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PacketParser.cc
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PacketParser.cc
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/***************************************************************************
* PacketParser.cc -- The PacketParser Class offers methods to parse *
* received network packets. Its main purpose is to facilitate the *
* conversion of raw sequences of bytes into chains of objects of the *
* PacketElement family. *
* *
***********************IMPORTANT NMAP LICENSE TERMS************************
*
* The Nmap Security Scanner is (C) 1996-2024 Nmap Software LLC ("The Nmap
* Project"). Nmap is also a registered trademark of the Nmap Project.
*
* This program is distributed under the terms of the Nmap Public Source
* License (NPSL). The exact license text applying to a particular Nmap
* release or source code control revision is contained in the LICENSE
* file distributed with that version of Nmap or source code control
* revision. More Nmap copyright/legal information is available from
* https://nmap.org/book/man-legal.html, and further information on the
* NPSL license itself can be found at https://nmap.org/npsl/ . This
* header summarizes some key points from the Nmap license, but is no
* substitute for the actual license text.
*
* Nmap is generally free for end users to download and use themselves,
* including commercial use. It is available from https://nmap.org.
*
* The Nmap license generally prohibits companies from using and
* redistributing Nmap in commercial products, but we sell a special Nmap
* OEM Edition with a more permissive license and special features for
* this purpose. See https://nmap.org/oem/
*
* If you have received a written Nmap license agreement or contract
* stating terms other than these (such as an Nmap OEM license), you may
* choose to use and redistribute Nmap under those terms instead.
*
* The official Nmap Windows builds include the Npcap software
* (https://npcap.com) for packet capture and transmission. It is under
* separate license terms which forbid redistribution without special
* permission. So the official Nmap Windows builds may not be redistributed
* without special permission (such as an Nmap OEM license).
*
* Source is provided to this software because we believe users have a
* right to know exactly what a program is going to do before they run it.
* This also allows you to audit the software for security holes.
*
* Source code also allows you to port Nmap to new platforms, fix bugs, and
* add new features. You are highly encouraged to submit your changes as a
* Github PR or by email to the [email protected] mailing list for possible
* incorporation into the main distribution. Unless you specify otherwise, it
* is understood that you are offering us very broad rights to use your
* submissions as described in the Nmap Public Source License Contributor
* Agreement. This is important because we fund the project by selling licenses
* with various terms, and also because the inability to relicense code has
* caused devastating problems for other Free Software projects (such as KDE
* and NASM).
*
* The free version of Nmap is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Warranties,
* indemnification and commercial support are all available through the
* Npcap OEM program--see https://nmap.org/oem/
*
