server.c

   1 #define FD_SET_MAX(fd, set, maxfd) do { \
   2                 FD_SET(fd, set);        \
   3                 if (fd > maxfd)         \
   4                         maxfd = fd;     \
   5         } while (0)
   6
   7 static Client *client_malloc(int socket) {
   8         Client *c = calloc(1, sizeof(Client));
   9         if (!c)
  10                 return NULL;
  11         c->socket = socket;
  12         return c;
  13 }
  14
  15 static void client_free(Client *c) {
  16         if (c && c->socket > 0)
  17                 close(c->socket);
  18         free(c);
  19 }
  20
  21 static int server_mark_socket_exec(bool exec) {
  22         struct stat sb;
  23         if (stat(sockaddr.sun_path, &sb) == -1)
  24                 return -1;
  25         mode_t mode = sb.st_mode;
  26         if (exec)
  27                 mode |= S_IXUSR;
  28         else
  29                 mode &= ~S_IXUSR;
  30         return chmod(sockaddr.sun_path, mode);
  31 }
  32
  33 static int server_create_socket(const char *name) {
  34         int socket = create_socket(name);
  35         if (socket == -1)
  36                 return -1;
  37         socklen_t socklen = offsetof(struct sockaddr_un, sun_path) + strlen(sockaddr.sun_path) + 1;
  38         mode_t mode = S_IRUSR|S_IWUSR;
  39         fchmod(socket, mode);
  40         if (bind(socket, (struct sockaddr*)&sockaddr, socklen) == -1)
  41                 return -1;
  42         if (fchmod(socket, mode) == -1 && chmod(sockaddr.sun_path, mode) == -1)
  43                 goto error;
  44         if (listen(socket, 5) == -1)
  45                 goto error;
  46         return socket;
  47 error:
  48         unlink(sockaddr.sun_path);
  49         return -1;
  50 }
  51
  52 static int server_set_socket_non_blocking(int sock) {
  53         int flags;
  54         if ((flags = fcntl(sock, F_GETFL, 0)) == -1)
  55                 flags = 0;
  56         return fcntl(sock, F_SETFL, flags | O_NONBLOCK);
  57 }
  58
  59 static Client *server_accept_client() {
  60         int newfd = accept(server.socket, NULL, NULL);
  61         if (newfd == -1)
  62                 return NULL;
  63         Client *c = client_malloc(newfd);
  64         if (!c)
  65                 return NULL;
  66         if (!server.clients)
  67                 server_mark_socket_exec(true);
  68         server_set_socket_non_blocking(newfd);
  69         c->socket = newfd;
  70         c->state = STATE_CONNECTED;
  71         c->next = server.clients;
  72         server.clients = c;
  73         server.read_pty = true;
  74         return c;
  75 }
  76
  77 static bool server_read_pty(Packet *pkt) {
  78         pkt->type = MSG_CONTENT;
  79         ssize_t len = read(server.pty, pkt->u.msg, sizeof(pkt->u.msg));
  80         if (len != -1)
  81                 pkt->len = len;
  82         else if (errno != EAGAIN && errno != EINTR)
  83                 server.running = false;
  84         print_packet("server-read-pty:", pkt);
  85         return len > 0;
  86 }
  87
  88 static bool server_write_pty(Packet *pkt) {
  89         print_packet("server-write-pty:", pkt);
  90         size_t size = pkt->len;
  91         if (write_all(server.pty, pkt->u.msg, size) == size)
  92                 return true;
  93         debug("FAILED\n");
  94         server.running = false;
  95         return false;
  96 }
  97
  98 static bool server_recv_packet(Client *c, Packet *pkt) {
  99         if (recv_packet(c->socket, pkt)) {
 100                 print_packet("server-recv:", pkt);
 101                 return true;
 102         }
 103         debug("server-recv: FAILED\n");
 104         c->state = STATE_DISCONNECTED;
 105         return false;
 106 }
 107
 108 static bool server_send_packet(Client *c, Packet *pkt) {
 109         print_packet("server-send:", pkt);
 110         if (send_packet(c->socket, pkt))
 111                 return true;
 112         debug("FAILED\n");
 113         c->state = STATE_DISCONNECTED;
 114         return false;
 115 }
 116
 117 static void server_pty_died_handler(int sig) {
 118         int errsv = errno;
 119         pid_t pid;
 120
 121         while ((pid = waitpid(-1, &server.exit_status, WNOHANG)) != 0) {
 122                 if (pid == -1)
 123                         break;
 124                 server.exit_status = WEXITSTATUS(server.exit_status);
 125         }
 126
 127         debug("server pty died: %d\n", server.exit_status);
 128         errno = errsv;
 129 }
 130
 131 static void server_sigterm_handler(int sig) {
 132         exit(EXIT_FAILURE); /* invoke atexit handler */
 133 }
 134
 135 static void server_sigusr1_handler(int sig) {
 136         int socket = server_create_socket(server.session_name);
 137         if (socket != -1) {
 138                 if (server.socket)
 139                         close(server.socket);
 140                 server.socket = socket;
 141         }
 142 }
 143
 144 static void server_atexit_handler() {
 145         unlink(sockaddr.sun_path);
 146 }
 147
 148 static void server_mainloop() {
 149         atexit(server_atexit_handler);
