In general, clean up and simplify the handling of frame writing from
handler goroutines.  Always select on streams closing, and don't try
to pass around and re-use channels. It was too confusing. Instead,
reuse channels in a very local manner that's easy to reason about.

Thanks to Github user @pabbott0 (who has signed the Google CLA) for
the initial bug report and test cases.

Fixes bradfitz/http2#45

Change-Id: Ib72a87cb6e33a4bb118ae23d765ba594e9182ade
Reviewed-on: https://go-review.googlesource.com/15820Reviewed-by: Andrew Gerrand <adg@golang.org>

There was a design problem earlier where the serve goroutine assumed
that the readFrame goroutine could return only connection-level
errors, but the readFrames goroutine (and the underlying Framer)
assumed it could return stream-level errors (type StreamError) and
have them handled as stream errors in the layers above. That's how it
should have been, and what this CL does.

Now readFrames returns both the Frame and error from ReadFrames
together as a pair, and an error isn't necessarily fatal to the
connection.

Fixes golang/go#12733
Fixes bradfitz/http2#53

Change-Id: If4406ceaa019886893d3c61e6bfce25ef74560d3
Reviewed-on: https://go-review.googlesource.com/15735Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

Return an error instead.

Fixes bradfitz/http2#56

Change-Id: I3d1e80a214a8635932479943f0ef9610ee02b233
Reviewed-on: https://go-review.googlesource.com/15738Reviewed-by: Andrew Gerrand <adg@golang.org>

In the first attempt to enforce the SETTINGS_MAX_HEADER_LIST_SIZE
(https://go-review.googlesource.com/15751), the enforcement happened
in the hpack decoder and the hpack decoder returned errors on Write
and Close if the limit was violated. This was incorrect because the
decoder is used over the life of the connection and all subsequent
requests and could therefore get out of sync.

Instead, this moves the counting of the limit up to the http2 package
in the serverConn type, and replaces the hpack counting mechanism with
a simple on/off switch. When SetEmitEnabled is set false, the header
field emit callbacks will be suppressed and the hpack Decoder will do
less work (less CPU and garbage) if possible, but will still return
nil from Write and Close on valid input, and will still stay in sync
it the stream.

The http2 Server then returns a 431 error if emits were disabled while
processing the HEADER or any CONTINUATION frames.

Fixes golang/go#12843

Change-Id: I3b41aaefc6c6ee6218225f8dc62bba6ae5fe8f2d
Reviewed-on: https://go-review.googlesource.com/15733Reviewed-by: Andrew Gerrand <adg@golang.org>

Fixes golang/go#12742

Change-Id: I04d65b0c68ccb5da5ee90650c7b0593fbdb1d470
Reviewed-on: https://go-review.googlesource.com/15736Reviewed-by: Andrew Gerrand <adg@golang.org>

Minor performance improvement, since len(staticTable) is then a
constant at compile time.

Change-Id: Ie51ecc985aa3f40d50f0a7d1ab6ac91738f696d5
Reviewed-on: https://go-review.googlesource.com/15731Reviewed-by: Dmitri Shuralyov <shurcool@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Thanks to Andy Bursavich for the example attack.
Pair programmed with Dmitri Shuralyov.

Fixes golang/go#12843

Change-Id: Ic412c9364b37a10e5164232aa809b956874fae08
Reviewed-on: https://go-review.googlesource.com/15751Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

There are already tests which cover the behavior. This is simply
moving where it happens. I'm not adding new tests to cover the very
bad behavior because once the rest of the bug is fixed, it won't be
possible to observe anyway. But even for smallish inputs, this is
faster.

Part of golang/go#12843

Change-Id: I7d69f2409e2adb4a01d101a915e09cf887b03f21
Reviewed-on: https://go-review.googlesource.com/15601Reviewed-by: Andrew Gerrand <adg@golang.org>

Change-Id: I2b0b87aed4ff5c338b0ae09b63f55411322a871e
Reviewed-on: https://go-review.googlesource.com/15436Reviewed-by: Andrew Gerrand <adg@golang.org>

Change-Id: Idd45c1be493f4535d73323fc2feda5efff45763e
Reviewed-on: https://go-review.googlesource.com/15243Reviewed-by: Andrew Gerrand <adg@golang.org>

Change-Id: I8bd9d181c4c2e8c4ea01342a306acdca69eabf18
Reviewed-on: https://go-review.googlesource.com/15085Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I8f41ef0d3eefecb26d073e21bc1d5b7b6a51d259
Reviewed-on: https://go-review.googlesource.com/15053Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I3d3905adab74a83c9d7d72c829f6686b514f3aaf
Reviewed-on: https://go-review.googlesource.com/15060Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This makes it correct for IPv6 too.

Change-Id: Ide2fc12ed97974b6abbafa66c4b83d0086c4e87c
Reviewed-on: https://go-review.googlesource.com/15030Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I55d6ad683b8021722fec8b42b2a8aa0a1883cb96
Reviewed-on: https://go-review.googlesource.com/15052Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I95471bf40cf5b0ceb2dfc01d4c831acb65265719
Reviewed-on: https://go-review.googlesource.com/14950Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

This adds the http2 directory from github.com/bradfitz/http2

(Merge reviewed by David Symonds <dsymonds@golang.org>)

In prep for move to golang.org/x/net/*.

StripPrefix in the webdav package strips prefixes from requests
(including the Destination headers) but cannot handle the paths
in the xml entities responses which are confusing some clients
(e.g. cadaver).

This patch replaces StripPrefix with Prefix in the Handler to
handle prefixes both in the requests and in the xml entities
responses.

