/***************************************************************************
* EchoHeader.cc -- The EchoHeader Class represents packets of the Nping *
* Echo Protocol. It contains the appropriate methods to set/get all *
* header fields. In general these methods do error checking and perform *
* byte order conversions. *
* *
***********************IMPORTANT NMAP LICENSE TERMS************************
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***************************************************************************/
#include "EchoHeader.h"
#include "nping.h"
#include "output.h"
#include <time.h>
#include <assert.h>
#include "Crypto.h"
EchoHeader::EchoHeader(){
this->reset();
} /* End of EchoHeader constructor */
EchoHeader::~EchoHeader(){
} /* End of EchoHeader destructor */
/** Sets every attribute to its default value. */
void EchoHeader::reset() {
memset(&this->h, 0, sizeof(echohdr_t) );
this->data_hsserv=(nep_hs_serv_data_t *)this->h.data;
this->data_hsclnt=(nep_hs_clnt_data_t *)this->h.data;
this->data_hsfinal=(nep_hs_final_data_t *)this->h.data;
this->data_pspec=(nep_packet_spec_data_t *)this->h.data;
this->data_ready=(nep_ready_data_t *)this->h.data;
this->data_echo=(nep_echo_data_t *)this->h.data;
this->data_error=(nep_error_data_t *)this->h.data;
this->fs_off=(u8 *)this->data_pspec->packetspec;
this->fs_bytes=0;
this->echo_mac=(u8 *)this->data_echo->payload_and_mac;
this->echo_bytes=0;
/* Some safe initilizations */
this->setVersion(ECHO_CURRENT_PROTO_VER);
this->setTotalLength(STD_NEP_HEADER_LEN + MAC_LENGTH);
this->length=STD_NEP_HEADER_LEN + MAC_LENGTH; /* Sets length in PacketElement superclass */
} /* End of reset() */
/** @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 * EchoHeader::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. */
int EchoHeader::storeRecvData(const u8 *buf, size_t len){
if(buf==NULL || len>(STD_NEP_HEADER_LEN+MAX_DATA_LEN)){
return OP_FAILURE;
}else{
this->reset(); /* Re-init the object, just in case the caller had used it already */
this->length=len;
memcpy(&(this->h), buf, 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 EchoHeader::protocol_id() const {
return HEADER_TYPE_NEP;
} /* End of protocol_id() */
/** Sets Version.
* @return OP_SUCCESS on success and OP_FAILURE in case of error. */
int EchoHeader::setVersion(u8 val){
this->h.echo_ver=val;
return OP_SUCCESS;
} /* End of setVersion() */
/** Returns value of attribute h.echo_ver */
u8 EchoHeader::getVersion(){
return this->h.echo_ver;
} /* End of getVersion() */
/** Sets MessageType.
* @return OP_SUCCESS on success and OP_FAILURE in case of error. */
int EchoHeader::setMessageType(u8 val){
this->h.echo_mtype=val;
return OP_SUCCESS;
} /* End of setMessageType() */
/** Returns value of attribute h.echo_mtype */
u8 EchoHeader::getMessageType(){
return this->h.echo_mtype;
} /* End of getsetMessageType() */
/** Sets Total Length.
* @return OP_SUCCESS on success and OP_FAILURE in case of error.
* @warning the length is expressed in 32bit words. */
int EchoHeader::setTotalLength(u16 val){
this->h.echo_tlen=htons(val);
this->length=val*4; /* Also, set superclass length attribute */
return OP_SUCCESS;
} /* End of setTotalLength() */
/** Sets Total Length.