 150         fd_set new_readfds, new_writefds;
 151         FD_ZERO(&new_readfds);
 152         FD_ZERO(&new_writefds);
 153         FD_SET(server.socket, &new_readfds);
 154         int new_fdmax = server.socket;
 155         if (server.read_pty)
 156                 FD_SET_MAX(server.pty, &new_readfds, new_fdmax);
 157         Packet *exit_pkt = NULL;
 158
 159         while (!exit_pkt) {
 160                 int fdmax = new_fdmax;
 161                 fd_set readfds = new_readfds;
 162                 fd_set writefds = new_writefds;
 163                 FD_SET_MAX(server.socket, &readfds, fdmax);
 164
 165                 if (select(fdmax+1, &readfds, &writefds, NULL, NULL) == -1) {
 166                         if (errno == EINTR)
 167                                 continue;
 168                         die("server-mainloop");
 169                 }
 170
 171                 FD_ZERO(&new_readfds);
 172                 FD_ZERO(&new_writefds);
 173                 new_fdmax = server.socket;
 174
 175                 bool pty_data = false;
 176
 177                 Packet server_packet, client_packet;
 178
 179                 if (FD_ISSET(server.socket, &readfds))
 180                         server_accept_client();
 181
 182                 if (FD_ISSET(server.pty, &readfds))
 183                         pty_data = server_read_pty(&server_packet);
 184
 185                 if (!server.running && server.exit_status != -1 && server.clients) { /* application terminated */
 186                         Packet pkt = {
 187                                 .type = MSG_EXIT,
 188                                 .u.i = server.exit_status,
 189                                 .len = sizeof(pkt.u.i),
 190                         };
 191                         exit_pkt = &pkt;
 192                         server.exit_status = -1;
 193                 }
 194
 195                 for (Client **prev_next = &server.clients, *c = server.clients; c;) {
 196                         if (c->state == STATE_DISCONNECTED) {
 197                                 bool first = (c == server.clients);
 198                                 Client *t = c->next;
 199                                 client_free(c);
 200                                 *prev_next = c = t;
 201                                 if (first && server.clients) {
 202                                         Packet pkt = {
 203                                                 .type = MSG_RESIZE,
 204                                                 .len = 0,
 205                                         };
 206                                         server_send_packet(server.clients, &pkt);
 207                                 } else if (!server.clients) {
 208                                         server_mark_socket_exec(false);
 209                                 }
 210                                 continue;
 211                         }
 212
 213                         if (FD_ISSET(c->socket, &readfds) && server_recv_packet(c, &client_packet)) {
 214                                 switch (client_packet.type) {
 215                                 case MSG_CONTENT:
 216                                         server_write_pty(&client_packet);
 217                                         break;
 218                                 case MSG_ATTACH:
 219                                         c->readonly = client_packet.u.b;
 220                                         break;
 221                                 case MSG_RESIZE:
 222                                         c->state = STATE_ATTACHED;
 223                                 case MSG_REDRAW:
 224                                         if (!c->readonly && (client_packet.type == MSG_REDRAW || c == server.clients)) {
 225                                                 debug("server-ioct: TIOCSWINSZ\n");
 226                                                 ioctl(server.pty, TIOCSWINSZ, &client_packet.u.ws);
 227                                         }
 228                                         kill(-server.pid, SIGWINCH);
 229                                         break;
 230                                 case MSG_DETACH:
 231                                         c->state = STATE_DETACHED;
 232                                         break;
 233                                 default: /* ignore package */
 234                                         break;
 235                                 }
 236                         }
 237
 238                         FD_SET_MAX(c->socket, &new_readfds, new_fdmax);
 239
 240                         if (pty_data)
 241                                 server_send_packet(c, &server_packet);
 242                         if (exit_pkt)
 243                                 server_send_packet(c, exit_pkt);
 244
 245                         prev_next = &c->next;
 246                         c = c->next;
 247                 }
 248
 249                 if (server.running && server.read_pty)
 250                         FD_SET_MAX(server.pty, &new_readfds, new_fdmax);
 251         }
 252
 253         exit(EXIT_SUCCESS);
 254 }