Split out rcon protocol handling to separate file

4 files changed, 258 insertions, 177 deletions

diff --git a/meson.build b/meson.build
index ca38341..3d82301 100644
--- a/meson.build
+++ b/meson.build
@@ -40,6 +40,7 @@ mcproxy_sources = [
 	'server-proxy.c',
 	'server-config.c',
 	'server-rcon.c',
+	'rcon-protocol.c',
 	'announce.c',
 	'config-parser.c',
 	'idle.c',
diff --git a/rcon-protocol.c b/rcon-protocol.c
new file mode 100644
index 0000000..0ea1245
--- /dev/null
+++ b/rcon-protocol.c
@@ -0,0 +1,185 @@
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+
+#include "rcon-protocol.h"
+
+static int32_t
+read_int(const char **pos, size_t *len)
+{
+	uint32_t val;
+	const char *p;
+
+	if (!pos || !*pos)
+		return 0;
+
+	if (len && *len < RCON_INT_LEN)
+		return 0;
+
+	p = *pos;
+	val  = ((uint8_t)p[0] <<  0);
+	val += ((uint8_t)p[1] <<  8);
+	val += ((uint8_t)p[2] << 16);
+	val += ((uint8_t)p[3] << 24);
+
+	*pos += RCON_INT_LEN;
+	if (len)
+		*len -= RCON_INT_LEN;
+
+	return (int32_t)val;
+}
+
+static void
+write_int(char **pos, size_t *len, int32_t orig)
+{
+	uint32_t val = (uint32_t)orig;
+	char *p;
+
+	if (!pos || !*pos)
+		return;
+
+	p = *pos;
+	p[0] = (val >>  0) & 0xff;
+	p[1] = (val >>  8) & 0xff;
+	p[2] = (val >> 16) & 0xff;
+	p[3] = (val >> 24) & 0xff;
+
+	*pos += RCON_INT_LEN;
+	if (len)
+		*len += RCON_INT_LEN;
+}
+
+static void
+write_str(char **pos, size_t *len, const char *str, size_t slen)
+{
+	if (!pos || !*pos || !str || *str == '\0' || slen < 1)
+		return;
+
+	memcpy(*pos, str, slen);
+	*pos += slen;
+	if (len)
+		*len += slen;
+}
+
+static void
+write_end(char **pos, size_t *len)
+{
+	char *p;
+
+	if (!pos || !*pos)
+		return;
+
+	p = *pos;
+	p[0] = 0x00;
+	p[1] = 0x00;
+
+	*pos += RCON_END_LEN;
+	if (len)
+		*len += RCON_END_LEN;
+}
+
+bool
+rcon_protocol_create_packet(char *buf, size_t len, size_t *rlen, int32_t reqid,
+			    enum rcon_packet_type type, const char *msg)
+{
+	size_t plen, msglen;
+	char *pos;
+
+	if (!buf || !rlen || !msg || msg[0] == '\0')
+		return false;
+
+	msglen = strlen(msg);
+	if (len < rcon_protocol_packet_len(msglen))
+		return false;
+
+	/* Body */
+	pos = buf + RCON_HDR_LEN;
+	plen = RCON_HDR_LEN;
+	write_int(&pos, &plen, reqid);
+	write_int(&pos, &plen, type);
+	write_str(&pos, &plen, msg, msglen);
+	write_end(&pos, &plen);
+
+	/* Header (length of body) */
+	pos = buf;
+	write_int(&pos, NULL, plen - RCON_HDR_LEN);
+
+	*rlen = plen;
+	return true;
+}
+
+/*
+ * Returns:
+ * < 0 = error
+ *   0 = packet not complete
+ * > 0 = packet complete (length)
+ */
+int32_t
+rcon_protocol_packet_complete(const char *buf, size_t len)
+{
+	const char *pos;
+	int32_t plen;
+
+	if (!buf)
+		return -1;
+
+	if (len < RCON_PKT_MIN_LEN)
+		return 0;
+
+	pos = buf;
+	plen = read_int(&pos, NULL) + RCON_HDR_LEN;
+
+	if (plen < RCON_HDR_LEN)
+		/* Read a negative int */
+		return -1;
+
+	if (len < plen)
+		return 0;
+	else
+		return plen;
+}
+
+bool
+rcon_protocol_read_packet(const char *buf, size_t len, int32_t *id, int32_t *type,
+			  const char **rmsg, const char **error)
+{
+	const char *pos;
+	int32_t plen;
+
+	if (!error)
+		return false;
+
+	if (!buf || !id || !type || !rmsg) {
+		*error = "invalid arguments";
+		return false;
+	}
+
+	plen = rcon_protocol_packet_complete(buf, len);
+	*error = "invalid packet length";
+	if (plen < RCON_PKT_MIN_LEN)
+		return false;
+
+	pos = buf + RCON_HDR_LEN;
