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// Copyright 2019 Path Network, Inc. All rights reserved.
// Copyright 2024 Konrad Zemek <konrad.zemek@gmail.com>
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package proxyprotocol
import (
"bytes"
"encoding/binary"
"fmt"
"net/netip"
"strings"
"github.com/kzemek/go-mmproxy/utils"
)
func readRemoteAddrPROXYv2(ctrlBuf []byte, protocol utils.Protocol) (saddr, daddr netip.AddrPort, data []byte, resultErr error) {
if (ctrlBuf[12] >> 4) != 2 {
resultErr = fmt.Errorf("unknown protocol version %d", ctrlBuf[12]>>4)
return
}
if ctrlBuf[12]&0xF > 1 {
resultErr = fmt.Errorf("unknown command %d", ctrlBuf[12]&0xF)
return
}
if ctrlBuf[12]&0xF == 1 && ((protocol == utils.TCP && ctrlBuf[13] != 0x11 && ctrlBuf[13] != 0x21) ||
(protocol == utils.UDP && ctrlBuf[13] != 0x12 && ctrlBuf[13] != 0x22)) {
resultErr = fmt.Errorf("invalid family/protocol %d/%d", ctrlBuf[13]>>4, ctrlBuf[13]&0xF)
return
}
var dataLen uint16
reader := bytes.NewReader(ctrlBuf[14:16])
if err := binary.Read(reader, binary.BigEndian, &dataLen); err != nil {
resultErr = fmt.Errorf("failed to decode address data length: %w", err)
return
}
if len(ctrlBuf) < 16+int(dataLen) {
resultErr = fmt.Errorf("incomplete PROXY header")
return
}
if ctrlBuf[12]&0xF == 0 { // LOCAL
data = ctrlBuf[16+dataLen:]
return
}
var sport, dport uint16
if ctrlBuf[13]>>4 == 0x1 { // IPv4
reader = bytes.NewReader(ctrlBuf[24:])
} else {
reader = bytes.NewReader(ctrlBuf[48:])
}
if err := binary.Read(reader, binary.BigEndian, &sport); err != nil {
resultErr = fmt.Errorf("failed to decode source port: %w", err)
return
}
if sport == 0 {
resultErr = fmt.Errorf("invalid source port %d", sport)
return
}
if err := binary.Read(reader, binary.BigEndian, &dport); err != nil {
resultErr = fmt.Errorf("failed to decode destination port: %w", err)
return
}
if dport == 0 {
resultErr = fmt.Errorf("invalid destination port %d", sport)
return
}
var srcIP, dstIP netip.Addr
if ctrlBuf[13]>>4 == 0x1 { // IPv4
srcIP, _ = netip.AddrFromSlice(ctrlBuf[16:20])
dstIP, _ = netip.AddrFromSlice(ctrlBuf[20:24])
} else {
srcIP, _ = netip.AddrFromSlice(ctrlBuf[16:32])
dstIP, _ = netip.AddrFromSlice(ctrlBuf[32:48])
}
saddr = netip.AddrPortFrom(srcIP, sport)
daddr = netip.AddrPortFrom(dstIP, dport)
data = ctrlBuf[16+dataLen:]
return
}
func readRemoteAddrPROXYv1(ctrlBuf []byte) (saddr, daddr netip.AddrPort, data []byte, resultErr error) {
str := string(ctrlBuf)
idx := strings.Index(str, "\r\n")
if idx < 0 {
resultErr = fmt.Errorf("did not find \\r\\n in first data segment")
return
}
var headerProtocol string
n, err := fmt.Sscanf(str, "PROXY %s", &headerProtocol)
if err != nil {
resultErr = err
return
}
if n != 1 {
resultErr = fmt.Errorf("failed to decode elements")
return
}
if headerProtocol == "UNKNOWN" {
data = ctrlBuf[idx+2:]
return
}
if headerProtocol != "TCP4" && headerProtocol != "TCP6" {
resultErr = fmt.Errorf("unknown protocol %s", headerProtocol)
return
}
var src, dst string
var sport, dport int
n, err = fmt.Sscanf(str, "PROXY %s %s %s %d %d", &headerProtocol, &src, &dst, &sport, &dport)
if err != nil {
resultErr = err
return
}
if n != 5 {
resultErr = fmt.Errorf("failed to decode elements")
return
}
if sport <= 0 || sport > 65535 {
resultErr = fmt.Errorf("invalid source port %d", sport)
return
}
if dport <= 0 || dport > 65535 {
resultErr = fmt.Errorf("invalid destination port %d", sport)
return
}
srcIP, err := netip.ParseAddr(src)
if err != nil {
resultErr = fmt.Errorf("failed to parse source IP address %s: %w", src, err)
return
}
dstIP, err := netip.ParseAddr(dst)
if err != nil {
resultErr = fmt.Errorf("failed to parse destination IP address %s: %w", dst, err)
return
}
saddr = netip.AddrPortFrom(srcIP, uint16(sport))
daddr = netip.AddrPortFrom(dstIP, uint16(dport))
data = ctrlBuf[idx+2:]
return
}
var proxyv2header = []byte{0x0D, 0x0A, 0x0D, 0x0A, 0x00, 0x0D, 0x0A, 0x51, 0x55, 0x49, 0x54, 0x0A}
func ReadRemoteAddr(buf []byte, protocol utils.Protocol) (saddr, daddr netip.AddrPort, rest []byte, err error) {
if len(buf) >= 16 && bytes.Equal(buf[:12], proxyv2header) {
saddr, daddr, rest, err = readRemoteAddrPROXYv2(buf, protocol)
if err != nil {
err = fmt.Errorf("failed to parse PROXY v2 header: %w", err)
}
return
}
// PROXYv1 only works with TCP
if protocol == utils.TCP && len(buf) >= 8 && bytes.Equal(buf[:5], []byte("PROXY")) {
saddr, daddr, rest, err = readRemoteAddrPROXYv1(buf)
if err != nil {
err = fmt.Errorf("failed to parse PROXY v1 header: %w", err)
}
return
}
err = fmt.Errorf("PROXY header missing")
return
}
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