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forgejo/modules/proxyprotocol/conn.go

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// Copyright 2020 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package proxyprotocol
import (
"bufio"
"bytes"
"encoding/binary"
"io"
"net"
"strconv"
"strings"
"sync"
"time"
"code.gitea.io/gitea/modules/log"
)
var (
// v1Prefix is the string we look for at the start of a connection
// to check if this connection is using the proxy protocol
v1Prefix = []byte("PROXY ")
v1PrefixLen = len(v1Prefix)
v2Prefix = []byte("\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A")
v2PrefixLen = len(v2Prefix)
)
// Conn is used to wrap and underlying connection which is speaking the
// Proxy Protocol. RemoteAddr() will return the address of the client
// instead of the proxy address.
type Conn struct {
bufReader *bufio.Reader
conn net.Conn
localAddr net.Addr
remoteAddr net.Addr
once sync.Once
proxyHeaderTimeout time.Duration
acceptUnknown bool
}
// NewConn is used to wrap a net.Conn speaking the proxy protocol into
// a proxyprotocol.Conn
func NewConn(conn net.Conn, timeout time.Duration) *Conn {
pConn := &Conn{
bufReader: bufio.NewReader(conn),
conn: conn,
proxyHeaderTimeout: timeout,
}
return pConn
}
// Read reads data from the connection.
// It will initially read the proxy protocol header.
// If there is an error parsing the header, it is returned and the socket is closed.
func (p *Conn) Read(b []byte) (int, error) {
if err := p.readProxyHeaderOnce(); err != nil {
return 0, err
}
return p.bufReader.Read(b)
}
// ReadFrom reads data from a provided reader and copies it to the connection.
func (p *Conn) ReadFrom(r io.Reader) (int64, error) {
if err := p.readProxyHeaderOnce(); err != nil {
return 0, err
}
if rf, ok := p.conn.(io.ReaderFrom); ok {
return rf.ReadFrom(r)
}
return io.Copy(p.conn, r)
}
// WriteTo reads data from the connection and writes it to the writer.
// It will initially read the proxy protocol header.
// If there is an error parsing the header, it is returned and the socket is closed.
func (p *Conn) WriteTo(w io.Writer) (int64, error) {
if err := p.readProxyHeaderOnce(); err != nil {
return 0, err
}
return p.bufReader.WriteTo(w)
}
// Write writes data to the connection.
// Write can be made to time out and return an error after a fixed
// time limit; see SetDeadline and SetWriteDeadline.
func (p *Conn) Write(b []byte) (int, error) {
if err := p.readProxyHeaderOnce(); err != nil {
return 0, err
}
return p.conn.Write(b)
}
// Close closes the connection.
// Any blocked Read or Write operations will be unblocked and return errors.
func (p *Conn) Close() error {
return p.conn.Close()
}
// LocalAddr returns the local network address.
func (p *Conn) LocalAddr() net.Addr {
_ = p.readProxyHeaderOnce()
if p.localAddr != nil {
return p.localAddr
}
return p.conn.LocalAddr()
}
// RemoteAddr returns the address of the client if the proxy
// protocol is being used, otherwise just returns the address of
// the socket peer. If there is an error parsing the header, the
// address of the client is not returned, and the socket is closed.
// One implication of this is that the call could block if the
// client is slow. Using a Deadline is recommended if this is called
// before Read()
func (p *Conn) RemoteAddr() net.Addr {
_ = p.readProxyHeaderOnce()
if p.remoteAddr != nil {
return p.remoteAddr
}
return p.conn.RemoteAddr()
}
// SetDeadline sets the read and write deadlines associated
// with the connection. It is equivalent to calling both
// SetReadDeadline and SetWriteDeadline.
//
// A deadline is an absolute time after which I/O operations
// fail instead of blocking. The deadline applies to all future
// and pending I/O, not just the immediately following call to
// Read or Write. After a deadline has been exceeded, the
// connection can be refreshed by setting a deadline in the future.
//
// If the deadline is exceeded a call to Read or Write or to other
// I/O methods will return an error that wraps os.ErrDeadlineExceeded.
// This can be tested using errors.Is(err, os.ErrDeadlineExceeded).
// The error's Timeout method will return true, but note that there
// are other possible errors for which the Timeout method will
// return true even if the deadline has not been exceeded.
