githubmirror/nmap

libnetutil/IPv4Header.cc
637 строк21 KB
dmiller
Assertions for TCP and IP header length field
27 июн 2026, 01:06
27 июн 2026, 01:064651a54
/***************************************************************************
 * IPv4Header.cc -- The IPv4Header Class represents an IPv4 datagram. It   *
 * contains methods to set any header field. In general, these methods do  *
 * error checkings and byte order conversion.                              *
 *                                                                         *
 ***********************IMPORTANT NMAP LICENSE TERMS************************
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 * Project"). Nmap is also a registered trademark of the Nmap Project.
 *
 * This program is distributed under the terms of the Nmap Public Source
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 * 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
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 ***************************************************************************/
/* This code was originally part of the Nping tool.                        */

#include "IPv4Header.h"
#include <assert.h>

/******************************************************************************/
/* CONTRUCTORS, DESTRUCTORS AND INITIALIZATION METHODS                        */
/******************************************************************************/
IPv4Header::IPv4Header() {
  this->reset();
} /* End of IPv4Header constructor */


IPv4Header::~IPv4Header() {

} /* End of IPv4Header destructor */


/** Sets every attribute to its default value */
void IPv4Header::reset() {
  memset(&this->h, 0, sizeof(nping_ipv4_hdr_t));
  this->ipoptlen=0;
  this->length=20;   /* Initial value 20. This will be incremented if options are used */
  this->setVersion();
  this->setHeaderLength();
  this->setTOS(IPv4_DEFAULT_TOS);
  this->setIdentification(IPv4_DEFAULT_ID);
  this->setTTL(IPv4_DEFAULT_TTL);
  this->setNextProto(IPv4_DEFAULT_PROTO);
  this->setTotalLength();
} /* End of IPv4Header destructor */


/******************************************************************************/
/* 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 *IPv4Header::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 IPv4Header class is able to hold a maximum of 60 bytes. If the
  * supplied buffer is longer than that, only the first 60 bytes will be stored
  * in the internal buffer.
  * @warning Supplied len MUST be at least 20 bytes (min IP header length).
  * @return OP_SUCCESS on success and OP_FAILURE in case of error */
int IPv4Header::storeRecvData(const u8 *buf, size_t len){
  if(buf==NULL || len<IP_HEADER_LEN){
    return OP_FAILURE;
  }else{
    int stored_len = MIN((IP_HEADER_LEN + MAX_IP_OPTIONS_LEN), len);
    this->reset(); /* Re-init the object, just in case the caller had used it already */
    this->length=stored_len;
    memcpy(&(this->h), buf, stored_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 IPv4Header::protocol_id() const {
    return HEADER_TYPE_IPv4;
} /* End of protocol_id() */


/** Performs some VERY BASIC checks that intend to validate the information
  * stored in the internal buffer, as a valid protocol header.
  * @warning If the information stored in the object has been set through a
  * call to storeRecvData(), the object's internal length count may be updated
  * if the validation is successful.
  * @return the length, in bytes, of the header, if its found to be valid or
  * OP_FAILURE (-1) otherwise. */
int IPv4Header::validate(){
  if(this->getVersion()!=4)
    return OP_FAILURE;
  else if( this->getHeaderLength()<5)
    return OP_FAILURE;
  else if( this->getHeaderLength()*4 > this->length)
    return OP_FAILURE;
  this->length=this->getHeaderLength()*4;
  return this->length;
} /* 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 IPv4Header::print(FILE *output, int detail) const {
  static char ipstring[256];
  memset(ipstring, 0, 256);
  struct in_addr addr;
  int frag_off = 8 * this->getFragOffset() & 8191; /* 2^13 - 1 */;
  char ipinfo[512] = "";                /* Temp info about IP.               */
  char fragnfo[64] = "";                /* Temp info about fragmentation.    */

  fprintf(output, "IPv4[");

  this->getSourceAddress(&addr);
  inet_ntop(AF_INET, &addr, ipstring, sizeof(ipstring));
  fprintf(output, "%s", ipstring);

  fprintf(output, " >");

  this->getDestinationAddress(&addr);
  inet_ntop(AF_INET, &addr, ipstring, sizeof(ipstring));
  fprintf(output, " %s", ipstring);

