proxyprotocol: Add PROXY protocol support to reverse_proxy, add HTTP listener wrapper (#5424)

Co-authored-by: WeidiDeng <weidi_deng@icloud.com>
Co-authored-by: Francis Lavoie <lavofr@gmail.com>

modules/caddyhttp/proxyprotocol/listenerwrapper.go

@@ -0,0 +1,68 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package proxyprotocol
+
+import (
+	"fmt"
+	"net"
+	"time"
+
+	"github.com/caddyserver/caddy/v2"
+	"github.com/mastercactapus/proxyprotocol"
+)
+
+// ListenerWrapper provides PROXY protocol support to Caddy by implementing
+// the caddy.ListenerWrapper interface. It must be loaded before the `tls` listener.
+//
+// Credit goes to https://github.com/mastercactapus/caddy2-proxyprotocol for having
+// initially implemented this as a plugin.
+type ListenerWrapper struct {
+	// Timeout specifies an optional maximum time for
+	// the PROXY header to be received.
+	// If zero, timeout is disabled. Default is 5s.
+	Timeout caddy.Duration `json:"timeout,omitempty"`
+
+	// Allow is an optional list of CIDR ranges to
+	// allow/require PROXY headers from.
+	Allow []string `json:"allow,omitempty"`
+
+	rules []proxyprotocol.Rule
+}
+
+// Provision sets up the listener wrapper.
+func (pp *ListenerWrapper) Provision(ctx caddy.Context) error {
+	rules := make([]proxyprotocol.Rule, 0, len(pp.Allow))
+	for _, s := range pp.Allow {
+		_, n, err := net.ParseCIDR(s)
+		if err != nil {
+			return fmt.Errorf("invalid subnet '%s': %w", s, err)
+		}
+		rules = append(rules, proxyprotocol.Rule{
+			Timeout: time.Duration(pp.Timeout),
+			Subnet:  n,
+		})
+	}
+
+	pp.rules = rules
+
+	return nil
+}
+
+// WrapListener adds PROXY protocol support to the listener.
+func (pp *ListenerWrapper) WrapListener(l net.Listener) net.Listener {
+	pl := proxyprotocol.NewListener(l, time.Duration(pp.Timeout))
+	pl.SetFilter(pp.rules)
+	return pl
+}

modules/caddyhttp/proxyprotocol/module.go

@@ -0,0 +1,75 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package proxyprotocol
+
+import (
+	"github.com/caddyserver/caddy/v2"
+	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
+)
+
+func init() {
+	caddy.RegisterModule(ListenerWrapper{})
+}
+
+func (ListenerWrapper) CaddyModule() caddy.ModuleInfo {
+	return caddy.ModuleInfo{
+		ID:  "caddy.listeners.proxy_protocol",
+		New: func() caddy.Module { return new(ListenerWrapper) },
+	}
+}
+
+// UnmarshalCaddyfile sets up the listener Listenerwrapper from Caddyfile tokens. Syntax:
+//
+//	proxy_protocol {
+//		timeout <duration>
+//		allow <IPs...>
+//	}
+func (w *ListenerWrapper) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
+	for d.Next() {
+		// No same-line options are supported
+		if d.NextArg() {
+			return d.ArgErr()
+		}
+
+		for d.NextBlock(0) {
+			switch d.Val() {
+			case "timeout":
+				if !d.NextArg() {
+					return d.ArgErr()
+				}
+				dur, err := caddy.ParseDuration(d.Val())
+				if err != nil {
+					return d.Errf("parsing proxy_protocol timeout duration: %v", err)
+				}
+				w.Timeout = caddy.Duration(dur)
+
+			case "allow":
+				w.Allow = append(w.Allow, d.RemainingArgs()...)
+
+			default:
+				return d.ArgErr()
+			}
+		}
+	}
+	return nil
+}
+
+// Interface guards
+var (
+	_ caddy.Provisioner     = (*ListenerWrapper)(nil)
+	_ caddy.Module          = (*ListenerWrapper)(nil)
+	_ caddy.ListenerWrapper = (*ListenerWrapper)(nil)
+	_ caddyfile.Unmarshaler = (*ListenerWrapper)(nil)
+)