ipsumdump_tcp.cc

Click is a modular router toolkit. To use it you ll need to know how to compile and install the sof

// -*- mode: c++; c-basic-offset: 4 -*-
/*
 * ipsumdump_tcp.{cc,hh} -- IP transport summary dump unparsers
 * Eddie Kohler
 *
 * Copyright (c) 2002 International Computer Science Institute
 * Copyright (c) 2004 Regents of the University of California
 * Copyright (c) 2008 Meraki, Inc.
 *
 * 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 "ipsumdump_tcp.hh"
#include <click/packet.hh>
#include <click/nameinfo.hh>
#include <clicknet/ip.h>
#include <clicknet/tcp.h>
#include <clicknet/udp.h>
#include <clicknet/icmp.h>
#include <click/confparse.hh>
CLICK_DECLS

namespace IPSummaryDump {

enum { T_TCP_SEQ, T_TCP_ACK, T_TCP_FLAGS, T_TCP_WINDOW, T_TCP_URP, T_TCP_OPT,
       T_TCP_NTOPT, T_TCP_SACK, T_TCP_OFF };

static bool tcp_extract(PacketDesc& d, const FieldWriter *f)
{
    int transport_length = d.p->transport_length();
    switch (f->user_data) {

#define CHECK(l) do { if (!d.tcph || transport_length < (l)) return field_missing(d, IP_PROTO_TCP, (l)); } while (0)

      case T_TCP_SEQ:
	CHECK(8);
	d.v = ntohl(d.tcph->th_seq);
	return true;
      case T_TCP_ACK:
	CHECK(12);
	d.v = ntohl(d.tcph->th_ack);
	return true;
      case T_TCP_FLAGS:
	CHECK(14);
	d.v = d.tcph->th_flags | (d.tcph->th_flags2 << 8);
	return true;
      case T_TCP_OFF:
	CHECK(13);
	d.v = d.tcph->th_off << 2;
	return true;
      case T_TCP_WINDOW:
	CHECK(16);
	d.v = ntohs(d.tcph->th_win);
	return true;
      case T_TCP_URP:
	CHECK(20);
	d.v = ntohs(d.tcph->th_urp);
	return true;
      case T_TCP_OPT:
	// need to check that d.tcph->th_off exists
	if (!d.tcph || transport_length < 13 || (d.tcph->th_off > 5 && transport_length < (int)(d.tcph->th_off << 2)))
	    goto no_tcp_opt;
	if (d.tcph->th_off <= 5)
	    d.vptr[0] = d.vptr[1] = 0;
	else {
	    d.vptr[0] = (const uint8_t *) (d.tcph + 1);
	    d.vptr[1] = d.vptr[0] + (d.tcph->th_off << 2) - sizeof(click_tcp);
	}
	return true;
      case T_TCP_NTOPT:
      case T_TCP_SACK:
	// need to check that d.tcph->th_off exists
	if (!d.tcph || transport_length < 13)
	    goto no_tcp_opt;
	else if (d.tcph->th_off <= 5
		 || (d.tcph->th_off == 8 && transport_length >= 24
		     && *(reinterpret_cast<const uint32_t *>(d.tcph + 1)) == htonl(0x0101080A)))
	    d.vptr[0] = d.vptr[1] = 0;
	else if (transport_length < (int)(d.tcph->th_off << 2))
	    goto no_tcp_opt;
	else {
	    d.vptr[0] = (const uint8_t *) (d.tcph + 1);
	    d.vptr[1] = d.vptr[0] + (d.tcph->th_off << 2) - sizeof(click_tcp);
	}
	return true;