  /* Is this a fragmented packet? is it the last fragment? */
  if (frag_off || this->getMF()) {
    Snprintf(fragnfo, sizeof(fragnfo), " frag offset=%d%s", frag_off, this->getMF() ? "+" : "");
  }

  /* Create a string with information relevant to the specified level of detail */
  if( detail == PRINT_DETAIL_LOW ){
      Snprintf(ipinfo, sizeof(ipinfo), "ttl=%d id=%d iplen=%d%s%s%s%s",
          this->getTTL(), this->getIdentification(), this->getTotalLength(), fragnfo,
          this->getHeaderLength()==5?"":" ipopts={",
          this->getHeaderLength()?"":format_ip_options(this->h.options , MIN(this->getHeaderLength()*4, this->length-IP_HEADER_LEN)),
          this->getHeaderLength()?"":"}");
  }else if( detail == PRINT_DETAIL_MED ){
      Snprintf(ipinfo, sizeof(ipinfo), "ttl=%d id=%d proto=%d csum=0x%04X iplen=%d%s%s%s%s",
          this->getTTL(), this->getIdentification(),
          this->getNextProto(), this->getSum(),
          this->getTotalLength(), fragnfo,
          this->getHeaderLength()==5?"":" ipopts={",
          this->getHeaderLength()==5?"":format_ip_options(this->h.options , MIN(this->getHeaderLength()*4, this->length-IP_HEADER_LEN)),
          this->getHeaderLength()==5?"":"}");
  }else if( detail>=PRINT_DETAIL_HIGH ){
      Snprintf(ipinfo, sizeof(ipinfo), "ver=%d ihl=%d tos=0x%02x iplen=%d id=%d%s%s%s%s foff=%d%s ttl=%d proto=%d csum=0x%04X%s%s%s",
          this->getVersion(), this->getHeaderLength(),
          this->getTOS(), this->getTotalLength(),
          this->getIdentification(),
          (this->getRF() ||this->getDF()||this->getMF()) ? " flg=" : "",
          (this->getRF()) ? "x" : "",
          (this->getDF() )? "D" : "",
          (this->getMF() )? "M": "",
          frag_off, (this->getMF()) ? "+" : "",
          this->getTTL(), this->getNextProto(),
          this->getSum(),
          this->getHeaderLength()==5?"":" ipopts={",
          this->getHeaderLength()==5?"":format_ip_options(this->h.options , MIN(this->getHeaderLength()*4, this->length-IP_HEADER_LEN)),
          this->getHeaderLength()==5?"":"}");
  }

  fprintf(output, " %s]", ipinfo);

  if(this->next!=NULL){
    print_separator(output, detail);
    next->print(output, detail);
  }
  return OP_SUCCESS;
} /* End of print() */


/******************************************************************************/
/* PROTOCOL-SPECIFIC METHODS                                                  */
/******************************************************************************/

int IPv4Header::setVersion(){
  h.ip_v   = 4;
  return 4;
} /* End of setVersion() */


u8 IPv4Header::getVersion() const {
  return (u8)h.ip_v;
} /* End of getVersion() */


int IPv4Header::setHeaderLength(){
  assert(ipoptlen <= 40);
  h.ip_hl  = 5 + (ipoptlen/4);
  return OP_SUCCESS;
} /* End of setHeaderLength() */


int IPv4Header::setHeaderLength(u8 l){
  assert(l <= 0x0f);
  h.ip_hl  = l;
  return OP_SUCCESS;
} /* End of setHeaderLength() */


u8 IPv4Header::getHeaderLength() const {
  return h.ip_hl;
} /* End of getHeaderLength() */


int IPv4Header::setTOS(u8 v){
  h.ip_tos = v;
  return OP_SUCCESS;
} /* End of setTOS() */


u8 IPv4Header::getTOS() const {
  return h.ip_tos;
} /* End of getTOS() */


int IPv4Header::setTotalLength(){
  int mylen = 4*getHeaderLength();
  int otherslen=0;

  if (next!=NULL)
      otherslen=next->getLen();
  h.ip_len=htons( mylen+otherslen );
  return OP_SUCCESS;
} /* End of setTotalLength() */


