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b31222cf SC |
1 | Packfile transfer protocols |
2 | =========================== | |
3 | ||
4 | Git supports transferring data in packfiles over the ssh://, git:// and | |
5 | file:// transports. There exist two sets of protocols, one for pushing | |
6 | data from a client to a server and another for fetching data from a | |
7 | server to a client. All three transports (ssh, git, file) use the same | |
8 | protocol to transfer data. | |
9 | ||
10 | The processes invoked in the canonical Git implementation are 'upload-pack' | |
11 | on the server side and 'fetch-pack' on the client side for fetching data; | |
12 | then 'receive-pack' on the server and 'send-pack' on the client for pushing | |
13 | data. The protocol functions to have a server tell a client what is | |
14 | currently on the server, then for the two to negotiate the smallest amount | |
15 | of data to send in order to fully update one or the other. | |
16 | ||
17 | Transports | |
18 | ---------- | |
19 | There are three transports over which the packfile protocol is | |
20 | initiated. The Git transport is a simple, unauthenticated server that | |
21 | takes the command (almost always 'upload-pack', though Git | |
22 | servers can be configured to be globally writable, in which 'receive- | |
23 | pack' initiation is also allowed) with which the client wishes to | |
24 | communicate and executes it and connects it to the requesting | |
25 | process. | |
26 | ||
27 | In the SSH transport, the client just runs the 'upload-pack' | |
28 | or 'receive-pack' process on the server over the SSH protocol and then | |
29 | communicates with that invoked process over the SSH connection. | |
30 | ||
31 | The file:// transport runs the 'upload-pack' or 'receive-pack' | |
32 | process locally and communicates with it over a pipe. | |
33 | ||
34 | Git Transport | |
35 | ------------- | |
36 | ||
37 | The Git transport starts off by sending the command and repository | |
38 | on the wire using the pkt-line format, followed by a NUL byte and a | |
8e50175d | 39 | hostname parameter, terminated by a NUL byte. |
b31222cf SC |
40 | |
41 | 0032git-upload-pack /project.git\0host=myserver.com\0 | |
42 | ||
43 | -- | |
44 | git-proto-request = request-command SP pathname NUL [ host-parameter NUL ] | |
45 | request-command = "git-upload-pack" / "git-receive-pack" / | |
46 | "git-upload-archive" ; case sensitive | |
47 | pathname = *( %x01-ff ) ; exclude NUL | |
48 | host-parameter = "host=" hostname [ ":" port ] | |
49 | -- | |
50 | ||
51 | Only host-parameter is allowed in the git-proto-request. Clients | |
52 | MUST NOT attempt to send additional parameters. It is used for the | |
53 | git-daemon name based virtual hosting. See --interpolated-path | |
54 | option to git daemon, with the %H/%CH format characters. | |
55 | ||
56 | Basically what the Git client is doing to connect to an 'upload-pack' | |
57 | process on the server side over the Git protocol is this: | |
58 | ||
59 | $ echo -e -n \ | |
60 | "0039git-upload-pack /schacon/gitbook.git\0host=example.com\0" | | |
61 | nc -v example.com 9418 | |
62 | ||
d78e5aec NTND |
63 | If the server refuses the request for some reasons, it could abort |
64 | gracefully with an error message. | |
65 | ||
66 | ---- | |
67 | error-line = PKT-LINE("ERR" SP explanation-text) | |
68 | ---- | |
69 | ||
b31222cf SC |
70 | |
71 | SSH Transport | |
72 | ------------- | |
73 | ||
74 | Initiating the upload-pack or receive-pack processes over SSH is | |
75 | executing the binary on the server via SSH remote execution. | |
76 | It is basically equivalent to running this: | |
77 | ||
78 | $ ssh git.example.com "git-upload-pack '/project.git'" | |
79 | ||
80 | For a server to support Git pushing and pulling for a given user over | |
81 | SSH, that user needs to be able to execute one or both of those | |
82 | commands via the SSH shell that they are provided on login. On some | |
