Add support of proxy protocol

internal/cli/run_proxy.go

@@ -10,6 +10,7 @@ import (
 	"github.com/9seconds/mtg/v2/antireplay"
 	"github.com/9seconds/mtg/v2/events"
 	"github.com/9seconds/mtg/v2/internal/config"
+	"github.com/9seconds/mtg/v2/internal/proxyprotocol"
 	"github.com/9seconds/mtg/v2/internal/utils"
 	"github.com/9seconds/mtg/v2/ipblocklist"
 	"github.com/9seconds/mtg/v2/ipblocklist/files"
@@ -17,6 +18,7 @@ import (
 	"github.com/9seconds/mtg/v2/mtglib"
 	"github.com/9seconds/mtg/v2/network"
 	"github.com/9seconds/mtg/v2/stats"
+	"github.com/pires/go-proxyproto"
 	"github.com/rs/zerolog"
 	"github.com/yl2chen/cidranger"
 )
@@ -275,6 +277,14 @@ func runProxy(conf *config.Config, version string) error { //nolint: funlen
 		return fmt.Errorf("cannot start proxy: %w", err)
 	}
 
+	if conf.ProxyProtocolListener.Get(false) {
+		listener = &proxyprotocol.ListenerAdapter{
+			Listener: proxyproto.Listener{
+				Listener: listener,
+			},
+		}
+	}
+
 	ctx := utils.RootContext()
 
 	go proxy.Serve(listener) //nolint: errcheck

internal/config/config.go

@@ -25,6 +25,7 @@ type Config struct {
 	AllowFallbackOnUnknownDC TypeBool        `json:"allowFallbackOnUnknownDc"`
 	Secret                   mtglib.Secret   `json:"secret"`
 	BindTo                   TypeHostPort    `json:"bindTo"`
+	ProxyProtocolListener    TypeBool        `json:"proxyProtocolListener"`
 	PreferIP                 TypePreferIP    `json:"preferIp"`
 	DomainFrontingPort       TypePort        `json:"domainFrontingPort"`
 	TolerateTimeSkewness     TypeDuration    `json:"tolerateTimeSkewness"`

internal/config/parse.go

@@ -13,6 +13,7 @@ type tomlConfig struct {
 	AllowFallbackOnUnknownDC bool   `toml:"allow-fallback-on-unknown-dc" json:"allowFallbackOnUnknownDc,omitempty"`
 	Secret                   string `toml:"secret" json:"secret"`
 	BindTo                   string `toml:"bind-to" json:"bindTo"`
+	ProxyProtocolListener    bool   `toml:"proxy-protocol-listener" json:"proxyProtocolListener"`
 	PreferIP                 string `toml:"prefer-ip" json:"preferIp,omitempty"`
 	DomainFrontingPort       uint   `toml:"domain-fronting-port" json:"domainFrontingPort,omitempty"`
 	TolerateTimeSkewness     string `toml:"tolerate-time-skewness" json:"tolerateTimeSkewness,omitempty"`

internal/proxyprotocol/adapter.go

@@ -0,0 +1,20 @@
+package proxyprotocol
+
+import (
+	"net"
+
+	"github.com/pires/go-proxyproto"
+)
+
+type ListenerAdapter struct {
+	proxyproto.Listener
+}
+
+func (l *ListenerAdapter) Accept() (net.Conn, error) {
+	conn, err := l.Listener.Accept()
+	if err != nil {
+		return nil, err
+	}
+
+	return connWrapper{conn.(*proxyproto.Conn)}, nil
+}

internal/proxyprotocol/conn.go

@@ -0,0 +1,25 @@
+package proxyprotocol
+
+import "github.com/pires/go-proxyproto"
+
+type connWrapper struct {
+	*proxyproto.Conn
+}
+
+func (c connWrapper) CloseRead() error {
+	tcpConn, ok := c.TCPConn()
+	if !ok {
+		panic("we support only tcp connections")
+	}
+
+	return tcpConn.CloseRead()
+}
+
+func (c connWrapper) CloseWrite() error {
+	tcpConn, ok := c.TCPConn()
+	if !ok {
+		panic("we support only tcp connections")
+	}
+
+	return tcpConn.CloseWrite()
+}