/** @warning Supplied value MUST be in host byte order because it will get
 *  converted by this method using htons() */
int IPv4Header::setTotalLength(u16 l){
  h.ip_len = htons(l);
  return OP_SUCCESS;
} /* End of setTotalLength() */


/** @warning Returned value is already in host byte order. */
u16 IPv4Header::getTotalLength() const {
  return ntohs(h.ip_len);
} /* End of getTotalLength() */


/** Sets identification field to a random value */
int IPv4Header::setIdentification(){
  h.ip_id=get_random_u16();
  return OP_SUCCESS;
} /* End of setIdentification() */


/** @warning Supplied value MUST be in host byte order because it will get
 *  converted by this method using htons() */
int IPv4Header::setIdentification(u16 i){
  h.ip_id = htons(i);
  return OP_SUCCESS;
} /* End of setIdentification() */


/** @warning Returned value is already in host byte order. */
u16 IPv4Header::getIdentification() const {
  return ntohs(h.ip_id);
} /* End of getIdentification() */


/** Sets fragment offset field to a random value */
int IPv4Header::setFragOffset(){
  /* TODO: Should we check here that i<8192 ? */
  h.ip_off=get_random_u16();
  return OP_SUCCESS;
} /* End of setFragOffset() */


/** @warning Supplied value MUST be in host byte order because it will get
 *  converted by this method using htons() */
int IPv4Header::setFragOffset(u16 i){
  /* TODO: Should we check here that i<8192 ? */
  h.ip_off = htons(i);
  return OP_SUCCESS;
} /* End of setFragOffset() */


/** @warning Returned value is already in host byte order. */
u16 IPv4Header::getFragOffset() const {
  return ntohs(h.ip_off);
} /* End of getFragOffset() */


/** Set RF flag */
int IPv4Header::setRF(){
  h.ip_off |= htons(IP_RF);
  return OP_SUCCESS;
} /* End of setRF() */

/** Unset RF flag */
int IPv4Header::unsetRF(){
  h.ip_off = h.ip_off & ~(htons(IP_RF));
  return OP_SUCCESS;
} /* End of unsetRF() */


/** Get RF flag */
bool IPv4Header::getRF() const {
  return h.ip_off & htons(IP_RF);
} /* End of getRF() */


/** Set MF flag */
int IPv4Header::setMF(){
  h.ip_off |= htons(IP_MF);
  return OP_SUCCESS;
} /* End of setMF() */


/** Unset MF flag */
int IPv4Header::unsetMF(){
  h.ip_off = h.ip_off & ~(htons(IP_MF));
  return OP_SUCCESS;
} /* End of unsetMF() */


/* Get MF flag */
bool IPv4Header::getMF() const {
  return h.ip_off & htons(IP_MF);
} /* End of getMF() */


/** Set DF flag */
int IPv4Header::setDF(){
  h.ip_off |= htons(IP_DF);
  return OP_SUCCESS;
} /* End of setDF() */


/** Unset DF flag */
int IPv4Header::unsetDF(){
  h.ip_off = h.ip_off & ~(htons(IP_DF));
  return OP_SUCCESS;
} /* End of unsetDF() */


/** Get DF flag */
bool IPv4Header::getDF() const {
  return h.ip_off & htons(IP_DF);
} /* End of getDF) */


/** Sets TTL field to a random value */
int IPv4Header::setTTL(){
  h.ip_ttl=get_random_u8();
  return OP_SUCCESS;
} /* End of setTTL() */