83 | systems, that shell access is limited to only being able to run those | |
84 | two commands, or even just one of them. | |
85 | ||
86 | In an ssh:// format URI, it's absolute in the URI, so the '/' after | |
87 | the host name (or port number) is sent as an argument, which is then | |
88 | read by the remote git-upload-pack exactly as is, so it's effectively | |
89 | an absolute path in the remote filesystem. | |
90 | ||
91 | git clone ssh://user@example.com/project.git | |
92 | | | |
93 | v | |
94 | ssh user@example.com "git-upload-pack '/project.git'" | |
95 | ||
96 | In a "user@host:path" format URI, its relative to the user's home | |
97 | directory, because the Git client will run: | |
98 | ||
99 | git clone user@example.com:project.git | |
100 | | | |
101 | v | |
102 | ssh user@example.com "git-upload-pack 'project.git'" | |
103 | ||
104 | The exception is if a '~' is used, in which case | |
105 | we execute it without the leading '/'. | |
106 | ||
107 | ssh://user@example.com/~alice/project.git, | |
108 | | | |
109 | v | |
110 | ssh user@example.com "git-upload-pack '~alice/project.git'" | |
111 | ||
112 | A few things to remember here: | |
113 | ||
114 | - The "command name" is spelled with dash (e.g. git-upload-pack), but | |
115 | this can be overridden by the client; | |
116 | ||
117 | - The repository path is always quoted with single quotes. | |
118 | ||
119 | Fetching Data From a Server | |
5316c8e9 | 120 | --------------------------- |
b31222cf SC |
121 | |
122 | When one Git repository wants to get data that a second repository | |
123 | has, the first can 'fetch' from the second. This operation determines | |
124 | what data the server has that the client does not then streams that | |
125 | data down to the client in packfile format. | |
126 | ||
127 | ||
128 | Reference Discovery | |
129 | ------------------- | |
130 | ||
131 | When the client initially connects the server will immediately respond | |
132 | with a listing of each reference it has (all branches and tags) along | |
133 | with the object name that each reference currently points to. | |
134 | ||
135 | $ echo -e -n "0039git-upload-pack /schacon/gitbook.git\0host=example.com\0" | | |
136 | nc -v example.com 9418 | |
5316c8e9 TA |
137 | 00887217a7c7e582c46cec22a130adf4b9d7d950fba0 HEAD\0multi_ack thin-pack |
138 | side-band side-band-64k ofs-delta shallow no-progress include-tag | |
b31222cf SC |
139 | 00441d3fcd5ced445d1abc402225c0b8a1299641f497 refs/heads/integration |
140 | 003f7217a7c7e582c46cec22a130adf4b9d7d950fba0 refs/heads/master | |
141 | 003cb88d2441cac0977faf98efc80305012112238d9d refs/tags/v0.9 | |
142 | 003c525128480b96c89e6418b1e40909bf6c5b2d580f refs/tags/v1.0 | |
143 | 003fe92df48743b7bc7d26bcaabfddde0a1e20cae47c refs/tags/v1.0^{} | |
144 | 0000 | |
145 | ||
146 | Server SHOULD terminate each non-flush line using LF ("\n") terminator; | |
147 | client MUST NOT complain if there is no terminator. | |
148 | ||
149 | The returned response is a pkt-line stream describing each ref and | |
150 | its current value. The stream MUST be sorted by name according to | |
151 | the C locale ordering. | |
152 | ||
153 | If HEAD is a valid ref, HEAD MUST appear as the first advertised | |
154 | ref. If HEAD is not a valid ref, HEAD MUST NOT appear in the | |
155 | advertisement list at all, but other refs may still appear. | |
156 | ||
157 | The stream MUST include capability declarations behind a NUL on the | |
158 | first ref. The peeled value of a ref (that is "ref^{}") MUST be | |
159 | immediately after the ref itself, if presented. A conforming server | |
6a5d0b0a | 160 | MUST peel the ref if it's an annotated tag. |
b31222cf SC |
161 | |
162 | ---- | |
163 | advertised-refs = (no-refs / list-of-refs) | |
ad491366 | 164 | *shallow |
b31222cf SC |
165 | flush-pkt |
166 | ||
167 | no-refs = PKT-LINE(zero-id SP "capabilities^{}" | |
168 | NUL capability-list LF) | |
169 | ||
170 | list-of-refs = first-ref *other-ref | |
171 | first-ref = PKT-LINE(obj-id SP refname | |
