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Diffstat (limited to 'Documentation/technical/protocol-v2.txt')
| -rw-r--r-- | Documentation/technical/protocol-v2.txt | 196 |
1 files changed, 156 insertions, 40 deletions
diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt index 09e4e0273f..1040d85319 100644 --- a/Documentation/technical/protocol-v2.txt +++ b/Documentation/technical/protocol-v2.txt @@ -1,5 +1,5 @@ - Git Wire Protocol, Version 2 -============================== +Git Wire Protocol, Version 2 +============================ This document presents a specification for a version 2 of Git's wire protocol. Protocol v2 will improve upon v1 in the following ways: @@ -22,8 +22,8 @@ will be commands which a client can request be executed. Once a command has completed, a client can reuse the connection and request that other commands be executed. - Packet-Line Framing ---------------------- +Packet-Line Framing +------------------- All communication is done using packet-line framing, just as in v1. See `Documentation/technical/pack-protocol.txt` and @@ -33,9 +33,11 @@ In protocol v2 these special packets will have the following semantics: * '0000' Flush Packet (flush-pkt) - indicates the end of a message * '0001' Delimiter Packet (delim-pkt) - separates sections of a message + * '0002' Response End Packet (response-end-pkt) - indicates the end of a + response for stateless connections - Initial Client Request ------------------------- +Initial Client Request +---------------------- In general a client can request to speak protocol v2 by sending `version=2` through the respective side-channel for the transport being @@ -43,22 +45,22 @@ used which inevitably sets `GIT_PROTOCOL`. More information can be found in `pack-protocol.txt` and `http-protocol.txt`. In all cases the response from the server is the capability advertisement. - Git Transport -~~~~~~~~~~~~~~~ +Git Transport +~~~~~~~~~~~~~ When using the git:// transport, you can request to use protocol v2 by sending "version=2" as an extra parameter: 003egit-upload-pack /project.git\0host=myserver.com\0\0version=2\0 - SSH and File Transport -~~~~~~~~~~~~~~~~~~~~~~~~ +SSH and File Transport +~~~~~~~~~~~~~~~~~~~~~~ When using either the ssh:// or file:// transport, the GIT_PROTOCOL environment variable must be set explicitly to include "version=2". - HTTP Transport -~~~~~~~~~~~~~~~~ +HTTP Transport +~~~~~~~~~~~~~~ When using the http:// or https:// transport a client makes a "smart" info/refs request as described in `http-protocol.txt` and requests that @@ -79,8 +81,8 @@ A v2 server would reply: Subsequent requests are then made directly to the service `$GIT_URL/git-upload-pack`. (This works the same for git-receive-pack). - Capability Advertisement --------------------------- +Capability Advertisement +------------------------ A server which decides to communicate (based on a request from a client) using protocol version 2, notifies the client by sending a version string @@ -101,8 +103,8 @@ to be executed by the client. key = 1*(ALPHA | DIGIT | "-_") value = 1*(ALPHA | DIGIT | " -_.,?\/{}[]()<>!@#$%^&*+=:;") - Command Request ------------------ +Command Request +--------------- After receiving the capability advertisement, a client can then issue a request to select the command it wants with any particular capabilities @@ -137,11 +139,11 @@ command be executed or can terminate the connection. A client may optionally send an empty request consisting of just a flush-pkt to indicate that no more requests will be made. - Capabilities --------------- +Capabilities +------------ There are two different types of capabilities: normal capabilities, -which can be used to to convey information or alter the behavior of a +which can be used to convey information or alter the behavior of a request, and commands, which are the core actions that a client wants to perform (fetch, push, etc). @@ -153,8 +155,8 @@ management on the server side in order to function correctly. This permits simple round-robin load-balancing on the server side, without needing to worry about state management. - agent -~~~~~~~ +agent +~~~~~ The server can advertise the `agent` capability with a value `X` (in the form `agent=X`) to notify the client that the server is running version @@ -168,8 +170,8 @@ printable ASCII characters except space (i.e., the byte range 32 < x < and debugging purposes, and MUST NOT be used to programmatically assume the presence or absence of particular features. - ls-refs -~~~~~~~~~ +ls-refs +~~~~~~~ `ls-refs` is the command used to request a reference advertisement in v2. Unlike the current reference advertisement, ls-refs takes in arguments @@ -190,17 +192,26 @@ ls-refs takes in the following arguments: When specified, only references having a prefix matching one of the provided prefixes are displayed. +If the 'unborn' feature is advertised the following argument can be +included in the client's request. + + 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>". + The