//
// An idle timeout can be implemented by repeatedly extending
// the deadline after successful Read or Write calls.
//
// A zero value for t means I/O operations will not time out.
func (p *Conn) SetDeadline(t time.Time) error {
return p.conn.SetDeadline(t)
}
// SetReadDeadline sets the deadline for future Read calls
// and any currently-blocked Read call.
// A zero value for t means Read will not time out.
func (p *Conn) SetReadDeadline(t time.Time) error {
return p.conn.SetReadDeadline(t)
}
// SetWriteDeadline sets the deadline for future Write calls
// and any currently-blocked Write call.
// Even if write times out, it may return n > 0, indicating that
// some of the data was successfully written.
// A zero value for t means Write will not time out.
func (p *Conn) SetWriteDeadline(t time.Time) error {
return p.conn.SetWriteDeadline(t)
}
// readProxyHeaderOnce will ensure that the proxy header has been read
func (p *Conn) readProxyHeaderOnce() (err error) {
p.once.Do(func() {
if err = p.readProxyHeader(); err != nil && err != io.EOF {
log.Error("Failed to read proxy prefix: %v", err)
p.Close()
p.bufReader = bufio.NewReader(p.conn)
}
})
return err
}
func (p *Conn) readProxyHeader() error {
if p.proxyHeaderTimeout != 0 {
readDeadLine := time.Now().Add(p.proxyHeaderTimeout)
_ = p.conn.SetReadDeadline(readDeadLine)
defer func() {
_ = p.conn.SetReadDeadline(time.Time{})
}()
}
inp, err := p.bufReader.Peek(v1PrefixLen)
if err != nil {
return err
}
if bytes.Equal(inp, v1Prefix) {
return p.readV1ProxyHeader()
}
inp, err = p.bufReader.Peek(v2PrefixLen)
if err != nil {
return err
}
if bytes.Equal(inp, v2Prefix) {
return p.readV2ProxyHeader()
}
return &ErrBadHeader{inp}
}
func (p *Conn) readV2ProxyHeader() error {
// The binary header format starts with a constant 12 bytes block containing the
// protocol signature :
//
// \x0D \x0A \x0D \x0A \x00 \x0D \x0A \x51 \x55 \x49 \x54 \x0A
//
// Note that this block contains a null byte at the 5th position, so it must not
// be handled as a null-terminated string.
if _, err := p.bufReader.Discard(v2PrefixLen); err != nil {
// This shouldn't happen as we have already asserted that there should be enough in the buffer
return err
}
// The next byte (the 13th one) is the protocol version and command.
version, err := p.bufReader.ReadByte()
if err != nil {
return err
}
// The 14th byte contains the transport protocol and address family.otocol.
familyByte, err := p.bufReader.ReadByte()
if err != nil {
return err
}
// The 15th and 16th bytes is the address length in bytes in network endian order.
var addressLen uint16
if err := binary.Read(p.bufReader, binary.BigEndian, &addressLen); err != nil {
return err
}
// Now handle the version byte: (14th byte).
// The highest four bits contains the version. As of this specification, it must
// always be sent as \x2 and the receiver must only accept this value.
if version>>4 != 0x2 {
return &ErrBadHeader{append(v2Prefix, version, familyByte, uint8(addressLen>>8), uint8(addressLen&0xff))}
}
// The lowest four bits represents the command :
switch version & 0xf {
case 0x0:
// - \x0 : LOCAL : the connection was established on purpose by the proxy
// without being relayed. The connection endpoints are the sender and the
// receiver. Such connections exist when the proxy sends health-checks to the
// server. The receiver must accept this connection as valid and must use the
// real connection endpoints and discard the protocol block including the
// family which is ignored.
// We therefore ignore the 14th, 15th and 16th bytes
p.remoteAddr = p.conn.LocalAddr()
p.localAddr = p.conn.RemoteAddr()
return nil
case 0x1:
// - \x1 : PROXY : the connection was established on behalf of another node,
// and reflects the original connection endpoints. The receiver must then use
// the information provided in the protocol block to get original the address.
default:
// - other values are unassigned and must not be emitted by senders. Receivers
// must drop connections presenting unexpected values here.
return &ErrBadHeader{append(v2Prefix, version, familyByte, uint8(addressLen>>8), uint8(addressLen&0xff))}
}
// Now handle the familyByte byte: (15th byte).
