package/docker-engine: fix port forwarding for hosts without IPv6

docker-engine 20.10.6 broke container port forwarding for hosts without IPv6
support:

docker: Error response from daemon: driver failed programming external
connectivity on endpoint naughty_moore
(038e9ed4b5ea77e1c52462d6d04ad001fbad9beb185a6511aadc217c8a271608): Error
starting userland proxy: listen tcp6 [::]:80: socket: address family not
supported by protocol.

Add a libnetwork patch from an upstream pull request to fix this, after
adjusting the patch to apply to docker-engine (which has libnetwork vendored
under vendor/github.com/docker/libnetwork):

- https://github.com/moby/libnetwork/pull/2635,
- https://github.com/moby/moby/pull/42322

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

diff --git a/package/docker-engine/0001-fix-port-forwarding-with-ipv6.disable-1.patch b/package/docker-engine/0001-fix-port-forwarding-with-ipv6.disable-1.patch
new file mode 100644 (file)
index 0000000..c5161ef
--- /dev/null
+++ b/package/docker-engine/0001-fix-port-forwarding-with-ipv6.disable-1.patch
@@ -0,0 +1,74 @@
+From 7b9c2905883df5171fda10a364a81b8c6176c8e2 Mon Sep 17 00:00:00 2001
+From: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
+Date: Mon, 26 Apr 2021 15:28:40 +0900
+Subject: [PATCH] fix port forwarding with ipv6.disable=1
+
+Make `docker run -p 80:80` functional again on environments with kernel boot parameter `ipv6.disable=1`.
+
+Fix moby/moby issue 42288
+
+Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
+[Upstream: https://github.com/moby/libnetwork/pull/2635,
+           https://github.com/moby/moby/pull/42322]
+[Rework path/drop test for docker-engine]
+Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
+---
+ vendor/github.com/docker/libnetwork/drivers/bridge/port_mapping.go | 31 +++++++++++++++++++++++++++++++
+ 1 file changed, 35 insertions(+), 0 deletion(-)
+
+diff --git a/vendor/github.com/docker/libnetwork/drivers/bridge/port_mapping.go b/vendor/github.com/docker/libnetwork/drivers/bridge/port_mapping.go
+index 946130ec..17bf36f9 100644
+--- a/vendor/github.com/docker/libnetwork/drivers/bridge/port_mapping.go
++++ b/vendor/github.com/docker/libnetwork/drivers/bridge/port_mapping.go
+@@ -5,6 +5,7 @@ import (
+       "errors"
+       "fmt"
+       "net"
++      "sync"
+ 
+       "github.com/docker/libnetwork/types"
+       "github.com/ishidawataru/sctp"
+@@ -50,6 +51,13 @@ func (n *bridgeNetwork) allocatePortsInternal(bindings []types.PortBinding, cont
+                       bs = append(bs, bIPv4)
+               }
+ 
++              // skip adding implicit v6 addr, when the kernel was booted with `ipv6.disable=1`
++              // https://github.com/moby/moby/issues/42288
++              isV6Binding := c.HostIP != nil && c.HostIP.To4() == nil
++              if !isV6Binding && !IsV6Listenable() {
++                      continue
++              }
++
+               // Allocate IPv6 Port mappings
+               // If the container has no IPv6 address, allow proxying host IPv6 traffic to it
+               // by setting up the binding with the IPv4 interface if the userland proxy is enabled
+@@ -211,3 +219,26 @@ func (n *bridgeNetwork) releasePort(bnd types.PortBinding) error {
+ 
+       return portmapper.Unmap(host)
+ }
++
++var (
++      v6ListenableCached bool
++      v6ListenableOnce   sync.Once
++)
++
++// IsV6Listenable returns true when `[::1]:0` is listenable.
++// IsV6Listenable returns false mostly when the kernel was booted with `ipv6.disable=1` option.
++func IsV6Listenable() bool {
++      v6ListenableOnce.Do(func() {
++              ln, err := net.Listen("tcp6", "[::1]:0")
++              if err != nil {
++                      // When the kernel was booted with `ipv6.disable=1`,
++                      // we get err "listen tcp6 [::1]:0: socket: address family not supported by protocol"
++                      // https://github.com/moby/moby/issues/42288
++                      logrus.Debugf("port_mapping: v6Listenable=false (%v)", err)
++              } else {
++                      v6ListenableCached = true
++                      ln.Close()
++              }
++      })
++      return v6ListenableCached
++}
+-- 
+2.20.1
+