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Diffstat (limited to 'libnetutil/UDPHeader.cc')
| -rw-r--r-- | libnetutil/UDPHeader.cc | 298 |
1 files changed, 298 insertions, 0 deletions
diff --git a/libnetutil/UDPHeader.cc b/libnetutil/UDPHeader.cc new file mode 100644 index 0000000..3c86d68 --- /dev/null +++ b/libnetutil/UDPHeader.cc @@ -0,0 +1,298 @@ +/*************************************************************************** + * UDPHeader.cc -- The UDPHeader Class represents a UDP packet. It * + * contains methods to set the different header fields. These methods * + * tipically perform the necessary error checks and byte order * + * conversions. * + * * + ***********************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 "UDPHeader.h" + +/******************************************************************************/ +/* CONTRUCTORS, DESTRUCTORS AND INITIALIZATION METHODS */ +/******************************************************************************/ +UDPHeader::UDPHeader(){ + this->reset(); +} /* End of UDPHeader constructor */ + + +UDPHeader::~UDPHeader(){ + +} /* End of UDPHeader destructor */ + + +/** Sets every attribute to its default value */ +void UDPHeader::reset(){ + this->length=UDP_HEADER_LEN; + this->setSourcePort(UDP_DEFAULT_SPORT); + this->setDestinationPort(UDP_DEFAULT_DPORT); + this->setTotalLength(UDP_HEADER_LEN); + this->setSum(0); +} /* End of reset() */ + + +/******************************************************************************/ +/* PacketElement:: OVERWRITTEN METHODS */ +/******************************************************************************/ + +/** @warning This method is essential for the superclass getBinaryBuffer() + * method to work. Do NOT change a thing unless you know what you're doing */ +u8 * UDPHeader::getBufferPointer(){ + return (u8*)(&h); +} /* End of getBufferPointer() */ + + +/** Stores supplied packet in the internal buffer so the information + * can be accessed using the standard get & set methods. + * @warning The UDPHeader class is able to hold a maximum of 8 bytes. If the + * supplied buffer is longer than that, only the first 8 bytes will be stored + * in the internal buffer. + * @warning Supplied len MUST be at least 8 bytes (UDP header length). + * @return OP_SUCCESS on success and OP_FAILURE in case of error */ +int UDPHeader::storeRecvData(const u8 *buf, size_t len){ + if(buf==NULL || len<UDP_HEADER_LEN){ + return OP_FAILURE; + }else{ + this->reset(); /* Re-init the object, just in case the caller had used it already */ + this->length=UDP_HEADER_LEN; + memcpy(&(this->h), buf, UDP_HEADER_LEN); + } + return OP_SUCCESS; +} /* End of storeRecvData() */ + + +/* Returns a protocol identifier. This is used by packet parsing funtions + * that return linked lists of PacketElement objects, to determine the protocol + * the object represents. */ +int UDPHeader::protocol_id() const { + return HEADER_TYPE_UDP; +} /* End of protocol_id() */ + + +/** Determines if the data stored in the object after an storeRecvData() call + * is valid and safe to use. This mainly checks the length of the data but may + * also test the value of certain protocol fields to ensure their correctness. + * @return the length, in bytes, of the header, if its found to be valid or + * OP_FAILURE (-1) otherwise. */ +int UDPHeader::validate(){ + if( this->length!=UDP_HEADER_LEN) + return OP_FAILURE; + else + return UDP_HEADER_LEN; +} /* End of validate() */ + + +/** Prints the contents of the header and calls print() on the next protocol + * header in the chain (if there is any). + * @return OP_SUCCESS on success and OP_FAILURE in case of error. */ +int UDPHeader::print(FILE *output, int detail) const { + fprintf(output, "UDP["); + fprintf(output, "%d", this->getSourcePort()); + fprintf(output, " >"); + fprintf(output, " %d", this->getDestinationPort()); + if(detail>=PRINT_DETAIL_HIGH) + fprintf(output, " len=%d", (int)this->getTotalLength() ); + if(detail>=PRINT_DETAIL_MED) + fprintf(output, " csum=0x%04X", ntohs( this->getSum() )); + fprintf(output, "]"); + if(this->next!