#undef CHECK

      default:
	return false;
      no_tcp_opt:
	return field_missing(d, IP_PROTO_TCP, transport_length + 1);
    }
}

static void tcp_inject(PacketOdesc& d, const FieldReader *f)
{
    if (!d.make_ip(IP_PROTO_TCP) || !d.make_transp())
	return;

    click_tcp *tcph = d.p->tcp_header();
    switch (f->user_data) {
    case T_TCP_SEQ:
	tcph->th_seq = htonl(d.v);
	break;
    case T_TCP_ACK:
	tcph->th_ack = htonl(d.v);
	break;
    case T_TCP_FLAGS:
	tcph->th_flags = d.v;
	tcph->th_flags2 = d.v >> 8;
	break;
    case T_TCP_OFF:
	d.v = (d.v + 3) & ~3;
	if ((int) d.v > (int) (tcph->th_off << 2)) {
	    int more = d.v - (tcph->th_off << 2);
	    if (!(d.p = d.p->put(more)))
		return;
	    tcph = d.p->tcp_header();
	    memset(d.p->transport_header() + d.v - more, TCPOPT_EOL, more);
	}
	tcph->th_off = d.v >> 2;
	break;
    case T_TCP_WINDOW:
	tcph->th_win = htons(d.v);
	break;
    case T_TCP_URP:
	tcph->th_urp = htons(d.v);
	break;
    case T_TCP_OPT:
    case T_TCP_NTOPT:
    case T_TCP_SACK: {
	if (!d.vptr[0] || d.vptr[0] == d.vptr[1])
	    return;
	int olen = d.vptr[1] - d.vptr[0];
	int th_off = (sizeof(click_tcp) + olen + 3) & ~3;
	if (d.p->transport_length() < th_off) {
	    if (!(d.p = d.p->put(th_off - d.p->transport_length())))
		return;
	    tcph = d.p->tcp_header();
	}
	if (th_off > (int) (tcph->th_off << 2))
	    tcph->th_off = th_off >> 2;
	memcpy(d.p->transport_header() + sizeof(click_tcp), d.vptr[0], olen);
	memset(d.p->transport_header() + sizeof(click_tcp) + olen,
	       TCPOPT_EOL, th_off - olen);
	break;
    }
    }
}

static void tcp_outa(const PacketDesc& d, const FieldWriter *f)
{
    switch (f->user_data) {
      case T_TCP_FLAGS:
	if (d.v == (TH_ACK | TH_PUSH))
	    *d.sa << 'P' << 'A';
	else if (d.v == TH_ACK)
	    *d.sa << 'A';
	else if (d.v == 0)
	    *d.sa << '.';
	else
	    for (int flag = 0; flag < 9; flag++)
		if (d.v & (1 << flag))
		    *d.sa << tcp_flags_word[flag];
	break;
      case T_TCP_OPT:
	if (!d.vptr)
	    *d.sa << '.';
	else
	    unparse_tcp_opt(*d.sa, d.vptr[0], d.vptr[1] - d.vptr[0], DO_TCPOPT_ALL_NOPAD);
	break;
      case T_TCP_NTOPT:
	if (!d.vptr)
	    *d.sa << '.';
	else
	    unparse_tcp_opt(*d.sa, d.vptr[0], d.vptr[1] - d.vptr[0], DO_TCPOPT_NTALL);
	break;
      case T_TCP_SACK:
	if (!d.vptr)
	    *d.sa << '.';
	else
	    unparse_tcp_opt(*d.sa, d.vptr[0], d.vptr[1] - d.vptr[0], DO_TCPOPT_SACK);
	break;
    }
}

static bool tcp_ina(PacketOdesc& d, const String &str, const FieldReader *f)
{
    switch (f->user_data) {
    case T_TCP_FLAGS:
	if (str.equals(".", 1))
	    d.v = 0;
	else if (!str)
	    return false;
	else if (isdigit((unsigned char) str[0]))
	    return cp_integer(str, &d.v) && d.v < 0x1000;
	else {
	    d.v = 0;
	    for (const char *s = str.begin(); s != str.end(); s++)
		if (uint8_t fm = IPSummaryDump::tcp_flag_mapping[(unsigned char) *s])
		    d.v |= 1 << (fm - 1);
		else
		    return false;
	}
	return true;
    default:
	return false;
    }
}

static void tcp_outb(const PacketDesc& d, bool ok, const FieldWriter *f)
{
    switch (f->user_data) {
      case T_TCP_OPT:
	if (!ok || !d.vptr)
	    *d.sa << '\0';
	else
	    unparse_tcp_opt_binary(*d.sa, d.vptr[0], d.vptr[1] - d.vptr[0], DO_TCPOPT_ALL);
	break;
      case T_TCP_NTOPT:
	if (!ok || !d.vptr)
	    *d.sa << '\0';
	else
	    unparse_tcp_opt_binary(*d.sa, d.vptr[0], d.vptr[1] - d.vptr[0], DO_TCPOPT_NTALL);
	break;
      case T_TCP_SACK:
	if (!ok || !d.vptr)
	    *d.sa << '\0';
	else
	    unparse_tcp_opt_binary(*d.sa, d.vptr[0], d.vptr[1] - d.vptr[0], DO_TCPOPT_SACK);
	break;
    }
}

static const uint8_t* tcp_inb(PacketOdesc& d, const uint8_t* s, const uint8_t* ends, const FieldReader *f)
{
    switch (f->user_data) {
      case T_TCP_OPT:
      case T_TCP_NTOPT:
      case T_TCP_SACK:
	if (s + s[0] + 1 <= ends) {
	    d.vptr[0] = s + 1;
	    d.vptr[1] = d.vptr[0] + s[0];
	    return s + s[0] + 1;
	}
	break;
    }
    return ends;
}


static int tcp_opt_mask_mapping[] = {
    DO_TCPOPT_PADDING, DO_TCPOPT_PADDING,	// EOL, NOP
    DO_TCPOPT_MSS, DO_TCPOPT_WSCALE,		// MAXSEG, WSCALE
    DO_TCPOPT_SACK, DO_TCPOPT_SACK,		// SACK_PERMITTED, SACK
    DO_TCPOPT_UNKNOWN, DO_TCPOPT_UNKNOWN,	// 6, 7
    DO_TCPOPT_TIMESTAMP				// TIMESTAMP
};

void unparse_tcp_opt(StringAccum& sa, const uint8_t* opt, int opt_len, int mask)
{
    int initial_sa_len = sa.length();
    const uint8_t *end_opt = opt + opt_len;
    const char *sep = "";

    while (opt < end_opt)
	switch (*opt) {
	  case TCPOPT_EOL:
	    if (mask & DO_TCPOPT_PADDING)
		sa << sep << "eol";
	    goto done;
	  case TCPOPT_NOP:
	    if (mask & DO_TCPOPT_PADDING) {
		sa << sep << "nop";
		sep = ";";
	    }
	    opt++;
	    break;
	  case TCPOPT_MAXSEG:
	    if (opt + opt[1] > end_opt || opt[1] != TCPOLEN_MAXSEG)
		goto bad_opt;
	    if (!(mask & DO_TCPOPT_MSS))
		goto unknown;
	    sa << sep << "mss" << ((opt[2] << 8) | opt[3]);
	    opt += TCPOLEN_MAXSEG;
	    sep = ";";
	    break;
	  case TCPOPT_WSCALE:
	    if (opt + opt[1] > end_opt || opt[1] != TCPOLEN_WSCALE)
		goto bad_opt;
	    if (!(mask & DO_TCPOPT_WSCALE))
		goto unknown;
	    sa << sep << "wscale" << (int)(opt[2]);
	    opt += TCPOLEN_WSCALE;
	    sep = ";";
	    break;
	  case TCPOPT_SACK_PERMITTED:
	    if (opt + opt[1] > end_opt || opt[1] != TCPOLEN_SACK_PERMITTED)
		goto bad_opt;
	    if (!(mask & DO_TCPOPT_SACK))
		goto unknown;
	    sa << sep << "sackok";
	    opt += TCPOLEN_SACK_PERMITTED;
	    sep = ";";