openssl: fix handling of buffered data #17601
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`SSL_pending()` only checks if the *current* TLS packet has more data. There might be more data in SSL's buffers. `SSL_has_pending()` only checks if there is data in buffers, but does *not* check if there is a complete TLS packet that can be decoded. If we only check the first, we will poll on socket events with having processed all data and may stall. If we only check the second, we would busy loop without SSL_read() ever giving something. Add the flag `connssl->input_pending` that is set on incoming data in the BIO receive. Clear the flag when encountering a CURLE_AGAIN on the filters receive (via SSL_read()). refs curl#17596
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@vszakats, when you have time it would be nice to merge this. Fixes Ci failures. Thanks! |
vszakats
approved these changes
Jun 12, 2025
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Thanks @icing, merged! |
denandz
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Jun 21, 2025
`SSL_pending()` only checks if the *current* TLS packet has more data. There might be more data in SSL's buffers. `SSL_has_pending()` only checks if there is data in buffers, but does *not* check if there is a complete TLS packet that can be decoded. If we only check the first, we will poll on socket events without having processed all data and may stall. If we only check the second, we would busy loop without SSL_read() ever giving something. Add the flag `connssl->input_pending` that is set on incoming data in the BIO receive. Clear the flag when encountering a CURLE_AGAIN on the filters receive (via SSL_read()) or see an EOF. Ref: curl#17596 Closes curl#17601
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SSL_pending()only checks if the current TLS packet has more data. There might be more data in SSL's buffers.SSL_has_pending()only checks if there is data in buffers, but does not check if there is a complete TLS packet that can be decoded.If we only check the first, we will poll on socket events without having processed all data and may stall. If we only check the second, we would busy loop without SSL_read() ever giving something.
Add the flag
connssl->input_pendingthat is set on incoming data in the BIO receive. Clear the flag when encountering a CURLE_AGAIN on the filters receive (via SSL_read()) or see an EOF.refs #17596