Implement patty_client_ping()

Implement patty_client_ping() to provide a means of testing if a client
connection is still active

include/patty/client.h

@@ -3,6 +3,7 @@
 
 enum patty_client_call {
     PATTY_CLIENT_NONE,
+    PATTY_CLIENT_PING,
     PATTY_CLIENT_SOCKET,
     PATTY_CLIENT_SETSOCKOPT,
     PATTY_CLIENT_BIND,
@@ -29,6 +30,11 @@ patty_client *patty_client_new(const char *path);
 
 void patty_client_destroy(patty_client *client);
 
+/*
+ * ping()
+ */
+int patty_client_ping(patty_client *client);
+
 /*
  * socket()
  */

src/client.c

@@ -101,6 +101,32 @@ void patty_client_destroy(patty_client *client) {
     free(client);
 }
 
+int patty_client_ping(patty_client *client) {
+    int call = PATTY_CLIENT_PING,
+        pong;
+
+    ssize_t len;
+
+    if ((len = write(client->fd, &call, sizeof(call))) < 0 || len == 0) {
+        goto done;
+    }
+
+    if ((len = read(client->fd, &pong, sizeof(pong))) < 0 || len == 0) {
+        goto done;
+    }
+
+    return pong;
+
+done:
+    if (errno == 0 || errno == EIO) {
+        errno = 0;
+
+        return 0;
+    }
+
+    return -1;
+}
+
 int patty_client_socket(patty_client *client,
                         int proto,
                         int type) {

src/server.c

@@ -563,6 +563,12 @@ static int respond_connect(int client, int ret, int eno) {
     return write(client, &response, sizeof(response));
 }
 
+static int server_ping(patty_ax25_server *server, int client) {
+    int pong = 1;
+
+    return write(client, &pong, sizeof(pong));
+}
+
 static int server_socket(patty_ax25_server *server, int client) {
     patty_client_socket_request request;
     patty_client_socket_response response;
@@ -981,6 +987,7 @@ error_io:
 
 static patty_ax25_server_call server_calls[PATTY_CLIENT_CALL_COUNT] = {
     NULL,
+    server_ping,
     server_socket,
     server_setsockopt,
     server_bind,