/abstract")) { + randaddr = 1; + reuse = 0; + } else if (strstr(address, "/dev/unix/abstract/") == address) { + p = &address[sizeof("/dev/unix/abstract/") - 1]; + n = strlen(p); + if (n & 1) + goto def; + for (q = p; *q; q++) + if (!isxdigit(*q)) + goto def; + if (n > sizeof(addr.sun_path) * 2) { + errno = ENAMETOOLONG; + goto bad_address; + } + a = addr.sun_path; + for (; *p; p += 2) { + hi = (p[0] & 15) + 9 * !isdigit(p[0]); + lo = (p[1] & 15) + 9 * !isdigit(p[1]); + *a++ = (hi << 4) | lo; + } + reuse = 0; + } else { + def: + if (strlen(address) >= sizeof(addr.sun_path)) { + errno = ENAMETOOLONG; + goto bad_address; + } + strcpy(addr.sun_path, address); + } + + if (reuse) + unlink(addr.sun_path); + + if (fd < 0) { + fd = socket(PF_UNIX, SOCK_SEQPACKET, 0); + if (fd < 0) + eprintf("socket PF_UNIX SOCK_SEQPACKET:"); + if (fchmod(fd, mode)) + eprintf("fchmod <socket> %o:", mode); + if (randaddr) { + srand((unsigned)time(NULL)); + for (;;) { + randomise(&addr.sun_path[1], sizeof(addr.sun_path) - 1); + if (!bind(fd, (void *)&addr, sizeof(addr))) + break; + else if (errno != EADDRINUSE) + eprintf("bind <random abstract address>:"); + } + print_address(); + } else { + if (bind(fd, (void *)&addr, sizeof(addr))) { + if (*addr.sun_path) + eprintf("bind %s:", addr.sun_path); + else + eprintf("bind <abstract:%s>:", &address[sizeof("/dev/unix/abstract/") - 1]); + } + } + } else { + if (mode & 0070) + weprintf("ignoring -g due to using passed down socket\n"); + if (mode & 0007) + weprintf("ignoring -o due to using passed down socket\n"); + if (getsockopt(fd, SOL_SOCKET, SO_ACCEPTCONN, &listening, &(socklen_t){sizeof(listening)})) + eprintf("getsockopt SOL_SOCKET SO_ACCEPTCONN:"); + } + + if (!listening && listen(fd, SOMAXCONN)) + eprintf("listen:"); + + return fd; + +bad_address: + eprintf("bad unix socket address:"); + exit(1); +} + +static void +daemonise(const char *pidfile) +{ + pid_t pid; + int rw[2], status = 0, fd; + FILE *fp; + + if (pipe(rw)) + eprintf("pipe:"); + + switch ((pid = fork())) { + case -1: + eprintf("fork:"); + + case 0: + close(rw[0]); + setsid(); + switch (fork()) { + case -1: + eprintf("fork:"); + + case 0: + if (signal(SIGHUP, SIG_IGN) == SIG_ERR) + weprintf("signal SIGHUP SIG_IGN:"); + if (signal(SIGINT, sigexit) == SIG_ERR) + weprintf("signal SIGINT <exit>:"); + if (strcmp(pidfile, "/dev/null")) { + pid = getpid(); + fd = open(pidfile, O_WRONLY | O_CREAT | O_EXCL, 0644); + if (fd < 0) + eprintf("open %s O_WRONLY O_CREAT O_EXCL:", pidfile); + fp = fdopen(fd, "w"); + fprintf(fp, "%li\n", (long int)pid); + if (fflush(fp) || ferror(fp)) + eprintf("fprintf %s:", pidfile); + fclose(fp); + } + if (chdir("/")) + eprintf("chdir /:"); + close(STDIN_FILENO); + close(STDOUT_FILENO); + if (isatty(STDERR_FILENO)) { + fd = open("/dev/null", O_WRONLY); + if (fd) + eprintf("open /dev/null O_WRONLY:"); + if (dup2(fd, STDERR_FILENO) != STDERR_FILENO) + eprintf("dup2 /dev/null /dev/stderr:"); + close(fd); + } + if (write(rw[1], &status, 1) < 1) + eprintf("write <pipe>:"); + close(rw[1]); + break; + + default: + exit(0); + } + break; + + default: + close(rw[1]); + if (waitpid(pid, &status, 0) != pid) + eprintf("waitpid:"); + if (status) + exit(1); + switch (read(rw[0], &status, 1)) { + case -1: + eprintf("read <pipe>:"); + case 0: + exit(1); + default: + exit(0); + } + } +} + +int +main(int argc, char *argv[]) +{ + struct epoll_event evs[32]; + const char *address = "/run/sbus.socket"; + const char *pidfile = "/run/sbus.pid"; + int auto_close = 0; + int foreground = 0; + mode_t mode = 0700; + int reuse_address = 0; + struct passwd *user; + int server, n; + long long int tmp; + char *arg; + + users = alloca(argc * sizeof(*users)); + + ARGBEGIN { + case 'a': + address = EARGF(); + break; + case 'c': + auto_close = 1; + break; + case 'f': + foreground = 1; + break; + case 'g': + mode |= 0070; + break; + case 'o': + mode |= 0007; + break; + case 'p': + pidfile = EARGF(); + break; + case 'r': + reuse_address = 1; + break; + case 'u': + arg = EARGF(); + if (!isdigit(*arg)) + goto user_by_name; + errno = 0; + tmp = strtoll(arg, &arg, 10); + if (errno || *arg || tmp < 0 || tmp > STYPE_MAX(uid_t)) + goto user_by_name; + users[nusers++] = (uid_t)tmp; + user_by_name: + user = getpwnam(arg); + if (!user) + eprintf("getpwnam %s:", arg); + users[nusers++] = user->pw_uid; + break; + default: + usage(); + } ARGEND; + if (argc) + usage(); + + umask(0); + server = make_socket(address, reuse_address, mode); + if (foreground) { + close(0); + close(1); + if (signal(SIGHUP, sigexit) == SIG_ERR) + weprintf("signal SIGHUP <exit>:"); + if (signal(SIGINT, sigexit) == SIG_ERR) + weprintf("signal SIGINT <exit>:"); + } else { + daemonise(pidfile); + } + + if (nusers) + users[nusers++] = getuid(); + + head.next = &tail; + tail.prev = &head; + + epfd = epoll_create1(0); + if (epfd < 0) + eprintf("epoll_create1:"); + + evs->events = EPOLLIN; + evs->data.ptr = NULL; + if (epoll_ctl(epfd, EPOLL_CTL_ADD, server, evs)) + eprintf("epoll_ctl EPOLL_CTL_ADD <socket>:"); + + while (!auto_close || !had_client || head.next->next) { + n = epoll_wait(epfd, evs, sizeof(evs) / sizeof(*evs), -1); + if (n < 0) + eprintf("epoll_wait:"); + while (n--) { + if (!evs[n].data.ptr) + accept_client(accept(server, NULL, NULL)); + else if (evs[n].events & (EPOLLRDHUP | EPOLLHUP)) + remove_client((void *)evs[n].data.ptr); + else + handle_message((void *)evs[n].data.ptr); + } + } + + return 0; +} |