(Un)StripTCPHeader

elements/tcpudp/striptcpheader.cc

@@ -0,0 +1,43 @@
+// -*- mode: c++; c-basic-offset: 4 -*-
+/*
+ * striptcpheader.{cc,hh} -- element strips TCP header from front of packet
+ * Tom Barbette
+ *
+ * Copyright (c) 2020 KTH Royal Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, subject to the conditions
+ * listed in the Click LICENSE file. These conditions include: you must
+ * preserve this copyright notice, and you cannot mention the copyright
+ * holders in advertising related to the Software without their permission.
+ * The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
+ * notice is a summary of the Click LICENSE file; the license in that file is
+ * legally binding.
+ */
+
+#include <click/config.h>
+#include <click/args.hh>
+#include <click/error.hh>
+#include <click/glue.hh>
+#include <click/packet_anno.hh>
+#include <clicknet/tcp.h>
+#include "striptcpheader.hh"
+CLICK_DECLS
+
+StripTCPHeader::StripTCPHeader()
+{
+}
+
+Packet *
+StripTCPHeader::simple_action(Packet *p)
+{
+	const click_tcp *th = p->tcp_header();
+	unsigned n = th->th_off << 2;
+	p->pull(n);
+    return p;
+}
+
+CLICK_ENDDECLS
+EXPORT_ELEMENT(StripTCPHeader)
+ELEMENT_MT_SAFE(StripTCPHeader)

elements/tcpudp/striptcpheader.hh

@@ -0,0 +1,43 @@
+// -*- mode: c++; c-basic-offset: 4 -*-
+#ifndef CLICK_STRIPTCPHEADER_HH
+#define CLICK_STRIPTCPHEADER_HH
+#include <click/element.hh>
+CLICK_DECLS
+
+/*
+ * =c
+ * StripTCPHeader()
+ *
+ * =s tcp
+ * Strip the TCP header from the front of packets
+ *
+ * =d
+ * Removes all bytes from the beginning of the packet up to the end of the TCP
+ * header.
+ *
+ * =e
+ * Use this to get rid of all headers up to the end of the TCP layer, check if
+ * the first bytes are "GET", and
+ * set back the pointer to the beginning of the IP layer:
+ *
+ *   StripTCPHeader()
+ *   -> c :: Classifier(0/474552,-)
+ *   -> UnstripIPHeader()
+ *
+ *
+ * =a Strip, StripIPHeader, UnstripTCPHeader
+ */
+
+class StripTCPHeader : public Element { public:
+
+    StripTCPHeader() CLICK_COLD;
+
+    const char *class_name() const		{ return "StripTCPHeader"; }
+    const char *port_count() const		{ return PORTS_1_1; }
+
+    Packet *simple_action(Packet *);
+
+};
+
+CLICK_ENDDECLS
+#endif

elements/tcpudp/unstriptcpheader.cc

@@ -0,0 +1,43 @@
+/*
+ * unstriptcpheader.{cc,hh} -- put TCP header back based on annotation
+ * Tom Barbette, based on Benjie Chen's UnstripIPHeader
+ *
+ * Copyright (c) 2020 KTH Royal Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, subject to the conditions
+ * listed in the Click LICENSE file. These conditions include: you must
+ * preserve this copyright notice, and you cannot mention the copyright
+ * holders in advertising related to the Software without their permission.
+ * The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
+ * notice is a summary of the Click LICENSE file; the license in that file is
+ * legally binding.
+ */
+
+#include <click/config.h>
+#include "unstriptcpheader.hh"
+#include <clicknet/ip.h>
+CLICK_DECLS
+
+UnstripTCPHeader::UnstripTCPHeader()
+{
+}
+
+UnstripTCPHeader::~UnstripTCPHeader()
+{
+}
+
+Packet *
+UnstripTCPHeader::simple_action(Packet *p)
+{
+    assert(p->tcp_header());
+    ptrdiff_t offset = (unsigned char*)p->tcp_header() - p->data();
+    if (offset < 0)
+        p = p->push(-offset);    // should never create a new packet
+    return p;
+}
+
+CLICK_ENDDECLS
+EXPORT_ELEMENT(UnstripTCPHeader)
+ELEMENT_MT_SAFE(UnstripTCPHeader)

elements/tcpudp/unstriptcpheader.hh

@@ -0,0 +1,34 @@
+#ifndef CLICK_UNSTRIPTCPHEADER_HH
+#define CLICK_UNSTRIPTCPHEADER_HH
+#include <click/element.hh>
+CLICK_DECLS
+
+/*
+ * =c
+ * UnstripTCPHeader()
+ *
+ * =s tcp
+ *
+ * restores outermost TCP header
+ * =d
+ *
+ * Put outermost TCP header back onto a stripped packet, based on the TCP
+ * Header annotation from MarkTCPHeader or CheckTCPHeader. If TCP header
+ * already on,forwards packet unmodified.
+ *
+ * =a StripTCPHeader, CheckIPHeader, MarkIPHeader, StripIPHeader */
+
+class UnstripTCPHeader : public Element { public:
+
+  UnstripTCPHeader() CLICK_COLD;
+  ~UnstripTCPHeader() CLICK_COLD;
+
+  const char *class_name() const		{ return "UnstripTCPHeader"; }
+  const char *port_count() const		{ return PORTS_1_1; }
+
+  Packet *simple_action(Packet *);
+
+};
+
+CLICK_ENDDECLS
+#endif

test/tcpudp/StripTCPHeader-01.testie

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+%info
+
+TCPRewriter and FTPPortMapper sequence number translation, even for SACK.
+
+%script
+$VALGRIND click -e "
+FromIPSummaryDump(IN1, STOP true, CHECKSUM true)
+	-> CheckIPHeader(VERBOSE true)
+	-> CheckTCPHeader(VERBOSE true)
+    -> StripIPHeader
+    -> StripTCPHeader
+    -> Print(PAY)
+    -> StoreData(OFFSET 0, DATA "ABC")
+    -> UnstripIPHeader()
+    -> Print(FULLTCP)
+	-> ToIPSummaryDump(OUT1, FIELDS src sport dst dport proto tcp_seq tcp_ack payload tcp_opt)
+"
+
+%file IN1
+!data src sport dst dport proto tcp_seq tcp_ack payload tcp_opt
+200.200.200.200 30 2.0.0.2 21 T 0 0 "XYZ" .
+200.200.200.200 30 2.0.0.2 21 T 30 0 "XYZ" .
+2.0.0.2 21 1.0.0.1 1024 T 0 0 "XYZ" sack1-10;sack1-18;sack18-20
+
+%expect OUT1
+!IPSummaryDump 1.3
+!data ip_src sport ip_dst dport ip_proto tcp_seq tcp_ack payload tcp_opt
+200.200.200.200 30 2.0.0.2 21 T 0 0 "ABC" .
+200.200.200.200 30 2.0.0.2 21 T 30 0 "ABC" .
+2.0.0.2 21 1.0.0.1 1024 T 0 0 "ABC" sack1-10;sack1-18;sack18-20
+
+
+%expect stderr
+PAY:    3 | 58595a
+FULLTCP:   43 | 4500002b 00000000 6406c33a c8c8c8c8 02000002 001e0015
+PAY:    3 | 58595a
+FULLTCP:   43 | 4500002b 00000000 6406c33a c8c8c8c8 02000002 001e0015
+PAY:    3 | 58595a
+FULLTCP:   75 | 4500004b 00000000 640653ab 02000002 01000001 00150400