172 | NUL capability-list LF) | |
173 | ||
174 | other-ref = PKT-LINE(other-tip / other-peeled) | |
175 | other-tip = obj-id SP refname LF | |
176 | other-peeled = obj-id SP refname "^{}" LF | |
177 | ||
ad491366 NTND |
178 | shallow = PKT-LINE("shallow" SP obj-id) |
179 | ||
b31222cf SC |
180 | capability-list = capability *(SP capability) |
181 | capability = 1*(LC_ALPHA / DIGIT / "-" / "_") | |
182 | LC_ALPHA = %x61-7A | |
183 | ---- | |
184 | ||
185 | Server and client MUST use lowercase for obj-id, both MUST treat obj-id | |
186 | as case-insensitive. | |
187 | ||
188 | See protocol-capabilities.txt for a list of allowed server capabilities | |
189 | and descriptions. | |
190 | ||
191 | Packfile Negotiation | |
192 | -------------------- | |
a1e90b23 AN |
193 | After reference and capabilities discovery, the client can decide to |
194 | terminate the connection by sending a flush-pkt, telling the server it can | |
195 | now gracefully terminate, and disconnect, when it does not need any pack | |
196 | data. This can happen with the ls-remote command, and also can happen when | |
197 | the client already is up-to-date. | |
198 | ||
199 | Otherwise, it enters the negotiation phase, where the client and | |
200 | server determine what the minimal packfile necessary for transport is, | |
4a1c2695 AN |
201 | by telling the server what objects it wants, its shallow objects |
202 | (if any), and the maximum commit depth it wants (if any). The client | |
203 | will also send a list of the capabilities it wants to be in effect, | |
204 | out of what the server said it could do with the first 'want' line. | |
b31222cf SC |
205 | |
206 | ---- | |
207 | upload-request = want-list | |
4a1c2695 AN |
208 | *shallow-line |
209 | *1depth-request | |
210 | flush-pkt | |
b31222cf SC |
211 | |
212 | want-list = first-want | |
213 | *additional-want | |
4a1c2695 | 214 | |
e543b3f6 | 215 | shallow-line = PKT-LINE("shallow" SP obj-id) |
4a1c2695 | 216 | |
e543b3f6 | 217 | depth-request = PKT-LINE("deepen" SP depth) |
b31222cf SC |
218 | |
219 | first-want = PKT-LINE("want" SP obj-id SP capability-list LF) | |
220 | additional-want = PKT-LINE("want" SP obj-id LF) | |
221 | ||
4a1c2695 | 222 | depth = 1*DIGIT |
b31222cf SC |
223 | ---- |
224 | ||
225 | Clients MUST send all the obj-ids it wants from the reference | |
226 | discovery phase as 'want' lines. Clients MUST send at least one | |
227 | 'want' command in the request body. Clients MUST NOT mention an | |
228 | obj-id in a 'want' command which did not appear in the response | |
229 | obtained through ref discovery. | |
230 | ||
4a1c2695 AN |
231 | The client MUST write all obj-ids which it only has shallow copies |
232 | of (meaning that it does not have the parents of a commit) as | |
233 | 'shallow' lines so that the server is aware of the limitations of | |
af04fa2a | 234 | the client's history. |
4a1c2695 AN |
235 | |
236 | The client now sends the maximum commit history depth it wants for | |
237 | this transaction, which is the number of commits it wants from the | |
238 | tip of the history, if any, as a 'deepen' line. A depth of 0 is the | |
239 | same as not making a depth request. The client does not want to receive | |
a58088ab JL |
240 | any commits beyond this depth, nor does it want objects needed only to |
241 | complete those commits. Commits whose parents are not received as a | |
242 | result are defined as shallow and marked as such in the server. This | |
243 | information is sent back to the client in the next step. | |
4a1c2695 AN |
244 | |
245 | Once all the 'want's and 'shallow's (and optional 'deepen') are | |
246 | transferred, clients MUST send a flush-pkt, to tell the server side | |
247 | that it is done sending the list. | |
248 | ||
249 | Otherwise, if the client sent a positive depth request, the server | |
250 | will determine which commits will and will not be shallow and | |
251 | send this information to the client. If the client did not request | |
252 | a positive depth, this step is skipped. | |
