Create a shared mc protocol implementation and use it in the proxy and cmd line tool

1 files changed, 19 insertions, 239 deletions

diff --git a/minecproxy/idle.c b/minecproxy/idle.c
index 8fcb934..70d8099 100644
--- a/minecproxy/idle.c
+++ b/minecproxy/idle.c
@@ -11,195 +11,32 @@
 #include "server.h"
 #include "idle.h"
 #include "ptimer.h"
+#include "mc-protocol.h"
 
 struct idle {
 	struct ptimer_task ptask;
 	struct uring_task task;
 };
 
-static inline void
-write_byte(char **pos, char byte)
-{
-	assert_return(pos && *pos);
-
-	**pos = byte;
-	(*pos)++;
-}
-
-#define MC_HELO 0x00
-#define MC_NEXT_STATE_STATUS 0x01
-#define MC_GET_STATUS 0x00
-#define MC_VARINT_MAX_BYTES 5
-#define MC_STATUS_REPLY 0x00
-#define MC_UNDEFINED_VERSION -1
-
-static inline void
-write_varint(char **pos, int32_t orig)
-{
-	assert_return(pos && *pos);
-
-	uint32_t val = (uint32_t)orig;
-
-	while (val) {
-		**pos = val & 0x7f;
-		val >>= 7;
-		if (val > 0)
-			**pos |= 0x80;
-		(*pos)++;
-	}
-}
-
-/*
- * return value:
- * positive = varint parsed
- * zero = need more bytes
- * negative = error
- */
-static inline int
-read_varint(char **pos, size_t *remain, int32_t *res)
-{
-	unsigned consumed;
-	uint32_t val = 0;
-
-	assert_return(pos && *pos && remain && res, -1);
-
-	for (consumed = 1; consumed <= *remain; consumed++) {
-		uint32_t tmp;
-
-		tmp = **pos & 0x7f;
-		val += (tmp << (7 * (consumed - 1)));
-		(*pos)++;
-
-		if (!(tmp & 0x80))
-			break;
-	}
-
-	if (consumed > *remain)
-		return 0;
-	else if (consumed > MC_VARINT_MAX_BYTES)
-		return -1;
-
-	*remain -= consumed;
-	*res = (int32_t)val;
-	return 1;
-}
-
-static inline void
-write_bytes(char **pos, const char *bytes, size_t n)
-{
-	assert_return(pos && *pos && bytes && n > 0);
-
-	memcpy(*pos, bytes, n);
-	*pos += n;
-}
-
-static inline void
-write_str(char **pos, const char *str)
-{
-	size_t len;
-
-	assert_return(pos && *pos && !empty_str(str));
-
-	len = strlen(str);
-	write_varint(pos, len);
-	write_bytes(pos, str, len);
-}
-
-static inline void
-write_cmd(char **pos, const char *begin, const char *end)
-{
-	assert_return(pos && *pos && begin && end && end > begin);
-
-	write_varint(pos, end - begin);
-	write_bytes(pos, begin, end - begin);
-}
-
 static int
 idle_check_handshake_complete(struct uring_task *task, _unused_ int res)
 {
-	size_t remain;
-	char *pos;
-	int32_t mclen;
 	int r;
 
 	assert_return(task, -EINVAL);
 	assert_task_alive_or(DBG_IDLE, task, return -EINTR);
 
-	remain = task->tbuf->len;
-	pos = task->tbuf->buf;
-
-	r = read_varint(&pos, &remain, &mclen);
-	if (r < 0) {
-		error("failed to parse message length");
-		return -EINVAL;
-	} else if (r == 0) {
-		return 0;
-	} else if (mclen < 2) {
-		error("short MC message");
-		return -EINVAL;
-	}
-
-	if (mclen < remain) {
-		debug(DBG_IDLE, "short MC message - len: %" PRIi32 ", remain: %zu",
-		      mclen, remain);
-		return 0;
-	} 
-
-	debug(DBG_IDLE, "Complete message");
-	return 1;
-}
-
-#define ONLINE_NEEDLE "\"online\""
-static int
-get_player_count(const char *pos, size_t remain)
-{
-	/*
-	 * Example JSON (line breaks added):
-	 * {"description":{
-	 *	"text":"A Minecraft Server"},
-	 *	"players":{"max":20,"online":0},
-	 *	"version":{"name":"1.15.2","protocol":578}
-	 * }
-	 */
-	char *online;
-	char *end;
-	unsigned count;
-
-	assert_return(pos && remain > 0, -1);
-
-	online = memmem(pos, remain, ONLINE_NEEDLE, STRLEN(ONLINE_NEEDLE));
-	if (!online) {
-		error("could not find online count in JSON");
-		return -1;
-	}
-
-	remain -= (online - pos);
-
-	end = memchr(online, '}', remain);
-	if (!end) {
-		error("could not parse JSON (no end)");
-		return -1;
-	}
-	*end = '\0';
-
-	if (sscanf(online, ONLINE_NEEDLE " : %u", &count) != 1) {
-		error("could not parse JSON (online count)");
-		return -1;
-	}
-
-	return count;
+	r = mc_is_handshake_complete(task->tbuf->buf, task->tbuf->len);
+	debug(DBG_IDLE, "mc_is_handshake_complete returned %i", r);
+	return r;
 }
 
