fix: backpressure data loss in socks/http proxy + comprehensive test
socks_proxy (client side):
- tx_buf buffering on send_data failure in RELAY path, retry in tx_waiter_cb
- process_http_request: version_str null-term fix (memcpy(vlen)+explicit \0)
- process_http_request: assemble hdr+body+extra into heap pkt, atomic send
- socks_proxy_handle_etcp: alloc failure logs write_queue state + byte counters
tcp_proxy_server (exit node):
- read_queue_drain_cb: tx_buf buffering on backpressure, retry_timer (500ms, force=1)
- on_fin_cb: defer FIN when read_queue+tx_buf has pending data (dst_fin_deferred)
- handle_data + drain_cb: per-stream byte counters (sent/recv/relayed/drain_count)
- on_fin_cb/on_error_cb: detailed state logging (counters, queues, buffers)
test_socks_http_proxy:
- 4 workers: socks_ipv4, socks_domain (DNS resolution via SOCKS), http_proxy, https_connect
- 4 file sizes: 1KB, 100KB, 1MB, 10MB — deterministic content, byte-by-byte cmp -s
- HTTPS server with self-signed cert, POST/echo, HEAD, OPTIONS
- 51/51 tests PASS
Evgeny