* @return OP_SUCCESS on success and OP_FAILURE in case of error. */
int EchoHeader::setTotalLength(){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_SERVER:
this->setTotalLength(NEP_HANDSHAKE_SERVER_LEN/4);
break;
case TYPE_NEP_HANDSHAKE_CLIENT:
this->setTotalLength(NEP_HANDSHAKE_CLIENT_LEN/4);
break;
case TYPE_NEP_HANDSHAKE_FINAL:
this->setTotalLength(NEP_HANDSHAKE_FINAL_LEN/4);
break;
case TYPE_NEP_PACKET_SPEC:
this->setTotalLength(NEP_PACKETSPEC_LEN/4);
break;
case TYPE_NEP_READY:
this->setTotalLength(NEP_READY_LEN/4);
break;
case TYPE_NEP_ECHO:
this->setTotalLength( (STD_NEP_HEADER_LEN + 4 + MAC_LENGTH + this->echo_bytes)/4 );
break;
case TYPE_NEP_ERROR:
this->setTotalLength(NEP_ERROR_LEN/4);
break;
default:
return OP_FAILURE;
break;
}
return OP_SUCCESS;
} /* End of setTotalLength() */
/** Returns value of attribute h.echo_tlen
* @warning Returned length is expressed in 32bit words. To get a byte count
* it must be multiplied by four */
u16 EchoHeader::getTotalLength(){
return ntohs(this->h.echo_tlen);
} /* End of getTotalLength() */
/** Sets SequenceNumber.
* @return OP_SUCCESS on success and OP_FAILURE in case of error. */
int EchoHeader::setSequenceNumber(u32 val){
this->h.echo_seq=htonl(val);
return OP_SUCCESS;
} /* End of setSequenceNumber() */
/** Returns value of attribute h.echo_seq */
u32 EchoHeader::getSequenceNumber(){
return ntohl(this->h.echo_seq);
} /* End of getSequenceNumber() */
/** Sets Timestamp.
* @return OP_SUCCESS on success and OP_FAILURE in case of error. */
int EchoHeader::setTimestamp(u32 val){
this->h.echo_ts=htonl(val);
return OP_SUCCESS;
} /* End of setTimestamp() */
/** Sets Timestamp.
* @return OP_SUCCESS on success and OP_FAILURE in case of error. */
int EchoHeader::setTimestamp(){
u32 t=(u32)time(NULL); /* TODO: Make sure this does not cause problems */
this->h.echo_ts=htonl(t);
return OP_SUCCESS;
} /* End of setTimestamp() */
/** Returns value of attribute h.echo_ts*/
u32 EchoHeader::getTimestamp(){
return ntohl(this->h.echo_ts);
} /* End of getTimestamp() */
/** Sets Reserved.
* @return OP_SUCCESS on success and OP_FAILURE in case of error. */
int EchoHeader::setReserved(u32 val){
this->h.echo_res=htonl(val);
return OP_SUCCESS;
} /* End of setReserved() */
/** Returns value of attribute h.echo_res */
u32 EchoHeader::getReserved(){
return this->h.echo_res;
} /* End of getReserved() */
int EchoHeader::setMessageAuthenticationCode(u8 *key, size_t keylen){
u8 *macpnt=NULL;
u8 *from=(u8 *)&(this->h);
size_t bytes=0;
/* Determine where the MAC field is and the length of the data that needs
* to be authenticated, based on message type. */
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_SERVER:
macpnt=this->data_hsserv->mac;
bytes=NEP_HANDSHAKE_SERVER_LEN-MAC_LENGTH;
break;
case TYPE_NEP_HANDSHAKE_CLIENT:
macpnt=this->data_hsclnt->mac;
bytes=NEP_HANDSHAKE_CLIENT_LEN-MAC_LENGTH;
break;
case TYPE_NEP_HANDSHAKE_FINAL:
macpnt=this->data_hsfinal->mac;
bytes=NEP_HANDSHAKE_FINAL_LEN-MAC_LENGTH;
break;
case TYPE_NEP_PACKET_SPEC:
macpnt=this->data_pspec->mac;
bytes=NEP_PACKETSPEC_LEN-MAC_LENGTH;
break;
case TYPE_NEP_READY:
macpnt=this->data_ready->mac;
bytes=NEP_READY_LEN-MAC_LENGTH;
