From 516e2b76bdcf53e757309481fa0e663217ee8039 Mon Sep 17 00:00:00 2001 From: Brandon Williams Date: Wed, 27 Jun 2018 15:30:17 -0700 Subject: [PATCH] upload-pack: implement ref-in-want Currently, while performing packfile negotiation, clients are only allowed to specify their desired objects using object ids. This causes a vulnerability to failure when an object turns non-existent during negotiation, which may happen if, for example, the desired repository is provided by multiple Git servers in a load-balancing arrangement and there exists replication delay. In order to eliminate this vulnerability, implement the ref-in-want feature for the 'fetch' command in protocol version 2. This feature enables the 'fetch' command to support requests in the form of ref names through a new "want-ref " parameter. At the conclusion of negotiation, the server will send a list of all of the wanted references (as provided by "want-ref" lines) in addition to the generated packfile. Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano --- Documentation/config.txt | 7 ++ Documentation/technical/protocol-v2.txt | 28 ++++- t/t5703-upload-pack-ref-in-want.sh | 160 ++++++++++++++++++++++++ upload-pack.c | 66 ++++++++++ 4 files changed, 260 insertions(+), 1 deletion(-) create mode 100755 t/t5703-upload-pack-ref-in-want.sh diff --git a/Documentation/config.txt b/Documentation/config.txt index ab641bf5a9..fb1dd7428a 100644 --- a/Documentation/config.txt +++ b/Documentation/config.txt @@ -3479,6 +3479,13 @@ Note that this configuration variable is ignored if it is seen in the repository-level config (this is a safety measure against fetching from untrusted repositories). +uploadpack.allowRefInWant:: + If this option is set, `upload-pack` will support the `ref-in-want` + feature of the protocol version 2 `fetch` command. This feature + is intended for the benefit of load-balanced servers which may + not have the same view of what OIDs their refs point to due to + replication delay. + url..insteadOf:: Any URL that starts with this value will be rewritten to start, instead, with . In cases where some site serves a diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt index 49bda76d23..1da71d0ddb 100644 --- a/Documentation/technical/protocol-v2.txt +++ b/Documentation/technical/protocol-v2.txt @@ -299,12 +299,21 @@ included in the client's request: for use with partial clone and partial fetch operations. See `rev-list` for possible "filter-spec" values. +If the 'ref-in-want' feature is advertised, the following argument can +be included in the client's request as well as the potential addition of +the 'wanted-refs' section in the server's response as explained below. + + want-ref + Indicates to the server that the client wants to retrieve a + particular ref, where is the full name of a ref on the + server. + The response of `fetch` is broken into a number of sections separated by delimiter packets (0001), with each section beginning with its section header. output = *section - section = (acknowledgments | shallow-info | packfile) + section = (acknowledgments | shallow-info | wanted-refs | packfile) (flush-pkt | delim-pkt) acknowledgments = PKT-LINE("acknowledgments" LF) @@ -319,6 +328,10 @@ header. shallow = "shallow" SP obj-id unshallow = "unshallow" SP obj-id + wanted-refs = PKT-LINE("wanted-refs" LF) + *PKT-LINE(wanted-ref LF) + wanted-ref = obj-id SP refname + packfile = PKT-LINE("packfile" LF) *PKT-LINE(%x01-03 *%x00-ff) @@ -379,6 +392,19 @@ header. * This section is only included if a packfile section is also included in the response. + wanted-refs section + * This section is only included if the client has requested a + ref using a 'want-ref' line and if a packfile section is also + included in the response. + + * Always begins with the section header "wanted-refs". + + * The server will send a ref listing (" ") for + each reference requested using 'want-ref' lines. + + * The server MUST NOT send any refs which were not requested + using 'want-ref' lines. + packfile section * This section is only included if the client has sent 'want' lines in its request and either requested that no more diff --git a/t/t5703-upload-pack-ref-in-want.sh b/t/t5703-upload-pack-ref-in-want.sh new file mode 100755 index 0000000000..da86f7cde0 --- /dev/null +++ b/t/t5703-upload-pack-ref-in-want.sh @@ -0,0 +1,160 @@ +#!