receive-pack: log received client session ID

When receive-pack receives a session-id capability from the client, log
the received session ID via a trace2 data event.

Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/receive-pack.c

@@ -2039,6 +2039,7 @@ static struct command *read_head_info(struct packet_reader *reader,
 		if (linelen < reader->pktlen) {
 			const char *feature_list = reader->line + linelen + 1;
 			const char *hash = NULL;
+			const char *client_sid;
 			int len = 0;
 			if (parse_feature_request(feature_list, "report-status"))
 				report_status = 1;
@@ -2061,6 +2062,12 @@ static struct command *read_head_info(struct packet_reader *reader,
 			}
 			if (xstrncmpz(the_hash_algo->name, hash, len))
 				die("error: unsupported object format '%s'", hash);
+			client_sid = parse_feature_value(feature_list, "session-id", &len, NULL);
+			if (client_sid) {
+				char *sid = xstrndup(client_sid, len);
+				trace2_data_string("transfer", NULL, "client-sid", client_sid);
+				free(sid);
+			}
 		}
 
 		if (!strcmp(reader->line, "push-cert")) {

t/t5705-session-id-in-capabilities.sh

@@ -28,13 +28,17 @@ do
 	'
 
 	test_expect_success "session IDs not advertised by default (push v${PROTO})" '
-		test_when_finished "rm -rf local tr2-client-events" &&
+		test_when_finished "rm -rf local tr2-client-events tr2-server-events" &&
+		test_when_finished "git -C local push --delete origin new-branch" &&
 		cp -r "$LOCAL_PRISTINE" local &&
 		git -C local pull --no-rebase origin &&
 		GIT_TRACE2_EVENT_NESTING=5 \
 		GIT_TRACE2_EVENT="$(pwd)/tr2-client-events" \
-		git -c protocol.version=$PROTO -C local push origin &&
-		test -z "$(grep \"key\":\"server-sid\" tr2-client-events)"
+		git -c protocol.version=$PROTO -C local push \
+			--receive-pack "GIT_TRACE2_EVENT=\"$(pwd)/tr2-server-events\" git-receive-pack" \
+			origin HEAD:new-branch &&
+		test -z "$(grep \"key\":\"server-sid\" tr2-client-events)" &&
+		test -z "$(grep \"key\":\"client-sid\" tr2-server-events)"
 	'
 done
 
@@ -57,13 +61,17 @@ do
 	'
 
 	test_expect_success "session IDs advertised (push v${PROTO})" '
-		test_when_finished "rm -rf local tr2-client-events" &&
+		test_when_finished "rm -rf local tr2-client-events tr2-server-events" &&
+		test_when_finished "git -C local push --delete origin new-branch" &&
 		cp -r "$LOCAL_PRISTINE" local &&
 		git -C local pull --no-rebase origin &&
 		GIT_TRACE2_EVENT_NESTING=5 \
 		GIT_TRACE2_EVENT="$(pwd)/tr2-client-events" \
-		git -c protocol.version=$PROTO -C local push origin &&
-		grep \"key\":\"server-sid\" tr2-client-events
+		git -c protocol.version=$PROTO -C local push \
+			--receive-pack "GIT_TRACE2_EVENT=\"$(pwd)/tr2-server-events\" git-receive-pack" \
+			origin HEAD:new-branch &&
+		grep \"key\":\"server-sid\" tr2-client-events &&
+		grep \"key\":\"client-sid\" tr2-server-events
 	'
 done