b31222cf | 253 | |
4a1c2695 AN |
254 | ---- |
255 | shallow-update = *shallow-line | |
256 | *unshallow-line | |
257 | flush-pkt | |
b31222cf | 258 | |
4a1c2695 AN |
259 | shallow-line = PKT-LINE("shallow" SP obj-id) |
260 | ||
261 | unshallow-line = PKT-LINE("unshallow" SP obj-id) | |
262 | ---- | |
263 | ||
264 | If the client has requested a positive depth, the server will compute | |
01f7d7f1 PO |
265 | the set of commits which are no deeper than the desired depth. The set |
266 | of commits start at the client's wants. | |
267 | ||
268 | The server writes 'shallow' lines for each | |
4a1c2695 AN |
269 | commit whose parents will not be sent as a result. The server writes |
270 | an 'unshallow' line for each commit which the client has indicated is | |
271 | shallow, but is no longer shallow at the currently requested depth | |
272 | (that is, its parents will now be sent). The server MUST NOT mark | |
273 | as unshallow anything which the client has not indicated was shallow. | |
b31222cf SC |
274 | |
275 | Now the client will send a list of the obj-ids it has using 'have' | |
4a1c2695 AN |
276 | lines, so the server can make a packfile that only contains the objects |
277 | that the client needs. In multi_ack mode, the canonical implementation | |
278 | will send up to 32 of these at a time, then will send a flush-pkt. The | |
279 | canonical implementation will skip ahead and send the next 32 immediately, | |
280 | so that there is always a block of 32 "in-flight on the wire" at a time. | |
281 | ||
282 | ---- | |
283 | upload-haves = have-list | |
284 | compute-end | |
285 | ||
286 | have-list = *have-line | |
287 | have-line = PKT-LINE("have" SP obj-id LF) | |
288 | compute-end = flush-pkt / PKT-LINE("done") | |
289 | ---- | |
b31222cf SC |
290 | |
291 | If the server reads 'have' lines, it then will respond by ACKing any | |
292 | of the obj-ids the client said it had that the server also has. The | |
293 | server will ACK obj-ids differently depending on which ack mode is | |
294 | chosen by the client. | |
295 | ||
296 | In multi_ack mode: | |
297 | ||
298 | * the server will respond with 'ACK obj-id continue' for any common | |
299 | commits. | |
300 | ||
301 | * once the server has found an acceptable common base commit and is | |
302 | ready to make a packfile, it will blindly ACK all 'have' obj-ids | |
303 | back to the client. | |
304 | ||
305 | * the server will then send a 'NACK' and then wait for another response | |
306 | from the client - either a 'done' or another list of 'have' lines. | |
307 | ||
308 | In multi_ack_detailed mode: | |
309 | ||
310 | * the server will differentiate the ACKs where it is signaling | |
311 | that it is ready to send data with 'ACK obj-id ready' lines, and | |
312 | signals the identified common commits with 'ACK obj-id common' lines. | |
313 | ||
314 | Without either multi_ack or multi_ack_detailed: | |
315 | ||
316 | * upload-pack sends "ACK obj-id" on the first common object it finds. | |
317 | After that it says nothing until the client gives it a "done". | |
318 | ||
319 | * upload-pack sends "NAK" on a flush-pkt if no common object | |
320 | has been found yet. If one has been found, and thus an ACK | |
6a5d0b0a | 321 | was already sent, it's silent on the flush-pkt. |
b31222cf SC |
322 | |
323 | After the client has gotten enough ACK responses that it can determine | |
324 | that the server has enough information to send an efficient packfile | |
325 | (in the canonical implementation, this is determined when it has received | |
326 | enough ACKs that it can color everything left in the --date-order queue | |
327 | as common with the server, or the --date-order queue is empty), or the | |
328 | client determines that it wants to give up (in the canonical implementation, | |
329 | this is determined when the client sends 256 'have' lines without getting | |
330 | any of them ACKed by the server - meaning there is nothing in common and | |