/** @warning Supplied value MUST be in host byte order because it will get
 *  converted by this method using htons() */
int IPv4Header::setTTL(u8 t){
  h.ip_ttl = t;
  return OP_SUCCESS;
} /* End of setTTL() */


/** @warning Returned value is already in host byte order. */
u8 IPv4Header::getTTL() const {
  return h.ip_ttl;
} /* End of getTTL() */


/** Sets field "next protocol" to the supplied value.
 *  @warning: No error checks are made. Make sure the supplied value
 *  corresponds to an actual IANA number. Check
 *  http://www.iana.org/assignments/protocol-numbers/ for more details.      */
int IPv4Header::setNextProto(u8 p){
  h.ip_p = p;
  return OP_SUCCESS;
} /* End of setNextProto() */


/** Sets field "next protocol" to the number that corresponds to the supplied
 *  protocol name. Currently only TCP, UDP and ICMP are supported. Any
 *  help to extend this functionality would be appreciated. For a list of all
 *  proto names and numbers check:
 *  http://www.iana.org/assignments/protocol-numbers/                        */
int IPv4Header::setNextProto(const char *p){
  if (p==NULL){
        printf("setNextProto(): NULL pointer supplied\n");
    return OP_FAILURE;
  }
  if( !strcasecmp(p, "TCP") )
        h.ip_p=6;   /* 6=IANA number for proto TCP */

  else if( !strcasecmp(p, "UDP") )
        h.ip_p=17;  /* 17=IANA number for proto UDP */

  else if( !strcasecmp(p, "ICMP") )
        h.ip_p=1;   /* 1=IANA number for proto ICMP */
  else{
        printf("setNextProto(): Invalid protocol number\n");
        return OP_FAILURE;
  }
  return OP_SUCCESS;
} /* End of setNextProto() */


/** Returns next protocol number */
u8 IPv4Header::getNextProto() const {
  return h.ip_p;
} /* End of getNextProto() */


u8 IPv4Header::getNextHeader() const {
  return this->getNextProto();
} /* End of getNextHeader() */


int IPv4Header::setNextHeader(u8 val){
  return this->setNextProto(val);
} /* End of setNextHeader() */


/** Computes the IPv4 header checksum and sets the ip_sum field to the right
 *  value. */
int IPv4Header::setSum(){
  h.ip_sum = 0;
  /* ip_checksum() comes from libdnet */
  ip_checksum((void*)&h, 20 + ipoptlen );
  return OP_SUCCESS;
} /* End of setSum() */


/** @warning Sum is set to supplied value with NO byte ordering conversion
 *  performed.
 *  @warning If sum is supplied this way, no error checks are made. Caller is
 *  responsible for the correctness of the value. */
int IPv4Header::setSum(u16 s){
  h.ip_sum = s;
  return OP_SUCCESS;
} /* End of setSum() */


/** Set the checksum field to a random value */
int IPv4Header::setSumRandom(){
  h.ip_sum=get_random_u16();
  return OP_SUCCESS;
} /* End of setRandomSum() */


/** Returns the value of the checksum field.
 *  @warning The returned value is in NETWORK byte order, no conversion is
 *  performed */
u16 IPv4Header::getSum() const {
  return h.ip_sum;
} /* End of getSum() */


/** Sets destination IP address.
 *  @warning Destination IP must be supplied in NETWORK byte order. Usually
 *  all regular library functions return IPs in network byte order so there
 *  should be no need to worry.  */
int IPv4Header::setDestinationAddress(u32 d){
  h.ip_dst.s_addr =  d;
  return OP_SUCCESS;
} /* End of setDestinationAddress() */

/** Sets destination IP address.
 *  @warning Destination IP must be supplied in NETWORK byte order. Usually
 *  all regular library functions return IPs in network byte order so there
 *  should be no need to worry.  */
int IPv4Header::setDestinationAddress(struct in_addr d){
  h.ip_dst=d;
  return OP_SUCCESS;
} /* End of setDestinationAddress() */


