003egit-upload-pack /project.git\0host=myserver.com\0\0version=2\0

C: GET $GIT_URL/info/refs?service=git-upload-pack HTTP/1.0
C: Git-Protocol: version=2

S: 200 OK
S: <Some headers>
S: ...
S:
S: 000eversion 2\n
S: <capability-advertisement>

   symrefs
In addition to the object pointed by it, show the underlying ref
pointed by it when showing a symbolic ref.


   peel
Show peeled tags.


   ref-prefix <prefix>
When specified, only references having a prefix matching one of
the provided prefixes are displayed. Multiple instances may be
given, in which case references matching any prefix will be
shown. Note that this is purely for optimization; a server MAY
show refs not matching the prefix if it chooses, and clients
should filter the result themselves.

   unborn
The server will send information about HEAD even if it is a symref
pointing to an unborn branch in the form "unborn HEAD
symref-target:<target>".

output = *ref


  flush-pkt
obj-id-or-unborn = (obj-id | "unborn")
ref = PKT-LINE(obj-id-or-unborn SP refname *(SP ref-attribute) LF)
ref-attribute = (symref | peeled)
symref = "symref-target:" symref-target
peeled = "peeled:" obj-id

   want <oid>
Indicates to the server an object which the client wants to
retrieve.  Wants can be anything and are not limited to
advertised objects.

   have <oid>
Indicates to the server an object which the client has locally.
This allows the server to make a packfile which only contains
the objects that the client needs. Multiple 'have' lines can be
supplied.

   done
Indicates to the server that negotiation should terminate (or
not even begin if performing a clone) and that the server should
use the information supplied in the request to construct the
packfile.

   thin-pack
Request that a thin pack be sent, which is a pack with deltas
which reference base objects not contained within the pack (but
are known to exist at the receiving end). This can reduce the
network traffic significantly, but it requires the receiving end
to know how to "thicken" these packs by adding the missing bases
to the pack.

   no-progress
Request that progress information that would normally be sent on
side-band channel 2, during the packfile transfer, should not be
sent.  However, the side-band channel 3 is still used for error
responses.

   include-tag
Request that annotated tags should be sent if the objects they
point to are being sent.

   ofs-delta
Indicate that the client understands PACKv2 with delta referring
to its base by position in pack rather than by an oid.  That is,
they can read OBJ_OFS_DELTA (aka type 6) in a packfile.

   shallow <oid>
A client must notify the server of all commits for which it only
has shallow copies (meaning that it doesn't have the parents of
a commit) by supplying a 'shallow <oid>' line for each such
object so that the server is aware of the limitations of the
client's history.  This is so that the server is aware that the
client may not have all objects reachable from such commits.

   deepen <depth>
Requests that the fetch/clone should be shallow having a commit
depth of <depth> relative to the remote side.

   deepen-relative
Requests that the semantics of the "deepen" command be changed
to indicate that the depth requested is relative to the client's
current shallow boundary, instead of relative to the requested
commits.

   deepen-since <timestamp>
Requests that the shallow clone/fetch should be cut at a
specific time, instead of depth.  Internally it's equivalent to
doing "git rev-list --max-age=<timestamp>". Cannot be used with
"deepen".

   deepen-not <rev>
Requests that the shallow clone/fetch should be cut at a
specific revision specified by '<rev>', instead of a depth.
Internally it's equivalent of doing "git rev-list --not <rev>".
Cannot be used with "deepen", but can be used with
"deepen-since".

   filter <filter-spec>
Request that various objects from the packfile be omitted
using one of several filtering techniques. These are intended
for use with partial clone and partial fetch operations. See
`rev-list` for possible "filter-spec" values. When communicating
with other processes, senders SHOULD translate scaled integers
(e.g. "1k") into a fully-expanded form (e.g. "1024") to aid
interoperability with older receivers that may not understand
newly-invented scaling suffixes. However, receivers SHOULD
accept the following suffixes: 'k', 'm', and 'g' for 1024,
1048576, and 1073741824, respectively.

   want-ref <ref>
Indicates to the server that the client wants to retrieve a
particular ref, where <ref> is the full name of a ref on the
server.  It is a protocol error to send want-ref for the
same ref more than once.

   sideband-all
Instruct the server to send the whole response multiplexed, not just
the packfile section. All non-flush and non-delim PKT-LINE in the
response (not only in the packfile section) will then start with a byte
indicating its sideband (1, 2, or 3), and the server may send "0005\2"
(a PKT-LINE of sideband 2 with no payload) as a keepalive packet.

   packfile-uris <comma-separated-list-of-protocols>
Indicates to the server that the client is willing to receive
URIs of any of the given protocols in place of objects in the
sent packfile. Before performing the connectivity check, the
client should download from all given URIs. Currently, the
protocols supported are "http" and "https".

   wait-for-done
Indicates to the server that it should never send "ready", but
should wait for the client to say "done" before sending the
packfile.

output = acknowledgements flush-pkt |


  [acknowledgments delim-pkt] [shallow-info delim-pkt]


  [wanted-refs delim-pkt] [packfile-uris delim-pkt]


  packfile flush-pkt

acknowledgments = PKT-LINE("acknowledgments" LF)


    (nak | *ack)


    (ready)
ready = PKT-LINE("ready" LF)
nak = PKT-LINE("NAK" LF)
ack = PKT-LINE("ACK" SP obj-id LF)

shallow-info = PKT-LINE("shallow-info" LF)


 *PKT-LINE((shallow | unshallow) LF)
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-uris = PKT-LINE("packfile-uris" LF) *packfile-uri
packfile-uri = PKT-LINE(40*(HEXDIGIT) SP *%x20-ff LF)

packfile = PKT-LINE("packfile" LF)


    *PKT-LINE(%x01-03 *%x00-ff)

   acknowledgments section
* If the client determines that it is finished with negotiations by


  sending a "done" line (thus requiring the server to send a packfile),


  the acknowledgments sections MUST be omitted from the server's


  response.

