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| author | Denton Liu <liu.denton@gmail.com> | 2020-05-19 10:54:00 (GMT) |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2020-05-24 23:26:00 (GMT) |
| commit | b0df0c16ead4c5512d506dcbbdf31194d992803c (patch) | |
| tree | c2a5f0b8bfb8fd410c5b3b1217202d8f91e3df39 /Documentation/technical/protocol-v2.txt | |
| parent | 0181b600a6deb66a346dbcbe8300cf9e2467ebbb (diff) | |
| download | git-b0df0c16ead4c5512d506dcbbdf31194d992803c.zip git-b0df0c16ead4c5512d506dcbbdf31194d992803c.tar.gz git-b0df0c16ead4c5512d506dcbbdf31194d992803c.tar.bz2 | |
stateless-connect: send response end packet
Currently, remote-curl acts as a proxy and blindly forwards packets
between an HTTP server and fetch-pack. In the case of a stateless RPC
connection where the connection is terminated before the transaction is
complete, remote-curl will blindly forward the packets before waiting on
more input from fetch-pack. Meanwhile, fetch-pack will read the
transaction and continue reading, expecting more input to continue the
transaction. This results in a deadlock between the two processes.
This can be seen in the following command which does not terminate:
$ git -c protocol.version=2 clone https://github.com/git/git.git --shallow-since=20151012
Cloning into 'git'...
whereas the v1 version does terminate as expected:
$ git -c protocol.version=1 clone https://github.com/git/git.git --shallow-since=20151012
Cloning into 'git'...
fatal: the remote end hung up unexpectedly
Instead of blindly forwarding packets, make remote-curl insert a
response end packet after proxying the responses from the remote server
when using stateless_connect(). On the RPC client side, ensure that each
response ends as described.
A separate control packet is chosen because we need to be able to
differentiate between what the remote server sends and remote-curl's
control packets. By ensuring in the remote-curl code that a server
cannot send response end packets, we prevent a malicious server from
being able to perform a denial of service attack in which they spoof a
response end packet and cause the described deadlock to happen.
Reported-by: Force Charlie <charlieio@outlook.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation/technical/protocol-v2.txt')
| -rw-r--r-- | Documentation/technical/protocol-v2.txt | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt index 7e3766c..3996d70 100644 --- a/Documentation/technical/protocol-v2.txt +++ b/Documentation/technical/protocol-v2.txt @@ -33,6 +33,8 @@ 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' Message Packet (response-end-pkt) - indicates the end of a response + for stateless connections Initial Client Request ---------------------- |