From 360006d894247ba78771d1244d5b849dabe3ce5a Mon Sep 17 00:00:00 2001
From: Ghanan Gowripalan <ghanan@google.com>
Date: Fri, 18 Sep 2020 00:46:26 -0700
Subject: Use common parsing utilities when sniffing

Extract parsing utilities so they can be used by the sniffer.

Fixes #3930

PiperOrigin-RevId: 332401880
---
 pkg/tcpip/transport/tcp/BUILD       |  1 +
 pkg/tcpip/transport/tcp/protocol.go | 18 ++----------------
 2 files changed, 3 insertions(+), 16 deletions(-)

(limited to 'pkg/tcpip/transport/tcp')

diff --git a/pkg/tcpip/transport/tcp/BUILD b/pkg/tcpip/transport/tcp/BUILD
index 234fb95ce..4778e7b1c 100644
--- a/pkg/tcpip/transport/tcp/BUILD
+++ b/pkg/tcpip/transport/tcp/BUILD
@@ -69,6 +69,7 @@ go_library(
         "//pkg/tcpip/buffer",
         "//pkg/tcpip/hash/jenkins",
         "//pkg/tcpip/header",
+        "//pkg/tcpip/header/parse",
         "//pkg/tcpip/ports",
         "//pkg/tcpip/seqnum",
         "//pkg/tcpip/stack",
diff --git a/pkg/tcpip/transport/tcp/protocol.go b/pkg/tcpip/transport/tcp/protocol.go
index 63ec12be8..74a17af79 100644
--- a/pkg/tcpip/transport/tcp/protocol.go
+++ b/pkg/tcpip/transport/tcp/protocol.go
@@ -29,6 +29,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/header/parse"
 	"gvisor.dev/gvisor/pkg/tcpip/seqnum"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/raw"
@@ -506,22 +507,7 @@ func (p *protocol) SynRcvdCounter() *synRcvdCounter {
 
 // Parse implements stack.TransportProtocol.Parse.
 func (*protocol) Parse(pkt *stack.PacketBuffer) bool {
-	// TCP header is variable length, peek at it first.
-	hdrLen := header.TCPMinimumSize
-	hdr, ok := pkt.Data.PullUp(hdrLen)
-	if !ok {
-		return false
-	}
-
-	// If the header has options, pull those up as well.
-	if offset := int(header.TCP(hdr).DataOffset()); offset > header.TCPMinimumSize && offset <= pkt.Data.Size() {
-		// TODO(gvisor.dev/issue/2404): Figure out whether to reject this kind of
-		// packets.
-		hdrLen = offset
-	}
-
-	_, ok = pkt.TransportHeader().Consume(hdrLen)
-	return ok
+	return parse.TCP(pkt)
 }
 
 // NewProtocol returns a TCP transport protocol.
-- 
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