***************************************************************************/
/* This code was originally part of the Nping tool. */
#include "PacketParser.h"
#include <assert.h>
#define PKTPARSERDEBUG false
PacketParser::PacketParser() {
this->reset();
} /* End of PacketParser constructor */
PacketParser::~PacketParser() {
} /* End of PacketParser destructor */
/** Sets every attribute to its default value- */
void PacketParser::reset() {
} /* End of PacketParser destructor */
const char *PacketParser::header_type2string(int val){
header_type_string_t header_types[]={
{HEADER_TYPE_IPv6_HOPOPT, "IPv6 Hop-by-Hop"},
{HEADER_TYPE_ICMPv4,"ICMPv4"},
{HEADER_TYPE_IGMP,"IGMP"},
{HEADER_TYPE_IPv4,"IPv4"},
{HEADER_TYPE_TCP,"TCP"},
{HEADER_TYPE_EGP,"EGP"},
{HEADER_TYPE_UDP,"UDP"},
{HEADER_TYPE_IPv6,"IPv6"},
{HEADER_TYPE_IPv6_ROUTE,"IPv6-Route"},
{HEADER_TYPE_IPv6_FRAG,"IPv6-Frag"},
{HEADER_TYPE_GRE,"GRE"},
{HEADER_TYPE_ESP,"ESP"},
{HEADER_TYPE_AH,"AH"},
{HEADER_TYPE_ICMPv6,"ICMPv6"},
{HEADER_TYPE_IPv6_NONXT,"IPv6-NoNxt"},
{HEADER_TYPE_IPv6_OPTS,"IPv6-Opts"},
{HEADER_TYPE_EIGRP,"EIGRP"},
{HEADER_TYPE_ETHERNET,"Ethernet"},
{HEADER_TYPE_L2TP,"L2TP"},
{HEADER_TYPE_SCTP,"SCTP"},
{HEADER_TYPE_IPv6_MOBILE,"Mobility Header"},
{HEADER_TYPE_MPLS_IN_IP,"MPLS-in-IP"},
{HEADER_TYPE_ARP,"ARP"},
{HEADER_TYPE_RAW_DATA,"Raw Data"},
{0,NULL}
};
int i=0;
for(i=0; header_types[i].str!=NULL; i++ ){
if((int)header_types[i].type==val)
return header_types[i].str;
}
return NULL;
} /* End of header_type2string() */
#define MAX_HEADERS_IN_PACKET 32
pkt_type_t *PacketParser::parse_packet(const u8 *pkt, size_t pktlen, bool eth_included){
if(PKTPARSERDEBUG)printf("%s(%p, %lu)\n", __func__, pkt, (long unsigned)pktlen);
static pkt_type_t this_packet[MAX_HEADERS_IN_PACKET+1]; /* Packet structure array */
u8 current_header=0; /* Current array position of "this_packet" */
const u8 *curr_pkt=pkt; /* Pointer to current part of the packet */
size_t curr_pktlen=pktlen; /* Remaining packet length */
int ethlen=0, arplen=0; /* Aux length variables: link layer */
int iplen=0,ip6len=0; /* Aux length variables: network layer */
int tcplen=0,udplen=0,icmplen=0; /* Aux length variables: transport layer */
int exthdrlen=0; /* Aux length variables: extension headers */
int next_layer=0; /* Next header type to process */
int expected=0; /* Next protocol expected */
bool finished=false; /* Loop breaking flag */
bool unknown_hdr=false; /* Indicates unknown header found */
IPv4Header ip4;
IPv6Header ip6;
TCPHeader tcp;
UDPHeader udp;
ICMPv4Header icmp4;
ICMPv6Header icmp6;
EthernetHeader eth;
DestOptsHeader ext_dopts;
FragmentHeader ext_frag;
HopByHopHeader ext_hopt;
RoutingHeader ext_routing;
ARPHeader arp;
memset(this_packet, 0, sizeof(this_packet));
/* Decide which layer we have to start from */
if( eth_included ){
next_layer=LINK_LAYER;
expected=HEADER_TYPE_ETHERNET;
}else{
next_layer=NETWORK_LAYER;
}
/* Header processing loop */
while(!finished && curr_pktlen>0 && current_header<MAX_HEADERS_IN_PACKET){
/* Ethernet and ARP headers ***********************************************/
if(next_layer==LINK_LAYER ){
if(PKTPARSERDEBUG)puts("Next Layer=Link");
if(expected==HEADER_TYPE_ETHERNET){
if(PKTPARSERDEBUG)puts("Expected Layer=Ethernet");
if(eth.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE){
unknown_hdr=true;
break;
}
if( (ethlen=eth.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
/* Determine next header type */
switch( eth.getEtherType() ){
case ETHTYPE_IPV4:
expected=HEADER_TYPE_IPv4;
next_layer=NETWORK_LAYER;
break;
case ETHTYPE_IPV6:
expected=HEADER_TYPE_IPv6;
next_layer=NETWORK_LAYER;
break;
case ETHTYPE_ARP:
next_layer=LINK_LAYER;
expected=HEADER_TYPE_ARP;
break;
default:
next_layer=APPLICATION_LAYER;
expected=HEADER_TYPE_RAW_DATA;
break;
}
this_packet[current_header].length=ethlen;
this_packet[current_header++].type=HEADER_TYPE_ETHERNET;
eth.reset();
curr_pkt+=ethlen;
curr_pktlen-=ethlen;
}else if(expected==HEADER_TYPE_ARP){
if(PKTPARSERDEBUG)puts("Expected Layer=ARP");
if(arp.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE){
unknown_hdr=true;
break;
}
if( (arplen=arp.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
this_packet[current_header].length=arplen;
this_packet[current_header++].type=HEADER_TYPE_ARP;
arp.reset();
curr_pkt+=arplen;
curr_pktlen-=arplen;
if(curr_pktlen>0){
next_layer=APPLICATION_LAYER;
expected=HEADER_TYPE_RAW_DATA;
}else{
finished=true;
}
}else{
assert(finished==true);
}
/* IPv4 and IPv6 headers **************************************************/
}else if(next_layer==NETWORK_LAYER){
if(PKTPARSERDEBUG)puts("Next Layer=Network");
/* Determine IP version */
if (ip4.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE){
unknown_hdr=true;
break;
}
/* IP version 4 ---------------------------------*/
if(ip4.getVersion()==4){
if( (iplen=ip4.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
/* Determine next header type */
switch(ip4.getNextProto()){
case HEADER_TYPE_ICMPv4:
next_layer=TRANSPORT_LAYER;
expected=HEADER_TYPE_ICMPv4;
break;
case HEADER_TYPE_IPv4: /* IP in IP */
next_layer=NETWORK_LAYER;
expected=HEADER_TYPE_IPv4;
break;
case HEADER_TYPE_TCP:
next_layer=TRANSPORT_LAYER;
expected=HEADER_TYPE_TCP;
break;
case HEADER_TYPE_UDP:
next_layer=TRANSPORT_LAYER;
expected=HEADER_TYPE_UDP;
break;
case HEADER_TYPE_IPv6: /* IPv6 in IPv4 */
next_layer=NETWORK_LAYER;
expected=HEADER_TYPE_IPv6;
break;
default:
next_layer=APPLICATION_LAYER;
expected=HEADER_TYPE_RAW_DATA;
break;
}
this_packet[current_header].length=iplen;
this_packet[current_header++].type=HEADER_TYPE_IPv4;
ip4.reset();
curr_pkt+=iplen;
curr_pktlen-=iplen;
/* IP version 6 ---------------------------------*/
}else if(ip4.getVersion()==6){
ip4.reset();
if (ip6.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE){
unknown_hdr=true;
break;
}
if( (ip6len=ip6.validate())==OP_FAILURE ){
unknown_hdr=true;
break;
}
switch( ip6.getNextHeader() ){
case HEADER_TYPE_ICMPv6:
next_layer=TRANSPORT_LAYER;
expected=HEADER_TYPE_ICMPv6;
break;
case HEADER_TYPE_IPv4: /* IPv4 in IPv6 */
next_layer=NETWORK_LAYER;
expected=HEADER_TYPE_IPv4;
break;
case HEADER_TYPE_TCP:
next_layer=TRANSPORT_LAYER;
expected=HEADER_TYPE_TCP;
break;
case HEADER_TYPE_UDP:
next_layer=TRANSPORT_LAYER;
expected=HEADER_TYPE_UDP;
break;
case HEADER_TYPE_IPv6: /* IPv6 in IPv6 */
next_layer=NETWORK_LAYER;
expected=HEADER_TYPE_IPv6;
break;
case HEADER_TYPE_IPv6_HOPOPT:
next_layer=EXTHEADERS_LAYER;
expected=HEADER_TYPE_IPv6_HOPOPT;
break;
case HEADER_TYPE_IPv6_OPTS:
next_layer=EXTHEADERS_LAYER;
expected=HEADER_TYPE_IPv6_OPTS;
break;
case HEADER_TYPE_IPv6_ROUTE:
next_layer=EXTHEADERS_LAYER;
expected=HEADER_TYPE_IPv6_ROUTE;
break;
case HEADER_TYPE_IPv6_FRAG:
next_layer=EXTHEADERS_LAYER;
expected=HEADER_TYPE_IPv6_FRAG;
break;
default:
