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GITPROTOCOL-HTTP(5) Git Manual GITPROTOCOL-HTTP(5)
gitprotocol-http - Git HTTP-based protocols
<over-the-wire-protocol>
Git supports two HTTP based transfer protocols. A "dumb" protocol
which requires only a standard HTTP server on the server end of
the connection, and a "smart" protocol which requires a Git aware
CGI (or server module). This document describes both protocols.
As a design feature smart clients can automatically upgrade
"dumb" protocol URLs to smart URLs. This permits all users to
have the same published URL, and the peers automatically select
the most efficient transport available to them.
URLs for Git repositories accessed by HTTP use the standard HTTP
URL syntax documented by RFC 1738, so they are of the form:
http://<host>:<port>/<path>?<searchpart>
Within this documentation the placeholder $GIT_URL will stand for
the http:// repository URL entered by the end-user.
Servers SHOULD handle all requests to locations matching
$GIT_URL, as both the "smart" and "dumb" HTTP protocols used by
Git operate by appending additional path components onto the end
of the user supplied $GIT_URL string.
An example of a dumb client requesting a loose object:
$GIT_URL: http://example.com:8080/git/repo.git
URL request: http://example.com:8080/git/repo.git/objects/d0/49f6c27a2244e12041955e262a404c7faba355
An example of a smart request to a catch-all gateway:
$GIT_URL: http://example.com/daemon.cgi?svc=git&q=
URL request: http://example.com/daemon.cgi?svc=git&q=/info/refs&service=git-receive-pack
An example of a request to a submodule:
$GIT_URL: http://example.com/git/repo.git/path/submodule.git
URL request: http://example.com/git/repo.git/path/submodule.git/info/refs
Clients MUST strip a trailing /, if present, from the user
supplied $GIT_URL string to prevent empty path tokens (//) from
appearing in any URL sent to a server. Compatible clients MUST
expand $GIT_URL/info/refs as foo/info/refs and not
foo//info/refs.
Standard HTTP authentication is used if authentication is
required to access a repository, and MAY be configured and
enforced by the HTTP server software.
Because Git repositories are accessed by standard path components
server administrators MAY use directory based permissions within
their HTTP server to control repository access.
Clients SHOULD support Basic authentication as described by RFC
2617. Servers SHOULD support Basic authentication by relying upon
the HTTP server placed in front of the Git server software.
Servers SHOULD NOT require HTTP cookies for the purposes of
authentication or access control.
Clients and servers MAY support other common forms of HTTP based
authentication, such as Digest authentication.
Clients and servers SHOULD support SSL, particularly to protect
passwords when relying on Basic HTTP authentication.
The Git over HTTP protocol (much like HTTP itself) is stateless
from the perspective of the HTTP server side. All state MUST be
retained and managed by the client process. This permits simple
round-robin load-balancing on the server side, without needing to
worry about state management.
Clients MUST NOT require state management on the server side in
order to function correctly.
Servers MUST NOT require HTTP cookies in order to function
correctly. Clients MAY store and forward HTTP cookies during
request processing as described by RFC 2616 (HTTP/1.1). Servers
SHOULD ignore any cookies sent by a client.
Except where noted, all standard HTTP behavior SHOULD be assumed
by both client and server. This includes (but is not necessarily
limited to):
If there is no repository at $GIT_URL, or the resource pointed to
by a location matching $GIT_URL does not exist, the server MUST
NOT respond with 200 OK response. A server SHOULD respond with
404 Not Found, 410 Gone, or any other suitable HTTP status code
which does not imply the resource exists as requested.
If there is a repository at $GIT_URL, but access is not currently
permitted, the server MUST respond with the 403 Forbidden HTTP
status code.
Servers SHOULD support both HTTP 1.0 and HTTP 1.1. Servers SHOULD
support chunked encoding for both request and response bodies.
Clients SHOULD support both HTTP 1.0 and HTTP 1.1. Clients SHOULD
support chunked encoding for both request and response bodies.
Servers MAY return ETag and/or Last-Modified headers.
Clients MAY revalidate cached entities by including
If-Modified-Since and/or If-None-Match request headers.
Servers MAY return 304 Not Modified if the relevant headers
appear in the request and the entity has not changed. Clients
MUST treat 304 Not Modified identical to 200 OK by reusing the
cached entity.
