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server/vendor/github.com/pion/stun/xoraddr.go

@@ -0,0 +1,150 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package stun
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"strconv"
+
+	"github.com/pion/transport/v2/utils/xor"
+)
+
+const (
+	familyIPv4 uint16 = 0x01
+	familyIPv6 uint16 = 0x02
+)
+
+// XORMappedAddress implements XOR-MAPPED-ADDRESS attribute.
+//
+// RFC 5389 Section 15.2
+type XORMappedAddress struct {
+	IP   net.IP
+	Port int
+}
+
+func (a XORMappedAddress) String() string {
+	return net.JoinHostPort(a.IP.String(), strconv.Itoa(a.Port))
+}
+
+// isIPv4 returns true if ip with len of net.IPv6Len seems to be ipv4.
+func isIPv4(ip net.IP) bool {
+	// Optimized for performance. Copied from net.IP.To4.
+	return isZeros(ip[0:10]) && ip[10] == 0xff && ip[11] == 0xff
+}
+
+// Is p all zeros?
+func isZeros(p net.IP) bool {
+	for i := 0; i < len(p); i++ {
+		if p[i] != 0 {
+			return false
+		}
+	}
+	return true
+}
+
+// ErrBadIPLength means that len(IP) is not net.{IPv6len,IPv4len}.
+var ErrBadIPLength = errors.New("invalid length of IP value")
+
+// AddToAs adds XOR-MAPPED-ADDRESS value to m as t attribute.
+func (a XORMappedAddress) AddToAs(m *Message, t AttrType) error {
+	var (
+		family = familyIPv4
+		ip     = a.IP
+	)
+	if len(a.IP) == net.IPv6len {
+		if isIPv4(ip) {
+			ip = ip[12:16] // like in ip.To4()
+		} else {
+			family = familyIPv6
+		}
+	} else if len(ip) != net.IPv4len {
+		return ErrBadIPLength
+	}
+	value := make([]byte, 32+128)
+	value[0] = 0 // first 8 bits are zeroes
+	xorValue := make([]byte, net.IPv6len)
+	copy(xorValue[4:], m.TransactionID[:])
+	bin.PutUint32(xorValue[0:4], magicCookie)
+	bin.PutUint16(value[0:2], family)
+	bin.PutUint16(value[2:4], uint16(a.Port^magicCookie>>16))
+	xor.XorBytes(value[4:4+len(ip)], ip, xorValue)
+	m.Add(t, value[:4+len(ip)])
+	return nil
+}
+
+// AddTo adds XOR-MAPPED-ADDRESS to m. Can return ErrBadIPLength
+// if len(a.IP) is invalid.
+func (a XORMappedAddress) AddTo(m *Message) error {
+	return a.AddToAs(m, AttrXORMappedAddress)
+}
+
+// GetFromAs decodes XOR-MAPPED-ADDRESS attribute value in message
+// getting it as for t type.
+func (a *XORMappedAddress) GetFromAs(m *Message, t AttrType) error {
+	v, err := m.Get(t)
+	if err != nil {
+		return err
+	}
+	family := bin.Uint16(v[0:2])
+	if family != familyIPv6 && family != familyIPv4 {
+		return newDecodeErr("xor-mapped address", "family",
+			fmt.Sprintf("bad value %d", family),
+		)
+	}
+	ipLen := net.IPv4len
+	if family == familyIPv6 {
+		ipLen = net.IPv6len
+	}
+	// Ensuring len(a.IP) == ipLen and reusing a.IP.
+	if len(a.IP) < ipLen {
+		a.IP = a.IP[:cap(a.IP)]
+		for len(a.IP) < ipLen {
+			a.IP = append(a.IP, 0)
+		}
+	}
+	a.IP = a.IP[:ipLen]
+	for i := range a.IP {
+		a.IP[i] = 0
+	}
+	if len(v) <= 4 {
+		return io.ErrUnexpectedEOF
+	}
+	if err := CheckOverflow(t, len(v[4:]), len(a.IP)); err != nil {
+		return err
+	}
+	a.Port = int(bin.Uint16(v[2:4])) ^ (magicCookie >> 16)
+	xorValue := make([]byte, 4+TransactionIDSize)
+	bin.PutUint32(xorValue[0:4], magicCookie)
+	copy(xorValue[4:], m.TransactionID[:])
+	xor.XorBytes(a.IP, v[4:], xorValue)
+	return nil
+}
+
+// GetFrom decodes XOR-MAPPED-ADDRESS attribute in message and returns
+// error if any. While decoding, a.IP is reused if possible and can be
+// rendered to invalid state (e.g. if a.IP was set to IPv6 and then
+// IPv4 value were decoded into it), be careful.
+//
+// Example:
+//
+//	expectedIP := net.ParseIP("213.141.156.236")
+//	expectedIP.String() // 213.141.156.236, 16 bytes, first 12 of them are zeroes
+//	expectedPort := 21254
+//	addr := &XORMappedAddress{
+//	  IP:   expectedIP,
+//	  Port: expectedPort,
+//	}
+//	// addr were added to message that is decoded as newMessage
+//	// ...
+//
+//	addr.GetFrom(newMessage)
+//	addr.IP.String()    // 213.141.156.236, net.IPv4Len
+//	expectedIP.String() // d58d:9cec::ffff:d58d:9cec, 16 bytes, first 4 are IPv4
+//	// now we have len(expectedIP) = 16 and len(addr.IP) = 4.
+func (a *XORMappedAddress) GetFrom(m *Message) error {
+	return a.GetFromAs(m, AttrXORMappedAddress)
+}