MINOR: server: Be more strict on the server-state line parsing

The srv_state_parse_line() function was rewritten to be more strict. First
of all, it is possible to make the difference between an ignored line and an
malformed one. Then, only blank characters (spaces and tabs) are now allowed
as field separator. An error is reported for truncated lines or for lines
with an unexpected number of arguments regarding the provided version.
However, for now, errors are ignored by the caller, invalid lines are just
skipped.

src/server.c

@@ -51,7 +51,7 @@ static void srv_update_status(struct server *s);
 static void srv_update_state(struct server *srv, int version, char **params);
 static int srv_apply_lastaddr(struct server *srv, int *err_code);
 static int srv_set_fqdn(struct server *srv, const char *fqdn, int resolv_locked);
-static void srv_state_parse_line(char *buf, const int version, char **params, char **srv_params);
+static int srv_state_parse_line(char *buf, const int version, char **params, char **srv_params);
 static int srv_state_get_version(FILE *f);
 static void srv_cleanup_connections(struct server *srv);
 static const char *update_server_check_addr_port(struct server *s, const char *addr,
@@ -3071,57 +3071,53 @@ static int srv_state_get_version(FILE *f) {
 
 /*
  * parses server state line stored in <buf> and supposedly in version <version>.
- * Set <params> and <srv_params> accordingly.
- * In case of error, params[0] is set to NULL.
+ * Set <params> and <srv_params> accordingly on success. It returns 1 on
+ * success, 0 if the line must be ignored and -1 on error.
  * The caller must provide a supported version
  */
-static void srv_state_parse_line(char *buf, const int version, char **params, char **srv_params)
+static int srv_state_parse_line(char *buf, const int version, char **params, char **srv_params)
 {
-	int buflen, arg, srv_arg;
-	char *cur, *end;
+	int buflen, arg, srv_arg, ret;
+	char *cur;
 
 	buflen = strlen(buf);
 	cur = buf;
-	end = cur + buflen;
+	ret = 1; /* be optimistic and pretend a success */
 
-	/* we need at least one character */
-	if (buflen == 0) {
-		params[0] = NULL;
-		return;
+	/* we need at least one character (the newline) and a non-truncated line */
+	if (buflen == 0 || buf[buflen - 1] != '\n') {
+		ret = -1;
+		goto out;
 	}
 
-	/* ignore blank characters at the beginning of the line */
-	while (isspace((unsigned char)*cur))
+	/* skip blank characters at the beginning of the line */
+	while (isblank((unsigned char)*cur))
 		++cur;
 
-	/* Ignore empty or commented lines */
-	if (cur == end || *cur == '#') {
-		params[0] = NULL;
-		return;
+	/* ignore empty or commented lines */
+	if (!*cur || *cur == '\n' || *cur == '#') {
+		ret = 0;
+		goto out;
 	}
 
-	/* truncated lines */
-	if (buf[buflen - 1] != '\n') {
-		//ha_warning("server-state file '%s': truncated line\n", filepath);
-		params[0] = NULL;
-		return;
-	}
-
-	/* Removes trailing '\n' */
+	/* Removes trailing '\n' to ease parsing */
 	buf[buflen - 1] = '\0';
 
-	/* we're now ready to move the line into *srv_params[] */
+	/* we're now ready to move the line into <params> and <srv_params> */
 	memset(params, 0, SRV_STATE_FILE_MAX_FIELDS * sizeof(*params));
 	memset(srv_params, 0, SRV_STATE_FILE_MAX_FIELDS * sizeof(*srv_params));
-
 	arg = 0;
 	srv_arg = 0;
-	while (*cur && arg < SRV_STATE_FILE_MAX_FIELDS) {
-		/* Search begining of the current field */
-		while (isspace((unsigned char)*cur)) {
+	while (*cur) {
+		/* first of all, stop if there are too many fields */
+		if (arg >= SRV_STATE_FILE_MAX_FIELDS)
+			break;
+
+		/* then skip leading spaces */
+		while (*cur && isblank((unsigned char)*cur)) {
 			++cur;
 			if (!*cur)
-				goto end;
+				break;
 		}
 
 		/* v1
@@ -3148,27 +3144,29 @@ static void srv_state_parse_line(char *buf, const int version, char **params, ch
 		 * srv_agent_addr:       params[23] => srv_params[19] (optional field)
 		 * srv_agent_port:       params[24] => srv_params[20] (optional field)
 		 */
-		if ((version == 1 && arg >= 4))
+		if (arg >= 4)
 			srv_params[srv_arg++] = cur;
 		params[arg++] = cur;
 
-		/* Search end of the current field: first space or \0 */
-		/* Search begining of the current field */
-		while (!isspace((unsigned char)*cur)) {
+		/* look for the end of the current field */
+		while (*cur && !isblank((unsigned char)*cur)) {
 			++cur;
 			if (!*cur)
-				goto end;
+				break;
 		}
+
+		/* otherwise, cut the field and move to the next one */
 		*cur++ = '\0';
 	}
 
-  end:
-	/* if line is incomplete line, then ignore it.
-	 * otherwise, update useful flags */
+	/* if the number of fields does not match the version, then return an error */
 	if (version == 1 &&
 	    (arg < SRV_STATE_FILE_MIN_FIELDS_VERSION_1 ||
 	     arg > SRV_STATE_FILE_MAX_FIELDS_VERSION_1))
-		params[0] = NULL;
+		ret = -1;
+
+  out:
+	return ret;
 }
 
 
@@ -3266,14 +3264,16 @@ void apply_server_state(void)
 			goto out_load_server_state_in_tree;
 
 		while (fgets(mybuf, SRV_STATE_LINE_MAXLEN, f)) {
+			int ret;
+
 			line = NULL;
 
 			line = strdup(mybuf);
 			if (line == NULL)
 				continue;
 
-			srv_state_parse_line(mybuf, global_file_version, params, srv_params);
-			if (params[0] == NULL)
+			ret = srv_state_parse_line(mybuf, global_file_version, params, srv_params);
+			if (ret <= 0)
 				goto nextline;
 
 			/* bkname */
@@ -3396,6 +3396,7 @@ void apply_server_state(void)
 			while (srv) {
 				struct ebmb_node *node;
 				struct state_line *st;
+				int ret;
 
 				chunk_printf(&trash, "%s %s", curproxy->id, srv->id);
 				node = ebst_lookup(&state_file, trash.area);
@@ -3406,8 +3407,8 @@ void apply_server_state(void)
 				memcpy(mybuf, st->line, strlen(st->line));
 				mybuf[strlen(st->line)] = 0;
 
-				srv_state_parse_line(mybuf, global_file_version, params, srv_params);
-				if (params[0] == NULL)
+				ret = srv_state_parse_line(mybuf, global_file_version, params, srv_params);
+				if (ret <= 0)
 					goto next;
 
 				srv_update_state(srv, global_file_version, srv_params);
@@ -3440,12 +3441,11 @@ void apply_server_state(void)
 				int bk_f_forced_id = 0;
 				int check_id = 0;
 				int check_name = 0;
+				int ret;
 
-				srv_state_parse_line(mybuf, version, params, srv_params);
-
-				if (params[0] == NULL) {
+				ret = srv_state_parse_line(mybuf, version, params, srv_params);
+				if (ret <= 0)
 					continue;
-				}
 
 				/* if line is incomplete line, then ignore it.
 				 * otherwise, update useful flags */