•Always begins with the section header "acknowledgments"

•The server will respond with "NAK" if none of the object ids sent as have lines were common.

•The server will respond with "ACK obj-id" for all of the object ids sent as have lines which are common.

•A response cannot have both "ACK" lines as well as a "NAK" line.

•The server will respond with a "ready" line indicating that the server has found an acceptable common base and is ready to make and send a packfile (which will be found in the packfile section of the same response)

•If the server has found a suitable cut point and has decided to send a "ready" line, then the server can decide to (as an optimization) omit any "ACK" lines it would have sent during its response. This is because the server will have already determined the objects it plans to send to the client and no further negotiation is needed.

•Always begins with the section header "shallow-info"

•If a positive depth is requested, the server will compute the set of commits which are no deeper than the desired depth.

•The server sends a "shallow obj-id" line for each commit whose parents will not be sent in the following packfile.

•The server sends an "unshallow obj-id" line for each commit which the client has indicated is shallow, but is no longer shallow as a result of the fetch (due to its parents being sent in the following packfile).

•The server MUST NOT send any "unshallow" lines for anything which the client has not indicated was shallow as a part of its request.

•Always begins with the section header "wanted-refs".

•The server will send a ref listing ("<oid> <refname>") for each reference requested using want-ref lines.

•The server MUST NOT send any refs which were not requested using want-ref lines.

•Always begins with the section header "packfile-uris".

•For each URI the server sends, it sends a hash of the pack’s contents (as output by git index-pack) followed by the URI.

•The hashes are 40 hex characters long. When Git upgrades to a new hash algorithm, this might need to be updated. (It should match whatever index-pack outputs after "pack\t" or "keep\t".

•Always begins with the section header "packfile"

•The transmission of the packfile begins immediately after the section header

•The data transfer of the packfile is always multiplexed, using the same semantics of the side-band-64k capability from protocol version 1. This means that each packet, during the packfile data stream, is made up of a leading 4-byte pkt-line length (typical of the pkt-line format), followed by a 1-byte stream code, followed by the actual data.

size
Requests size information to be returned for each listed object id.

oid <oid>
Indicates to the server an object which the client wants to obtain
information for.

output = info flush-pkt

info = PKT-LINE(attrs) LF)
	*PKT-LINE(obj-info LF)

attrs = attr | attrs SP attrs

attr = "size"

obj-info = obj-id SP obj-size

The intent of the feature is optimize for server resource consumption in the common case by changing the common case of fetching a very large PACK during git-clone(1) into a smaller incremental fetch.

It also allows servers to achieve better caching in combination with an uploadpack.packObjectsHook (see git-config(1)).

By having new clones or fetches be a more predictable and common negotiation against the tips of recently produces *.bundle file(s). Servers might even pre-generate the results of such negotiations for the uploadpack.packObjectsHook as new pushes come in.

One way that servers could take advantage of these bundles is that the server would anticipate that fresh clones will download a known bundle, followed by catching up to the current state of the repository using ref tips found in that bundle (or bundles).

A bundle-uri request takes no arguments, and as noted above does not currently advertise a capability value. Both may be added in the future.

When the client issues a command=bundle-uri request, the response is a list of key-value pairs provided as packet lines with value <key>=<value>. Each <key> should be interpreted as a config key from the bundle.* namespace to construct a list of bundles. These keys are grouped by a bundle.<id>. subsection, where each key corresponding to a given <id> contributes attributes to the bundle defined by that <id>. See git-config(1) for the specific details of these keys and how the Git client will interpret their values.

Clients MUST parse the line according to the above format, lines that do not conform to the format SHOULD be discarded. The user MAY be warned in such a case.

URI CONTENTS

bundle-uri CLIENT ERROR RECOVERY

bundle-uri SERVER TO CLIENT

bundle-uri CLIENT TO SERVER

WHEN ADVERTISED BUNDLE(S) REQUIRE NO FURTHER NEGOTIATION

EARLY CLIENT DISCONNECTIONS AND ERROR RECOVERY

WHEN ADVERTISED BUNDLE(S) REQUIRE FURTHER NEGOTIATION

The client constructs a bundle list from the <key>=<value> pairs provided by the server. These pairs are part of the bundle.* namespace as documented in git-config(1). In this section, we discuss some of these keys and describe the actions the client will do in response to this information.

In particular, the bundle.version key specifies an integer value. The only accepted value at the moment is 1, but if the client sees an unexpected value here then the client MUST ignore the bundle list.

As long as bundle.version is understood, all other unknown keys MAY be ignored by the client. The server will guarantee compatibility with older clients, though newer clients may be better able to use the extra keys to minimize downloads.

Any backwards-incompatible addition of pre-URI key-value will be guarded by a new bundle.version value or values in bundle-uri capability advertisement itself, and/or by new future bundle-uri request arguments.

Some example key-value pairs that are not currently implemented but could be implemented in the future include: