Update MTProxy checker documentation and logic to clarify probing modes and improve error handling. Modify README and Docker documentation to reflect changes in the -probe flag behavior, including detailed descriptions of exit codes and timeout handling. Refactor connection handling to enhance robustness and align with Telethon's approach.

internal/tgquick/probe.go

@@ -112,6 +112,7 @@ func isResPQ(mtInner []byte) bool {
 // DrainPostInitEE reads inbound fake-TLS records after MTProxy init and before req_pq (Telethon TcpMTProxy waits for data ~2s).
 // Consumes 0x17 payloads with dec so the CTR stream stays aligned with the server; discards MTProto frames until idle.
 func DrainPostInitEE(ctx context.Context, br *bufio.Reader, conn net.Conn, dec cipher.Stream, maxWait time.Duration) error {
+	defer func() { _ = conn.SetReadDeadline(time.Time{}) }()
 	end := time.Now().Add(maxWait)
 	if d, ok := ctx.Deadline(); ok && d.Before(end) {
 		end = d
@@ -139,6 +140,9 @@ func DrainPostInitEE(ctx context.Context, br *bufio.Reader, conn net.Conn, dec c
 		}
 		_ = conn.SetReadDeadline(time.Now().Add(d))
 		if err := sniffCleartextHTTP(br); err != nil {
+			if ne, ok := err.(net.Error); ok && ne.Timeout() {
+				continue
+			}
 			return err
 		}
 		chunk, err := readNextTLS17Payload(br)
@@ -219,6 +223,12 @@ func VerifyResPQ(ctx context.Context, conn net.Conn, enc, dec cipher.Stream, tls
 		var rerr error
 		if tlsBR != nil {
 			if err := sniffCleartextHTTP(tlsBR); err != nil {
+				if ne, ok := err.(net.Error); ok && ne.Timeout() {
+					if time.Now().Before(deadline) {
+						continue
+					}
+					break
+				}
 				return err
 			}
 			chunk, rerr = readNextTLS17Payload(tlsBR)