Add support for the --max-clients option

README.md

@@ -88,6 +88,7 @@ OPTIONS:
     --readonly, -R          Do not allow clients to write to the TTY
     --client-option, -t     Send option to client (format: key=value), repeat to add more options
     --check-origin, -O      Do not allow websocket connection from different origin
+    --max-clients, -m       Maximum clients to support (default: 0, no limit)
     --once, -o              Accept only one client and exit on disconnection
     --browser, -B           Open terminal with the default system browser
     --index, -I             Custom index.html path

man/ttyd.1

@@ -72,6 +72,10 @@ Cross platform: macOS, Linux, FreeBSD, OpenWrt/LEDE, Windows
 \-O, \-\-check\-origin
       Do not allow websocket connection from different origin
 
+.PP
+\-m, \-\-max\-clients
+      Maximum clients to support (default: 0, no limit)
+
 .PP
 \-o, \-\-once
       Accept only one client and exit on disconnection

man/ttyd.man.md

@@ -51,6 +51,9 @@ ttyd 1 "September 2016" ttyd "User Manual"
   -O, --check-origin
       Do not allow websocket connection from different origin
 
+  -m, --max-clients
+      Maximum clients to support (default: 0, no limit)
+
   -o, --once
       Accept only one client and exit on disconnection
 

src/http.c

@@ -61,7 +61,7 @@ callback_http(struct lws *wsi, enum lws_callback_reasons reason, void *user, voi
             }
 
             lws_get_peer_addresses(wsi, lws_get_socket_fd(wsi), name, sizeof(name), rip, sizeof(rip));
-            lwsl_notice("HTTP %s - %s (%s)\n", in, rip, name);
+            lwsl_notice("HTTP %s - %s (%s)\n", (char *) in, rip, name);
 
             switch (check_auth(wsi)) {
                 case 0:

src/protocol.c

@@ -188,6 +188,10 @@ callback_tty(struct lws *wsi, enum lws_callback_reasons reason,
                 lwsl_warn("refuse to serve WS client due to the --once option.\n");
                 return 1;
             }
+            if (server->max_clients > 0 && server->client_count == server->max_clients) {
+                lwsl_warn("refuse to serve WS client due to the --max-clients option.\n");
+                return 1;
+            }
             if (lws_hdr_copy(wsi, buf, sizeof(buf), WSI_TOKEN_GET_URI) <= 0 || strcmp(buf, WS_PATH)) {
                 lwsl_warn("refuse to serve WS client for illegal ws path: %s\n", buf);
                 return 1;

src/server.c

@@ -35,6 +35,7 @@ static const struct option options[] = {
         {"ssl-ca",       required_argument, NULL, 'A'},
         {"readonly",     no_argument,       NULL, 'R'},
         {"check-origin", no_argument,       NULL, 'O'},
+        {"max-clients",  required_argument, NULL, 'm'},
         {"once",         no_argument,       NULL, 'o'},
         {"browser",      no_argument,       NULL, 'B'},
         {"debug",        required_argument, NULL, 'd'},
@@ -42,7 +43,7 @@ static const struct option options[] = {
         {"help",         no_argument,       NULL, 'h'},
         {NULL,           0,                 0,     0}
 };
-static const char *opt_string = "p:i:c:u:g:s:r:I:aSC:K:A:Rt:OoBd:vh";
+static const char *opt_string = "p:i:c:u:g:s:r:I:aSC:K:A:Rt:Om:oBd:vh";
 
 void print_help() {
     fprintf(stderr, "ttyd is a tool for sharing terminal over the web\n\n"
@@ -62,6 +63,7 @@ void print_help() {
                     "    --readonly, -R          Do not allow clients to write to the TTY\n"
                     "    --client-option, -t     Send option to client (format: key=value), repeat to add more options\n"
                     "    --check-origin, -O      Do not allow websocket connection from different origin\n"
+                    "    --max-clients, -m       Maximum clients to support (default: 0, no limit)\n"
                     "    --once, -o              Accept only one client and exit on disconnection\n"
                     "    --browser, -B           Open terminal with the default system browser\n"
                     "    --index, -I             Custom index.html path\n"
@@ -251,6 +253,9 @@ main(int argc, char **argv) {
             case 'O':
                 server->check_origin = true;
                 break;
+            case 'm':
+                server->max_clients = atoi(optarg);
+                break;
             case 'o':
                 server->once = true;
                 break;
@@ -418,6 +423,8 @@ main(int argc, char **argv) {
         lwsl_notice("  check origin: true\n");
     if (server->readonly)
         lwsl_notice("  readonly: true\n");
+    if (server->max_clients > 0)
+        lwsl_notice("  max clients: %d\n", server->max_clients);
     if (server->once)
         lwsl_notice("  once: true\n");
     if (server->index != NULL) {

src/server.h

@@ -110,6 +110,7 @@ struct tty_server {
     char *sig_name;                           // human readable signal string
     bool readonly;                            // whether not allow clients to write to the TTY
     bool check_origin;                        // whether allow websocket connection from different origin
+    int max_clients;                          // maximum clients to support
     bool once;                                // whether accept only one client and exit on disconnection
     char *socket_path;                        // UNIX domain socket path
     pthread_mutex_t lock;