curl_setup: Disable by default recv-before-send in Windows #10409
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Maybe just disable recv-before-send for the handshakes and use it for the data transfers? |
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Of the other hand, this workaround was implemented for HTTP servers not following RFC requirements: https://www.rfc-editor.org/rfc/rfc9112#section-9.6-9 |
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Prior to this change a workaround for Windows to recv before every send was enabled by default. The way it works is a recv is called before every send and saves the received data, in case send fails because in Windows apparently that can wipe out the socket's internal received data buffer. This feature has led to several bugs because the way libcurl operates it waits on a socket to read or to write, and may not at all times check for buffered receive data. Two recent significant bugs this workaround caused: - Broken Schannel TLS 1.3 connections (curl#9431) - HTTP/2 arbitrary hangs (curl#10253) The actual code remains though it is disabled by default. Though future changes to connection filter buffering could improve the situation IMO it's just not tenable to manage this workaround. Ref: curl#657 Ref: curl#668 Ref: curl#720 Ref: curl#9431 Ref: curl#10253 Closes curl#10409
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Thanks for your feedback. Yes, unfortunately premature server responses may be lost on Windows if they're followed by RST. |
jay
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Prior to this change a workaround for Windows to recv before every send was enabled by default. The way it works is a recv is called before every send and saves the received data, in case send fails because in Windows apparently that can wipe out the socket's internal received data buffer. This feature has led to several bugs because the way libcurl operates it waits on a socket to read or to write, and may not at all times check for buffered receive data. Two recent significant bugs this workaround caused: - Broken Schannel TLS 1.3 connections (curl#9431) - HTTP/2 arbitrary hangs (curl#10253) The actual code remains though it is disabled by default. Though future changes to connection filter buffering could improve the situation IMO it's just not tenable to manage this workaround. Ref: curl#657 Ref: curl#668 Ref: curl#720 Ref: curl#9431 Ref: curl#10253 Closes curl#10409
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Prior to this change a workaround for Windows to recv before every send was enabled by default. The way it works is a recv is called before every send and saves the received data, in case send fails because in Windows apparently that can wipe out the socket's internal received data buffer.
This feature has led to several bugs because the way libcurl operates it waits on a socket to read or to write, and may not at all times check for buffered receive data.
Two recent significant bugs this workaround caused:
The actual code remains though it is disabled by default. Though future changes to connection filter buffering could improve the situation IMO it's just not tenable to manage this behavior, though it could possibly be handled more correctly at a higher level (eg transfer handling checks for server error response before it has completed sending its request).
Ref: #9431
Ref: #10253
Closes #xxxx
/cc @Karlson2k