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EC_TTL_EXPIRED error is sent down idle connection, and treated as application-layer traffic by client #53

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bschofield opened this issue Feb 1, 2022 · 0 comments
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EC_TTL_EXPIRED error is sent down idle connection, and treated as application-layer traffic by client #53

bschofield opened this issue Feb 1, 2022 · 0 comments

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@bschofield
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bschofield commented Feb 1, 2022 •
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In the case where connect_socks_target() succeeds, the proxy client receives an EC_SUCCESS message and the client thread passes control to copyloop().

If both the client and remote connections are idle for too long, the call to poll() inside copyloop() returns zero, giving microsocks the opportunity to reap the inactive connection. This seems sensible. However, before closing the connection an EC_TTL_EXPIRED message is returned to the client:

send_error(fd1, EC_TTL_EXPIRED);

Because the client has already previously received EC_SUCCESS, it believes it is receiving application-layer data from the proxied target. With at least the client I was using (golang), this causes the user to receive a false \x05\x06\x00\x01\x00\x00\x00\x00\x00\x00 data sequence before the connection is closed.

From my reading of RFC1928, it isn't possible to send further control messages after an EC_SUCCESS. Am I reading that correctly, and if so should this call to send_error() be removed?
bschofield pushed a commit to bschofield/microsocks that referenced this issue Feb 1, 2022
[rofl0r#53] Remove call to send_error() before closing idle connection
314a519
@bschofield bschofield mentioned this issue Feb 1, 2022
Merged
bschofield added a commit to bschofield/microsocks that referenced this issue Feb 1, 2022
@bschofield
In the case where connect_socks_target() succeeds, the proxy client r…
95164f2 
…eceives

an EC_SUCCESS message and the client thread passes control to copyloop(),
which then proxies application-layer data. If both the client and remote
connections are idle for too long, the call to poll() inside copyloop()
returns zero, giving microsocks the opportunity to reap the inactive
connection.

Before closing the idle connection an EC_TTL_EXPIRED message is returned to
the client. Since the client has already previously received EC_SUCCESS, it
believes it is receiving application-layer data from the proxied target. This
causes the user to receive a false \x05\x06\x00\x01\x00\x00\x00\x00\x00\x00
data sequence before the connection is closed.

This commit removes the call to send_error() that returns the EC_TTL_EXPIRED
message for an idle connection. An EC_TTL_EXPIRED error can still correctly be
returned in the case where the initial socket() call to the remote address
returns ETIMEDOUT.

Fixes issue rofl0r#53.
bschofield added a commit to bschofield/microsocks that referenced this issue Feb 1, 2022
@bschofield
Remove nugatory EC_TTL_EXPIRED error before idle connection closes.
79235fe 
In the case where connect_socks_target() succeeds, the proxy client receives
an EC_SUCCESS message and the client thread passes control to copyloop(),
which then proxies application-layer data. If both the client and remote
connections are idle for too long, the call to poll() inside copyloop()
returns zero, giving microsocks the opportunity to reap the inactive
connection.

Before closing the idle connection an EC_TTL_EXPIRED message is returned to
the client. Since the client has already previously received EC_SUCCESS, it
believes it is receiving application-layer data from the proxied target. This
causes the user to receive a false \x05\x06\x00\x01\x00\x00\x00\x00\x00\x00
data sequence before the connection is closed.

This commit removes the call to send_error() that returns the EC_TTL_EXPIRED
message for an idle connection. An EC_TTL_EXPIRED error can still correctly be
returned in the case where the initial socket() call to the remote address
returns ETIMEDOUT.

Fixes issue rofl0r#53.
rofl0r pushed a commit that referenced this issue Feb 1, 2022
@bschofield @rofl0r
Remove nugatory EC_TTL_EXPIRED error before idle connection closes.
375e5a6 
In the case where connect_socks_target() succeeds, the proxy client receives
an EC_SUCCESS message and the client thread passes control to copyloop(),
which then proxies application-layer data. If both the client and remote
connections are idle for too long, the call to poll() inside copyloop()
returns zero, giving microsocks the opportunity to reap the inactive
connection.

Before closing the idle connection an EC_TTL_EXPIRED message is returned to
the client. Since the client has already previously received EC_SUCCESS, it
believes it is receiving application-layer data from the proxied target. This
causes the user to receive a false \x05\x06\x00\x01\x00\x00\x00\x00\x00\x00
data sequence before the connection is closed.

This commit removes the call to send_error() that returns the EC_TTL_EXPIRED
message for an idle connection. An EC_TTL_EXPIRED error can still correctly be
returned in the case where the initial socket() call to the remote address
returns ETIMEDOUT.

Fixes issue #53.
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