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Our table of v2 "capabilities" contains everything we might tell the
client we support. But there are differences in how we expect the client
to respond. Some of the entries are true capabilities (i.e., we expect
the client to say "yes, I support this"), and some are ones we expect
them to send as commands (with "command=ls-refs" or similar).
When we receive a capability used as a command, we complain about that.
But when we receive a command used as a capability (e.g., just "ls-refs"
in a pkt-line by itself), we silently ignore it.
This isn't really hurting anything (clients shouldn't send it, and we'll
ignore it), but we can tighten up the protocol to match what we expect
to happen.
There are two new tests here. The first one checks a capability used as
a command, which already passes. The second tests a command as a
capability, which this patch fixes.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we see a line from the client like "command=ls-refs", we parse
everything after the equals sign as a capability, which we check against
our capabilities table. If we don't recognize the command (e.g.,
"command=foo"), we'll reject it.
But in parse_command(), we use the same get_capability() parser for
parsing non-command lines. So if we see "command=ls-refs=foo", we will
feed "ls-refs=foo" to get_capability(), which will say "OK, that's
ls-refs, with value 'foo'". But then we simply ignore the value
entirely.
The client is violating the spec here, which says:
command = PKT-LINE("command=" key LF)
key = 1*(ALPHA | DIGIT | "-_")
I.e., the key is not even allowed to have an equals sign in it. Whereas
a real non-command capability does allow a value:
capability = PKT-LINE(key[=value] LF)
So by reusing the same get_capability() parser, we are mixing up the
"key" and "capability" tokens. However, since that parser tells us
whether it saw an "=", we can still use it; we just need to reject any
input that produces a non-NULL value field.
The current behavior isn't really hurting anything (the client should
never send such a request, and if it does, we just ignore the "value"
part). But since it does violate the spec, let's tighten it up to
prevent any surprising behavior.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We collect the set of capabilities the client sends us in a strvec.
While this is usually small, there's no limit to the number of
capabilities the client can send us (e.g., they could just send us
"agent" pkt-lines over and over, and we'd keep adding them to the list).
Since all code has been converted away from using this list, let's get
rid of it. This avoids a potential attack where clients waste our
memory.
Note that we do have to replace it with a flag, because some of the
flush-packet logic checks whether we've seen any valid commands or keys.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Rather than pulling the session-id string from the list of collected
capabilities, we can handle it as soon as we receive it. This gets us
closer to dropping the collected list entirely.
The behavior should be the same, with one exception. Previously if the
client sent us multiple session-id lines, we'd report only the first.
Now we'll pass each one along to trace2. This shouldn't matter in
practice, since clients shouldn't do that (and if they do, it's probably
sensible to log them all).
As this removes the last caller of the static has_capability(), we can
remove it, as well (and in fact we must to avoid -Wunused-function
complaining).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We get any "object-format" specified by the client by searching for it
in the collected list of capabilities the client sent. We can instead
just handle it as soon as they send it. This is slightly more efficient,
and gets us one step closer to dropping that collected list.
Note that we do still have to do our final hash check after receiving
all capabilities (because they might not have sent an object-format line
at all, and we still have to check that the default matches our
repository algorithm). Since the check_algorithm() function would now be
down to a single if() statement, I've just inlined it in its only
caller.
There should be no change of behavior here, except for two
broken-protocol cases:
- if the client sends multiple conflicting object-format capabilities
(which they should not), we'll now choose the last one rather than
the first. We could also detect and complain about the duplicates
quite easily now, which we could not before, but I didn't do so
here.
- if the client sends a bogus "object-format" with no equals sign,
we'll now say so, rather than "unknown object format: ''"
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We have a capabilities table that tells us what we should tell the
client we are capable of, and what to do when a client gives us a
particular command (e.g., "command=ls-refs"). But it doesn't tell us
what to do when the client sends us back a capability (e.g.,
"object-format=sha256"). We just collect them all in a strvec and hope
somebody can use them later.
