Implementation of adding new port and the capabilities

Signed-off-by: Shivshankar-Reddy <[email protected]>

src/config.c

@@ -3193,6 +3193,7 @@ standardConfig static_configs[] = {
     /* Integer configs */
     createIntConfig("databases", NULL, IMMUTABLE_CONFIG, 1, INT_MAX, server.dbnum, 16, INTEGER_CONFIG, NULL, NULL),
     createIntConfig("port", NULL, MODIFIABLE_CONFIG, 0, 65535, server.port, 6379, INTEGER_CONFIG, NULL, updatePort),                    /* TCP port. */
+    createIntConfig("admin-port", NULL, IMMUTABLE_CONFIG, 0, 65535, server.admin_port, 0, INTEGER_CONFIG, NULL, NULL),                  /* TCP admin port. */
     createIntConfig("io-threads", NULL, DEBUG_CONFIG | IMMUTABLE_CONFIG, 1, 128, server.io_threads_num, 1, INTEGER_CONFIG, NULL, NULL), /* Single threaded by default */
     createIntConfig("events-per-io-thread", NULL, MODIFIABLE_CONFIG, 0, INT_MAX, server.events_per_io_thread, 2, INTEGER_CONFIG, NULL, NULL),
     createIntConfig("prefetch-batch-max-size", NULL, MODIFIABLE_CONFIG, 0, 128, server.prefetch_batch_max_size, 16, INTEGER_CONFIG, NULL, NULL),

src/networking.c

@@ -1387,6 +1387,7 @@ void clientAcceptHandler(connection *conn) {
 void acceptCommonHandler(connection *conn, struct ClientFlags flags, char *ip) {
     client *c;
     UNUSED(ip);
+    int port;
 
     if (connGetState(conn) != CONN_STATE_ACCEPTING) {
         char addr[NET_ADDR_STR_LEN] = {0};
@@ -1399,12 +1400,26 @@ void acceptCommonHandler(connection *conn, struct ClientFlags flags, char *ip) {
         return;
     }
 
+    if (connAddrSockName(conn, NULL, 0, &port)) {
+        serverLog(LL_WARNING, "Unable to retrieve socket port");
+        connClose(conn);
+        return;
+    }
+
+    if (port == server.admin_port && connIsLocal(conn) != 1) {
+        serverLog(LL_WARNING, "Denied connection. On admin-port, connections are"
+                  " only accepted from the loopback interface.");
+        server.stat_rejected_conn++;
+        connClose(conn);
+        return;
+    }
+
     /* Limit the number of connections we take at the same time.
      *
      * Admission control will happen before a client is created and connAccept()
      * called, because we don't want to even start transport-level negotiation
      * if rejected. */
-    if (listLength(server.clients) + getClusterConnectionsCount() >= server.maxclients) {
+    if (port != server.admin_port && listLength(server.clients) + getClusterConnectionsCount() >= server.maxclients) {
         char *err;
         if (server.cluster_enabled)
             err = "-ERR max number of clients + cluster "

src/server.c

@@ -2819,6 +2819,25 @@ void initListeners(void) {
         listener->priv2 = server.unixsocketgroup; /* Unix socket group specified */
     }
 
+    if (server.admin_port != 0) {
+        conn_index = connectionIndexByType(CONN_TYPE_SOCKET);
+        if (conn_index < 0) serverPanic("Failed finding connection listener of %s", CONN_TYPE_SOCKET);
+
+        // Check if the current index is already occupied
+        while (server.listeners[conn_index].ct != NULL) {
+            conn_index++;
+            if (conn_index >= CONN_TYPE_MAX) {
+                serverPanic("No available index for additional TCP listener.");
+            }
+        }
+
+        listener = &server.listeners[conn_index];
+        listener->bindaddr = server.bindaddr;
+        listener->bindaddr_count = server.bindaddr_count;
+        listener->port = server.admin_port;
+        listener->ct = connectionByType(CONN_TYPE_SOCKET);
+    }
+
     /* create all the configured listener, and add handler to start to accept */
     int listen_fds = 0;
     for (int j = 0; j < CONN_TYPE_MAX; j++) {