// The highest 4 bits contain the address family, the lowest 4 bits contain the protocol
// The address family maps to the original socket family without necessarily
// matching the values internally used by the system. It may be one of :
//
// - 0x0 : AF_UNSPEC : the connection is forwarded for an unknown, unspecified
// or unsupported protocol. The sender should use this family when sending
// LOCAL commands or when dealing with unsupported protocol families. The
// receiver is free to accept the connection anyway and use the real endpoint
// addresses or to reject it. The receiver should ignore address information.
//
// - 0x1 : AF_INET : the forwarded connection uses the AF_INET address family
// (IPv4). The addresses are exactly 4 bytes each in network byte order,
// followed by transport protocol information (typically ports).
//
// - 0x2 : AF_INET6 : the forwarded connection uses the AF_INET6 address family
// (IPv6). The addresses are exactly 16 bytes each in network byte order,
// followed by transport protocol information (typically ports).
//
// - 0x3 : AF_UNIX : the forwarded connection uses the AF_UNIX address family
// (UNIX). The addresses are exactly 108 bytes each.
//
// - other values are unspecified and must not be emitted in version 2 of this
// protocol and must be rejected as invalid by receivers.
// The transport protocol is specified in the lowest 4 bits of the 14th byte :
//
// - 0x0 : UNSPEC : the connection is forwarded for an unknown, unspecified
// or unsupported protocol. The sender should use this family when sending
// LOCAL commands or when dealing with unsupported protocol families. The
// receiver is free to accept the connection anyway and use the real endpoint
// addresses or to reject it. The receiver should ignore address information.
//
// - 0x1 : STREAM : the forwarded connection uses a SOCK_STREAM protocol (eg:
// TCP or UNIX_STREAM). When used with AF_INET/AF_INET6 (TCP), the addresses
// are followed by the source and destination ports represented on 2 bytes
// each in network byte order.
//
// - 0x2 : DGRAM : the forwarded connection uses a SOCK_DGRAM protocol (eg:
// UDP or UNIX_DGRAM). When used with AF_INET/AF_INET6 (UDP), the addresses
// are followed by the source and destination ports represented on 2 bytes
// each in network byte order.
//
// - other values are unspecified and must not be emitted in version 2 of this
// protocol and must be rejected as invalid by receivers.
if familyByte>>4 == 0x0 || familyByte&0xf == 0x0 {
// - hi 0x0 : AF_UNSPEC : the connection is forwarded for an unknown address type
// or
// - lo 0x0 : UNSPEC : the connection is forwarded for an unspecified protocol
if !p.acceptUnknown {
p.conn.Close()
return &ErrBadHeader{append(v2Prefix, version, familyByte, uint8(addressLen>>8), uint8(addressLen&0xff))}
}
p.remoteAddr = p.conn.LocalAddr()
p.localAddr = p.conn.RemoteAddr()
_, err = p.bufReader.Discard(int(addressLen))
return err
}
// other address or protocol
if (familyByte>>4) > 0x3 || (familyByte&0xf) > 0x2 {
return &ErrBadHeader{append(v2Prefix, version, familyByte, uint8(addressLen>>8), uint8(addressLen&0xff))}
}
// Handle AF_UNIX addresses
if familyByte>>4 == 0x3 {
// - \x31 : UNIX stream : the forwarded connection uses SOCK_STREAM over the
// AF_UNIX protocol family. Address length is 2*108 = 216 bytes.
// - \x32 : UNIX datagram : the forwarded connection uses SOCK_DGRAM over the
// AF_UNIX protocol family. Address length is 2*108 = 216 bytes.
if addressLen != 216 {
return &ErrBadHeader{append(v2Prefix, version, familyByte, uint8(addressLen>>8), uint8(addressLen&0xff))}
}
remoteName := make([]byte, 108)
localName := make([]byte, 108)
if _, err := p.bufReader.Read(remoteName); err != nil {
return err
}
if _, err := p.bufReader.Read(localName); err != nil {
return err
}
protocol := "unix"
if familyByte&0xf == 2 {
protocol = "unixgram"
}
p.remoteAddr = &net.UnixAddr{
Name: string(remoteName),
Net: protocol,
}
p.localAddr = &net.UnixAddr{
Name: string(localName),
Net: protocol,
}
return nil
}
var remoteIP []byte
var localIP []byte
var remotePort uint16
var localPort uint16
if familyByte>>4 == 0x1 {
// AF_INET
// - \x11 : TCP over IPv4 : the forwarded connection uses TCP over the AF_INET
// protocol family. Address length is 2*4 + 2*2 = 12 bytes.