next_layer=APPLICATION_LAYER;
expected=HEADER_TYPE_RAW_DATA;
break;
}
this_packet[current_header].length=ip6len;
this_packet[current_header++].type=HEADER_TYPE_IPv6;
ip6.reset();
curr_pkt+=ip6len;
curr_pktlen-=ip6len;
/* Bogus IP version -----------------------------*/
}else{
/* Wrong IP version, treat as raw data. */
next_layer=APPLICATION_LAYER;
expected=HEADER_TYPE_RAW_DATA;
}
/* TCP, UDP, ICMPv4 and ICMPv6 headers ************************************/
}else if(next_layer==TRANSPORT_LAYER){
if(PKTPARSERDEBUG)puts("Next Layer=Transport");
if(expected==HEADER_TYPE_TCP){
if(PKTPARSERDEBUG)puts("Expected Layer=TCP");
if(tcp.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE ){
unknown_hdr=true;
break;
}
if( (tcplen=tcp.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
expected=HEADER_TYPE_RAW_DATA;
this_packet[current_header].length=tcplen;
this_packet[current_header++].type=HEADER_TYPE_TCP;
tcp.reset();
curr_pkt+=tcplen;
curr_pktlen-=tcplen;
next_layer=APPLICATION_LAYER;
}else if(expected==HEADER_TYPE_UDP){
if(PKTPARSERDEBUG)puts("Expected Layer=UDP");
if(udp.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE ){
unknown_hdr=true;
break;
}
if( (udplen=udp.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
expected=HEADER_TYPE_RAW_DATA;
this_packet[current_header].length=udplen;
this_packet[current_header++].type=HEADER_TYPE_UDP;
udp.reset();
curr_pkt+=udplen;
curr_pktlen-=udplen;
next_layer=APPLICATION_LAYER;
}else if(expected==HEADER_TYPE_ICMPv4){
if(PKTPARSERDEBUG)puts("Expected Layer=ICMPv4");
if(icmp4.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE ){
unknown_hdr=true;
break;
}
if( (icmplen=icmp4.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
switch( icmp4.getType() ){
/* Types that include an IPv4 packet as payload */
case ICMP_UNREACH:
case ICMP_TIMXCEED:
case ICMP_PARAMPROB:
case ICMP_SOURCEQUENCH:
case ICMP_REDIRECT:
next_layer=NETWORK_LAYER;
expected=HEADER_TYPE_IPv4;
break;
/* ICMP types that include misc payloads (or no payload) */
default:
expected=HEADER_TYPE_RAW_DATA;
next_layer=APPLICATION_LAYER;
break;
}
this_packet[current_header].length=icmplen;
this_packet[current_header++].type=HEADER_TYPE_ICMPv4;
icmp4.reset();
curr_pkt+=icmplen;
curr_pktlen-=icmplen;
}else if(expected==HEADER_TYPE_ICMPv6){
if(PKTPARSERDEBUG)puts("Expected Layer=ICMPv6");
if(icmp6.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE){
unknown_hdr=true;
break;
}
if( (icmplen=icmp6.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
switch( icmp6.getType() ){
/* Types that include an IPv6 packet as payload */
case ICMPv6_UNREACH:
case ICMPv6_PKTTOOBIG:
case ICMPv6_TIMXCEED:
case ICMPv6_PARAMPROB:
next_layer=NETWORK_LAYER;
expected=HEADER_TYPE_IPv6;
break;
/* ICMPv6 types that include misc payloads (or no payload) */
default:
expected=HEADER_TYPE_RAW_DATA;
next_layer=APPLICATION_LAYER;
break;
}
this_packet[current_header].length=icmplen;
this_packet[current_header++].type=HEADER_TYPE_ICMPv6;
icmp6.reset();
curr_pkt+=icmplen;
curr_pktlen-=icmplen;
}else{
/* Wrong application layer protocol, treat as raw data. */
next_layer=APPLICATION_LAYER;
expected=HEADER_TYPE_RAW_DATA;
}
/* IPv6 Extension Headers */
}else if(next_layer==EXTHEADERS_LAYER){
if(PKTPARSERDEBUG)puts("Next Layer=ExtHdr");
u8 ext_next=0;
/* Hop-by-Hop Options */
if(expected==HEADER_TYPE_IPv6_HOPOPT){
if(PKTPARSERDEBUG)puts("Expected=Hopt");
