Fix SFTP server hang on WS_WANT_WRITE with non-blocking sockets#876
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LinuxJedi wants to merge 1 commit intowolfSSL:masterfrom
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Fix SFTP server hang on WS_WANT_WRITE with non-blocking sockets#876LinuxJedi wants to merge 1 commit intowolfSSL:masterfrom
LinuxJedi wants to merge 1 commit intowolfSSL:masterfrom
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When wolfSSH_SFTP_buffer_send() called wolfSSH_stream_send(), the data would be consumed into the SSH output buffer even if the underlying socket returned EWOULDBLOCK/EAGAIN. SendChannelData() returns the positive dataSz on WS_WANT_WRITE, causing the SFTP layer to advance its buffer index as if the data was sent. The SSH output buffer still had pending data that was never flushed, leading to an indefinite hang. Fix: At the start of wolfSSH_SFTP_buffer_send(), check if there's pending data in ssh->outputBuffer from a previous WS_WANT_WRITE. If so, attempt to flush it first and return WS_WANT_WRITE if the flush fails. This ensures the caller retries until all pending data is sent. Also expose WS_SFTP_BUFFER and wolfSSH_SFTP_buffer_send() as WOLFSSH_LOCAL for unit testing, and add regression test that verifies the fix catches the bug. Fixes ZD 21157
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When wolfSSH_SFTP_buffer_send() called wolfSSH_stream_send(), the data would be consumed into the SSH output buffer even if the underlying socket returned EWOULDBLOCK/EAGAIN. SendChannelData() returns the positive dataSz on WS_WANT_WRITE, causing the SFTP layer to advance its buffer index as if the data was sent. The SSH output buffer still had pending data that was never flushed, leading to an indefinite hang.
Fix: At the start of wolfSSH_SFTP_buffer_send(), check if there's pending data in ssh->outputBuffer from a previous WS_WANT_WRITE. If so, attempt to flush it first and return WS_WANT_WRITE if the flush fails. This ensures the caller retries until all pending data is sent.
Also expose WS_SFTP_BUFFER and wolfSSH_SFTP_buffer_send() as WOLFSSH_LOCAL for unit testing, and add regression test that verifies the fix catches the bug.
Fixes ZD 21157