added simple UDP protocol

1 files changed, 20 insertions, 4 deletions

diff --git a/src/sydra.c b/src/sydra.c
index c7503b6..624ce2e 100644
--- a/src/sydra.c
+++ b/src/sydra.c
@@ -459,6 +459,13 @@ static void udp_remove_client(struct sockaddr_storage *addr, socklen_t addrlen,
   g_free(name);
 }
 
+#define UDP_PROTO_MAGIC "SYDRA:"
+#define UDP_PROTO_MAGIC_LEN (sizeof(UDP_PROTO_MAGIC)-1)
+#define UDP_PROTO_CMD_ADD_CLIENT "add_client\n"
+#define UDP_PROTO_CMD_ADD_CLIENT_LEN (sizeof(UDP_PROTO_CMD_ADD_CLIENT)-1)
+#define UDP_PROTO_CMD_RM_CLIENT "remove_client\n"
+#define UDP_PROTO_CMD_RM_CLIENT_LEN (sizeof(UDP_PROTO_CMD_RM_CLIENT)-1)
+
 static gboolean on_udp_desc_ready(gint fd, GIOCondition cond, gpointer user_data)
 {
   struct udp_sink* sink = (struct udp_sink*)user_data;
@@ -469,7 +476,7 @@ static gboolean on_udp_desc_ready(gint fd, GIOCondition cond, gpointer user_data
 
   struct sockaddr_storage addr;
   socklen_t addrlen = sizeof(addr);
-  char buf[2048];
+  u_int8_t buf[2048];
   ssize_t bytes = recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr *)&addr, &addrlen);
   if(bytes < 1) {
     if(errno == EINTR)
@@ -479,11 +486,20 @@ static gboolean on_udp_desc_ready(gint fd, GIOCondition cond, gpointer user_data
     return FALSE;
   }
 
-      // TODO: parse real packet format
-  if(buf[0] == 'a') {
+  if(bytes < UDP_PROTO_MAGIC_LEN || memcmp(UDP_PROTO_MAGIC, buf, UDP_PROTO_MAGIC_LEN)) {
+    log_printf(DEBUG, "client discovery: ignoring invalid incoming packet");
+    return TRUE;
+  }
+
+  u_int8_t* cmd = &(buf[UDP_PROTO_MAGIC_LEN]);
+  if(bytes == (UDP_PROTO_MAGIC_LEN+UDP_PROTO_CMD_ADD_CLIENT_LEN) &&
+     !memcmp(UDP_PROTO_CMD_ADD_CLIENT, cmd, UDP_PROTO_CMD_ADD_CLIENT_LEN)) {
     udp_add_client(&addr, addrlen, sink);
-  } else {
+  } else if(bytes == (UDP_PROTO_MAGIC_LEN+UDP_PROTO_CMD_RM_CLIENT_LEN) &&
+     !memcmp(UDP_PROTO_CMD_RM_CLIENT, cmd, UDP_PROTO_CMD_RM_CLIENT_LEN)) {
     udp_remove_client(&addr, addrlen, sink);
+  } else {
+    log_printf(DEBUG, "client discovery: ignoring invalid command");
   }
   return TRUE;
 }