Allow sending UDP commands from RetroArch.

docs/retroarch.1

@@ -177,6 +177,16 @@ Clients can connect and disconnect at any time.
 Clients thus cannot interact as player 2.
 For spectating mode to work, both host and clients will need to use this flag.
 
+.TP
+\fB--command CMD\fR
+Sends a command over UDP to an already running RetroArch application, and exit.
+The command is formatted as "COMMAND:HOST:PORT".
+HOST and PORT are both optional. "COMMAND:HOST" will set PORT to
+"network_cmd_port" default setting.
+If only "COMMAND" is used, HOST and PORT will be assumed to be "localhost" and "network_cmd_port" respectively.
+
+The available commands are listed if "COMMAND" is invalid.
+
 .TP
 \fB--nick NICK\fR
 Pick a nickname for use with netplay.

network_cmd.c

@@ -17,9 +17,13 @@
 #include "network_cmd.h"
 #include "driver.h"
 #include "general.h"
+#include "compat/strl.h"
+#include "compat/posix_string.h"
 #include <stdio.h>
 #include <string.h>
 
+#define DEFAULT_NETWORK_CMD_PORT 55355
+
 struct network_cmd
 {
    int fd;
@@ -42,6 +46,8 @@ network_cmd_t *network_cmd_new(uint16_t port)
    if (!handle)
       return NULL;
 
+   RARCH_LOG("Bringing up command interface on port %hu.\n", (unsigned short)port);
+
    handle->fd = -1;
 
    struct addrinfo hints, *res = NULL;
@@ -76,7 +82,6 @@ network_cmd_t *network_cmd_new(uint16_t port)
    }
 
    freeaddrinfo(res);
-
    return handle;
 
 error:
@@ -190,3 +195,111 @@ void network_cmd_pre_frame(network_cmd_t *handle)
    }
 }
 
+static bool send_udp_packet(const char *host, uint16_t port, const char *msg)
+{
+   struct addrinfo hints, *res = NULL;
+   memset(&hints, 0, sizeof(hints));
+#if defined(_WIN32) || defined(HAVE_SOCKET_LEGACY)
+   hints.ai_family   = AF_INET;
+#else
+   hints.ai_family   = AF_UNSPEC;
+#endif
+   hints.ai_socktype = SOCK_DGRAM;
+
+   int fd = -1;
+   bool ret = true;
+   char port_buf[16];
+
+   snprintf(port_buf, sizeof(port_buf), "%hu", (unsigned short)port);
+   if (getaddrinfo(host, port_buf, &hints, &res) < 0)
+      return false;
+
+   // Send to all possible targets.
+   // "localhost" might resolve to several different IPs.
+   const struct addrinfo *tmp = res;
+   while (tmp)
+   {
+      fd = socket(tmp->ai_family, tmp->ai_socktype, tmp->ai_protocol);
+      if (fd < 0)
+      {
+         ret = false;
+         goto end;
+      }
+
+      ssize_t len = strlen(msg);
+      ssize_t ret = sendto(fd, msg, len, 0, tmp->ai_addr, tmp->ai_addrlen);
+      if (ret < len)
+      {
+         ret = false;
+         goto end;
+      }
+
+      close(fd);
+      fd = -1;
+      tmp = tmp->ai_next;
+   }
+
+end:
+   freeaddrinfo(res);
+   if (fd >= 0)
+      close(fd);
+   return ret;
+}
+
+static bool verify_command(const char *cmd)
+{
+   for (unsigned i = 0; i < sizeof(map) / sizeof(map[0]); i++)
+   {
+      if (strcmp(map[i].str, cmd) == 0)
+         return true;
+   }
+
+   RARCH_ERR("Command \"%s\" is not recognized by RetroArch.\n", cmd);
+   RARCH_ERR("\tValid commands:\n");
+   for (unsigned i = 0; i < sizeof(map) / sizeof(map[0]); i++)
+      RARCH_ERR("\t\t%s\n", map[i].str);
+
+   return false;
+}
+
+bool network_cmd_send(const char *cmd_)
+{
+   char *command = strdup(cmd_);
+   if (!command)
+      return false;
+
+   bool old_verbose = g_extern.verbose;
+   g_extern.verbose = true;
+
+   const char *cmd = NULL;
+   const char *host = NULL;
+   const char *port_ = NULL;
+   uint16_t port = DEFAULT_NETWORK_CMD_PORT;
+
+   cmd = strtok(command, ":");
+   if (cmd)
+      host = strtok(NULL, ":");
+   if (host)
+      port_ = strtok(NULL, ":");
+
+   if (!host)
+   {
+#ifdef _WIN32
+      host = "127.0.0.1";
+#else
+      host = "localhost";
+#endif
+   }
+
+   if (port_)
+      port = strtoul(port_, NULL, 0);
+
+   RARCH_LOG("Sending command: \"%s\" to %s:%hu\n", cmd, host, (unsigned short)port);
+
+   bool ret = verify_command(cmd) && send_udp_packet(host, port, cmd);
+   free(command);
+
+   g_extern.verbose = old_verbose;
+   return ret;
+}
+

network_cmd.h

@@ -28,5 +28,7 @@ void network_cmd_pre_frame(network_cmd_t *handle);
 void network_cmd_set(network_cmd_t *handle, unsigned id);
 bool network_cmd_get(network_cmd_t *handle, unsigned id);
 
+bool network_cmd_send(const char *cmd);
+
 #endif
 

retroarch.c

@@ -539,6 +539,10 @@ static void print_help(void)
    puts("\t\tHowever, the client will not be able to play. Multiple clients can connect to the host.");
    puts("\t--nick: Picks a nickname for use with netplay. Not mandatory.");
 #endif
+#ifdef HAVE_NETWORK_CMD
+   puts("\t--command: Sends a command over UDP to an already running RetroArch process.");
+   puts("\t\tAvailable commands are listed if command is invalid.");
+#endif
 
 #ifdef HAVE_FFMPEG
    puts("\t-r/--record: Path to record video file.\n\t\tUsing .mkv extension is recommended.");
@@ -695,6 +699,9 @@ static void parse_input(int argc, char *argv[])
       { "port", 1, &val, 'p' },
       { "spectate", 0, &val, 'S' },
       { "nick", 1, &val, 'N' },
+#endif
+#ifdef HAVE_NETWORK_CMD
+      { "command", 1, &val, 'c' },
 #endif
       { "ups", 1, NULL, 'U' },
       { "bps", 1, &val, 'B' },
@@ -892,8 +899,6 @@ static void parse_input(int argc, char *argv[])
 
          case 'F':
             g_extern.netplay_sync_frames = strtol(optarg, NULL, 0);
-            if (g_extern.netplay_sync_frames > 16)
-               g_extern.netplay_sync_frames = 16;
             break;
 #endif
 
@@ -929,6 +934,15 @@ static void parse_input(int argc, char *argv[])
                   break;
 #endif
 
+#ifdef HAVE_NETWORK_CMD
+               case 'c':
+                  if (network_cmd_send(optarg))
+                     exit(0);
+                  else
+                     rarch_fail(1, "network_cmd_send()");
+                  break;
+#endif
+
                case 'B':
                   strlcpy(g_extern.bps_name, optarg, sizeof(g_extern.bps_name));
                   g_extern.bps_pref = true;