if(ext_hopt.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE ){
unknown_hdr=true;
break;
}
if( (exthdrlen=ext_hopt.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
ext_next=ext_hopt.getNextHeader();
ext_hopt.reset();
/* Routing Header */
}else if(expected==HEADER_TYPE_IPv6_ROUTE){
if(PKTPARSERDEBUG)puts("Expected=Route");
if(ext_routing.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE ){
unknown_hdr=true;
break;
}
if( (exthdrlen=ext_routing.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
ext_next=ext_routing.getNextHeader();
ext_routing.reset();
/* Fragmentation Header */
}else if(expected==HEADER_TYPE_IPv6_FRAG){
if(PKTPARSERDEBUG)puts("Expected=Frag");
if(ext_frag.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE ){
unknown_hdr=true;
break;
}
if( (exthdrlen=ext_frag.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
ext_next=ext_frag.getNextHeader();
ext_frag.reset();
/* Destination Options Header */
}else if(expected==HEADER_TYPE_IPv6_OPTS){
if(PKTPARSERDEBUG)puts("Expected=Dopts");
if(ext_dopts.storeRecvData(curr_pkt, curr_pktlen)==OP_FAILURE ){
unknown_hdr=true;
break;
}
if( (exthdrlen=ext_dopts.validate())==OP_FAILURE){
unknown_hdr=true;
break;
}
ext_next=ext_dopts.getNextHeader();
ext_dopts.reset();
}else{
/* Should never happen. */
unknown_hdr=true;
break;
}
/* Update the info for this header */
this_packet[current_header].length=exthdrlen;
this_packet[current_header++].type=expected;
curr_pkt+=exthdrlen;
curr_pktlen-=exthdrlen;
/* Lets's see what comes next */
switch(ext_next){
case HEADER_TYPE_ICMPv6:
next_layer=TRANSPORT_LAYER;
expected=HEADER_TYPE_ICMPv6;
break;
case HEADER_TYPE_IPv4: /* IPv4 in IPv6 */
next_layer=NETWORK_LAYER;
expected=HEADER_TYPE_IPv4;
break;
case HEADER_TYPE_TCP:
next_layer=TRANSPORT_LAYER;
expected=HEADER_TYPE_TCP;
break;
case HEADER_TYPE_UDP:
next_layer=TRANSPORT_LAYER;
expected=HEADER_TYPE_UDP;
break;
case HEADER_TYPE_IPv6: /* IPv6 in IPv6 */
next_layer=NETWORK_LAYER;
expected=HEADER_TYPE_IPv6;
break;
case HEADER_TYPE_IPv6_HOPOPT:
next_layer=EXTHEADERS_LAYER;
expected=HEADER_TYPE_IPv6_HOPOPT;
break;
case HEADER_TYPE_IPv6_OPTS:
next_layer=EXTHEADERS_LAYER;
expected=HEADER_TYPE_IPv6_OPTS;
break;
case HEADER_TYPE_IPv6_ROUTE:
next_layer=EXTHEADERS_LAYER;
expected=HEADER_TYPE_IPv6_ROUTE;
break;
case HEADER_TYPE_IPv6_FRAG:
next_layer=EXTHEADERS_LAYER;
expected=HEADER_TYPE_IPv6_FRAG;
break;
default:
next_layer=APPLICATION_LAYER;
expected=HEADER_TYPE_RAW_DATA;
break;
}
/* Miscellaneous payloads *************************************************/
}else{ // next_layer==APPLICATION_LAYER
if(PKTPARSERDEBUG)puts("Next Layer=Application");
/* If we get here it is possible that the packet is ARP but
* we have no access to the original Ethernet header. We
* determine if this header is ARP by checking its size
* and checking for some common values. */
if(arp.storeRecvData(curr_pkt, curr_pktlen)!=OP_FAILURE){
if( (arplen=arp.validate())!=OP_FAILURE){
if(arp.getHardwareType()==HDR_ETH10MB){
if(arp.getProtocolType()==0x0800){
if(arp.getHwAddrLen()==ETH_ADDRESS_LEN){
if(arp.getProtoAddrLen()==IPv4_ADDRESS_LEN){
this_packet[current_header].length=arplen;
this_packet[current_header++].type=HEADER_TYPE_ARP;
arp.reset();
curr_pkt+=arplen;
curr_pktlen-=arplen;
if(curr_pktlen>0){
next_layer=APPLICATION_LAYER;
expected=HEADER_TYPE_RAW_DATA;
}else{
finished=true;
}
}
}
}
}
}
}
//if(expected==HEADER_TYPE_DNS){