+	len -= RCON_HDR_LEN;
+
+	*id = read_int(&pos, &len);
+	*type = read_int(&pos, &len);
+	*rmsg = NULL;
+
+	if (len < RCON_END_LEN)
+		return false;
+	else if (len > RCON_END_LEN) {
+		*rmsg = pos;
+		pos += len - RCON_END_LEN;
+		len = RCON_END_LEN;
+	}
+
+	if (pos[0] != '\0' || pos[1] != '\0') {
+		*error = "invalid trailer";
+		return false;
+	}
+
+	*error = NULL;
+	return true;
+}
diff --git a/rcon-protocol.h b/rcon-protocol.h
new file mode 100644
index 0000000..fd83d79
--- /dev/null
+++ b/rcon-protocol.h
@@ -0,0 +1,38 @@
+#ifndef foorconprotocolhfoo
+#define foorconprotocolhfoo
+
+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,
+};
+
+#define RCON_INT_LEN 4
+
+#define RCON_END_LEN 2
+
+#define RCON_HDR_LEN 4
+
+/* header + reqid + type + end */
+#define RCON_PKT_MIN_LEN (RCON_HDR_LEN + 2 * RCON_INT_LEN + RCON_END_LEN)
+
+static inline size_t
+rcon_protocol_packet_len(size_t msglen)
+{
+	/* header + reqid + type + msg + end */
+	return (RCON_PKT_MIN_LEN + msglen);
+}
+
+bool rcon_protocol_create_packet(char *buf, size_t len, size_t *rlen,
+				 int32_t reqid, enum rcon_packet_type type,
+				 const char *msg);
+
+int32_t rcon_protocol_packet_complete(const char *buf, size_t len);
+
+bool rcon_protocol_read_packet(const char *buf, size_t len, int32_t *id,
+			       int32_t *type, const char **rmsg,
+			       const char **error);
+
+#endif
diff --git a/server-rcon.c b/server-rcon.c
index 710d969..1f8ef70 100644
--- a/server-rcon.c
+++ b/server-rcon.c
@@ -14,181 +14,42 @@
 #include "uring.h"
 #include "server.h"
 #include "server-rcon.h"
-
-static int32_t
-read_int(char **pos, size_t *len)
-{
-	uint32_t val;
-	char *p;
-
-	assert_return(pos && *pos, 0);
-
-	if (len && *len < 4)
-		return 0;
-
-	p = *pos;
-	val  = ((uint8_t)p[0] <<  0);
-	val += ((uint8_t)p[1] <<  8);
-	val += ((uint8_t)p[2] << 16);
-	val += ((uint8_t)p[3] << 24);
-
-	*pos += 4;
-	if (len)
-		*len -= 4;
-
-	return (int32_t)val;
-}
-
-static void
-write_int(char **pos, size_t *len, int32_t orig)
-{
-	uint32_t val = (uint32_t)orig;
-	char *p;
-
-	assert_return(pos && *pos);
-
-	p = *pos;
-	p[0] = (val >>  0) & 0xff;
-	p[1] = (val >>  8) & 0xff;
-	p[2] = (val >> 16) & 0xff;
-	p[3] = (val >> 24) & 0xff;
-
-	*pos += 4;
-	if (len)
-		*len += 4;
-}
-
-static void
-write_str(char **pos, size_t *len, const char *str)
-{
-	size_t towrite;
-
-	assert_return(pos && *pos && !empty_str(str));
-
-	towrite = strlen(str);
-	memcpy(*pos, str, towrite);
-	*pos += towrite;
-	if (len)
-		*len += towrite;
-}
-
-static void
-write_end(char **pos, size_t *len)
-{
-	char *p;
-
-	assert_return(pos && *pos);
-
-	p = *pos;
-	p[0] = 0x00;
-	p[1] = 0x00;
-
-	*pos += 2;
-	if (len)
-		*len += 2;
-}
-
-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,
-};
-
-static void
-rcon_create_packet(struct uring_task_buf *tbuf, int32_t reqid,
-		   enum rcon_packet_type type, const char *msg)
-{
-	char *pos;
-
-	assert_return(tbuf && !empty_str(msg));
-
-	/* Body */
-	pos = &tbuf->buf[4];
-	tbuf->len = 4;
-	write_int(&pos, &tbuf->len, reqid);
-	write_int(&pos, &tbuf->len, type);
-	write_str(&pos, &tbuf->len, msg);
-	write_end(&pos, &tbuf->len);
-
-	/* Header (length of body) */
-	pos = &tbuf->buf[0];
-	write_int(&pos, NULL, tbuf->len - 4);
-
-	debug(DBG_RCON, "created packet (reqid: %" PRIi32 ", type %" PRIi32 
-	      ", len %zu, payload: %s)",
-	      reqid, type, tbuf->len, msg);
-}
+#include "rcon-protocol.h"
 