Clients MAY reuse a cached entity without revalidation if the
Cache-Control and/or Expires header permits caching. Clients and
servers MUST follow RFC 2616 for cache controls.
All HTTP clients MUST begin either a fetch or a push exchange by
discovering the references available on the remote repository.
Dumb Clients
HTTP clients that only support the "dumb" protocol MUST discover
references by making a request for the special info/refs file of
the repository.
Dumb HTTP clients MUST make a GET request to $GIT_URL/info/refs,
without any search/query parameters.
C: GET $GIT_URL/info/refs HTTP/1.0
S: 200 OK
S:
S: 95dcfa3633004da0049d3d0fa03f80589cbcaf31 refs/heads/maint
S: d049f6c27a2244e12041955e262a404c7faba355 refs/heads/master
S: 2cb58b79488a98d2721cea644875a8dd0026b115 refs/tags/v1.0
S: a3c2e2402b99163d1d59756e5f207ae21cccba4c refs/tags/v1.0^{}
The Content-Type of the returned info/refs entity SHOULD be
text/plain; charset=utf-8, but MAY be any content type. Clients
MUST NOT attempt to validate the returned Content-Type. Dumb
servers MUST NOT return a return type starting with
application/x-git-.
Cache-Control headers MAY be returned to disable caching of the
returned entity.
When examining the response clients SHOULD only examine the HTTP
status code. Valid responses are 200 OK, or 304 Not Modified.
The returned content is a UNIX formatted text file describing
each ref and its known value. The file SHOULD be sorted by name
according to the C locale ordering. The file SHOULD NOT include
the default ref named HEAD.
info_refs = *( ref_record )
ref_record = any_ref / peeled_ref
any_ref = obj-id HTAB refname LF
peeled_ref = obj-id HTAB refname LF
obj-id HTAB refname "^{}" LF
Smart Clients
HTTP clients that support the "smart" protocol (or both the
"smart" and "dumb" protocols) MUST discover references by making
a parameterized request for the info/refs file of the repository.
The request MUST contain exactly one query parameter,
service=$servicename, where $servicename MUST be the service name
the client wishes to contact to complete the operation. The
request MUST NOT contain additional query parameters.
C: GET $GIT_URL/info/refs?service=git-upload-pack HTTP/1.0
dumb server reply:
S: 200 OK
S:
S: 95dcfa3633004da0049d3d0fa03f80589cbcaf31 refs/heads/maint
S: d049f6c27a2244e12041955e262a404c7faba355 refs/heads/master
S: 2cb58b79488a98d2721cea644875a8dd0026b115 refs/tags/v1.0
S: a3c2e2402b99163d1d59756e5f207ae21cccba4c refs/tags/v1.0^{}
smart server reply:
S: 200 OK
S: Content-Type: application/x-git-upload-pack-advertisement
S: Cache-Control: no-cache
S:
S: 001e# service=git-upload-pack\n
S: 0000
S: 004895dcfa3633004da0049d3d0fa03f80589cbcaf31 refs/heads/maint\0multi_ack\n
S: 003fd049f6c27a2244e12041955e262a404c7faba355 refs/heads/master\n
S: 003c2cb58b79488a98d2721cea644875a8dd0026b115 refs/tags/v1.0\n
S: 003fa3c2e2402b99163d1d59756e5f207ae21cccba4c refs/tags/v1.0^{}\n
S: 0000
The client may send Extra Parameters (see gitprotocol-pack(5)) as
a colon-separated string in the Git-Protocol HTTP header.
Uses the --http-backend-info-refs option to git-upload-pack(1).
Dumb Server Response
Dumb servers MUST respond with the dumb server reply format.
See the prior section under dumb clients for a more detailed
description of the dumb server response.
Smart Server Response
If the server does not recognize the requested service name,
or the requested service name has been disabled by the server
administrator, the server MUST respond with the 403 Forbidden
HTTP status code.
Otherwise, smart servers MUST respond with the smart server
reply format for the requested service name.
Cache-Control headers SHOULD be used to disable caching of
the returned entity.
The Content-Type MUST be
application/x-$servicename-advertisement. Clients SHOULD fall
back to the dumb protocol if another content type is
returned. When falling back to the dumb protocol clients
SHOULD NOT make an additional request to $GIT_URL/info/refs,
but instead SHOULD use the response already in hand. Clients
MUST NOT continue if they do not support the dumb protocol.
