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socket_get_option

NAME​

socket_get_option - get socket option values

SYNOPSIS​

mixed socket_get_option(int socket, int option);

DESCRIPTION​

Retrieves the current value of a socket option. This efun allows you to
query socket configuration parameters, particularly those related to
TLS/SSL connections.

ARGUMENTS​

  • socket - The socket descriptor returned by socket_create()
  • option - The option constant to query (see Options below)

OPTIONS​

SO_TLS_VERIFY_PEER (1)​

Returns whether TLS peer certificate verification is enabled.

  • Returns: integer
    • 0 - Peer verification disabled
    • 1 - Peer verification enabled

SO_TLS_SNI_HOSTNAME (2)​

Returns the Server Name Indication (SNI) hostname set for the socket.

  • Returns: string
    • The SNI hostname, or an empty string if not set

RETURN VALUE​

The return type depends on the option being queried:

  • SO_TLS_VERIFY_PEER returns an integer (0 or 1)
  • SO_TLS_SNI_HOSTNAME returns a string

ERRORS​

  • Generates an error if the socket descriptor is invalid
  • Generates an error if the option is unknown

EXAMPLES​

Query socket TLS settings:

void check_socket_config(int sock) {
    int verify_peer;
    string sni_hostname;

    verify_peer = socket_get_option(sock, SO_TLS_VERIFY_PEER);
    sni_hostname = socket_get_option(sock, SO_TLS_SNI_HOSTNAME);

    write(sprintf("Socket %d TLS verification: %s\n",
                  sock, verify_peer ? "enabled" : "disabled"));
    write(sprintf("Socket %d SNI hostname: %s\n",
                  sock, sni_hostname));
}

Verify socket configuration before connecting:

void safe_connect(string hostname, int port) {
    int sock;

    sock = socket_create(STREAM_TLS, "read_callback", "close_callback");
    socket_set_option(sock, SO_TLS_VERIFY_PEER, 1);
    socket_set_option(sock, SO_TLS_SNI_HOSTNAME, hostname);

    // Verify settings were applied
    if (socket_get_option(sock, SO_TLS_VERIFY_PEER) != 1) {
        write("Warning: TLS verification not enabled!\n");
        return;
    }

    if (socket_get_option(sock, SO_TLS_SNI_HOSTNAME) != hostname) {
        write("Warning: SNI hostname mismatch!\n");
        return;
    }

    socket_connect(sock, hostname + ":" + port, "connected_callback");
}

Debug socket configuration:

void debug_socket(int sock) {
    mapping opts = ([]);

    opts["verify_peer"] = socket_get_option(sock, SO_TLS_VERIFY_PEER);
    opts["sni_hostname"] = socket_get_option(sock, SO_TLS_SNI_HOSTNAME);

    write("Socket configuration:\n" + dump_value(opts));
}

Conditional behavior based on socket settings:

void handle_connection(int sock) {
    if (socket_get_option(sock, SO_TLS_VERIFY_PEER) == 0) {
        log_message("WARNING: Connecting without certificate verification");
        // Maybe add additional validation or logging
    }

    // Proceed with connection logic
    socket_connect(sock, "server.example.com:443", "on_connect");
}

SEE ALSO​

NOTES​

Option Constants: The option constants should be defined in your mudlib include files:

#define SO_TLS_VERIFY_PEER    1
#define SO_TLS_SNI_HOSTNAME   2

Default Values:

  • SO_TLS_VERIFY_PEER defaults to 1 (verification enabled) for security
  • SO_TLS_SNI_HOSTNAME defaults to an empty string (not set)

Use Cases:

  • Debugging socket configuration
  • Validating security settings before connection
  • Conditional logic based on socket setup
  • Logging and auditing connection parameters

AVAILABILITY​

Added in commit 1fd7f61 (2023). Requires the sockets package to be enabled.