STRLCPY/dnstt

Apply a timeout to upstream dials in the server.

In my testing locally, these dials would time out after about 30 seconds
anyway:
	2021/04/20 23:26:46 begin session 54cafb53
	2021/04/20 23:26:47 begin stream 54cafb53:3
	2021/04/20 23:27:19 stream 54cafb53:3 handleStream: stream 54cafb53:3 connect upstream: dial tcp X.X.X.X:YYYY: connect: connection timed out
	2021/04/20 23:27:19 end stream 54cafb53:3
Which is in line with the documentation for net.Dialer:
	https://golang.org/pkg/net/#Dialer
	With or without a timeout, the operating system may impose its
	own earlier timeout. For instance, TCP timeouts are often around
	3 minutes.
But may as well be explicit.

This commit has the side effect of changing the error message from
"connection timed out" to "i/o timeout".
	2021/04/20 23:28:08 begin session 05b0a46e
	2021/04/20 23:28:09 begin stream 05b0a46e:3
	2021/04/20 23:28:39 stream 05b0a46e:3 handleStream: stream 05b0a46e:3 connect upstream: dial tcp X.X.X.X:YYYY: i/o timeout
	2021/04/20 23:28:39 end stream 05b0a46e:3

David Fifield committed 3 years ago

23759e20

1 parent 6e5ba30a

Total 1 files

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dnstt-server/main.go

		skipped 70 lines
71	71		// to be the query timeout of the Quad9 DoH server.
72	72		// https://dnsencryption.info/imc19-doe.html Section 4.2, Finding 2.4
73	73		maxResponseDelay = 1 * time.Second
	74	+
	75	+	// How long to wait for a TCP connection to upstream to be established.
	76	+	upstreamDialTimeout = 30 * time.Second
74	77		)
75	78
76	79		var (
		skipped 105 lines
182	185		// handleStream bidirectionally connects a client stream with a TCP socket
183	186		// addressed by upstream.
184	187		func handleStream(stream *smux.Stream, upstream string, conv uint32) error {
185		-	upstreamConn, err := net.Dial("tcp", upstream)
	188	+	dialer := net.Dialer{
	189	+	Timeout: upstreamDialTimeout,
	190	+	}
	191	+	upstreamConn, err := dialer.Dial("tcp", upstream)
186	192		if err != nil {
187	193		return fmt.Errorf("stream %08x:%d connect upstream: %v", conv, stream.ID(), err)
188	194		}
		skipped 740 lines