Packet timestamp support#3
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Under OpenSSL 3.0+, unexpected socket closures before a clean SSL/TLS shutdown alert is exchanged are classified as protocol errors rather than clean EOFs. This behavior change causes various regression tests to fail. To resolve these compatibility issues: 1. bufferevent_openssl.c: Identify the SSL_R_UNEXPECTED_EOF_WHILE_READING protocol error and treat it as a dirty shutdown (clean TCP closure) to ensure backward compatibility. 2. test/regress_http.c (https_bev): Enable 'allow_dirty_shutdown = 1' on server bufferevents inside the mock HTTPS server to cleanly handle abrupt client socket closures. 3. test/regress_http.c (http_incomplete_errorcb): Recognize SSL protocol errors arising from raw socket shutdowns on OpenSSL 3.0 as successful terminations during the incomplete HTTP request test.
Implement kernel-measured socket receive timestamps with nanosecond precision on supported platforms via the recvmsg() syscall. Each recvmsg() call writes into a freshly allocated evbuffer chain so that every call gets an independent timestamp; timestamps are never silently discarded due to chain reuse. Infrastructure changes: - evbuffer-internal.h: Add timestamp storage and validity flag to evbuffer_chain structure. - evbuffer_read_with_timestamp(): New internal function for reading data via recvmsg(), parsing control messages for timestamps, and safeguarding against MSG_CTRUNC truncation. Always allocates a fresh chain per call so per-call timestamps are preserved independently. - bufferevent-internal.h: Add recv_timestamps_enabled flag to the bufferevent_private structure. - bufferevent_sock.c: Enable receive timestamps and swap standard reads with evbuffer_read_with_timestamp() when requested. - bufferevent_openssl.c: Add a custom socket BIO to extract kernel timestamps during direct socket reads, and propagate timestamps from underlying bufferevents in filtered TLS mode. - Build system: Add CMake and Autotools socket timestamp checks for SO_TIMESTAMP and SO_TIMESTAMPNS option availability. Read sizing: - On Linux, use recv(MSG_PEEK|MSG_TRUNC) with a zero-length buffer to determine the exact datagram size before allocating the chain. This avoids truncating UDP datagrams larger than EVBUFFER_MAX_READ and sizes the chain precisely. If the peek returns nothing useful (TCP stream), fall back to EVBUFFER_MAX_READ directly to prevent FIONREAD from inflating howmuch and bypassing rate limiting on TCP connections. - On macOS and Windows, MSG_PEEK|MSG_TRUNC is skipped entirely (macOS treats MSG_TRUNC as an output-only flag) and FIONREAD is used for sizing. The howmuch override is also guarded to Linux-only to prevent FIONREAD from inflating reads on TCP sockets on those platforms. - EVBUFFER_MAX_READ is no longer applied as an upper cap when use_recvmsg is set, allowing large UDP datagrams to be received without truncation. Public API additions: - BEV_OPT_RECV_TIMESTAMPS option flag for socket bufferevents. - evbuffer_get_timestamp() to fetch the receipt timestamp of the oldest data currently in the buffer. - evbuffer_commit_space_with_timespec() to commit reserved space and manually attach a timestamp to the committed chains. Platform support: - Linux 2.6.22+: Nanosecond (SO_TIMESTAMPNS) and microsecond (SO_TIMESTAMP) precision. - macOS 10.12+: Microsecond (SO_TIMESTAMP) precision. Testing: - Added unit tests for evbuffer receive timestamping. - Added direct socket and filtered OpenSSL bufferevent timestamp regress tests. - Verified all 344 unit tests pass successfully.
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Add support for bufferevents to register for receiving the network packet timestamp (on platforms supporting it).
When enabled it'll use recvmsg to receive the full "packet" from the kernel into an evbuffer and store the timestamp. Given that the memcached protocol doesn't necessarily map 1:1 to a packet, evbuffers will be squashed together and in such cases the oldest timestamp will be used to represet the MCBP packet.