diff options
Diffstat (limited to 'pkg/tcpip/network/ipv4/ipv4.go')
| -rw-r--r-- | pkg/tcpip/network/ipv4/ipv4.go | 21 |
1 files changed, 9 insertions, 12 deletions
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go index 7e9f16c90..b1776e5ee 100644 --- a/pkg/tcpip/network/ipv4/ipv4.go +++ b/pkg/tcpip/network/ipv4/ipv4.go @@ -225,12 +225,10 @@ func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu int, func (e *endpoint) addIPHeader(r *stack.Route, hdr *buffer.Prependable, payloadSize int, params stack.NetworkHeaderParams) header.IPv4 { ip := header.IPv4(hdr.Prepend(header.IPv4MinimumSize)) length := uint16(hdr.UsedLength() + payloadSize) - id := uint32(0) - if length > header.IPv4MaximumHeaderSize+8 { - // Packets of 68 bytes or less are required by RFC 791 to not be - // fragmented, so we only assign ids to larger packets. - id = atomic.AddUint32(&e.protocol.ids[hashRoute(r, params.Protocol, e.protocol.hashIV)%buckets], 1) - } + // RFC 6864 section 4.3 mandates uniqueness of ID values for non-atomic + // datagrams. Since the DF bit is never being set here, all datagrams + // are non-atomic and need an ID. + id := atomic.AddUint32(&e.protocol.ids[hashRoute(r, params.Protocol, e.protocol.hashIV)%buckets], 1) ip.Encode(&header.IPv4Fields{ IHL: header.IPv4MinimumSize, TotalLength: length, @@ -376,13 +374,12 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu // Set the packet ID when zero. if ip.ID() == 0 { - id := uint32(0) - if pkt.Data.Size() > header.IPv4MaximumHeaderSize+8 { - // Packets of 68 bytes or less are required by RFC 791 to not be - // fragmented, so we only assign ids to larger packets. - id = atomic.AddUint32(&e.protocol.ids[hashRoute(r, 0 /* protocol */, e.protocol.hashIV)%buckets], 1) + // RFC 6864 section 4.3 mandates uniqueness of ID values for + // non-atomic datagrams, so assign an ID to all such datagrams + // according to the definition given in RFC 6864 section 4. + if ip.Flags()&header.IPv4FlagDontFragment == 0 || ip.Flags()&header.IPv4FlagMoreFragments != 0 || ip.FragmentOffset() > 0 { + ip.SetID(uint16(atomic.AddUint32(&e.protocol.ids[hashRoute(r, 0 /* protocol */, e.protocol.hashIV)%buckets], 1))) } - ip.SetID(uint16(id)) } // Always set the checksum. |