6a5d0b0a | 331 | the server should just send all of its objects), then the client will send |
b31222cf | 332 | a 'done' command. The 'done' command signals to the server that the client |
6a5d0b0a | 333 | is ready to receive its packfile data. |
b31222cf SC |
334 | |
335 | However, the 256 limit *only* turns on in the canonical client | |
336 | implementation if we have received at least one "ACK %s continue" | |
337 | during a prior round. This helps to ensure that at least one common | |
338 | ancestor is found before we give up entirely. | |
339 | ||
340 | Once the 'done' line is read from the client, the server will either | |
32752e96 NTND |
341 | send a final 'ACK obj-id' or it will send a 'NAK'. 'obj-id' is the object |
342 | name of the last commit determined to be common. The server only sends | |
b31222cf SC |
343 | ACK after 'done' if there is at least one common base and multi_ack or |
344 | multi_ack_detailed is enabled. The server always sends NAK after 'done' | |
345 | if there is no common base found. | |
346 | ||
6a5d0b0a | 347 | Then the server will start sending its packfile data. |
b31222cf SC |
348 | |
349 | ---- | |
350 | server-response = *ack_multi ack / nak | |
351 | ack_multi = PKT-LINE("ACK" SP obj-id ack_status LF) | |
352 | ack_status = "continue" / "common" / "ready" | |
353 | ack = PKT-LINE("ACK SP obj-id LF) | |
354 | nak = PKT-LINE("NAK" LF) | |
355 | ---- | |
356 | ||
357 | A simple clone may look like this (with no 'have' lines): | |
358 | ||
359 | ---- | |
79135e4c | 360 | C: 0054want 74730d410fcb6603ace96f1dc55ea6196122532d multi_ack \ |
b31222cf SC |
361 | side-band-64k ofs-delta\n |
362 | C: 0032want 7d1665144a3a975c05f1f43902ddaf084e784dbe\n | |
363 | C: 0032want 5a3f6be755bbb7deae50065988cbfa1ffa9ab68a\n | |
364 | C: 0032want 7e47fe2bd8d01d481f44d7af0531bd93d3b21c01\n | |
365 | C: 0032want 74730d410fcb6603ace96f1dc55ea6196122532d\n | |
366 | C: 0000 | |
367 | C: 0009done\n | |
368 | ||
369 | S: 0008NAK\n | |
370 | S: [PACKFILE] | |
371 | ---- | |
372 | ||
373 | An incremental update (fetch) response might look like this: | |
374 | ||
375 | ---- | |
79135e4c | 376 | C: 0054want 74730d410fcb6603ace96f1dc55ea6196122532d multi_ack \ |
b31222cf SC |
377 | side-band-64k ofs-delta\n |
378 | C: 0032want 7d1665144a3a975c05f1f43902ddaf084e784dbe\n | |
379 | C: 0032want 5a3f6be755bbb7deae50065988cbfa1ffa9ab68a\n | |
380 | C: 0000 | |
381 | C: 0032have 7e47fe2bd8d01d481f44d7af0531bd93d3b21c01\n | |
382 | C: [30 more have lines] | |
383 | C: 0032have 74730d410fcb6603ace96f1dc55ea6196122532d\n | |
384 | C: 0000 | |
385 | ||
386 | S: 003aACK 7e47fe2bd8d01d481f44d7af0531bd93d3b21c01 continue\n | |
387 | S: 003aACK 74730d410fcb6603ace96f1dc55ea6196122532d continue\n | |
388 | S: 0008NAK\n | |
389 | ||
390 | C: 0009done\n | |
391 | ||
c8a97906 | 392 | S: 0031ACK 74730d410fcb6603ace96f1dc55ea6196122532d\n |
b31222cf SC |
393 | S: [PACKFILE] |
394 | ---- | |
395 | ||
396 | ||
397 | Packfile Data | |
398 | ------------- | |
399 | ||
400 | Now that the client and server have finished negotiation about what | |
401 | the minimal amount of data that needs to be sent to the client is, the server | |
402 | will construct and send the required data in packfile format. | |
403 | ||
404 | See pack-format.txt for what the packfile itself actually looks like. | |
405 | ||
406 | If 'side-band' or 'side-band-64k' capabilities have been specified by | |
407 | the client, the server will send the packfile data multiplexed. | |
408 | ||
409 | Each packet starting with the packet-line length of the amount of data | |
410 | that follows, followed by a single byte specifying the sideband the | |
411 | following data is coming in on. | |
412 | ||
413 | In 'side-band' mode, it will send up to 999 data bytes plus 1 control | |
414 | code, for a total of up to 1000 bytes in a pkt-line. In 'side-band-64k' | |
415 | mode it will send up to 65519 data bytes plus 1 control code, for a | |
416 | total of up to 65520 bytes in a pkt-line. | |
417 | ||
