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Diffstat (limited to 'libnetutil/TransportLayerElement.cc')
| -rw-r--r-- | libnetutil/TransportLayerElement.cc | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/libnetutil/TransportLayerElement.cc b/libnetutil/TransportLayerElement.cc new file mode 100644 index 0000000..cdbbb9e --- /dev/null +++ b/libnetutil/TransportLayerElement.cc @@ -0,0 +1,126 @@ +/*************************************************************************** + * TransportLayerElement.cc -- Class TransportLayerElement is a generic * + * class that represents a transport layer protocol header. Classes like * + * TCPHeader or UDPHeader inherit from it. * + * * + ***********************IMPORTANT NMAP LICENSE TERMS************************ + * + * The Nmap Security Scanner is (C) 1996-2023 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 dev@nmap.org 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 "TransportLayerElement.h" +#include "IPv4Header.h" +#include "IPv6Header.h" + + +/** Computes and returns the Internet checksum. + * @warning This method requires the object to be linked to either an IPv6Header + * object or an IPv4Header one, so the caller must ensure that objects are + * properly linked with calls to setNextElement() like this: + * + * IPv6Header ip6; + * TCPHeader tcp; + * [...] # Set header fields + * ip6.setNextElement(&tcp); + * tcp.setSum(); + * + * Note that there can be a number of other headers (like IPv6 extension headers) + * between the transport header and the network one, but all of them need to + * be linked in order for this method to traverse the list of headers and find + * the IP source and destination address, required to compute the checksum. So + * things like the following are OK: + * + * IPv6Header ip6; + * HopByHopHeader hop; + * RoutingHeader rte; + * FragmentHeader frg; + * UDPHeader udp; + * [...] # Set whatever header fields you need + * ip6.setNextElement(&hop); + * hop.setNextElement(&rte); + * rte.setNextElement(&frg); + * frg.setNextElement(&udp); + * udp.setSum(); # setSum() will be able to reach the IPv6Header. */ +u16 TransportLayerElement::compute_checksum(){ + PacketElement *hdr; + hdr=this->getPrevElement(); + u16 final_sum=0; + /* Traverse the list of headers backwards until we find an IP header */ + while(hdr!=NULL){ + if (hdr->protocol_id()==HEADER_TYPE_IPv6){ + IPv6Header *v6hdr=(IPv6Header *)hdr; + struct in6_addr i6src, i6dst; + memcpy(i6src.s6_addr, v6hdr->getSourceAddress(), 16); + memcpy(i6dst.s6_addr, v6hdr->getDestinationAddress(), 16); + u8 *buff=(u8 *)safe_malloc(this->getLen()); + this->dumpToBinaryBuffer(buff, this->getLen()); + final_sum=ipv6_pseudoheader_cksum(&i6src, &i6dst, this->protocol_id(), this->getLen(), buff); + free(buff); + return final_sum; + }else if(hdr->protocol_id()==HEADER_TYPE_IPv4){ + IPv4Header *v4hdr=(IPv4Header *)hdr; + struct in_addr i4src, i4dst; + memcpy(&(i4src.s_addr), v4hdr->getSourceAddress(), 4); + memcpy(&(i4dst.s_addr), v4hdr->getDestinationAddress(), 4); + u8 *buff=(u8 *)safe_malloc(this->getLen()); + this->dumpToBinaryBuffer(buff, this->getLen()); + final_sum=ipv4_pseudoheader_cksum(&i4src, &i4dst, this->protocol_id(), this->getLen(), buff); + free(buff); + return final_sum; + }else{ + hdr=hdr->getPrevElement(); + } + } + return 0; +} /* End of setSum() */ |