diff options
Diffstat (limited to 'pkg/tcpip/header')
| -rw-r--r-- | pkg/tcpip/header/ipv4.go | 4 | ||||
| -rw-r--r-- | pkg/tcpip/header/tcp.go | 17 |
2 files changed, 20 insertions, 1 deletions
diff --git a/pkg/tcpip/header/ipv4.go b/pkg/tcpip/header/ipv4.go index 7da4c4845..7b8034de4 100644 --- a/pkg/tcpip/header/ipv4.go +++ b/pkg/tcpip/header/ipv4.go @@ -85,6 +85,10 @@ const ( // units, the header cannot exceed 15*4 = 60 bytes. IPv4MaximumHeaderSize = 60 + // MinIPFragmentPayloadSize is the minimum number of payload bytes that + // the first fragment must carry when an IPv4 packet is fragmented. + MinIPFragmentPayloadSize = 8 + // IPv4AddressSize is the size, in bytes, of an IPv4 address. IPv4AddressSize = 4 diff --git a/pkg/tcpip/header/tcp.go b/pkg/tcpip/header/tcp.go index 1141443bb..82cfe785c 100644 --- a/pkg/tcpip/header/tcp.go +++ b/pkg/tcpip/header/tcp.go @@ -176,6 +176,21 @@ const ( // TCPProtocolNumber is TCP's transport protocol number. TCPProtocolNumber tcpip.TransportProtocolNumber = 6 + + // TCPMinimumMSS is the minimum acceptable value for MSS. This is the + // same as the value TCP_MIN_MSS defined net/tcp.h. + TCPMinimumMSS = IPv4MaximumHeaderSize + TCPHeaderMaximumSize + MinIPFragmentPayloadSize - IPv4MinimumSize - TCPMinimumSize + + // TCPMaximumMSS is the maximum acceptable value for MSS. + TCPMaximumMSS = 0xffff + + // TCPDefaultMSS is the MSS value that should be used if an MSS option + // is not received from the peer. It's also the value returned by + // TCP_MAXSEG option for a socket in an unconnected state. + // + // Per RFC 1122, page 85: "If an MSS option is not received at + // connection setup, TCP MUST assume a default send MSS of 536." + TCPDefaultMSS = 536 ) // SourcePort returns the "source port" field of the tcp header. @@ -306,7 +321,7 @@ func ParseSynOptions(opts []byte, isAck bool) TCPSynOptions { synOpts := TCPSynOptions{ // Per RFC 1122, page 85: "If an MSS option is not received at // connection setup, TCP MUST assume a default send MSS of 536." - MSS: 536, + MSS: TCPDefaultMSS, // If no window scale option is specified, WS in options is // returned as -1; this is because the absence of the option // indicates that the we cannot use window scaling on the |