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159 lines
9.4 KiB
C++
159 lines
9.4 KiB
C++
/***************************************************************************
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* TransportLayerElement.cc -- Class TransportLayerElement is a generic *
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* class that represents a transport layer protocol header. Classes like *
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* TCPHeader or UDPHeader inherit from it. *
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* *
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***********************IMPORTANT NMAP LICENSE TERMS************************
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* *
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* The Nmap Security Scanner is (C) 1996-2012 Insecure.Com LLC. Nmap is *
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* also a registered trademark of Insecure.Com LLC. This program is free *
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* software; you may redistribute and/or modify it under the terms of the *
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* GNU General Public License as published by the Free Software *
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* Foundation; Version 2 with the clarifications and exceptions described *
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* below. This guarantees your right to use, modify, and redistribute *
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* this software under certain conditions. If you wish to embed Nmap *
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* technology into proprietary software, we sell alternative licenses *
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* (contact sales@insecure.com). Dozens of software vendors already *
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* license Nmap technology such as host discovery, port scanning, OS *
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* detection, version detection, and the Nmap Scripting Engine. *
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* *
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* Note that the GPL places important restrictions on "derived works", yet *
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* it does not provide a detailed definition of that term. To avoid *
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* misunderstandings, we interpret that term as broadly as copyright law *
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* allows. For example, we consider an application to constitute a *
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* "derivative work" for the purpose of this license if it does any of the *
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* following: *
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* o Integrates source code from Nmap *
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* o Reads or includes Nmap copyrighted data files, such as *
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* nmap-os-db or nmap-service-probes. *
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* o Executes Nmap and parses the results (as opposed to typical shell or *
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* execution-menu apps, which simply display raw Nmap output and so are *
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* not derivative works.) *
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* o Integrates/includes/aggregates Nmap into a proprietary executable *
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* installer, such as those produced by InstallShield. *
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* o Links to a library or executes a program that does any of the above *
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* *
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* The term "Nmap" should be taken to also include any portions or derived *
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* works of Nmap, as well as other software we distribute under this *
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* license such as Zenmap, Ncat, and Nping. This list is not exclusive, *
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* but is meant to clarify our interpretation of derived works with some *
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* common examples. Our interpretation applies only to Nmap--we don't *
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* speak for other people's GPL works. *
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* *
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* If you have any questions about the GPL licensing restrictions on using *
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* Nmap in non-GPL works, we would be happy to help. As mentioned above, *
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* we also offer alternative license to integrate Nmap into proprietary *
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* applications and appliances. These contracts have been sold to dozens *
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* of software vendors, and generally include a perpetual license as well *
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* as providing for priority support and updates. They also fund the *
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* continued development of Nmap. Please email sales@insecure.com for *
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* further information. *
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* *
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* As a special exception to the GPL terms, Insecure.Com LLC grants *
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* permission to link the code of this program with any version of the *
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* OpenSSL library which is distributed under a license identical to that *
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* listed in the included docs/licenses/OpenSSL.txt file, and distribute *
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* linked combinations including the two. You must obey the GNU GPL in all *
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* respects for all of the code used other than OpenSSL. If you modify *
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* this file, you may extend this exception to your version of the file, *
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* but you are not obligated to do so. *
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* *
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* If you received these files with a written license agreement or *
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* contract stating terms other than the terms above, then that *
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* alternative license agreement takes precedence over these comments. *
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* *
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* Source is provided to this software because we believe users have a *
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* right to know exactly what a program is going to do before they run it. *
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* This also allows you to audit the software for security holes (none *
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* have been found so far). *
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* *
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* Source code also allows you to port Nmap to new platforms, fix bugs, *
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* and add new features. You are highly encouraged to send your changes *
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* to the dev@nmap.org mailing list for possible incorporation into the *
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* main distribution. By sending these changes to Fyodor or one of the *
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* Insecure.Org development mailing lists, or checking them into the Nmap *
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* source code repository, it is understood (unless you specify otherwise) *
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* that you are offering the Nmap Project (Insecure.Com LLC) the *
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* unlimited, non-exclusive right to reuse, modify, and relicense the *
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* code. Nmap will always be available Open Source, but this is important *
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* because the inability to relicense code has caused devastating problems *
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* for other Free Software projects (such as KDE and NASM). We also *
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* occasionally relicense the code to third parties as discussed above. *
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* If you wish to specify special license conditions of your *
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* contributions, just say so when you send them. *
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* *
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* This program is distributed in the hope that it will be useful, but *
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* WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the Nmap *
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* license file for more details (it's in a COPYING file included with *
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* Nmap, and also available from https://svn.nmap.org/nmap/COPYING *
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* *
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***************************************************************************/
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/* This code was originally part of the Nping tool. */
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#include "TransportLayerElement.h"
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#include "IPv4Header.h"
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#include "IPv6Header.h"
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/** Computes and returns the Internet checksum.
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* @warning This method requires the object to be linked to either an IPv6Header
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* object or an IPv4Header one, so the caller must ensure that objects are
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* properly linked with calls to setNextElement() like this:
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*
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* IPv6Header ip6;
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* TCPHeader tcp;
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* [...] # Set header fields
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* ip6.setNextElement(&tcp);
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* tcp.setSum();
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*
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* Note that there can be a number of other headers (like IPv6 extension headers)
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* between the transport header and the network one, but all of them need to
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* be linked in order for this method to traverse the list of headers and find
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* the IP source and destination address, required to compute the checksum. So
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* things like the following are OK:
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*
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* IPv6Header ip6;
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* HopByHopHeader hop;
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* RoutingHeader rte;
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* FragmentHeader frg;
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* UDPHeader udp;
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* [...] # Set whatever header fields you need
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* ip6.setNextElement(&hop);
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* hop.setNextElement(&rte);
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* rte.setNextElement(&frg);
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* frg.setNextElement(&udp);
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* udp.setSum(); # setSum() will be able to reach the IPv6Header. */
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u16 TransportLayerElement::compute_checksum(){
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PacketElement *hdr;
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hdr=this->getPrevElement();
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u16 final_sum=0;
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/* Traverse the list of headers backwards until we find an IP header */
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while(hdr!=NULL){
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if (hdr->protocol_id()==HEADER_TYPE_IPv6){
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IPv6Header *v6hdr=(IPv6Header *)hdr;
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struct in6_addr i6src, i6dst;
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memcpy(i6src.s6_addr, v6hdr->getSourceAddress(), 16);
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memcpy(i6dst.s6_addr, v6hdr->getDestinationAddress(), 16);
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u8 *buff=(u8 *)safe_malloc(this->getLen());
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this->dumpToBinaryBuffer(buff, this->getLen());
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final_sum=ipv6_pseudoheader_cksum(&i6src, &i6dst, this->protocol_id(), this->getLen(), buff);
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free(buff);
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return final_sum;
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}else if(hdr->protocol_id()==HEADER_TYPE_IPv4){
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IPv4Header *v4hdr=(IPv4Header *)hdr;
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struct in_addr i4src, i4dst;
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memcpy(&(i4src.s_addr), v4hdr->getSourceAddress(), 4);
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memcpy(&(i4dst.s_addr), v4hdr->getDestinationAddress(), 4);
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u8 *buff=(u8 *)safe_malloc(this->getLen());
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this->dumpToBinaryBuffer(buff, this->getLen());
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final_sum=ipv4_pseudoheader_cksum(&i4src, &i4dst, this->protocol_id(), this->getLen(), buff);
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free(buff);
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return final_sum;
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}else{
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hdr=hdr->getPrevElement();
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}
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}
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return 0;
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} /* End of setSum() */
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