/***************************************************************************
* 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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***************************************************************************/
/* This code was originally part of the Nping tool. */
#include "IPv4Header.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(){
h.ip_hl = 5 + (ipoptlen/4);
return OP_SUCCESS;
} /* End of setHeaderLength() */
int IPv4Header::setHeaderLength(u8 l){
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 ^= 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 ^= 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 ^= 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 onyl 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 getDestinationAddress() */
/** 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 getDestinationAddress() */
/** 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 */
memcpy(h.options, buffer, ret);
this->ipoptlen=ret;
this->length += ret;
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");
*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() */