diff options
| author | Kevin Krakauer <krakauer@google.com> | 2020-06-07 13:37:25 -0700 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2020-06-07 13:38:43 -0700 |
| commit | 32b823fcdb00a7d6eb5ddcd378f19a659edc3da3 (patch) | |
| tree | bed24f8b692caa0e24cd1351d22bb35522cbfe3e /pkg/tcpip/header/ipv4.go | |
| parent | 62603041792021f654cfb3418e9a728220feaf60 (diff) | |
netstack: parse incoming packet headers up-front
Netstack has traditionally parsed headers on-demand as a packet moves up the
stack. This is conceptually simple and convenient, but incompatible with
iptables, where headers can be inspected and mangled before even a routing
decision is made.
This changes header parsing to happen early in the incoming packet path, as soon
as the NIC gets the packet from a link endpoint. Even if an invalid packet is
found (e.g. a TCP header of insufficient length), the packet is passed up the
stack for proper stats bookkeeping.
PiperOrigin-RevId: 315179302
Diffstat (limited to 'pkg/tcpip/header/ipv4.go')
| -rw-r--r-- | pkg/tcpip/header/ipv4.go | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go index 76839eb92..62ac932bb 100644 --- a/pkg/tcpip/header/ipv4.go +++ b/pkg/tcpip/header/ipv4.go @@ -159,6 +159,11 @@ func (b IPv4) Flags() uint8 { return uint8(binary.BigEndian.Uint16(b[flagsFO:]) >> 13) } +// More returns whether the more fragments flag is set. +func (b IPv4) More() bool { + return b.Flags()&IPv4FlagMoreFragments != 0 +} + // TTL returns the "TTL" field of the ipv4 header. func (b IPv4) TTL() uint8 { return b[ttl] |