=NULL){ + print_separator(output, detail); + next->print(output, detail); + } + return OP_SUCCESS; +} /* End of print() */ + + +/******************************************************************************/ +/* PROTOCOL-SPECIFIC METHODS */ +/******************************************************************************/ + +/** Sets source port. + * @warning Port must be supplied in host byte order. This method performs + * byte order conversion using htons() */ +int UDPHeader::setSourcePort(u16 p){ + h.uh_sport = htons(p); + return OP_SUCCESS; +} /* End of setSrcPort() */ + + +/** Returns source port in HOST byte order */ +u16 UDPHeader::getSourcePort() const { + return ntohs(h.uh_sport); +} /* End of getSrcPort() */ + + +/** Sets destination port. + * @warning Port must be supplied in host byte order. This method performs + * byte order conversion using htons() */ +int UDPHeader::setDestinationPort(u16 p){ + h.uh_dport = htons(p); + return OP_SUCCESS; +} /* End of setDstPort() */ + + +/** Returns destination port in HOST byte order */ +u16 UDPHeader::getDestinationPort() const { + return ntohs(h.uh_dport); +} /* End of getDstPort() */ + + +int UDPHeader::setSum(struct in_addr src, struct in_addr dst){ + int bufflen; + u8 aux[ 65535-8 ]; + /* FROM: RFC 5405 Unicast UDP Usage Guidelines, November 2008 + * "A UDP datagram is carried in a single IP packet and is hence limited to + * a maximum payload of 65,507 bytes for IPv4 and 65,527 bytes for IPv6" + * + * So, UDP is supposed to be able to carry 65535-8 bytes but in fact it can + * only carry 65,507 or 65,527. However, we are not taking that into account + * here because UDP is supposed to be independent of IPv4, IPv6 or + * whatever other network layer protocol is used to carry the UDP datagrams.*/ + h.uh_sum = 0; + + /* Copy packet contents to a buffer */ + bufflen=dumpToBinaryBuffer(aux, 65536-8 ); + + /* Compute checksum */ + h.uh_sum = ipv4_pseudoheader_cksum(&src, &dst, IPPROTO_UDP,bufflen, (char *) aux); + + return OP_SUCCESS; +} /* End of setSum() */ + + +/** @warning Sum is set to supplied value with NO byte ordering conversion + * performed. */ +int UDPHeader::setSum(u16 s){ + h.uh_sum = s; + return OP_SUCCESS; +} /* End of setSum() */ + + +int UDPHeader::setSum(){ + this->h.uh_sum=0; + this->h.uh_sum = this->compute_checksum(); + return OP_SUCCESS; +} /* End of setSum() */ + + +/** Set the UDP checksum field to a random value, which may accidentally + * match the correct checksum */ +int UDPHeader::setSumRandom(){ + h.uh_sum=(1 + (get_random_u16()%(65535-1))); /* Discard value zero */ + return OP_SUCCESS; +} /* End of setSumRandom() */ + + +/** Set the UDP checksum field to a random value. It takes the source and + * destination address to make sure the random generated sum does not + * accidentally match the correct checksum. This function only handles + * IPv4 address. */ +int UDPHeader::setSumRandom(struct in_addr source, struct in_addr destination){ + u16 correct_csum=0; + /* Compute the correct checksum */ + this->setSum(source, destination); + correct_csum=this->getSum(); + /* Generate numbers until one does not match the correct sum */ + while( (h.uh_sum=(1 + (get_random_u16()%(65535-1))))==correct_csum); + return OP_SUCCESS; +} /* End of setSumRandom() */ + + +u16 UDPHeader::getSum() const { + return h.uh_sum; +} /* End of getSum() */ + + +int UDPHeader::setTotalLength(){ + int mylen = 8; + int otherslen=0; + + if (next!=NULL) + otherslen=next->getLen(); + + /* FROM: RFC 5405 Unicast UDP Usage Guidelines, November 2008 + * "A UDP datagram is carried in a single IP packet and is hence limited to + * a maximum payload of 65,507 bytes for IPv4 and 65,527 bytes for IPv6" + * + * So, UDP is supposed to be able to carry 65535-8 bytes but in fact it can + * only carry 65,507 or 65,527. However, we are not taking that into account + * here because UDP is supposed to be independent of IPv4, IPv6 or + * whatever other network layer protocol is used to carry the UDP datagrams.*/ + if (otherslen < 0 || otherslen > 65535 || (mylen+otherslen) > 65535){ + printf("UDPHeader::setTotalLength(): Invalid length.\n"); + return OP_FAILURE; + } + + h.uh_ulen=htons( mylen+otherslen ); + + return OP_SUCCESS; +} /* End of setTotalLength() */ + + +/** @warning Supplied value MUST be in HOST byte order */ +int UDPHeader::setTotalLength(u16 l){ + this->h.uh_ulen=htons(l); + return OP_SUCCESS; +} /* End of setTotalLength() */ + + +/** @warning Returned value is in HOST byte order */ +u16 UDPHeader::getTotalLength() const { + return ntohs(this->h.uh_ulen); +} /* End of getTotalLength() */ + + |