break;
case TYPE_NEP_ECHO:
macpnt=this->echo_mac;
bytes=STD_NEP_HEADER_LEN + 4 + this->echo_bytes;
break;
case TYPE_NEP_ERROR:
macpnt=this->data_error->mac;
bytes=NEP_ERROR_LEN-MAC_LENGTH;
break;
default:
return OP_FAILURE;
break;
}
/* Compute the code */
Crypto::hmac_sha256(from, bytes, macpnt, key, keylen);
return OP_SUCCESS;
} /* End of setMessageAuthenticationCode() */
u8 *EchoHeader::getMessageAuthenticationCode(){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_SERVER:
return this->data_hsserv->mac;
break;
case TYPE_NEP_HANDSHAKE_CLIENT:
return this->data_hsclnt->mac;
break;
case TYPE_NEP_HANDSHAKE_FINAL:
return this->data_hsfinal->mac;
break;
case TYPE_NEP_PACKET_SPEC:
return this->data_pspec->mac;
break;
case TYPE_NEP_READY:
return this->data_ready->mac;
break;
case TYPE_NEP_ECHO:
this->updateEchoInternals();
return this->echo_mac;
break;
case TYPE_NEP_ERROR:
return this->data_error->mac;
break;
default:
return NULL;
break;
}
return NULL;
} /* End of getMessageAuthenticationCode() */
int EchoHeader::verifyMessageAuthenticationCode(u8 *key, size_t keylen){
u8 mac_backup[MAC_LENGTH];
u8 *aux;
/* Make a copy of the current MAC */
if( (aux=this->getMessageAuthenticationCode())==NULL )
return OP_FAILURE;
memcpy(mac_backup, aux, MAC_LENGTH);
/* Recompute the MAC */
memset(aux, 0, MAC_LENGTH);
this->setMessageAuthenticationCode(key, keylen);
/* Try to match both MACs*/
if( (aux=this->getMessageAuthenticationCode())==NULL )
return OP_FAILURE;
if( memcmp(mac_backup, aux, MAC_LENGTH)==0 ){
return OP_SUCCESS;
}else{
/* Restore original MAC */
memcpy(aux, mac_backup, MAC_LENGTH);
return OP_FAILURE;
}
} /* End of verifyMessageAuthenticationCode() */
/******************************************************************************/
/* NEP_HANDSHAKE methods */
/******************************************************************************/
int EchoHeader::setServerNonce(u8 *nonce){
assert(nonce);
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_SERVER:
memcpy(this->data_hsserv->server_nonce, nonce, NONCE_LEN);
break;
case TYPE_NEP_HANDSHAKE_CLIENT:
memcpy(this->data_hsclnt->server_nonce, nonce, NONCE_LEN);
break;
default:
return OP_FAILURE;
break;
}
return OP_SUCCESS;
} /* End of getServerNonce() */
u8 *EchoHeader::getServerNonce(){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_SERVER:
return this->data_hsserv->server_nonce;
break;
case TYPE_NEP_HANDSHAKE_CLIENT:
return this->data_hsclnt->server_nonce;
break;
default:
return NULL;
break;
}
} /* End of getServerNonce() */
int EchoHeader::setClientNonce(u8 *nonce){
assert(nonce);
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_CLIENT:
memcpy(this->data_hsclnt->client_nonce, nonce, NONCE_LEN);
break;
case TYPE_NEP_HANDSHAKE_FINAL:
memcpy(this->data_hsfinal->client_nonce , nonce, NONCE_LEN);
break;
default:
return OP_FAILURE;
break;
}
return OP_SUCCESS;
} /* End of getClientNonce() */
u8 *EchoHeader::getClientNonce(){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_CLIENT:
return this->data_hsclnt->client_nonce;
break;
case TYPE_NEP_HANDSHAKE_FINAL:
return this->data_hsfinal->client_nonce;
break;
default:
return NULL;
break;
}
} /* End of getClientNonce() */