// - \x12 : UDP over IPv4 : the forwarded connection uses UDP over the AF_INET
// protocol family. Address length is 2*4 + 2*2 = 12 bytes.
if addressLen != 12 {
return &ErrBadHeader{append(v2Prefix, version, familyByte, uint8(addressLen>>8), uint8(addressLen&0xff))}
}
remoteIP = make([]byte, 4)
localIP = make([]byte, 4)
} else {
// AF_INET6
// - \x21 : TCP over IPv6 : the forwarded connection uses TCP over the AF_INET6
// protocol family. Address length is 2*16 + 2*2 = 36 bytes.
// - \x22 : UDP over IPv6 : the forwarded connection uses UDP over the AF_INET6
// protocol family. Address length is 2*16 + 2*2 = 36 bytes.
if addressLen != 36 {
return &ErrBadHeader{append(v2Prefix, version, familyByte, uint8(addressLen>>8), uint8(addressLen&0xff))}
}
remoteIP = make([]byte, 16)
localIP = make([]byte, 16)
}
if _, err := p.bufReader.Read(remoteIP); err != nil {
return err
}
if _, err := p.bufReader.Read(localIP); err != nil {
return err
}
if err := binary.Read(p.bufReader, binary.BigEndian, &remotePort); err != nil {
return err
}
if err := binary.Read(p.bufReader, binary.BigEndian, &localPort); err != nil {
return err
}
if familyByte&0xf == 1 {
p.remoteAddr = &net.TCPAddr{
IP: remoteIP,
Port: int(remotePort),
}
p.localAddr = &net.TCPAddr{
IP: localIP,
Port: int(localPort),
}
} else {
p.remoteAddr = &net.UDPAddr{
IP: remoteIP,
Port: int(remotePort),
}
p.localAddr = &net.UDPAddr{
IP: localIP,
Port: int(localPort),
}
}
return nil
}
func (p *Conn) readV1ProxyHeader() error {
// Read until a newline
header, err := p.bufReader.ReadString('\n')
if err != nil {
p.conn.Close()
return err
}
if header[len(header)-2] != '\r' {
return &ErrBadHeader{[]byte(header)}
}
// Strip the carriage return and new line
header = header[:len(header)-2]
// Split on spaces, should be (PROXY <type> <remote addr> <local addr> <remote port> <local port>)
parts := strings.Split(header, " ")
if len(parts) < 2 {
p.conn.Close()
return &ErrBadHeader{[]byte(header)}
}
// Verify the type is known
switch parts[1] {
case "UNKNOWN":
if !p.acceptUnknown || len(parts) != 2 {
p.conn.Close()
return &ErrBadHeader{[]byte(header)}
}
p.remoteAddr = p.conn.LocalAddr()
p.localAddr = p.conn.RemoteAddr()
return nil
case "TCP4":
case "TCP6":
default:
p.conn.Close()
return &ErrBadAddressType{parts[1]}
}
if len(parts) != 6 {
p.conn.Close()
return &ErrBadHeader{[]byte(header)}
}
// Parse out the remote address
ip := net.ParseIP(parts[2])
if ip == nil {
p.conn.Close()
return &ErrBadRemote{parts[2], parts[4]}
}
port, err := strconv.Atoi(parts[4])
if err != nil {
p.conn.Close()
return &ErrBadRemote{parts[2], parts[4]}
}
p.remoteAddr = &net.TCPAddr{IP: ip, Port: port}
// Parse out the destination address
ip = net.ParseIP(parts[3])
if ip == nil {
p.conn.Close()
return &ErrBadLocal{parts[3], parts[5]}
}
port, err = strconv.Atoi(parts[5])
if err != nil {
p.conn.Close()
return &ErrBadLocal{parts[3], parts[5]}
}
p.localAddr = &net.TCPAddr{IP: ip, Port: port}
return nil
}