//}else if(expected==HEADER_TYPE_HTTP){
//}... ETC
this_packet[current_header].length=curr_pktlen;
this_packet[current_header++].type=HEADER_TYPE_RAW_DATA;
curr_pktlen=0;
finished=true;
}
} /* End of header processing loop */
/* If we couldn't validate some header, treat that header and any remaining
* data, as raw application data. */
if (unknown_hdr==true){
if(curr_pktlen>0){
if(PKTPARSERDEBUG)puts("Unknown layer found. Treating it as raw data.");
this_packet[current_header].length=curr_pktlen;
this_packet[current_header++].type=HEADER_TYPE_RAW_DATA;
}
}
return this_packet;
} /* End of parse_received_packet() */
/* TODO: remove */
int PacketParser::dummy_print_packet_type(const u8 *pkt, size_t pktlen, bool eth_included){
pkt_type_t *packetheaders=PacketParser::parse_packet(pkt, pktlen, eth_included);
for(int i=0; packetheaders[i].length!=0; i++){
printf("%s:", header_type2string(packetheaders[i].type));
}
printf("\n");
return OP_SUCCESS;
} /* End of dummy_print_packet_type() */
int PacketParser::dummy_print_packet(const u8 *pkt, size_t pktlen, bool eth_included){
PacketElement *me=NULL, *aux=NULL;
if( (me=split(pkt, pktlen, eth_included))==NULL )
return OP_FAILURE;
else{
me->print(stdout, PRINT_DETAIL_HIGH);
printf("\n");
}
/* Free the structs */
while(me!=NULL){
aux=me->getNextElement();
delete me;
me=aux;
}
return OP_SUCCESS;
} /* End of dummy_print_packet() */
/** For a given packet, this method determines where the application layer data
* begins. It returs a positive offset if any application data was found, zero
* if the packet did not contain application data and a negative integer in
* case of error. */
int PacketParser::payload_offset(const u8 *pkt, size_t pktlen, bool link_included){
PacketElement *me=NULL, *aux=NULL;
size_t offset=pktlen; /* Initially, point to the end of the packet. */
/* Safe checks*/
if(pkt==NULL || pktlen<=0)
return -1;
dummy_print_packet_type(pkt, pktlen, link_included);
/* Split the packet into separate protocol headers */
if( (me=split(pkt, pktlen, link_included))==NULL )
return -2;
else{
aux=me;
}
/* Find if there is application data and where it begins */
while(me!=NULL){
/* When we find application data, we compute the offset by substacting the
length of the application data from the packet's total length */
if(me->protocol_id()==HEADER_TYPE_RAW_DATA){
offset = pktlen - me->getLen();
break;
}
me = me->getNextElement();
}
/* Free the structs */
me=aux;
while(me!=NULL){
aux=me->getNextElement();
delete me;
me=aux;
}
/* Return 0 if we didn't find any application data */
if(offset==pktlen){
return 0;
}else{
return offset;
}
} /* End of payload_offset() */
PacketElement *PacketParser::split(const u8 *pkt, size_t pktlen){
return split(pkt, pktlen, false);
} /* End of split() */
PacketElement *PacketParser::split(const u8 *pkt, size_t pktlen, bool eth_included){
pkt_type_t *packetheaders=NULL;
const u8 *curr_pkt=pkt;
PacketElement *first=NULL;
PacketElement *last=NULL;
IPv4Header *ip4=NULL;
IPv6Header *ip6=NULL;
DestOptsHeader *ext_dopts=NULL;
FragmentHeader *ext_frag=NULL;
HopByHopHeader *ext_hopt=NULL;
RoutingHeader *ext_routing=NULL;
TCPHeader *tcp=NULL;
UDPHeader *udp=NULL;
ICMPv4Header *icmp4=NULL;
ICMPv6Header *icmp6=NULL;
EthernetHeader *eth=NULL;
ARPHeader *arp=NULL;
RawData *raw=NULL;
/* Analyze the packet. This returns a list of header types and lengths */
