Allow withholding the SYN|ACK packet by user code #863
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
In certain use cases, it's desirable to not send a SYN|ACK packet immediately after receiving a SYN -- for example, a TCP proxy that doesn't want to do so until it's connected to the end destination, because the outgoing connection might get refused. (Currently, you have to send a SYN|ACK and then reset the connection afterwards in this case.) To fix this, add a simple `synack_paused` flag, controllable by user code, that withholds SYN|ACK packets in `SynReceived` state until it is unset.
Codecov ReportAttention:
Additional details and impacted files@@ Coverage Diff @@
## main #863 +/- ##
==========================================
- Coverage 79.55% 79.53% -0.02%
==========================================
Files 78 78
Lines 27917 27896 -21
==========================================
- Hits 22208 22186 -22
- Misses 5709 5710 +1 ☔ View full report in Codecov by Sentry. |
whitequark
reviewed
Dec 2, 2023
|
Fair enough! |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In certain use cases, it's desirable to not send a SYN|ACK packet immediately after receiving a SYN -- for example, a TCP proxy that doesn't want to do so until it's connected to the end destination, because the outgoing connection might get refused. (Currently, you have to send a SYN|ACK and then reset the connection afterwards in this case, which is what we do in onionmasq.)
To fix this, add a simple
synack_pausedflag, controllable by user code, that withholds SYN|ACK packets inSynReceivedstate until it is unset.