418 | The sideband byte will be a '1', '2' or a '3'. Sideband '1' will contain | |
419 | packfile data, sideband '2' will be used for progress information that the | |
420 | client will generally print to stderr and sideband '3' is used for error | |
421 | information. | |
422 | ||
423 | If no 'side-band' capability was specified, the server will stream the | |
424 | entire packfile without multiplexing. | |
425 | ||
426 | ||
427 | Pushing Data To a Server | |
5316c8e9 | 428 | ------------------------ |
b31222cf SC |
429 | |
430 | Pushing data to a server will invoke the 'receive-pack' process on the | |
431 | server, which will allow the client to tell it which references it should | |
432 | update and then send all the data the server will need for those new | |
433 | references to be complete. Once all the data is received and validated, | |
434 | the server will then update its references to what the client specified. | |
435 | ||
436 | Authentication | |
437 | -------------- | |
438 | ||
439 | The protocol itself contains no authentication mechanisms. That is to be | |
440 | handled by the transport, such as SSH, before the 'receive-pack' process is | |
441 | invoked. If 'receive-pack' is configured over the Git transport, those | |
442 | repositories will be writable by anyone who can access that port (9418) as | |
443 | that transport is unauthenticated. | |
444 | ||
445 | Reference Discovery | |
446 | ------------------- | |
447 | ||
448 | The reference discovery phase is done nearly the same way as it is in the | |
449 | fetching protocol. Each reference obj-id and name on the server is sent | |
450 | in packet-line format to the client, followed by a flush-pkt. The only | |
451 | real difference is that the capability listing is different - the only | |
452 | possible values are 'report-status', 'delete-refs' and 'ofs-delta'. | |
453 | ||
454 | Reference Update Request and Packfile Transfer | |
455 | ---------------------------------------------- | |
456 | ||
457 | Once the client knows what references the server is at, it can send a | |
458 | list of reference update requests. For each reference on the server | |
459 | that it wants to update, it sends a line listing the obj-id currently on | |
460 | the server, the obj-id the client would like to update it to and the name | |
461 | of the reference. | |
462 | ||
463 | This list is followed by a flush-pkt and then the packfile that should | |
464 | contain all the objects that the server will need to complete the new | |
465 | references. | |
466 | ||
467 | ---- | |
4adf569d | 468 | update-request = *shallow ( command-list | push-cert ) [pack-file] |
5dbd7676 NTND |
469 | |
470 | shallow = PKT-LINE("shallow" SP obj-id) | |
b31222cf SC |
471 | |
472 | command-list = PKT-LINE(command NUL capability-list LF) | |
473 | *PKT-LINE(command LF) | |
474 | flush-pkt | |
475 | ||
476 | command = create / delete / update | |
477 | create = zero-id SP new-id SP name | |
478 | delete = old-id SP zero-id SP name | |
479 | update = old-id SP new-id SP name | |
480 | ||
481 | old-id = obj-id | |
482 | new-id = obj-id | |
483 | ||
4adf569d JH |
484 | push-cert = PKT-LINE("push-cert" NUL capability-list LF) |
485 | PKT-LINE("certificate version 0.1" LF) | |
486 | PKT-LINE("pusher" SP ident LF) | |
487 | PKT-LINE(LF) | |
488 | *PKT-LINE(command LF) | |
489 | *PKT-LINE(gpg-signature-lines LF) | |
490 | PKT-LINE("push-cert-end" LF) | |
491 | ||
b31222cf SC |
492 | pack-file = "PACK" 28*(OCTET) |
493 | ---- | |
494 | ||
495 | If the receiving end does not support delete-refs, the sending end MUST | |
496 | NOT ask for delete command. | |
497 | ||
4adf569d JH |
498 | If the receiving end does not support push-cert, the sending end |
499 | MUST NOT send a push-cert command. When a push-cert command is | |
500 | sent, command-list MUST NOT be sent; the commands recorded in the | |
501 | push certificate is used instead. | |
502 | ||
b31222cf SC |
503 | The pack-file MUST NOT be sent if the only command used is 'delete'. |