Instead, let's provide a function pointer in the table to act on these.
This will eventually help us avoid collecting the strings, which will be
more efficient and less prone to mischief.
Using the new method is optional, which helps in two ways:
- we can move existing capabilities over to this new system gradually
in individual commits
- some capabilities we don't actually do anything with anyway. For
example, the client is free to say "agent=git/1.2.3" to us, but we
do not act on the information in any way.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When the client sends v2 capabilities, they may be simple, like:
foo
or have a value like:
foo=bar
(all of the current capabilities actually expect a value, but the
protocol allows for boolean ones).
We use get_capability() to make sure the client's pktline matches a
capability. In doing so, we parse enough to see the "=" and the value
(if any), but we immediately forget it. Nobody cares for now, because they end
up parsing the values out later using has_capability(). But in
preparation for changing that, let's pass back a pointer so the callers
know what we found.
Note that unlike has_capability(), we'll return NULL for a "simple"
capability. Distinguishing these will be useful for some future patches.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The is_command() function not only tells us whether the pktline is a
valid command string, but it also parses out the command (and complains
if we see a duplicate). Let's rename it to make those extra functions
a bit more obvious.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The "advertise capabilities" mode of serve.c added in
ed10cb952d3 (serve: introduce git-serve, 2018-03-15) is only used by
the http-backend.c to call {upload,receive}-pack with the
--advertise-refs parameter. See 42526b478e3 (Add stateless RPC options
to upload-pack, receive-pack, 2009-10-30).
Let's just make cmd_upload_pack() take the two (v2) or three (v2)
parameters the the v2/v1 servicing functions need directly, and pass
those in via the function signature. The logic of whether daemon mode
is implied by the timeout belongs in the v1 function (only used
there).
Once we split up the "advertise v2 refs" from "serve v2 request" it
becomes clear that v2 never cared about those in combination. The only
time it mattered was for v1 to emit its ref advertisement, in that
case we wanted to emit the smart-http-only "no-done" capability.
Since we only do that in the --advertise-refs codepath let's just have
it set "do_done" itself in v1's upload_pack() just before send_ref(),
at that point --advertise-refs and --stateless-rpc in combination are
redundant (the only user is get_info_refs() in http-backend.c), so we
can just pass in --advertise-refs only.
Since we need to touch all the serve() and advertise_capabilities()
codepaths let's rename them to less clever and obvious names, it's
been suggested numerous times, the latest of which is [1]'s suggestion
for protocol_v2_serve_loop(). Let's go with that.
1. https://lore.kernel.org/git/CAFQ2z_NyGb8rju5CKzmo6KhZXD0Dp21u-BbyCb2aNxLEoSPRJw@mail.gmail.com/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The advertise_capabilities() is only called from serve() and we always
emit this version line before it. In a subsequent commit I'll make
builtin/upload-pack.c sometimes call advertise_capabilities()
directly, so it'll make sense to have this line emitted by
advertise_capabilities(), not serve() itself.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In 6b5b6e422ee (serve: advertise session ID in v2 capabilities,
2020-11-11) the check for transfer.advertiseSID was added to the
beginning of the main serve() loop. Thus on startup of the server we'd
populate it.
Let's instead use an explicit lazy initialization pattern in
session_id_advertise() itself, we'll still look the config up only
once per-process, but by moving it out of serve() itself the further
changing of that routine becomes easier.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The serve.c API added in ed10cb952d3 (serve: introduce git-serve,
2018-03-15) was passing in the raw capabilities "keys", but nothing
downstream of it ever used them.
Let's remove that code because it's not needed. If we do end up
needing to pass information about the advertisement in the future
it'll make more sense to have serve.c parse the capabilities keys and
pass the result of its parsing, rather than expecting expecting its
API users to parse the same keys again.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Change the declaration of the protocol_capability struct to use
designated initializers, this makes this more verbose now, but a
follow-up commit will add a new field. At that point these lines would
be too dense to be on one line comfortably.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The has_capability() function introduced in ed10cb952d3 (serve:
introduce git-serve, 2018-03-15) has never been used anywhere except
serve.c, so let's mark it as static.