Clients MUST validate the status code is either 200 OK or 304
Not Modified.
Clients MUST validate the first five bytes of the response
entity matches the regex ^[0-9a-f]{4}#. If this test fails,
clients MUST NOT continue.
Clients MUST parse the entire response as a sequence of
pkt-line records.
Clients MUST verify the first pkt-line is #
service=$servicename. Servers MUST set $servicename to be the
request parameter value. Servers SHOULD include an LF at the
end of this line. Clients MUST ignore an LF at the end of the
line.
Servers MUST terminate the response with the magic 0000 end
pkt-line marker.
The returned response is a pkt-line stream describing each
ref and its known value. The stream SHOULD be sorted by name
according to the C locale ordering. The stream SHOULD include
the default ref named HEAD as the first ref. The stream MUST
include capability declarations behind a NUL on the first
ref.
The returned response contains "version 1" if "version=1" was
sent as an Extra Parameter.
smart_reply = PKT-LINE("# service=$servicename" LF)
"0000"
*1("version 1")
ref_list
"0000"
ref_list = empty_list / non_empty_list
empty_list = PKT-LINE(zero-id SP "capabilities^{}" NUL cap-list LF)
non_empty_list = PKT-LINE(obj-id SP name NUL cap_list LF)
*ref_record
cap-list = capability *(SP capability)
capability = 1*(LC_ALPHA / DIGIT / "-" / "_")
LC_ALPHA = %x61-7A
ref_record = any_ref / peeled_ref
any_ref = PKT-LINE(obj-id SP name LF)
peeled_ref = PKT-LINE(obj-id SP name LF)
PKT-LINE(obj-id SP name "^{}" LF
This service reads from the repository pointed to by $GIT_URL.
Clients MUST first perform ref discovery with
$GIT_URL/info/refs?service=git-upload-pack.
C: POST $GIT_URL/git-upload-pack HTTP/1.0
C: Content-Type: application/x-git-upload-pack-request
C:
C: 0032want 0a53e9ddeaddad63ad106860237bbf53411d11a7\n
C: 0032have 441b40d833fdfa93eb2908e52742248faf0ee993\n
C: 0000
S: 200 OK
S: Content-Type: application/x-git-upload-pack-result
S: Cache-Control: no-cache
S:
S: ....ACK %s, continue
S: ....NAK
Clients MUST NOT reuse or revalidate a cached response. Servers
MUST include sufficient Cache-Control headers to prevent caching
of the response.
Servers SHOULD support all capabilities defined here.
Clients MUST send at least one "want" command in the request
body. Clients MUST NOT reference an id in a "want" command which
did not appear in the response obtained through ref discovery
unless the server advertises capability allow-tip-sha1-in-want or
allow-reachable-sha1-in-want.
compute_request = want_list
have_list
request_end
request_end = "0000" / "done"
want_list = PKT-LINE(want SP cap_list LF)
*(want_pkt)
want_pkt = PKT-LINE(want LF)
want = "want" SP id
cap_list = capability *(SP capability)
have_list = *PKT-LINE("have" SP id LF)
TODO: Document this further.
The Negotiation Algorithm
The computation to select the minimal pack proceeds as follows (C
= client, S = server):
init step:
C: Use ref discovery to obtain the advertised refs.
C: Place any object seen into set advertised.
C: Build an empty set, common, to hold the objects that are later
determined to be on both ends.
C: Build a set, want, of the objects from advertised that the
client wants to fetch, based on what it saw during ref discovery.
C: Start a queue, c_pending, ordered by commit time (popping
newest first). Add all client refs. When a commit is popped from
the queue its parents SHOULD be automatically inserted back.
Commits MUST only enter the queue once.
one compute step:
C: Send one $GIT_URL/git-upload-pack request:
C: 0032want <want-#1>...............................
C: 0032want <want-#2>...............................
....
C: 0032have <common-#1>.............................
C: 0032have <common-#2>.............................
....
C: 0032have <have-#1>...............................
C: 0032have <have-#2>...............................
....
C: 0000
The stream is organized into "commands", with each command
appearing by itself in a pkt-line. Within a command line, the
text leading up to the first space is the command name, and the
remainder of the line to the first LF is the value. Command lines
are terminated with an LF as the last byte of the pkt-line value.