if((packetheaders=PacketParser::parse_packet(pkt, pktlen, eth_included))==NULL)
return NULL;
/* Store each header in its own PacketHeader object type */
for(int i=0; packetheaders[i].length!=0; i++){
switch(packetheaders[i].type){
case HEADER_TYPE_ETHERNET:
eth=new EthernetHeader();
eth->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=eth;
}else{
last->setNextElement(eth);
}
last=eth;
break;
case HEADER_TYPE_ARP:
arp=new ARPHeader();
arp->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=arp;
}else{
last->setNextElement(arp);
}
last=arp;
break;
case HEADER_TYPE_IPv4:
ip4=new IPv4Header();
ip4->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=ip4;
}else{
last->setNextElement(ip4);
}
last=ip4;
break;
case HEADER_TYPE_IPv6:
ip6=new IPv6Header();
ip6->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=ip6;
}else{
last->setNextElement(ip6);
}
last=ip6;
break;
case HEADER_TYPE_TCP:
tcp=new TCPHeader();
tcp->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=tcp;
}else{
last->setNextElement(tcp);
}
last=tcp;
break;
case HEADER_TYPE_UDP:
udp=new UDPHeader();
udp->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=udp;
}else{
last->setNextElement(udp);
}
last=udp;
break;
case HEADER_TYPE_ICMPv4:
icmp4=new ICMPv4Header();
icmp4->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=icmp4;
}else{
last->setNextElement(icmp4);
}
last=icmp4;
break;
case HEADER_TYPE_ICMPv6:
icmp6=new ICMPv6Header();
icmp6->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=icmp6;
}else{
last->setNextElement(icmp6);
}
last=icmp6;
break;
case HEADER_TYPE_IPv6_HOPOPT:
ext_hopt=new HopByHopHeader();
ext_hopt->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=ext_hopt;
}else{
last->setNextElement(ext_hopt);
}
last=ext_hopt;
break;
case HEADER_TYPE_IPv6_ROUTE:
ext_routing=new RoutingHeader();
ext_routing->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=ext_routing;
}else{
last->setNextElement(ext_routing);
}
last=ext_routing;
break;
case HEADER_TYPE_IPv6_FRAG:
ext_frag=new FragmentHeader();
ext_frag->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=ext_frag;
}else{
last->setNextElement(ext_frag);
}
last=ext_frag;
break;
case HEADER_TYPE_IPv6_OPTS:
ext_dopts=new DestOptsHeader();
ext_dopts->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=ext_dopts;
}else{
last->setNextElement(ext_dopts);
}
last=ext_dopts;
break;
case HEADER_TYPE_RAW_DATA:
default:
raw=new RawData();
raw->storeRecvData(curr_pkt, packetheaders[i].length);
if(first==NULL){
first=raw;
}else{
last->setNextElement(raw);
}
last=raw;
break;
}
curr_pkt+=packetheaders[i].length;
}
return first;
} /* End of split() */
/* This method frees a chain of PacketElement objects. Note that objects in
* the chain are freed by calling "delete" on them, so only those instances
* that have been obtained through a call to "new" should be passed to this
* method. Chains returned by PacketParser::split() are safe to use with this.*/
int PacketParser::freePacketChain(PacketElement *first){
PacketElement *curr=first;
PacketElement *next=NULL;
while(curr!=NULL){
next=curr->getNextElement();
delete curr;
curr=next;
}
return OP_SUCCESS;
} /* End of freePacketChain() */
/* This method is for debugging purposes only. It tests the packet parser and
* the PacketElement class family. Basically it checks that the supplied
* chain of PacketElements can be serialized and de-serialized correctly.