Change-Id: I67062e30337b2ae422c82a2f927454f5a8a00e34
Reviewed-on: https://go-review.googlesource.com/13857Reviewed-by: Nigel Tao <nigeltao@golang.org>

Fixes golang/go#12387

Change-Id: Iecc42d9f809bed10036d1c3af8838c2fbf7ea93d
Reviewed-on: https://go-review.googlesource.com/14014Reviewed-by: David Symonds <dsymonds@golang.org>

These expose the main HTML rendering functions of this package
for use with alternate HTTP muxes and on alternate paths.

Fixes golang/go#12195.

Change-Id: I679583fd26116bc83ff551a5d2a1d73ffa1e01f0
Reviewed-on: https://go-review.googlesource.com/13825Reviewed-by: Dave Day <djd@golang.org>

This will make it easier to serve /debug/requests off a different path.

This is groundwork towards addressing golang/go#12195.

Change-Id: If29a4c329609df1d5b09a3a88b8bdf1f8b622e49
Reviewed-on: https://go-review.googlesource.com/13824Reviewed-by: Dave Day <djd@golang.org>

Updates golang/go#12163.

Change-Id: I91c57e76be680dea8b60196ad07f8c7ed093e008
Reviewed-on: https://go-review.googlesource.com/13655Reviewed-by: Ian Lance Taylor <iant@golang.org>

Updates golang/go#12163.

Change-Id: I1cd3b6324eb37d7a2285683590acd188758e7d90
Reviewed-on: https://go-review.googlesource.com/13654Reviewed-by: Ian Lance Taylor <iant@golang.org>

Also fixes ping tests. Latest Linux kernels prohibit to access ICMPv6
properties with non-privileged sockets.

Fixes golang/go#12163.

Change-Id: I439b41556e8d4c2f3a9f725131267469e08c9599
Reviewed-on: https://go-review.googlesource.com/13653Reviewed-by: Ian Lance Taylor <iant@golang.org>

When making a request to an IPv6 address with a zone identifier, for
exmaple [fe80::1%en0], RFC 6874 says HTTP clients must remove the zone
identifier "%en0" before writing the request for security reason.

This change removes any IPv6 zone identifer attached to URI in the Host
header field in requests.

See golang/go#9544.

Change-Id: Ie5d18a0bc5f2768a95c59ec2b159ac0abdf685e8
Reviewed-on: https://go-review.googlesource.com/13296Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

An event log is typically associated with a long-lived object, like an
RPC connection.  Printf calls record events; Errorf calls record
events marked as errors.  The HTTP endpoint /debug/events organizes
event logs by family (usually the Go type name) and by
time-since-last-error.  The expanded view shows recent events in the
log and the call stack where the event log was created.

Change-Id: I3461e0d63f39ce6495e16300299048e572b3aa19
Reviewed-on: https://go-review.googlesource.com/12025Reviewed-by: David Symonds <dsymonds@golang.org>

ctxhttp provides helper functions for performing context-aware HTTP
requests.

Fixes golang/go#11904

Change-Id: Ib9d2fef48953dbb52f0a70e1ed49ea7fe12b7801
Reviewed-on: https://go-review.googlesource.com/12755Reviewed-by: David Symonds <dsymonds@golang.org>
Reviewed-by: Aaron Jacobs <jacobsa@google.com>
Reviewed-by: Dave Day <djd@golang.org>

This change prevents Read from failing with io.EOF, ErrNotImplemented on
exchanging control frames such as ping and pong.

Fixes golang/go#6377.
Fixes golang/go#7825.
Fixes golang/go#10156.

Change-Id: I600cf493de3671d7e3d11e2e12d32f43928b7bfc
Reviewed-on: https://go-review.googlesource.com/13054Reviewed-by: Andrew Gerrand <adg@golang.org>

Fixes golang/go#11999.

Change-Id: I7ee0966d2e8f79973814f48afc7e8f2cd4af1e50
Reviewed-on: https://go-review.googlesource.com/13059Reviewed-by: Andrew Gerrand <adg@golang.org>

Updates golang/go#12004.

Change-Id: Id3c1e543a1fc4d246d04d26302b9da46f199fdee
Reviewed-on: https://go-review.googlesource.com/13055Reviewed-by: Nigel Tao <nigeltao@golang.org>

Change-Id: I526ecbab37b68d689ddffa60c2e231099c1477b6
Reviewed-on: https://go-review.googlesource.com/13056Reviewed-by: Dave Day <djd@golang.org>

Change-Id: I54bcd2803ef270e8bb785a3ecb85ee7bf0a5b18b
Reviewed-on: https://go-review.googlesource.com/13053Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I414c02fb0178e3280e1df4c04f0cff528f5de341
Reviewed-on: https://go-review.googlesource.com/12910Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

Updates golang/go#11454.

Change-Id: Ib3762897b15d47d42002aafcdb1f634504c5d82c
Reviewed-on: https://go-review.googlesource.com/12889Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes golang/go#10102.

Change-Id: I34779a81797cb3b7e8820f5af8b0dde54f949164
Reviewed-on: https://go-review.googlesource.com/7034Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates golang/go#11453.

Change-Id: Ia3560d382daffde995e9824b924d1938f08e6e41
Reviewed-on: https://go-review.googlesource.com/12880Reviewed-by: Nigel Tao <nigeltao@golang.org>

The Go 1.5 version of the standard library's encoding/xml package was
rolled back to the 1.4 behavior. See #11841

Change-Id: I5a5d6636b90b19d59dbcfdc44adf54b4f0b3ccb7
Reviewed-on: https://go-review.googlesource.com/12772Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I94a8b7e876a8cbe4d565bab021f16c1c91f5aa10
Reviewed-on: https://go-review.googlesource.com/12651Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>