Commands MUST appear in the following order, if they appear at
all in the request stream:
• "want"
• "have"
The stream is terminated by a pkt-line flush (0000).
A single "want" or "have" command MUST have one hex formatted
object name as its value. Multiple object names MUST be sent by
sending multiple commands. Object names MUST be given using the
object format negotiated through the object-format capability
(default SHA-1).
The have list is created by popping the first 32 commits from
c_pending. Fewer can be supplied if c_pending empties.
If the client has sent 256 "have" commits and has not yet
received one of those back from s_common, or the client has
emptied c_pending it SHOULD include a "done" command to let the
server know it won’t proceed:
C: 0009done
S: Parse the git-upload-pack request:
Verify all objects in want are directly reachable from refs.
The server MAY walk backwards through history or through the
reflog to permit slightly stale requests.
If no "want" objects are received, send an error: TODO: Define
error if no "want" lines are requested.
If any "want" object is not reachable, send an error: TODO:
Define error if an invalid "want" is requested.
Create an empty list, s_common.
If "have" was sent:
Loop through the objects in the order supplied by the client.
For each object, if the server has the object reachable from a
ref, add it to s_common. If a commit is added to s_common, do not
add any ancestors, even if they also appear in have.
S: Send the git-upload-pack response:
If the server has found a closed set of objects to pack or the
request ends with "done", it replies with the pack. TODO:
Document the pack based response
S: PACK...
The returned stream is the side-band-64k protocol supported by
the git-upload-pack service, and the pack is embedded into stream
1. Progress messages from the server side MAY appear in stream 2.
Here a "closed set of objects" is defined to have at least one
path from every "want" to at least one "common" object.
If the server needs more information, it replies with a status
continue response: TODO: Document the non-pack response
C: Parse the upload-pack response: TODO: Document parsing
response
Do another compute step.
This service reads from the repository pointed to by $GIT_URL.
Clients MUST first perform ref discovery with
$GIT_URL/info/refs?service=git-receive-pack.
C: POST $GIT_URL/git-receive-pack HTTP/1.0
C: Content-Type: application/x-git-receive-pack-request
C:
C: ....0a53e9ddeaddad63ad106860237bbf53411d11a7 441b40d833fdfa93eb2908e52742248faf0ee993 refs/heads/maint\0 report-status
C: 0000
C: PACK....
S: 200 OK
S: Content-Type: application/x-git-receive-pack-result
S: Cache-Control: no-cache
S:
S: ....
Clients MUST NOT reuse or revalidate a cached response. Servers
MUST include sufficient Cache-Control headers to prevent caching
of the response.
Servers SHOULD support all capabilities defined here.
Clients MUST send at least one command in the request body.
Within the command portion of the request body clients SHOULD
send the id obtained through ref discovery as old_id.
update_request = command_list
"PACK" <binary-data>
command_list = PKT-LINE(command NUL cap_list LF)
*(command_pkt)
command_pkt = PKT-LINE(command LF)
cap_list = *(SP capability) SP
command = create / delete / update
create = zero-id SP new_id SP name
delete = old_id SP zero-id SP name
update = old_id SP new_id SP name
TODO: Document this further.
RFC 1738: Uniform Resource Locators (URL)[1] RFC 2616: Hypertext
Transfer Protocol — HTTP/1.1[2]
gitprotocol-pack(5) gitprotocol-capabilities(5)
Part of the git(1) suite
1. RFC 1738: Uniform Resource Locators (URL)
https://www.ietf.org/rfc/rfc1738.txt
2. RFC 2616: Hypertext Transfer Protocol — HTTP/1.1
https://www.ietf.org/rfc/rfc2616.txt
This page is part of the git (Git distributed version control
system) project. Information about the project can be found at
⟨http://git-scm.com/⟩. If you have a bug report for this manual
page, see ⟨http://git-scm.com/community⟩. This page was obtained
from the project's upstream Git repository
⟨https://github.com/git/git.git⟩ on 2024-06-14. (At that time,
the date of the most recent commit that was found in the
repository was 2024-06-12.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
Git 2.45.2.492.gd63586 2024-06-12 GITPROTOCOL-HTTP(5)
Pages that refer to this page: git(1), git-upload-pack(1), gitprotocol-pack(5), gitprotocol-v2(5)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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