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net/stun: Remove unreachable code 

- Reuse IP length constants from net package.
- Remove beu16 to make endianness functions consistent.

Signed-off-by: Quoc-Viet Nguyen <afelion@gmail.com>
pull/475/head
Quoc-Viet Nguyen 2020-06-15 23:28:49 +10:00 committed by Brad Fitzpatrick
parent a036c8c718
commit 15a23ce65f
1 changed files with 6 additions and 12 deletions
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18
net/stun/stun.go
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@ -29,8 +29,6 @@ const (
bindingRequest = "\x00\x01" bindingRequest = "\x00\x01"
magicCookie = "\x21\x12\xa4\x42" magicCookie = "\x21\x12\xa4\x42"
lenFingerprint = 8 // 2+byte header + 2-byte length + 4-byte crc32 lenFingerprint = 8 // 2+byte header + 2-byte length + 4-byte crc32
ipv4Len = 4
ipv6Len = 16
headerLen = 20 headerLen = 20
) )
@ -135,7 +133,6 @@ var (
func foreachAttr(b []byte, fn func(attrType uint16, a []byte) error) error { func foreachAttr(b []byte, fn func(attrType uint16, a []byte) error) error {
for len(b) > 0 { for len(b) > 0 {
if len(b) < 4 { if len(b) < 4 {
return errors.New("effed-f1")
return ErrMalformedAttrs return ErrMalformedAttrs
} }
attrType := binary.BigEndian.Uint16(b[:2]) attrType := binary.BigEndian.Uint16(b[:2])
@ -143,7 +140,6 @@ func foreachAttr(b []byte, fn func(attrType uint16, a []byte) error) error {
attrLenPad := attrLen % 4 attrLenPad := attrLen % 4
b = b[4:] b = b[4:]
if attrLen+attrLenPad > len(b) { if attrLen+attrLenPad > len(b) {
return errors.New("effed-f2")
return ErrMalformedAttrs return ErrMalformedAttrs
} }
if err := fn(attrType, b[:attrLen]); err != nil { if err := fn(attrType, b[:attrLen]); err != nil {
@ -161,9 +157,9 @@ func Response(txID TxID, ip net.IP, port uint16) []byte {
} }
var fam byte var fam byte
switch len(ip) { switch len(ip) {
case 4: case net.IPv4len:
fam = 1 fam = 1
case 16: case net.IPv6len:
fam = 2 fam = 2
default: default:
return nil return nil
@ -194,8 +190,6 @@ func Response(txID TxID, ip net.IP, port uint16) []byte {
return b return b
} }
func beu16(b []byte) uint16 { return binary.BigEndian.Uint16(b) }
// ParseResponse parses a successful binding response STUN packet. // ParseResponse parses a successful binding response STUN packet.
// The IP address is extracted from the XOR-MAPPED-ADDRESS attribute. // The IP address is extracted from the XOR-MAPPED-ADDRESS attribute.
// The returned addr slice is owned by the caller and does not alias b. // The returned addr slice is owned by the caller and does not alias b.
@ -207,7 +201,7 @@ func ParseResponse(b []byte) (tID TxID, addr []byte, port uint16, err error) {
if b[0] != 0x01 || b[1] != 0x01 { if b[0] != 0x01 || b[1] != 0x01 {
return tID, nil, 0, ErrNotSuccessResponse return tID, nil, 0, ErrNotSuccessResponse
} }
attrsLen := int(beu16(b[2:4])) attrsLen := int(binary.BigEndian.Uint16(b[2:4]))
b = b[headerLen:] // remove STUN header b = b[headerLen:] // remove STUN header
if attrsLen > len(b) { if attrsLen > len(b) {
return tID, nil, 0, ErrMalformedAttrs return tID, nil, 0, ErrMalformedAttrs
@ -272,7 +266,7 @@ func xorMappedAddress(tID TxID, b []byte) (addr []byte, port uint16, err error)
if len(b) < 4 { if len(b) < 4 {
return nil, 0, ErrMalformedAttrs return nil, 0, ErrMalformedAttrs
} }
xorPort := beu16(b[2:4]) xorPort := binary.BigEndian.Uint16(b[2:4])
addrField := b[4:] addrField := b[4:]
port = xorPort ^ 0x2112 // first half of magicCookie port = xorPort ^ 0x2112 // first half of magicCookie
@ -298,9 +292,9 @@ func xorMappedAddress(tID TxID, b []byte) (addr []byte, port uint16, err error)
func familyAddrLen(fam byte) int { func familyAddrLen(fam byte) int {
switch fam { switch fam {
case 0x01: // IPv4 case 0x01: // IPv4
return ipv4Len return net.IPv4len
case 0x02: // IPv6 case 0x02: // IPv6
return ipv6Len return net.IPv6len
default: default:
return 0 return 0
} }