use a hash of the lock token as the suffix for PUT/MOVE

After 753bc91 ("Remove the requirement opaquelocktoken uri scheme"),
lock tokens are in the URI forms in which they are received from the
server, eg. 'opaquelocktoken:', 'urn:uuid:'.

However, "start_put" (and consequently "start_move"), which attempts to
create a unique temporary file using the UUID of the lock token,
inadvertently uses the lock token in its URI form. These file
operations on the server may not be successful (specifically, in
Windows), due to the colon ':' character from the URI form of the lock
token in the file path.

This patch uses a hash of the lock token instead, guaranteeing only
"safe" characters (a-f, 0-9) are used in the file path.

The token's hash is generated when the lock token is received from the
server in handle_new_lock_ctx, minimizing the number of times of
hashing.

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http-push.c

@@ -152,6 +152,7 @@ struct remote_lock
 	char *url;
 	char *owner;
 	char *token;
+	char tmpfile_suffix[41];
 	time_t start_time;
 	long timeout;
 	int refreshing;
@@ -556,8 +557,7 @@ static void start_put(struct transfer_request *request)
 	request->dest = strbuf_detach(&buf, NULL);
 
 	append_remote_object_url(&buf, remote->url, hex, 0);
-	strbuf_addstr(&buf, "_");
-	strbuf_addstr(&buf, request->lock->token);
+	strbuf_add(&buf, request->lock->tmpfile_suffix, 41);
 	request->url = strbuf_detach(&buf, NULL);
 
 	slot = get_active_slot();
@@ -1129,6 +1129,8 @@ static void handle_lockprop_ctx(struct xml_ctx *ctx, int tag_closed)
 static void handle_new_lock_ctx(struct xml_ctx *ctx, int tag_closed)
 {
 	struct remote_lock *lock = (struct remote_lock *)ctx->userData;
+	git_SHA_CTX sha_ctx;
+	unsigned char lock_token_sha1[20];
 
 	if (tag_closed && ctx->cdata) {
 		if (!strcmp(ctx->name, DAV_ACTIVELOCK_OWNER)) {
@@ -1141,6 +1143,13 @@ static void handle_new_lock_ctx(struct xml_ctx *ctx, int tag_closed)
 		} else if (!strcmp(ctx->name, DAV_ACTIVELOCK_TOKEN)) {
 			lock->token = xmalloc(strlen(ctx->cdata) + 1);
 			strcpy(lock->token, ctx->cdata);
+
+			git_SHA1_Init(&sha_ctx);
+			git_SHA1_Update(&sha_ctx, lock->token, strlen(lock->token));
+			git_SHA1_Final(lock_token_sha1, &sha_ctx);
+
+			lock->tmpfile_suffix[0] = '_';
+			memcpy(lock->tmpfile_suffix + 1, sha1_to_hex(lock_token_sha1), 40);
 		}
 	}
 }

t/t5540-http-push.sh

@@ -94,6 +94,13 @@ test_expect_success 'MKCOL sends directory names with trailing slashes' '
 
 '
 
+test_expect_success 'PUT and MOVE sends object to URLs with SHA-1 hash suffix' '
+
+	grep -P "\"(?:PUT|MOVE) .+objects/[\da-z]{2}/[\da-z]{38}_[\da-z\-]{40} HTTP/[0-9.]+\" 20\d" \
+		< "$HTTPD_ROOT_PATH"/access.log
+
+'
+
 stop_httpd
 
 test_done