Smart fetch over HTTP: client side

The git-remote-curl backend detects if the remote server supports
the git-upload-pack service, and if so, runs git-fetch-pack locally
in a pipe to generate the want/have commands.

The advertisements from the server that were obtained during the
discovery are passed into git-fetch-pack before the POST request
starts, permitting server capability discovery and enablement.

Common objects that are discovered are appended onto the request as
have lines and are sent again on the next request.  This allows the
remote side to reinitialize its in-memory list of common objects
during the next request.

Because all requests are relatively short, below git-remote-curl's
1 MiB buffer limit, requests will use the standard Content-Length
header and be valid HTTP/1.0 POST requests.  This makes the fetch
client more tolerant of proxy servers which don't support HTTP/1.1
or the chunked transfer encoding.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 65 insertions, 4 deletions

diff --git a/remote-curl.c b/remote-curl.c
index f1206cb572..0eb6fc48fb 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -45,7 +45,7 @@ static int set_option(const char *name, const char *value)
 			options.progress = 0;
 		else
 			return -1;
-		return 1 /* TODO implement later */;
+		return 0;
 	}
 	else if (!strcmp(name, "depth")) {
 		char *end;
@@ -53,7 +53,7 @@ static int set_option(const char *name, const char *value)
 		if (value == end || *end)
 			return -1;
 		options.depth = v;
-		return 1 /* TODO implement later */;
+		return 0;
 	}
 	else if (!strcmp(name, "followtags")) {
 		if (!strcmp(value, "true"))
@@ -62,7 +62,7 @@ static int set_option(const char *name, const char *value)
 			options.followtags = 0;
 		else
 			return -1;
-		return 1 /* TODO implement later */;
+		return 0;
 	}
 	else if (!strcmp(name, "dry-run")) {
 		if (!strcmp(value, "true"))
@@ -463,6 +463,8 @@ static int fetch_dumb(int nr_heads, struct ref **to_fetch)
 	char **targets = xmalloc(nr_heads * sizeof(char*));
 	int ret, i;
 
+	if (options.depth)
+		die("dumb http transport does not support --depth");
 	for (i = 0; i < nr_heads; i++)
 		targets[i] = xstrdup(sha1_to_hex(to_fetch[i]->old_sha1));
 
@@ -481,6 +483,65 @@ static int fetch_dumb(int nr_heads, struct ref **to_fetch)
 	return ret ? error("Fetch failed.") : 0;
 }
 
+static int fetch_git(struct discovery *heads,
+	int nr_heads, struct ref **to_fetch)
+{
+	struct rpc_state rpc;
+	char *depth_arg = NULL;
+	const char **argv;
+	int argc = 0, i, err;
+
+	argv = xmalloc((15 + nr_heads) * sizeof(char*));
+	argv[argc++] = "fetch-pack";
+	argv[argc++] = "--stateless-rpc";
+	argv[argc++] = "--lock-pack";
+	if (options.followtags)
+		argv[argc++] = "--include-tag";
+	if (options.thin)
+		argv[argc++] = "--thin";
+	if (options.verbosity >= 3) {
+		argv[argc++] = "-v";
+		argv[argc++] = "-v";
+	}
+	if (!options.progress)
+		argv[argc++] = "--no-progress";
+	if (options.depth) {
+		struct strbuf buf = STRBUF_INIT;
+		strbuf_addf(&buf, "--depth=%lu", options.depth);
+		depth_arg = strbuf_detach(&buf, NULL);
+		argv[argc++] = depth_arg;
+	}
+	argv[argc++] = url;
+	for (i = 0; i < nr_heads; i++) {
+		struct ref *ref = to_fetch[i];
+		if (!ref->name || !*ref->name)
+			die("cannot fetch by sha1 over smart http");
+		argv[argc++] = ref->name;
+	}
+	argv[argc++] = NULL;
+
+	memset(&rpc, 0, sizeof(rpc));
+	rpc.service_name = "git-upload-pack",
+	rpc.argv = argv;
+
+	err = rpc_service(&rpc, heads);
+	if (rpc.result.len)
+		safe_write(1, rpc.result.buf, rpc.result.len);
+	strbuf_release(&rpc.result);
+	free(argv);
+	free(depth_arg);
+	return err;
+}
+
+static int fetch(int nr_heads, struct ref **to_fetch)
+{
+	struct discovery *d = discover_refs("git-upload-pack");
+	if (d->proto_git)
+		return fetch_git(d, nr_heads, to_fetch);
+	else
+		return fetch_dumb(nr_heads, to_fetch);
+}
+
 static void parse_fetch(struct strbuf *buf)
 {
 	struct ref **to_fetch = NULL;
@@ -523,7 +584,7 @@ static void parse_fetch(struct strbuf *buf)
 			break;
 	} while (1);
 
-	if (fetch_dumb(nr_heads, to_fetch))
+	if (fetch(nr_heads, to_fetch))
 		exit(128); /* error already reported */
 	free_refs(list_head);
 	free(to_fetch);