504 | ||
505 | A pack-file MUST be sent if either create or update command is used, | |
506 | even if the server already has all the necessary objects. In this | |
507 | case the client MUST send an empty pack-file. The only time this | |
508 | is likely to happen is if the client is creating | |
509 | a new branch or a tag that points to an existing obj-id. | |
510 | ||
511 | The server will receive the packfile, unpack it, then validate each | |
512 | reference that is being updated that it hasn't changed while the request | |
513 | was being processed (the obj-id is still the same as the old-id), and | |
514 | it will run any update hooks to make sure that the update is acceptable. | |
515 | If all of that is fine, the server will then update the references. | |
516 | ||
4adf569d JH |
517 | Push Certificate |
518 | ---------------- | |
519 | ||
520 | A push certificate begins with a set of header lines. After the | |
521 | header and an empty line, the protocol commands follow, one per | |
522 | line. | |
523 | ||
524 | Currently, the following header fields are defined: | |
525 | ||
526 | `pusher` ident:: | |
527 | Identify the GPG key in "Human Readable Name <email@address>" | |
528 | format. | |
529 | ||
530 | The GPG signature lines are a detached signature for the contents | |
531 | recorded in the push certificate before the signature block begins. | |
532 | The detached signature is used to certify that the commands were | |
533 | given by the pusher, who must be the signer. | |
534 | ||
b31222cf SC |
535 | Report Status |
536 | ------------- | |
537 | ||
538 | After receiving the pack data from the sender, the receiver sends a | |
539 | report if 'report-status' capability is in effect. | |
540 | It is a short listing of what happened in that update. It will first | |
541 | list the status of the packfile unpacking as either 'unpack ok' or | |
542 | 'unpack [error]'. Then it will list the status for each of the references | |
543 | that it tried to update. Each line is either 'ok [refname]' if the | |
544 | update was successful, or 'ng [refname] [error]' if the update was not. | |
545 | ||
546 | ---- | |
547 | report-status = unpack-status | |
548 | 1*(command-status) | |
549 | flush-pkt | |
550 | ||
551 | unpack-status = PKT-LINE("unpack" SP unpack-result LF) | |
552 | unpack-result = "ok" / error-msg | |
553 | ||
554 | command-status = command-ok / command-fail | |
555 | command-ok = PKT-LINE("ok" SP refname LF) | |
556 | command-fail = PKT-LINE("ng" SP refname SP error-msg LF) | |
557 | ||
558 | error-msg = 1*(OCTECT) ; where not "ok" | |
559 | ---- | |
560 | ||
561 | Updates can be unsuccessful for a number of reasons. The reference can have | |
562 | changed since the reference discovery phase was originally sent, meaning | |
563 | someone pushed in the meantime. The reference being pushed could be a | |
564 | non-fast-forward reference and the update hooks or configuration could be | |
565 | set to not allow that, etc. Also, some references can be updated while others | |
566 | can be rejected. | |
567 | ||
568 | An example client/server communication might look like this: | |
569 | ||
570 | ---- | |
571 | S: 007c74730d410fcb6603ace96f1dc55ea6196122532d refs/heads/local\0report-status delete-refs ofs-delta\n | |
572 | S: 003e7d1665144a3a975c05f1f43902ddaf084e784dbe refs/heads/debug\n | |
573 | S: 003f74730d410fcb6603ace96f1dc55ea6196122532d refs/heads/master\n | |
574 | S: 003f74730d410fcb6603ace96f1dc55ea6196122532d refs/heads/team\n | |
575 | S: 0000 | |
576 | ||
577 | C: 003e7d1665144a3a975c05f1f43902ddaf084e784dbe 74730d410fcb6603ace96f1dc55ea6196122532d refs/heads/debug\n | |
578 | C: 003e74730d410fcb6603ace96f1dc55ea6196122532d 5a3f6be755bbb7deae50065988cbfa1ffa9ab68a refs/heads/master\n | |
579 | C: 0000 | |
580 | C: [PACKDATA] | |
581 | ||
c8a97906 TRC |
582 | S: 000eunpack ok\n |
583 | S: 0018ok refs/heads/debug\n | |
584 | S: 002ang refs/heads/master non-fast-forward\n | |
b31222cf | 585 | ---- |