output of ls-refs is as follows: output = *ref flush-pkt - ref = PKT-LINE(obj-id SP refname *(SP ref-attribute) LF) + 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 - fetch -~~~~~~~ +fetch +~~~~~ `fetch` is the command used to fetch a packfile in v2. It can be looked at as a modified version of the v1 fetch where the ref-advertisement is @@ -252,7 +263,7 @@ A `fetch` request can take the following arguments: 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 (ake type 6) in a packfile. + they can read OBJ_OFS_DELTA (aka type 6) in a packfile. If the 'shallow' feature is advertised the following arguments can be included in the clients request as well as the potential addition of the @@ -296,7 +307,13 @@ included in the client's request: 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. + `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. 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 @@ -307,13 +324,44 @@ the 'wanted-refs' section in the server's response as explained below. particular ref, where <ref> is the full name of a ref on the server. +If the 'sideband-all' feature is advertised, the following argument can be +included in the client's request: + + 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. + +If the 'packfile-uris' feature is advertised, the following argument +can be included in the client's request as well as the potential +addition of the 'packfile-uris' section in the server's response as +explained below. + + 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". + +If the 'wait-for-done' feature is advertised, the following argument +can be included in the client's request. + + 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. + The response of `fetch` is broken into a number of sections separated by delimiter packets (0001), with each section beginning with its section -header. +header. Most sections are sent only when the packfile is sent. - output = *section - section = (acknowledgments | shallow-info | wanted-refs | packfile) - (flush-pkt | delim-pkt) + 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) @@ -331,13 +379,17 @@ header. *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, the acknowledgments sections MUST be - omitted from the server's response. + * 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" @@ -388,9 +440,6 @@ header. which the client has not indicated was shallow as a part of its request. - * 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 @@ -404,6 +453,20 @@ header. * The server MUST NOT send any refs which were not requested using 'want-ref' lines. + packfile-uris section + * This section is only included if the client sent + 'packfile-uris' and the server has at least one such URI to + send. + + * 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". + packfile section * This section is only included if the client has sent 'want' lines in its request and either requested that no more @@ -428,8 +491,8 @@ header. 2 - progress messages 3 - fatal error message just before stream aborts - server-option -~~~~~~~~~~~~~~~ +server-option +~~~~~~~~~~~~~ If advertised, indicates that any number of server specific options can be included in a request. This is done by sending each option as a @@ -437,3 +500,56 @@ included in a request. This is done by sending each option as a a request. The provided options must not contain a NUL or LF character. + + object-format +~~~~~~~~~~~~~~~ + +The server can advertise the `object-format` capability with a value `X` (in the +form `object-format=X`) to notify the client that the server is able to deal +with objects using hash algorithm X. If not specified, the server is assumed to +only handle SHA-1. If the client would like to use a hash algorithm other than +SHA-1, it should specify its object-format string. + +session-id=<session id> +~~~~~~~~~~~~~~~~~~~~~~~ + +The server may advertise a session ID that can be used to identify this process +across multiple requests. The client may advertise its own session ID back to +the server as well. + +Session IDs should be unique to a given process. They must fit within a +packet-line, and must not contain non-printable or whitespace characters. The +current implementation uses trace2 session IDs (see +link:api-trace2.html[api-trace2] for details), but this may change and users of +the session ID should not rely on this fact. + +object-info +~~~~~~~~~~~ + +`object-info` is the command to retrieve information about one or more objects. +Its main purpose is to allow a client to make decisions based on this +information without having to fully fetch objects. Object size is the only +information that is currently supported. + +An `object-info` request takes the following arguments: + + 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. + +The response of `object-info` is a list of the requested object ids +and associated requested information, each separated by a single space. + + 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 |