It was later changed from "extern" in 554544276a6 (*.[ch]: remove
extern from function declarations using spatch, 2019-04-29), but we
could have simply marked it as "static" instead.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Error message update.
* dl/packet-read-response-end-fix:
pkt-line: replace "stateless separator" with "response end"
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In 0181b600a6 (pkt-line: define PACKET_READ_RESPONSE_END, 2020-05-19),
the Response End packet was defined for Git's network protocol. When the
patch was sent, it included an oversight where the error messages
referenced "stateless separator", the work-in-progress name, over
"response end", the final name chosen.
Correct these error messages by having them correctly reference
a "response end" packet.
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Sometimes it is useful to get information of an object without having to
download it completely.
Add the "object-info" capability that lets the client ask for
object-related information with their full hexadecimal object names.
Only sizes are returned for now.
Signed-off-by: Bruno Albuquerque <bga@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When cloning, we choose the default branch based on the remote HEAD.
But if there is no remote HEAD reported (which could happen if the
target of the remote HEAD is unborn), we'll fall back to using our local
init.defaultBranch. Traditionally this hasn't been a big deal, because
most repos used "master" as the default. But these days it is likely to
cause confusion if the server and client implementations choose
different values (e.g., if the remote started with "main", we may choose
"master" locally, create commits there, and then the user is surprised
when they push to "master" and not "main").
To solve this, the remote needs to communicate the target of the HEAD
symref, even if it is unborn, and "git clone" needs to use this
information.
Currently, symrefs that have unborn targets (such as in this case) are
not communicated by the protocol. Teach Git to advertise and support the
"unborn" feature in "ls-refs" (by default, this is advertised, but
server administrators may turn this off through the lsrefs.unborn
config). This feature indicates that "ls-refs" supports the "unborn"
argument; when it is specified, "ls-refs" will send the HEAD symref with
the name of its unborn target.
This change is only for protocol v2. A similar change for protocol v0
would require independent protocol design (there being no analogous
position to signal support for "unborn") and client-side plumbing of the
data required, so the scope of this patch set is limited to protocol v2.
The client side will be updated to use this in a subsequent commit.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When upload-pack (protocol v0/v1) or a protocol v2 server receives a
session-id capability from a 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>
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When transfer.advertiseSID is true, advertise the server's session ID
for all protocol v2 connections via the new session-id capability.
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The "argc" and "argv" names made sense when the struct was argv_array,
but now they're just confusing. Let's rename them to "nr" (which we use
for counts elsewhere) and "v" (which is rather terse, but reads well
when combined with typical variable names like "args.v").
Note that we have to update all of the callers immediately. Playing
tricks with the preprocessor is hard here, because we wouldn't want to
rewrite unrelated tokens.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We eventually want to drop the argv_array name and just use strvec
consistently. There's no particular reason we have to do it all at once,
or care about interactions between converted and unconverted bits.
Because of our preprocessor compat layer, the names are interchangeable
to the compiler (so even a definition and declaration using different
names is OK).
This patch converts all of the remaining files, as the resulting diff is
reasonably sized.
The conversion was done purely mechanically with:
git ls-files '*.c' '*.h' |
xargs perl -i -pe '
s/ARGV_ARRAY/STRVEC/g;
s/argv_array/strvec/g;
'
We'll deal with any indentation/style fallouts separately.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This requires updating #include lines across the code-base, but that's
all fairly mechanical, and was done with:
git ls-files '*.c' '*.h' |
xargs perl -i -pe 's/argv-array.h/strvec.h/'
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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SHA-256 migration work continues.
* bc/sha-256-part-2: (44 commits)
remote-testgit: adapt for object-format
bundle: detect hash algorithm when reading refs
t5300: pass --object-format to git index-pack
t5704: send object-format capability with SHA-256
t5703: use object-format serve option
t5702: offer an object-format capability in the test
t/helper: initialize the repository for test-sha1-array
remote-curl: avoid truncating refs with ls-remote
t1050: pass algorithm to index-pack when outside repo
builtin/index-pack: add option to specify hash algorithm
remote-curl: detect algorithm for dumb HTTP by size
builtin/ls-remote: initialize repository based on fetch
t5500: make hash independent
serve: advertise object-format capability for protocol v2
connect: parse v2 refs with correct hash algorithm
connect: pass full packet reader when parsing v2 refs
Documentation/technical: document object-format for protocol v2
t1302: expect repo format version 1 for SHA-256
builtin/show-index: provide options to determine hash algo
t5302: modernize test formatting
...
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In order to communicate the protocol supported by the server side, add
support for advertising the object-format capability. We check that the
client side sends us an identical algorithm if it sends us its own
object-format capability, and assume it speaks SHA-1 if not.
In the test, when we're using an algorithm other than SHA-1, we need to
specify the algorithm in use so we don't get a failure with an "unknown
format" message. Add a test that we handle a mismatched algorithm.
Remove the test_oid_init call since it's no longer necessary.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In a future commit, we will use PACKET_READ_RESPONSE_END to separate
messages proxied by remote-curl. To prepare for this, add the
PACKET_READ_RESPONSE_END enum value.
In switch statements that need a case added, die() or BUG() when a
PACKET_READ_RESPONSE_END is unexpected. Otherwise, mirror how
PACKET_READ_DELIM is implemented (especially in cases where packets are
being forwarded).
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In the Git pack protocol definition, an error packet may appear only in
a certain context. However, servers can face a runtime error (e.g. I/O
error) at an arbitrary timing. This patch changes the protocol to allow
an error packet to be sent instead of any packet.
Without this protocol spec change, when a server cannot process a
request, there's no way to tell that to a client. Since the server
cannot produce a valid response, it would be forced to cut a connection
without telling why. With this protocol spec change, the server can be
more gentle in this situation. An old client may see these error packets
as an unexpected packet, but this is not worse than having an unexpected
EOF.
Following this protocol spec change, the error packet handling code is
moved to pkt-line.c. Implementation wise, this implementation uses
pkt-line to communicate with a subprocess. Since this is not a part of
Git protocol, it's possible that a packet that is not supposed to be an
error packet is mistakenly parsed as an error packet. This error packet
handling is enabled only for the Git pack protocol parsing code
considering this.
Signed-off-by: Masaya Suzuki <masayasuzuki@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Introduce the "server-option" capability to protocol version 2. This
enables future clients the ability to send server specific options in
command requests when using protocol version 2.
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When communicating with a v2 server, perform a fetch by requesting the
'fetch' command.
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Introduce the 'fetch' server command.
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Introduce the ls-refs server command. In protocol v2, the ls-refs
command is used to request the ref advertisement from the server. Since
it is a command which can be requested (as opposed to mandatory in v1),
a client can sent a number of parameters in its request to limit the ref
advertisement based on provided ref-prefixes.
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Introduce git-serve, the base server for protocol version 2.
Protocol version 2 is intended to be a replacement for Git's current
wire protocol. The intention is that it will be a simpler, less
wasteful protocol which can evolve over time.
Protocol version 2 improves upon version 1 by eliminating the initial
ref advertisement. In its place a server will export a list of
capabilities and commands which it supports in a capability
advertisement. A client can then request that a particular command be
executed by providing a number of capabilities and command specific
parameters. At the completion of a command, a client can request that
another command be executed or can terminate the connection by sending a
flush packet.
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Jeff King
Ævar Arnfjörð Bjarmason
Junio C Hamano
Denton Liu
Bruno Albuquerque
Jonathan Tan
Josh Steadmon
brian m. carlson
Masaya Suzuki
Brandon Williams