http: don't always add Git-Protocol header

Instead of always sending the Git-Protocol header with the configured
version with every http request, explicitly send it when discovering
refs and then only send it on subsequent http requests if the server
understood the version requested.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http.c

@@ -904,21 +904,6 @@ static void set_from_env(const char **var, const char *envname)
 		*var = val;
 }
 
-static void protocol_http_header(void)
-{
-	if (get_protocol_version_config() > 0) {
-		struct strbuf protocol_header = STRBUF_INIT;
-
-		strbuf_addf(&protocol_header, GIT_PROTOCOL_HEADER ": version=%d",
-			    get_protocol_version_config());
-
-
-		extra_http_headers = curl_slist_append(extra_http_headers,
-						       protocol_header.buf);
-		strbuf_release(&protocol_header);
-	}
-}
-
 void http_init(struct remote *remote, const char *url, int proactive_auth)
 {
 	char *low_speed_limit;
@@ -949,8 +934,6 @@ void http_init(struct remote *remote, const char *url, int proactive_auth)
 	if (remote)
 		var_override(&http_proxy_authmethod, remote->http_proxy_authmethod);
 
-	protocol_http_header();
-
 	pragma_header = curl_slist_append(http_copy_default_headers(),
 		"Pragma: no-cache");
 	no_pragma_header = curl_slist_append(http_copy_default_headers(),

remote-curl.c

@@ -291,6 +291,19 @@ static int show_http_message(struct strbuf *type, struct strbuf *charset,
 	return 0;
 }
 
+static int get_protocol_http_header(enum protocol_version version,
+				    struct strbuf *header)
+{
+	if (version > 0) {
+		strbuf_addf(header, GIT_PROTOCOL_HEADER ": version=%d",
+			    version);
+
+		return 1;
+	}
+
+	return 0;
+}
+
 static struct discovery *discover_refs(const char *service, int for_push)
 {
 	struct strbuf exp = STRBUF_INIT;
@@ -299,6 +312,8 @@ static struct discovery *discover_refs(const char *service, int for_push)
 	struct strbuf buffer = STRBUF_INIT;
 	struct strbuf refs_url = STRBUF_INIT;
 	struct strbuf effective_url = STRBUF_INIT;
+	struct strbuf protocol_header = STRBUF_INIT;
+	struct string_list extra_headers = STRING_LIST_INIT_DUP;
 	struct discovery *last = last_discovery;
 	int http_ret, maybe_smart = 0;
 	struct http_get_options http_options;
@@ -318,11 +333,16 @@ static struct discovery *discover_refs(const char *service, int for_push)
 		strbuf_addf(&refs_url, "service=%s", service);
 	}
 
+	/* Add the extra Git-Protocol header */
+	if (get_protocol_http_header(get_protocol_version_config(), &protocol_header))
+		string_list_append(&extra_headers, protocol_header.buf);
+
 	memset(&http_options, 0, sizeof(http_options));
 	http_options.content_type = &type;
 	http_options.charset = &charset;
 	http_options.effective_url = &effective_url;
 	http_options.base_url = &url;
+	http_options.extra_headers = &extra_headers;
 	http_options.initial_request = 1;
 	http_options.no_cache = 1;
 	http_options.keep_error = 1;
@@ -389,6 +409,8 @@ static struct discovery *discover_refs(const char *service, int for_push)
 	strbuf_release(&charset);
 	strbuf_release(&effective_url);
 	strbuf_release(&buffer);
+	strbuf_release(&protocol_header);
+	string_list_clear(&extra_headers, 0);
 	last_discovery = last;
 	return last;
 }
@@ -425,6 +447,7 @@ struct rpc_state {
 	char *service_url;
 	char *hdr_content_type;
 	char *hdr_accept;
+	char *protocol_header;
 	char *buf;
 	size_t alloc;
 	size_t len;
@@ -611,6 +634,10 @@ static int post_rpc(struct rpc_state *rpc)
 	headers = curl_slist_append(headers, needs_100_continue ?
 		"Expect: 100-continue" : "Expect:");
 
+	/* Add the extra Git-Protocol header */
+	if (rpc->protocol_header)
+		headers = curl_slist_append(headers, rpc->protocol_header);
+
 retry:
 	slot = get_active_slot();
 
@@ -751,6 +778,11 @@ static int rpc_service(struct rpc_state *rpc, struct discovery *heads)
 	strbuf_addf(&buf, "Accept: application/x-%s-result", svc);
 	rpc->hdr_accept = strbuf_detach(&buf, NULL);
 
+	if (get_protocol_http_header(heads->version, &buf))
+		rpc->protocol_header = strbuf_detach(&buf, NULL);
+	else
+		rpc->protocol_header = NULL;
+
 	while (!err) {
 		int n = packet_read(rpc->out, NULL, NULL, rpc->buf, rpc->alloc, 0);
 		if (!n)
@@ -778,6 +810,7 @@ static int rpc_service(struct rpc_state *rpc, struct discovery *heads)
 	free(rpc->service_url);
 	free(rpc->hdr_content_type);
 	free(rpc->hdr_accept);
+	free(rpc->protocol_header);
 	free(rpc->buf);
 	strbuf_release(&buf);
 	return err;