 static void
 idle_check_handshake_reply(struct uring_task *task, int res)
 {
 	struct server *server = container_of(task, struct server, idle_task);
-	int32_t mclen;
-	int32_t jsonlen;
-	char *pos;
-	size_t remain;
+	unsigned online, max;
 	int player_count = -1;
-	int r;
 
 	assert_return(task);
 	assert_task_alive(DBG_IDLE, task);
@@ -208,55 +45,12 @@ idle_check_handshake_reply(struct uring_task *task, int res)
 	if (res < 0)
 		goto out;
 
-	/*
-	fprintf(stderr, "Received MC message (%i bytes):", res);
-	for (int i = 0; i < res; i++)
-		fprintf(stderr, "0x%02hhx ", idle->remotebuf[i]);
-	fprintf(stderr, "n");
-	*/
-
-	remain = server->idle_buf.len;
-	pos = server->idle_buf.buf;
-
-	r = read_varint(&pos, &remain, &mclen);
-	if (r <= 0 || mclen < 2 || mclen < remain) {
-		/* Should not happen since the msg has been checked already */
-		error("invalid message");
-		goto out;
-	}
-
-	debug(DBG_IDLE, "MC message - len: %" PRIi32 ", remain: %zu",
-	      mclen, remain);
-
-	if (*pos != MC_STATUS_REPLY) {
-		error("unknown server reply (0x%02hhx)", *pos);
-		goto out;
-	}
-
-	pos++;
-	remain--;
-
-	r = read_varint(&pos, &remain, &jsonlen);
-	if (r <= 0) {
-		error("could not read JSON length");
-		goto out;
-	}
-
-	debug(DBG_IDLE, "MC - json len: %" PRIi32 ", remain: %zu",
-	      jsonlen, remain);
-
-	if (jsonlen < remain) {
-		error("invalid JSON length");
-		goto out;
-	}
-
-	/*
-	fprintf(stderr, "JSON: ");
-	for (int i = 0; i < jsonlen; i++)
-		fprintf(stderr, "%c", pos[i]);
-	*/
-
-	player_count = get_player_count(pos, remain);
+	if (mc_protocol_parse_status_reply(server->idle_buf.buf,
+					   server->idle_buf.len,
+					   &online, &max))
+		player_count = online;
+	else
+		error("failed to parse reply");
 
 out:
 	uring_task_close_fd(task);
@@ -284,31 +78,17 @@ idle_check_handshake_sent(struct uring_task *task, int res)
 void
 idle_check_get_player_count(struct server *server, struct connection *conn)
 {
-	char buf[1024];
-	char *pos;
-	char *cmdbuf = server->idle_buf.buf;
-	uint16_t port;
-	char hostname[INET6_ADDRSTRLEN];
-
 	assert_return(server && conn && server->idle_task.priv);
 
-	port = saddr_port(&conn->remote);
-	saddr_addr(&conn->remote, hostname, sizeof(hostname));
-
-	pos = buf;
-	write_byte(&pos, MC_HELO);
-	write_varint(&pos, MC_UNDEFINED_VERSION);
-	write_str(&pos, hostname);
-	write_byte(&pos, (port >> 8) & 0xff);
-	write_byte(&pos, (port >> 0) & 0xff);
-	write_byte(&pos, MC_NEXT_STATE_STATUS);
-	write_cmd(&cmdbuf, buf, pos);
-
-	pos = buf;
-	write_byte(&pos, MC_GET_STATUS);
-	write_cmd(&cmdbuf, buf, pos);
+	if (!mc_protocol_create_status_request(server->idle_buf.buf,
+					       sizeof(server->idle_buf.buf),
+					       &server->idle_buf.len,
+					       &conn->remote)) {
+		error("failed to create mc request");
+		/* FIXME: is this enough? */
+		return;
+	}
 
-	server->idle_buf.len = (cmdbuf - server->idle_buf.buf);
 	debug(DBG_IDLE, "sending MC message (%zu bytes)", server->idle_buf.len);
 
 	uring_tbuf_write(&server->idle_task, idle_check_handshake_sent);