schannel, ignore error on recv beyond close notify#15381
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When receiving data, schannel does a recv from the lower filters, e.g. the socket, *before* it decrypts and analyses the buffered data it already has. When that buffer contains a close-notify, e.g. the end of the TLS stream, any error on the previous receive from the socket are not applicable to its return codes. Example from #153345: a server sends a close notify and closes its connection. The encrypted data, including the close notify is received. Another receive on the sockets gets a CONNABORTED which curl reports as CURLE_RECV_ERROR. Schannel analyses its bufferi, sees the close notify and early returns to the caller. On this return, the error on the attempted receive does not apply.
bagder
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Oct 24, 2024
jay
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Oct 24, 2024
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It occurs to me though this works for shutdown it could potentially cause a problem during a transfer because the recv error state recv_unrecoverable_err is not returned for future calls, so it may be safer to handle this directly in shutdown if possible. In other words, we would want future recv calls to error. Let me know if you think #15391 would work |
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When receiving data, schannel does a recv from the lower filters, e.g. the socket, *before* it decrypts and analyses the buffered data it already has. When that buffer contains a close-notify, e.g. the end of the TLS stream, any error on the previous receive from the socket are not applicable to its return codes. Example from #153345: a server sends a close notify and closes its connection. The encrypted data, including the close notify is received. Another receive on the sockets gets a CONNABORTED which curl reports as CURLE_RECV_ERROR. Schannel analyses its bufferi, sees the close notify and early returns to the caller. On this return, the error on the attempted receive does not apply. Closes curl#15381
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When receiving data, schannel does a recv from the lower filters, e.g. the socket, before it decrypts and analyses the buffered data it already has. When that buffer contains a close-notify, e.g. the end of the TLS stream, any error on the previous receive from the socket are not applicable to its return codes.
Example from #15345: a server sends a close notify and closes its connection. The encrypted data, including the close notify is received. Another receive on the sockets gets a CONNABORTED which curl reports as CURLE_RECV_ERROR. Schannel analyses its bufferi, sees the close notify and early returns to the caller. On this return, the error on the attempted receive does not apply.