* Returns NULL on success or an error string in case of failure. */
const char *PacketParser::test_packet_parser(PacketElement *test_pkt){
const char *errmsg=NULL;
PacketElement *parsed_pkt=NULL;
PacketElement *orig_pkt=NULL;
PacketElement *new_pkt=NULL;
u8 *mypktbuff2=NULL;
u8 *mypktbuff=NULL;
if(test_pkt==NULL){
errmsg="NULL pointer supplied";
goto end;
}
/* Generate a serialized version of the packet */
mypktbuff=(u8 *)safe_malloc(test_pkt->getLen());
test_pkt->dumpToBinaryBuffer(mypktbuff, test_pkt->getLen());
/* Generate a chain of PacketElement objects from the serialized version. */
parsed_pkt=PacketParser::split(mypktbuff, test_pkt->getLen());
if(parsed_pkt==NULL){
errmsg="PacketParser::split() returned NULL";
goto end;
}
if(parsed_pkt->getLen()!=test_pkt->getLen()){
errmsg="Packets have different lengths";
goto end;
}
/* Generate a serialized version of the new chain */
mypktbuff2=(u8 *)safe_malloc(parsed_pkt->getLen());
parsed_pkt->dumpToBinaryBuffer(mypktbuff2, parsed_pkt->getLen());
/* Make sure both packets produce the exact same binary buffer */
if(memcmp(mypktbuff, mypktbuff2, parsed_pkt->getLen())!=0){
errmsg="The two packets do not result in the same binary buffer";
goto end;
}
/* Now let's check that both chains have the same number and type of
* PacketElements. */
orig_pkt=test_pkt;
new_pkt=parsed_pkt;
while(orig_pkt!=NULL && new_pkt!=NULL){
if(orig_pkt->protocol_id() != new_pkt->protocol_id() ){
errmsg="Protocol IDs do not match";
goto end;
}
orig_pkt=orig_pkt->getNextElement();
new_pkt=new_pkt->getNextElement();
}
if(orig_pkt!=NULL || new_pkt!=NULL){
errmsg="The two packets do not have the same number of chained elements.";
goto end;
}
end:
/* Free our allocations */
if(mypktbuff!=NULL)
free(mypktbuff);
if(mypktbuff2!=NULL)
free(mypktbuff2);
if(parsed_pkt!=NULL)
PacketParser::freePacketChain(parsed_pkt);
/* If everything went well, errmsg should still be NULL. Otherwise it
* should point to an error message.*/
return errmsg;
}
/* Returns true if the supplied "rcvd" packet is a response to the "sent" packet.
* This method currently handles IPv4, IPv6, ICMPv4, ICMPv6, TCP and UDP. Here
* some examples of what can be matched using it:
*
* Probe: TCP SYN -> Response TCP SYN|ACK
* Probe: TCP SYN -> Response TCP RST|ACK
* Probe: UDP:53 -> Response UDP from port 53.
* Probe ICMP Echo -> Response ICMP Echo reply
* Probe ICMPv6 Neighbor Solicitation -> Response ICMPv6 Neighbor Advert
* Probe Malformed IPv6 -> Response ICMPv6 Parameter Problem
* Probe MLDv1 Query -> Response MLDv1 Report
* Probe ICMP Timestamp request -> Response ICMP timestamp response
* etc...
*
* Note that ICMP error messages are matched against sent probes (e.g: an ICMP
* Parameter Problem generated as a result of an invalid TCP segment is matched
* positively with the original TCP segment). Therefore, the caller must ensure
* that the received packet is what it expects before using it (e.g: the packet
* is an actual TCP packet, not an ICMP error).
*
* Warning: this method assumes that the probes you send are reasonably
* different from each other. Don't expect a 100% accuracy if you send a bunch
* of TCP segments with the same source and destination port numbers, or a
* bunch of ICMP messages with the same identifier and sequence number. */
bool PacketParser::is_response(PacketElement *sent, PacketElement *rcvd){
if(PKTPARSERDEBUG)printf("%s(): called\n", __func__);
if(sent==NULL || rcvd==NULL)
return false;
/* If any of the packets is encapsulated in an Ethernet frame, strip the
* link layer header before proceeding with the matching process. */
if(rcvd->protocol_id()==HEADER_TYPE_ETHERNET)
if( (rcvd=rcvd->getNextElement())==NULL)
return false;
if(sent->protocol_id()==HEADER_TYPE_ETHERNET)
if( (sent=sent->getNextElement())==NULL)
return false;