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sbusd.c
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sbusd.c
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/* See LICENSE file for copyright and license details. */
#include <sys/epoll.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <alloca.h>
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "arg.h"
#include "libsbusd.h"
enum blocking_mode {
BLOCKING_QUEUE,
BLOCKING_DISCARD,
BLOCKING_BLOCK,
BLOCKING_ERROR
};
enum order {
ORDER_QUEUE = 0,
ORDER_STACK = 1,
ORDER_RANDOM_QUEUE = 2,
ORDER_RANDOM_STACK = 3,
};
#define ORDER_RANDOM 2
enum client_flags {
ECHO_OFF = 1
};
struct client {
int fd;
enum blocking_mode soft_blocking_mode;
enum blocking_mode hard_blocking_mode;
enum order order;
enum client_flags flags;
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 = 0;
static const char *pidfile = "/run/sbus.pid";
static const char *credprefix = "";
static void
usage(void)
{
fprintf(stderr, "usage: %s [-a address] [-f | -p pidfile] [-u user] ... [-cgor]\n", argv0);
exit(1);
}
static void
sigexit(int signo)
{
if (*addr.sun_path)
if (unlink(addr.sun_path))
weprintf("unlink %s:", addr.sun_path);
if (pidfile)
if (unlink(pidfile))
weprintf("unlink %s:", pidfile);
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->soft_blocking_mode = BLOCKING_QUEUE;
cl->hard_blocking_mode = BLOCKING_DISCARD;
cl->order = ORDER_RANDOM_QUEUE;
cl->flags = 0;
cl->subs = NULL;
cl->nsubs = 0;
cl->subs_siz = 0;
DLLIST_ADD_BEFORE(cl, &tail);
return cl;
}
static void
remove_client(struct client *cl)
{
close(cl->fd);
DLLIST_REMOVE(cl);
while (cl->nsubs--)
free(cl->subs[cl->nsubs]);
free(cl->subs);
free(cl);
}
static void
accept_client(int fd)
{
struct epoll_event ev;
if (libsbusd_checkuser(fd, users, nusers))
return;
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_acceptable(struct client *cl, const char *key)
{
if (!strncmp(key, "!/cred/", sizeof("!/cred/") - 1))
return libsbusd_iscredok(cl->fd, key, credprefix);
return 1;
}
static void
add_subscription(struct client *cl, const char *key)
{
size_t n;
char **new, *k;
switch (is_subscription_acceptable(cl, key)) {
case -1:
remove_client(cl);
return;
case 0:
weprintf("client subscribed to unacceptable routing key\n");
remove_client(cl);
return;
default:
break;
}
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 int
send_packet(struct client *cl, const char *buf, size_t n)
{
/* TODO honour cl->soft_blocking_mode, cl->hard_blocking_mode, and cl->order */
return -(send(cl->fd, buf, n, 0) < 0);
}
static void
handle_cmsg(struct client *cl, char *buf, size_t n)
{
int r;
if (!strcmp(buf, "CMSG !/cred/whoami")) {
n = sizeof("CMSG !/cred/whoami");
n += (size_t)(r = libsbusd_who(cl->fd, &buf[n], credprefix));
if (r < 0) {
remove_client(cl);
return;
}
if (send_packet(cl, buf, n)) {
weprintf("send <client>:");
remove_client(cl);
}
} else if (!strcmp(buf, "CMSG blocking/soft/queue")) {
cl->soft_blocking_mode = BLOCKING_QUEUE;
} else if (!strcmp(buf, "CMSG blocking/soft/discard")) {
cl->soft_blocking_mode = BLOCKING_DISCARD;
} else if (!strcmp(buf, "CMSG blocking/soft/block")) {
cl->soft_blocking_mode = BLOCKING_BLOCK;
} else if (!strcmp(buf, "CMSG blocking/soft/error")) {
cl->soft_blocking_mode = BLOCKING_ERROR;
} else if (!strcmp(buf, "CMSG blocking/hard/discard")) {
cl->hard_blocking_mode = BLOCKING_DISCARD;
} else if (!strcmp(buf, "CMSG blocking/hard/block")) {
cl->hard_blocking_mode = BLOCKING_BLOCK;
} else if (!strcmp(buf, "CMSG blocking/hard/error")) {
cl->hard_blocking_mode = BLOCKING_ERROR;
} else if (!strcmp(buf, "CMSG order/queue")) {
cl->order = ORDER_QUEUE;
} else if (!strcmp(buf, "CMSG order/stack")) {
cl->order = ORDER_STACK;
} else if (!strcmp(buf, "CMSG order/random")) {
cl->order |= ORDER_RANDOM;
} else if (!strcmp(buf, "CMSG echo/off")) {
cl->flags |= ECHO_OFF;
} else if (!strcmp(buf, "CMSG echo/on")) {
cl->flags &= ~ECHO_OFF;
}
}
static void
broadcast(const char *msg, size_t n, struct client *ignore)
{
struct client *cl = head.next, *tmp;
for (; cl->next; cl = cl->next) {
if (cl == ignore)
continue;
if (!libsbusd_issubed(cl->subs, cl->nsubs, &msg[4]))
continue;
if (send_packet(cl, msg, n)) {
cl = (tmp = cl)->prev;
weprintf("send <client>:");
remove_client(tmp);
}
}
}
static void
handle_message(struct client *cl)
{
static char buf[409600 + 1];
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, (cl->flags & ECHO_OFF) ? cl : NULL);
} else if (!strncmp(buf, "UNSUB ", 6)) {
remove_subscription(cl, &buf[6]);
} else if (!strncmp(buf, "SUB ", 4)) {
add_subscription(cl, &buf[4]);
} else if (!strncmp(buf, "CMSG ", 5)) {
handle_cmsg(cl, buf, r);
} else {
weprintf("received bad message\n");
remove_client(cl);
}
}
int
main(int argc, char *argv[])
{
struct epoll_event evs[32];
const char *address = "/run/sbus.socket";
int auto_close = 0;
int foreground = 0;
mode_t mode = 0700;
int reuse_address = 0;
int server, n;
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':
libsbusd_adduser(users, &nusers, EARGF());
break;
default:
usage();
} ARGEND;
if (argc)
usage();
umask(0);
server = libsbusd_mksocket(&addr, address, reuse_address, mode);
libsbusd_initalise(foreground, &pidfile, sigexit);
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);
}
}
sigexit(0);
}