x/net/http2: error dialing IPv6 literal hostnames without ports

[sajal]

What version of Go are you using (go version)?

go version go1.7.4 linux/amd64

Same behavior on 1.7

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/sajal/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build245028891=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"

What did you do?

We are doing something custom with the http package, this issue might not be relevant for common use cases...

Our issue: turbobytes/pulse#5
Example reproduce code: https://gist.github.com/sajal/1e052792023b0a8ff04eba77deeab487

GODEBUG=http2debug=1 go run pilse-5.go --ssl --host="www.cloudflare.com" --endpoint="[2400:cb00:2048:1::c629:d7a2]"
GODEBUG=http2debug=1 run pilse-5.go --ssl --host="dyn.com" --endpoint="[2600:2001:0:3::106]"

First one fails(h2 enabled website), second one works(non-h2 site).

We are using http package along with the awesome httptrace to run some custom tests, to get timing information.

Our terminology :-

1. host : This is value of the Host request header as well as the ServerName for TLS handshake when accessing over https
2. endpoint : This is the server we connect to, can be a hostname, IPv4 or IPv6
3. path: The path being accessed.

The above issue only happens if :-

1. The website is being accessed using explicit IPv6 endpoint and not a hostname.
2. The website supports h2

What did you expect to see?

A successful http response. Or at least some err. At worst timeouts being honored.

What did you see instead?

Infinite loop of following messages, and client not respecting timeouts configured.

2016/12/08 23:54:02 https://[2400:cb00:2048:1::c629:d7a2]/
2016/12/08 23:54:02 http2: Transport failed to get client conn for [[2400:cb00:2048:1::c629:d7a2]]:443: http2: no cached connection was available
2016/12/08 23:54:02 0 ConnectStart:  tcp [2400:cb00:2048:1::c629:d7a2]:443
2016/12/08 23:54:02 61 ConnectDone:  tcp [2400:cb00:2048:1::c629:d7a2]:443 <nil>
2016/12/08 23:54:02 http2: Transport creating client conn 0xc420082000 to [2400:cb00:2048:1::c629:d7a2]:443
2016/12/08 23:54:02 http2: Transport failed to get client conn for [[2400:cb00:2048:1::c629:d7a2]]:443: http2: no cached connection was available
2016/12/08 23:54:02 459 ConnectStart:  tcp [2400:cb00:2048:1::c629:d7a2]:443
2016/12/08 23:54:02 http2: Transport received SETTINGS len=18, settings: MAX_CONCURRENT_STREAMS=128, INITIAL_WINDOW_SIZE=65536, MAX_FRAME_SIZE=16777215
2016/12/08 23:54:02 http2: Transport received WINDOW_UPDATE len=4 (conn) incr=2147418112
2016/12/08 23:54:02 509 ConnectDone:  tcp [2400:cb00:2048:1::c629:d7a2]:443 <nil>
2016/12/08 23:54:02 http2: Transport received SETTINGS flags=ACK len=0
2016/12/08 23:54:03 http2: Transport failed to get client conn for [[2400:cb00:2048:1::c629:d7a2]]:443: http2: no cached connection was available
2016/12/08 23:54:03 707 ConnectStart:  tcp [2400:cb00:2048:1::c629:d7a2]:443
2016/12/08 23:54:03 758 ConnectDone:  tcp [2400:cb00:2048:1::c629:d7a2]:443 <nil>
2016/12/08 23:54:03 http2: Transport failed to get client conn for [[2400:cb00:2048:1::c629:d7a2]]:443: http2: no cached connection was available
2016/12/08 23:54:03 954 ConnectStart:  tcp [2400:cb00:2048:1::c629:d7a2]:443
2016/12/08 23:54:03 1008 ConnectDone:  tcp [2400:cb00:2048:1::c629:d7a2]:443 <nil>
2016/12/08 23:54:03 http2: Transport failed to get client conn for [[2400:cb00:2048:1::c629:d7a2]]:443: http2: no cached connection was available
2016/12/08 23:54:03 1209 ConnectStart:  tcp [2400:cb00:2048:1::c629:d7a2]:443
2016/12/08 23:54:03 1257 ConnectDone:  tcp [2400:cb00:2048:1::c629:d7a2]:443 <nil>
2016/12/08 23:54:03 http2: Transport failed to get client conn for [[2400:cb00:2048:1::c629:d7a2]]:443: http2: no cached connection was available
2016/12/08 23:54:03 1442 ConnectStart:  tcp [2400:cb00:2048:1::c629:d7a2]:443
2016/12/08 23:54:03 1494 ConnectDone:  tcp [2400:cb00:2048:1::c629:d7a2]:443 <nil>
2016/12/08 23:54:04 http2: Transport failed to get client conn for [[2400:cb00:2048:1::c629:d7a2]]:443: http2: no cached connection was available

And goes on like this for what seems like forever...

PS: I think the custom Resolver in tip might help me do what I'm doing in a more elegant manner. I have yet to try it out.

[sajal]

I have a hunch this is from https://golang.org/src/net/http/h2_bundle.go#L5143

https://play.golang.org/p/I4HIN5LMC4

net.JoinHostPort("[2400:cb00:2048:1::c629:d7a2]", "443") returns [[2400:cb00:2048:1::c629:d7a2]]:443 instead of [2400:cb00:2048:1::c629:d7a2]:443 which could be the cause of this issue?

When running my code with following arguments:-

GODEBUG=http2debug=1 go run pilse-5.go --ssl --host="www.cloudflare.com" --endpoint="[2400:cb00:2048:1::c629:d7a2]:443"

It works as expected.

[bradfitz]

Thanks. Looks like authorityAddr does have a problem. Sending a fix now.

There are a few unrelated suspicious things in your https://gist.github.com/sajal/1e052792023b0a8ff04eba77deeab487 code, but we can address those separately.

[gopherbot]

CL https://golang.org/cl/34143 mentions this issue.

[sajal]

Thanks @bradfitz . Would appreciate feedback in the gist :)

[gopherbot]

CL https://golang.org/cl/34495 mentions this issue.