2 files changed, 39 insertions, 6 deletions

diff --git a/shared/rcon-protocol.c b/shared/rcon-protocol.c
index 0cf73fc..1941662 100644
--- a/shared/rcon-protocol.c
+++ b/shared/rcon-protocol.c
@@ -75,6 +75,35 @@ static void write_end(char **pos, size_t *len)
 		*len += RCON_END_LEN;
 }
 
+bool rcon_protocol_verify_response(int32_t id_sent, int32_t id_recv,
+				   enum rcon_packet_type t_sent,
+				   enum rcon_packet_type t_recv,
+				   const char **error)
+{
+	if (t_sent == RCON_PACKET_LOGIN) {
+		if (t_recv != RCON_PACKET_LOGIN_RESPONSE) {
+			*error = "invalid reply id";
+			return false;
+		} else if (id_recv == RCON_PACKET_LOGIN_FAIL_ID) {
+			*error = "login failure";
+			return false;
+		} else if (id_recv != id_sent) {
+			*error = "invalid reply id";
+			return false;
+		}
+	} else {
+		if (t_recv != RCON_PACKET_RESPONSE) {
+			*error = "invalid reply type";
+			return false;
+		} else if (id_recv != id_sent) {
+			*error = "invalid reply id";
+			return false;
+		}
+	}
+
+	return true;
+}
+
 bool rcon_protocol_create_packet(char *buf, size_t len, size_t *rlen,
 				 int32_t reqid, enum rcon_packet_type type,
 				 const char *msg)
diff --git a/shared/rcon-protocol.h b/shared/rcon-protocol.h
index b3aea98..593a43f 100644
--- a/shared/rcon-protocol.h
+++ b/shared/rcon-protocol.h
@@ -4,14 +4,13 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-/* FIXME: FAIL is an id, not type, LOGIN_OK should be LOGIN_RESPONSE */
 /* clang-format off */
+#define RCON_PACKET_LOGIN_FAIL_ID   -1
 enum rcon_packet_type {
-	RCON_PACKET_LOGIN	= 3,
-	RCON_PACKET_LOGIN_OK	= 2,
-	RCON_PACKET_LOGIN_FAIL	= -1,
-	RCON_PACKET_COMMAND	= 2,
-	RCON_PACKET_RESPONSE	= 0,
+	RCON_PACKET_LOGIN	   = 3,
+	RCON_PACKET_LOGIN_RESPONSE = 2,
+	RCON_PACKET_COMMAND	   = 2,
+	RCON_PACKET_RESPONSE	   = 0,
 };
 /* clang-format on */
 
@@ -30,6 +29,11 @@ static inline size_t rcon_protocol_packet_len(size_t msglen)
 	return (RCON_PKT_MIN_LEN + msglen);
 }
 
+bool rcon_protocol_verify_response(int32_t id_sent, int32_t id_recv,
+				   enum rcon_packet_type t_sent,
+				   enum rcon_packet_type t_recv,
+				   const char **error);
+
 bool rcon_protocol_create_packet(char *buf, size_t len, size_t *rlen,
 				 int32_t reqid, enum rcon_packet_type type,
 				 const char *msg);