v0 protocol: use size_t for capability length/offset

When parsing server capabilities, we use "int" to store lengths and
offsets. At first glance this seems like a spot where our parser may be
confused by integer overflow if somebody sent us a malicious response.

In practice these strings are all bounded by the 64k limit of a
pkt-line, so using "int" is OK. However, it makes the code simpler to
audit if they just use size_t everywhere. Note that because we take
these parameters as pointers, this also forces many callers to update
their declared types.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/receive-pack.c

@@ -2093,7 +2093,7 @@ static struct command *read_head_info(struct packet_reader *reader,
 			const char *feature_list = reader->line + linelen + 1;
 			const char *hash = NULL;
 			const char *client_sid;
-			int len = 0;
+			size_t len = 0;
 			if (parse_feature_request(feature_list, "report-status"))
 				report_status = 1;
 			if (parse_feature_request(feature_list, "report-status-v2"))

connect.c

@@ -22,7 +22,7 @@
 
 static char *server_capabilities_v1;
 static struct strvec server_capabilities_v2 = STRVEC_INIT;
-static const char *next_server_feature_value(const char *feature, int *len, int *offset);
+static const char *next_server_feature_value(const char *feature, size_t *len, size_t *offset);
 
 static int check_ref(const char *name, unsigned int flags)
 {
@@ -205,10 +205,10 @@ static void parse_one_symref_info(struct string_list *symref, const char *val, i
 static void annotate_refs_with_symref_info(struct ref *ref)
 {
 	struct string_list symref = STRING_LIST_INIT_DUP;
-	int offset = 0;
+	size_t offset = 0;
 
 	while (1) {
-		int len;
+		size_t len;
 		const char *val;
 
 		val = next_server_feature_value("symref", &len, &offset);
@@ -231,7 +231,7 @@ static void annotate_refs_with_symref_info(struct ref *ref)
 static void process_capabilities(struct packet_reader *reader, int *linelen)
 {
 	const char *feat_val;
-	int feat_len;
+	size_t feat_len;
 	const char *line = reader->line;
 	int nul_location = strlen(line);
 	if (nul_location == *linelen)
@@ -596,10 +596,10 @@ struct ref **get_remote_refs(int fd_out, struct packet_reader *reader,
 	return list;
 }
 
-const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp, int *offset)
+const char *parse_feature_value(const char *feature_list, const char *feature, size_t *lenp, size_t *offset)
 {
 	const char *orig_start = feature_list;
-	int len;
+	size_t len;
 
 	if (!feature_list)
 		return NULL;
@@ -623,7 +623,7 @@ const char *parse_feature_value(const char *feature_list, const char *feature, i
 			}
 			/* feature with a value (e.g., "agent=git/1.2.3") */
 			else if (*value == '=') {
-				int end;
+				size_t end;
 
 				value++;
 				end = strcspn(value, " \t\n");
@@ -645,8 +645,8 @@ const char *parse_feature_value(const char *feature_list, const char *feature, i
 
 int server_supports_hash(const char *desired, int *feature_supported)
 {
-	int offset = 0;
+	size_t offset = 0;
-	int len;
+	size_t len;
 	const char *hash;
 
 	hash = next_server_feature_value("object-format", &len, &offset);
@@ -670,12 +670,12 @@ int parse_feature_request(const char *feature_list, const char *feature)
 	return !!parse_feature_value(feature_list, feature, NULL, NULL);
 }
 
-static const char *next_server_feature_value(const char *feature, int *len, int *offset)
+static const char *next_server_feature_value(const char *feature, size_t *len, size_t *offset)
 {
 	return parse_feature_value(server_capabilities_v1, feature, len, offset);
 }
 
-const char *server_feature_value(const char *feature, int *len)
+const char *server_feature_value(const char *feature, size_t *len)
 {
 	return parse_feature_value(server_capabilities_v1, feature, len, NULL);
 }

connect.h

@@ -12,14 +12,14 @@ int finish_connect(struct child_process *conn);
 int git_connection_is_socket(struct child_process *conn);
 int server_supports(const char *feature);
 int parse_feature_request(const char *features, const char *feature);
-const char *server_feature_value(const char *feature, int *len_ret);
+const char *server_feature_value(const char *feature, size_t *len_ret);
 int url_is_local_not_ssh(const char *url);
 
 struct packet_reader;
 enum protocol_version discover_version(struct packet_reader *reader);
 
 int server_supports_hash(const char *desired, int *feature_supported);
-const char *parse_feature_value(const char *feature_list, const char *feature, int *lenp, int *offset);
+const char *parse_feature_value(const char *feature_list, const char *feature, size_t *lenp, size_t *offset);
 int server_supports_v2(const char *c);
 void ensure_server_supports_v2(const char *c);
 int server_feature_v2(const char *c, const char **v);

fetch-pack.c

@@ -1099,7 +1099,7 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
 	struct ref *ref = copy_ref_list(orig_ref);
 	struct object_id oid;
 	const char *agent_feature;
-	int agent_len;
+	size_t agent_len;
 	struct fetch_negotiator negotiator_alloc;
 	struct fetch_negotiator *negotiator;
 
@@ -1117,7 +1117,7 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
 		agent_supported = 1;
 		if (agent_len)
 			print_verbose(args, _("Server version is %.*s"),
-				      agent_len, agent_feature);
+				      (int)agent_len, agent_feature);
 	}
 
 	if (!server_supports("session-id"))

send-pack.c

@@ -538,7 +538,7 @@ int send_pack(struct send_pack_args *args,
 		die(_("the receiving end does not support this repository's hash algorithm"));
 
 	if (args->push_cert != SEND_PACK_PUSH_CERT_NEVER) {
-		int len;
+		size_t len;
 		push_cert_nonce = server_feature_value("push-cert", &len);
 		if (push_cert_nonce) {
 			reject_invalid_nonce(push_cert_nonce, len);

transport.c

@@ -317,7 +317,7 @@ static struct ref *handshake(struct transport *transport, int for_push,
 	struct git_transport_data *data = transport->data;
 	struct ref *refs = NULL;
 	struct packet_reader reader;
-	int sid_len;
+	size_t sid_len;
 	const char *server_sid;
 
 	connect_setup(transport, for_push);

upload-pack.c

@@ -1067,7 +1067,7 @@ static void receive_needs(struct upload_pack_data *data,
 		const char *features;
 		struct object_id oid_buf;
 		const char *arg;
-		int feature_len;
+		size_t feature_len;
 
 		reset_timeout(data->timeout);
 		if (packet_reader_read(reader) != PACKET_READ_NORMAL)