diff options
Diffstat (limited to 'pkg/tcpip/header/ipv4.go')
| -rw-r--r-- | pkg/tcpip/header/ipv4.go | 33 |
1 files changed, 20 insertions, 13 deletions
diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go index 17fc9c68e..554632a64 100644 --- a/pkg/tcpip/header/ipv4.go +++ b/pkg/tcpip/header/ipv4.go @@ -21,16 +21,18 @@ import ( ) const ( - versIHL = 0 - tos = 1 - totalLen = 2 - id = 4 - flagsFO = 6 - ttl = 8 - protocol = 9 - checksum = 10 - srcAddr = 12 - dstAddr = 16 + versIHL = 0 + tos = 1 + // IPv4TotalLenOffset is the offset of the total length field in the + // IPv4 header. + IPv4TotalLenOffset = 2 + id = 4 + flagsFO = 6 + ttl = 8 + protocol = 9 + checksum = 10 + srcAddr = 12 + dstAddr = 16 ) // IPv4Fields contains the fields of an IPv4 packet. It is used to describe the @@ -103,6 +105,11 @@ const ( // IPv4Any is the non-routable IPv4 "any" meta address. IPv4Any tcpip.Address = "\x00\x00\x00\x00" + + // IPv4MinimumProcessableDatagramSize is the minimum size of an IP + // packet that every IPv4 capable host must be able to + // process/reassemble. + IPv4MinimumProcessableDatagramSize = 576 ) // Flags that may be set in an IPv4 packet. @@ -163,7 +170,7 @@ func (b IPv4) FragmentOffset() uint16 { // TotalLength returns the "total length" field of the ipv4 header. func (b IPv4) TotalLength() uint16 { - return binary.BigEndian.Uint16(b[totalLen:]) + return binary.BigEndian.Uint16(b[IPv4TotalLenOffset:]) } // Checksum returns the checksum field of the ipv4 header. @@ -209,7 +216,7 @@ func (b IPv4) SetTOS(v uint8, _ uint32) { // SetTotalLength sets the "total length" field of the ipv4 header. func (b IPv4) SetTotalLength(totalLength uint16) { - binary.BigEndian.PutUint16(b[totalLen:], totalLength) + binary.BigEndian.PutUint16(b[IPv4TotalLenOffset:], totalLength) } // SetChecksum sets the checksum field of the ipv4 header. @@ -265,7 +272,7 @@ func (b IPv4) Encode(i *IPv4Fields) { // packets are produced. func (b IPv4) EncodePartial(partialChecksum, totalLength uint16) { b.SetTotalLength(totalLength) - checksum := Checksum(b[totalLen:totalLen+2], partialChecksum) + checksum := Checksum(b[IPv4TotalLenOffset:IPv4TotalLenOffset+2], partialChecksum) b.SetChecksum(^checksum) } |