 static int
 rcon_packet_complete(struct uring_task *task, int res)
 {
-	char *pos;
-	size_t len;
-	int32_t plen;
-
-	assert_return(task, 0);
+	assert_return(task, -EINVAL);
 	assert_task_alive_or(DBG_RCON, task, return -EINTR);
 
-	pos = task->tbuf->buf;
-	len = task->tbuf->len;
-	if (task->tbuf->len < 14)
-		return 0;
-
-	plen = read_int(&pos, &len);
-	debug(DBG_RCON, "reply size: %zu bytes, packet size %" PRIi32,
-	      task->tbuf->len, plen + 4);
-
-	if (task->tbuf->len < plen + 4)
-		return 0;
-	else
-		return 1;
+	return rcon_protocol_packet_complete(task->tbuf->buf, task->tbuf->len);
 }
 
 static bool
-rcon_read_packet(struct uring_task_buf *tbuf, int32_t *id,
-		 int32_t *type, char **rmsg)
+rcon_check_reply(struct uring_task *task, int res, int32_t *id,
+		 int32_t *type, const char **msg)
 {
-	char *pos;
-	size_t len;
-	int32_t plen;
-
-	assert_return(tbuf && id && type && rmsg, false);
-
-	pos = tbuf->buf;
-	len = tbuf->len;
-	plen = read_int(&pos, &len);
-	*id = read_int(&pos, &len);
-	*type = read_int(&pos, &len);
-	*rmsg = NULL;
-
-	if (plen < 10) {
-		error("invalid packet length: %" PRIi32, plen);
-		return false;
-	}
-
-	if (len > 2) {
-		*rmsg = pos;
-		pos += len - 2;
-		len = 2;
-	}
+	struct server *server = container_of(task, struct server, rcon_task);
+	const char *error;
 
-	if (len < 2) {
-		error("short message");
-		return false;
+	if (res < 0) {
+		error("rcon(%s): reading reply failed, res: %i",
+		      server->name, res);
+		goto error;
 	}
 
-	if (pos[0] != '\0' || pos[1] != '\0') {
-		error("invalid trailer");
-		return false;
+	if (!rcon_protocol_read_packet(task->tbuf->buf, task->tbuf->len,
+				       id, type, msg, &error)) {
+		error("rcon(%s): failed to parse packet: %s",
+		      server->name, error);
+		goto error;
 	}
 
-	debug(DBG_RCON, "response - len: %" PRIi32 ", id: %" PRIi32
-	      ", type: %" PRIi32 ", msg: %s",
-	      plen, *id, *type, *rmsg);
-
 	return true;
+
+error:
+	uring_task_close_fd(task);
+	return false;
 }
 
 static void
@@ -197,18 +58,13 @@ rcon_stop_reply(struct uring_task *task, int res)
 	struct server *server = container_of(task, struct server, rcon_task);
 	int32_t id;
 	int32_t type;
-	char *msg;
+	const char *msg;
 
 	assert_return(task);
 	assert_task_alive(DBG_RCON, task);
 
-	if (res < 0) {
-		error("rcon(%s): reading stop cmd reply failed, res: %i",
-		      server->name, res);
-		goto out;
-	}
-
-	rcon_read_packet(task->tbuf, &id, &type, &msg);
+	if (!rcon_check_reply(task, res, &id, &type, &msg))
+		return;
 
 	if (id != 2) {
 		error("rcon(%s): stop cmd failed, reply id (%" PRIi32 ")",
@@ -251,18 +107,13 @@ rcon_login_reply(struct uring_task *task, int res)
 	struct server *server = container_of(task, struct server, rcon_task);
 	int32_t id;
 	int32_t type;
-	char *msg;
+	const char *msg;
 
 	assert_return(task);
 	assert_task_alive(DBG_RCON, task);
 
-	if (res < 0) {
-		error("rcon(%s): reading login reply failed, res: %i",
-		      server->name, res);
-		goto error;
-	}
-
-	rcon_read_packet(task->tbuf, &id, &type, &msg);
+	if (!rcon_check_reply(task, res, &id, &type, &msg))
+		return;
 
 	if (id != 1) {
 		error("rcon(%s): login failed, reply id (%" PRIi32 ")",
@@ -279,7 +130,9 @@ rcon_login_reply(struct uring_task *task, int res)
 	}
 
 	debug(DBG_RCON, "rcon(%s): login successful", server->name);
-	rcon_create_packet(task->tbuf, 2, RCON_PACKET_COMMAND, "stop");
+	rcon_protocol_create_packet(task->tbuf->buf, sizeof(task->tbuf->buf),
+				    &task->tbuf->len, 2, RCON_PACKET_COMMAND,
+				    "stop");
 	uring_tbuf_write(task, rcon_stop_sent);
 	return;
 
@@ -319,7 +172,11 @@ rcon_connected_cb(struct connection *conn, bool connected)
 		return;
 	}
 
-	rcon_create_packet(&server->rcon_tbuf, 1, RCON_PACKET_LOGIN, server->rcon_password);
+	rcon_protocol_create_packet(server->rcon_tbuf.buf,
+				    sizeof(server->rcon_tbuf.buf),
+				    &server->rcon_tbuf.len, 1,
+				    RCON_PACKET_LOGIN,
+				    server->rcon_password);
 	uring_tbuf_write(&server->rcon_task, rcon_login_sent);
 }