src/server.h

@@ -1697,6 +1697,7 @@ struct valkeyServer {
     _Atomic int module_gil_acquiring; /* Indicates whether the GIL is being acquiring by the main thread. */
     /* Networking */
     int port;                              /* TCP listening port */
+    int admin_port;                        /* TCP listening admin port */
     int tls_port;                          /* TLS listening port */
     int tcp_backlog;                       /* TCP listen() backlog */
     char *bindaddr[CONFIG_BINDADDR_MAX];   /* Addresses we should bind to */

tests/support/server.tcl

@@ -534,7 +534,9 @@ proc start_server {options {code undefined}} {
         dict set config "tls-cluster" "yes"
         dict set config "tls-replication" "yes"
     } else {
-        dict set config port $port
+        set aport [find_available_port $::baseport $::portcount]
+        dict set config "port" $port
+        dict set config "admin-port" $aport
     }
 
     set unixsocket [file normalize [format "%s/%s" [dict get $config "dir"] "socket"]]
@@ -604,7 +606,9 @@ proc start_server {options {code undefined}} {
                 dict set config port $pport
                 dict set config "tls-port" $port
             } else {
+                set aport [find_available_port $::baseport $::portcount]
                 dict set config port $port
+                dict set config admin-port $aport
             }
             create_server_config_file $config_file $config $config_lines
 
@@ -638,15 +642,18 @@ proc start_server {options {code undefined}} {
     # setup properties to be able to initialize a client object
     set port_param [expr $::tls ? {"tls-port"} : {"port"}]
     set host $::host
+    set admin_port 0
     if {[dict exists $config bind]} { set host [lindex [dict get $config bind] 0] }
     if {[dict exists $config $port_param]} { set port [dict get $config $port_param] }
+    if {[dict exists $config admin-port]} { set admin_port [lindex [dict get $config admin-port] 0] }
 
     # setup config dict
     dict set srv "config_file" $config_file
     dict set srv "config" $config
     dict set srv "pid" $pid
     dict set srv "host" $host
     dict set srv "port" $port
+    dict set srv "admin-port" $admin_port
     dict set srv "stdout" $stdout
     dict set srv "stderr" $stderr
     dict set srv "unixsocket" $unixsocket

tests/unit/admin-port.tcl

@@ -0,0 +1,36 @@
+tags {external:skip tls:skip} {
+    test {admin-port: CONFIG SET port number should fail} {
+        start_server {} {
+            set avail_port [find_available_port $::baseport $::portcount]
+            set rd [valkey [srv 0 host] [srv 0 admin-port]]
+            assert_error {*can't set immutable config*} {$rd CONFIG SET admin-port $avail_port}
+            $rd PING
+            $rd close
+        }
+    }
+
+    test {admin-port: connection should fail on non-loopback interface} {
+        start_server {} {
+            catch {valkey [get_nonloopback_addr] [srv 0 admin-port]} e
+            assert_match {*connection refused*} $e
+        }
+    }
+
+    test {admin-port: client could connect on admin-port after maxclients reached} {
+        start_server {} {
+            set original_maxclients [lindex [r config get maxclients] 1]
+            r config set maxclients 2
+            set rd [valkey [srv 0 host] [srv 0 port]]
+            assert_match "PONG" [$rd PING]
+            set rd1 [valkey [srv 0 host] [srv 0 port]]
+            catch {$rd1 PING} e
+            assert_match "*ERR max*reached*" $e
+            set rd2 [valkey [srv 0 host] [srv 0 admin-port]]
+            assert_match "PONG" [$rd2 PING]
+            r config set maxclients $original_maxclients
+            $rd close
+            $rd1 close
+            $rd2 close
+        }
+    }
+}

tests/unit/introspection.tcl

@@ -559,6 +559,7 @@ start_server {tags {"introspection"}} {
             req-res-logfile
             client-default-resp
             dual-channel-replication-enabled
+            admin-port
         }
 
         if {!$::tls} {