scp: fix duplicate file header on send - #1128
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Pull request overview
Fixes an SCP server-side edge case where the file header could be transmitted more than once when the SCP send callback returns 0 bytes on its first invocation, and adds a regression test by allowing tests to inject a custom SCP send callback into the echoserver harness.
Changes:
- Add
scpFileHeaderSentstate to gate header emission per file (instead of relying onscpFileOffset == 0). - Avoid emitting zero-length
CHANNEL_DATAwhen the send buffer is empty, and reset SCP per-file state on source init / connection reuse paths. - Add
test_wolfSSH_SCP_SendZeroFirstregression test and enable callback injection viafunc_args.
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| wolfssh/test.h | Includes wolfscp.h under WOLFSSH_SCP and extends func_args with an injectable scp_send callback. |
| wolfssh/internal.h | Adds scpFileHeaderSent to SCP state tracked on the WOLFSSH object. |
| tests/api.c | Adds a regression test ensuring a 0-byte-first send callback does not cause a duplicated SCP file header. |
| src/wolfscp.c | Uses scpFileHeaderSent to gate header sending, skips zero-length sends, and resets per-file state for reuse. |
| src/internal.c | Initializes scpFileHeaderSent during SSH session initialization. |
| examples/echoserver/echoserver.c | Applies an injected SCP send callback to the server context for tests. |
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- Gate header on new scpFileHeaderSent flag, not scpFileOffset==0 - A send callback returning 0 bytes first no longer re-sends header - Skip zero-length SCP_SEND_FILE send to avoid empty CHANNEL_DATA - Abort on a second consecutive 0-byte send callback return with file data outstanding; skipping the send would otherwise spin SCP_SEND_FILE -> SCP_TRANSFER with no socket I/O - Reset offset/bufferedSz/flags in ScpSourceInit for connection reuse - Document the WS_CallbackScpSend contract, including when a 0 return is valid, next to the typedef - Add test_wolfSSH_SCP_SendZeroFirst regression (func_args scp_send hook) - Zero func_args in kex.c/testsuite.c so the new scp_send field is not read uninitialized Issue: ZD-22176
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- Track the scpFileName allocation size in a new scpFileNameCap field, so GetScpFileName() and ScpCheckForRename() reuse the buffer whenever the name plus its terminator fits, instead of testing against the previous name length - Pass scpFileNameCap to the send callback, which writes into scpFileName and needs the capacity; scpFileNameSz is now the name length on every path, including the source path - Free and reallocate the transfer buffer in ScpSourceInit(), clearing the size fields alongside the pointers they describe - Wrap a long line in ScpProcessEntry() - Add test_ScpGetFileName covering the reuse-vs-realloc branch, the exact-fit boundary, a grow-by-one that catches an off-by-one in the reuse condition, and a source-path buffer holding no name yet - Add test_wolfSSH_SCP_RecursiveTwoFiles, a real "scp -r" transfer of two files, covering the scpFileHeaderSent reset on the recursive path added in the duplicate-header fix; it clears leftovers from an aborted run up front and bounds its recv so a regression fails instead of hanging. Not built on Windows, where a recursive transfer through the default callbacks does not reproduce the sent file
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Fenrir Automated Review — PR #1128
Scan targets checked: wolfssh-bugs, wolfssh-src
No new issues found in the changed files. ✅
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Issue: ZD-22176