/bin/sh + +test_description='upload-pack ref-in-want' + +. ./test-lib.sh + +get_actual_refs () { + sed -n -e '/wanted-refs/,/0001/{ + /wanted-refs/d + /0001/d + p + }' actual_refs +} + +get_actual_commits () { + sed -n -e '/packfile/,/0000/{ + /packfile/d + p + }' o.pack && + git index-pack o.pack && + git verify-pack -v o.idx | grep commit | cut -c-40 | sort >actual_commits +} + +check_output () { + get_actual_refs && + test_cmp expected_refs actual_refs && + get_actual_commits && + test_cmp expected_commits actual_commits +} + +# c(o/foo) d(o/bar) +# \ / +# b e(baz) f(master) +# \__ | __/ +# \ | / +# a +test_expect_success 'setup repository' ' + test_commit a && + git checkout -b o/foo && + test_commit b && + test_commit c && + git checkout -b o/bar b && + test_commit d && + git checkout -b baz a && + test_commit e && + git checkout master && + test_commit f +' + +test_expect_success 'config controls ref-in-want advertisement' ' + git serve --advertise-capabilities >out && + ! grep -a ref-in-want out && + + git config uploadpack.allowRefInWant false && + git serve --advertise-capabilities >out && + ! grep -a ref-in-want out && + + git config uploadpack.allowRefInWant true && + git serve --advertise-capabilities >out && + grep -a ref-in-want out +' + +test_expect_success 'invalid want-ref line' ' + test-pkt-line pack >in <<-EOF && + command=fetch + 0001 + no-progress + want-ref refs/heads/non-existent + done + 0000 + EOF + + test_must_fail git serve --stateless-rpc 2>out expected_refs <<-EOF && + $(git rev-parse f) refs/heads/master + EOF + git rev-parse f | sort >expected_commits && + + test-pkt-line pack >in <<-EOF && + command=fetch + 0001 + no-progress + want-ref refs/heads/master + have $(git rev-parse a) + done + 0000 + EOF + + git serve --stateless-rpc >out expected_refs <<-EOF && + $(git rev-parse c) refs/heads/o/foo + $(git rev-parse d) refs/heads/o/bar + EOF + git rev-parse c d | sort >expected_commits && + + test-pkt-line pack >in <<-EOF && + command=fetch + 0001 + no-progress + want-ref refs/heads/o/foo + want-ref refs/heads/o/bar + have $(git rev-parse b) + done + 0000 + EOF + + git serve --stateless-rpc >out expected_refs <<-EOF && + $(git rev-parse f) refs/heads/master + EOF + git rev-parse e f | sort >expected_commits && + + test-pkt-line pack >in <<-EOF && + command=fetch + 0001 + no-progress + want-ref refs/heads/master + want $(git rev-parse e) + have $(git rev-parse a) + done + 0000 + EOF + + git serve --stateless-rpc >out expected_refs <<-EOF && + $(git rev-parse c) refs/heads/o/foo + EOF + >expected_commits && + + test-pkt-line pack >in <<-EOF && + command=fetch + 0001 + no-progress + want-ref refs/heads/o/foo + have $(git rev-parse c) + done + 0000 + EOF + + git serve --stateless-rpc >out wants = wants; + data->wanted_refs = wanted_refs; data->haves = haves; data->shallows = shallows; data->deepen_not = deepen_not; @@ -1149,6 +1155,7 @@ static void upload_pack_data_init(struct upload_pack_data *data) static void upload_pack_data_clear(struct upload_pack_data *data) { object_array_clear(&data->wants); + string_list_clear(&data->wanted_refs, 1); oid_array_clear(&data->haves); object_array_clear(&data->shallows); string_list_clear(&data->deepen_not, 0); @@ -1185,6 +1192,34 @@ static int parse_want(const char *line) return 0; } +static int parse_want_ref(const char *line, struct string_list *wanted_refs) +{ + const char *arg; + if (skip_prefix(line, "want-ref ", &arg)) { + struct object_id oid; + struct string_list_item *item; + struct object *o; + + if (read_ref(arg, &oid)) { + packet_write_fmt(1, "ERR unknown ref %s", arg); + die("unknown ref %s", arg); + } + + item = string_list_append(wanted_refs, arg); + item->util = oiddup(&oid); + + o = parse_object_or_die(&oid, arg); + if (!(o->flags & WANTED)) { + o->flags |= WANTED; + add_object_array(o, NULL, &want_obj); + } + + return 1; + } + + return 0; +} + static int parse_have(const char *line, struct oid_array *haves) { const char *arg; @@ -1210,6 +1245,8 @@ static void process_args(struct packet_reader *request, /* process want */ if (parse_want(arg)) continue; + if (allow_ref_in_want && parse_want_ref(arg, &data->wanted_refs)) + continue; /* process have line */ if (parse_have(arg, &data->haves)) continue; @@ -1352,6 +1389,24 @@ static int process_haves_and_send_acks(struct upload_pack_data *data) return ret; } +static void send_wanted_ref_info(struct upload_pack_data *data) +{ + const struct string_list_item *item; + + if (!data->wanted_refs.nr) + return; + + packet_write_fmt(1, "wanted-refs\n"); + + for_each_string_list_item(item, &data->wanted_refs) { + packet_write_fmt(1, "%s %s\n", + oid_to_hex(item->util), + item->string); + } + + packet_delim(1); +} + static void send_shallow_info(struct upload_pack_data *data) { /* No shallow info needs to be sent */ @@ -1418,6 +1473,7 @@ int upload_pack_v2(struct repository *r, struct argv_array *keys, state = FETCH_DONE; break; case FETCH_SEND_PACK: + send_wanted_ref_info(&data); send_shallow_info(&data); packet_write_fmt(1, "packfile\n"); @@ -1438,12 +1494,22 @@ int upload_pack_advertise(struct repository *r, { if (value) { int allow_filter_value; + int allow_ref_in_want; + strbuf_addstr(value, "shallow"); + if (!repo_config_get_bool(the_repository, "uploadpack.allowfilter", &allow_filter_value) && allow_filter_value) strbuf_addstr(value, " filter"); + + if (!repo_config_get_bool(the_repository, + "uploadpack.allowrefinwant", + &allow_ref_in_want) && + allow_ref_in_want) + strbuf_addstr(value, " ref-in-want"); } + return 1; }