Skip to content

Try writing again to the channel if LIBSSH2_ERROR_EAGAIN is returned. #3

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
yo-bur wants to merge 1 commit into
base: master
Choose a base branch
from
+4 −1
Open

Try writing again to the channel if LIBSSH2_ERROR_EAGAIN is returned. #3

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 4 additions & 1 deletion libssh2-tunnel-example.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -106,7 +106,10 @@ int forward_tunnel(LIBSSH2_SESSION *session, LIBSSH2_CHANNEL *channel) {
}
wr = 0;
do {
i = libssh2_channel_write(channel, buf, len);
i = LIBSSH2_ERROR_EAGAIN;
while (i == LIBSSH2_ERROR_EAGAIN) {
Copy link
Copy Markdown
Owner

@marianafranco marianafranco Mar 10, 2019

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This can cause an infinite loop, blocking the tunnel on write.
The correct way to handle this is to check if the socket is alive before sending it again: https://stackoverflow.com/a/9811061/2052076

Some code examples that I found:
https://github.com/allisrc/libgit2-allisrc/blob/62ab0e1fc2a471db960b0bd881aab116b350a961/src/transports/ssh.c#L266

https://github.com/u35s/xtools/blob/99fe76fffb5d893573b1aa21e8032dc5385c2837/src/common/ssh2_client.cc#L185

i = libssh2_channel_write(channel, buf, len);
}
if (i < 0) {
fprintf(stderr, "Error writing on the SSH channel: %d\n", i);
goto shutdown;
Expand Down