/** Returns destination IP address.
 *  @warning Returned value is in NETWORK byte order. */
const u8 *IPv4Header::getDestinationAddress() const {
  return (u8 *)(&h.ip_dst.s_addr);
} /* End of getDestinationAddress() */


/** Returns destination IP address.
 *  @warning Returned value is in NETWORK byte order. */
struct in_addr IPv4Header::getDestinationAddress(struct in_addr *result) const {
  if(result!=NULL)
      *result=this->h.ip_dst;
  return h.ip_dst;
} /* End of getDestinationAddress() */


/** Sets source IP address.
 *  @warning Destination IP must be supplied in NETWORK byte order. Usually
 *  all regular library functions return IPs in network byte order so there
 *  should be no need to worry.  */
int IPv4Header::setSourceAddress(u32 d){
  h.ip_src.s_addr =  d;
  return OP_SUCCESS;
} /* End of setSourceAddress() */


/** Sets source IP address.
 *  @warning Destination IP must be supplied in NETWORK byte order. Usually
 *  all regular library functions return IPs in network byte order so there
 *  should be no need to worry. */
int IPv4Header::setSourceAddress(struct in_addr d){
  h.ip_src=d;
  return OP_SUCCESS;
} /* End of setSourceAddress() */


/** Returns source ip
 *  @warning Returned value is in NETWORK byte order. */
const u8 *IPv4Header::getSourceAddress() const {
  return (u8 *)(&h.ip_src.s_addr);
} /* End of getSourceAddress() */


/** Returns source ip
 *  @warning Returned value is in NETWORK byte order. */
struct in_addr IPv4Header::getSourceAddress(struct in_addr *result) const {
  if(result!=NULL)
      *result=this->h.ip_src;
  return h.ip_src;
} /* End of getSourceAddress() */


/** Returns the length of an IPv4 address. */
u16 IPv4Header::getAddressLength() const {
    return 4;
} /* End of getAddressLength()*/


int IPv4Header::setOpts(const char *txt){
  int foo=0;
  int bar=0;
  int ret=0;
  u8 buffer[128];
  char errstr[256];

   if(txt==NULL){
    printf("setOpts(): NULL pointer supplied.\n");
    return OP_FAILURE;
   }

   /* Parse IP options */
   if((ret=parse_ip_options(txt, buffer, 128, &foo, &bar, errstr, sizeof(errstr)))==OP_FAILURE){
    printf("%s\n", errstr);
    return OP_FAILURE;
   }else{
     /* Copy options to our IP header */
     this->setOpts(buffer, ret);
   }
   return OP_SUCCESS;
} /* End of setOpts() */


int IPv4Header::setOpts(u8 *opts_buff,  u32 opts_len){
  if(opts_buff==NULL || opts_len==0)
   return OP_FAILURE;
  assert(opts_len<=MAX_IP_OPTIONS_LEN); /* Max length for IP options */
  memcpy(this->h.options, opts_buff, opts_len);
  this->ipoptlen=opts_len;
  this->length += opts_len;
  this->setHeaderLength();
  return OP_SUCCESS;
} /* End of setOpts() */


const u8 *IPv4Header::getOpts() const {
  return h.options;
} /* End of getOpts() */


const u8 *IPv4Header::getOpts(int *len) const {
  if(len==NULL)
    printf("getOpts(): NULL pointer supplied.\n");
  else
    *len=ipoptlen;
  return h.options;
} /* End of getOpts() */


int IPv4Header::printOptions() const {
  char *p=format_ip_options(this->h.options, this->ipoptlen);
  printf("%s", p);
  return OP_SUCCESS;
} /* End of printOptions() */

const char *IPv4Header::getOptionsString() const {
  return format_ip_options(this->h.options, this->ipoptlen);
} /* End of getOptionsString() */