int EchoHeader::setPartnerAddress(struct in_addr val){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_CLIENT:
memset(this->data_hsclnt->partner_ip, 0, 16);
memcpy(this->data_hsclnt->partner_ip , &val, sizeof(struct in_addr));
break;
case TYPE_NEP_HANDSHAKE_FINAL:
memset(this->data_hsfinal->partner_ip, 0, 16);
memcpy(this->data_hsfinal->partner_ip , &val, sizeof(struct in_addr));
break;
default:
return OP_FAILURE;
break;
}
this->setIPVersion(0x04);
return OP_SUCCESS;
} /* End of setPartnerAddress() */
int EchoHeader::setPartnerAddress(struct in6_addr val){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_CLIENT:
memset(this->data_hsclnt->partner_ip, 0, 16);
memcpy(this->data_hsclnt->partner_ip , &val, sizeof(struct in6_addr));
break;
case TYPE_NEP_HANDSHAKE_FINAL:
memset(this->data_hsfinal->partner_ip, 0, 16);
memcpy(this->data_hsfinal->partner_ip , &val, sizeof(struct in6_addr));
break;
default:
return OP_FAILURE;
break;
}
this->setIPVersion(0x06);
return OP_SUCCESS;
} /* End of setPartnerAddress() */
int EchoHeader::getPartnerAddress(struct in_addr *dst){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_CLIENT:
memcpy(dst, this->data_hsclnt->partner_ip,sizeof(struct in_addr));
break;
case TYPE_NEP_HANDSHAKE_FINAL:
memcpy(dst, this->data_hsfinal->partner_ip,sizeof(struct in_addr));
break;
default:
return OP_FAILURE;
break;
}
return OP_SUCCESS;
} /* End of getPartnerAddress() */
int EchoHeader::getPartnerAddress(struct in6_addr *dst){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_CLIENT:
memcpy(dst, this->data_hsclnt->partner_ip,sizeof(struct in6_addr));
break;
case TYPE_NEP_HANDSHAKE_FINAL:
memcpy(dst, this->data_hsfinal->partner_ip,sizeof(struct in6_addr));
break;
default:
return OP_FAILURE;
break;
}
return OP_SUCCESS;
} /* End of getPartnerAddress() */
/* On failure, it returns 0xAB */
u8 EchoHeader::getIPVersion(){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_CLIENT:
return this->data_hsclnt->ip_version;
break;
case TYPE_NEP_HANDSHAKE_FINAL:
return this->data_hsfinal->ip_version;
break;
case TYPE_NEP_PACKET_SPEC:
return this->data_pspec->ip_version;
break;
default:
return 0xAB;
break;
}
} /* End of getIPVersion() */
int EchoHeader::setIPVersion(u8 ver){
switch( this->getMessageType() ){
case TYPE_NEP_HANDSHAKE_CLIENT:
this->data_hsclnt->ip_version=ver;
break;
case TYPE_NEP_HANDSHAKE_FINAL:
this->data_hsfinal->ip_version=ver;
break;
case TYPE_NEP_PACKET_SPEC:
this->data_pspec->ip_version=ver;
break;
default:
return OP_FAILURE;
break;
}
return OP_SUCCESS;
} /* End of setIPVersion() */
/******************************************************************************/
/* NEP_PACKET_SPEC methods */
/******************************************************************************/
int EchoHeader::setProtocol(u8 proto){
switch( this->getMessageType() ){
case TYPE_NEP_PACKET_SPEC:
this->data_pspec->protocol=proto;
break;
default:
return OP_FAILURE;
break;
}
return OP_SUCCESS;
} /* End of setProtocol() */
/* On failure, it returns 0xAB */
u8 EchoHeader::getProtocol(){
switch( this->getMessageType() ){
case TYPE_NEP_PACKET_SPEC:
return this->data_pspec->protocol;
break;
default:
return 0xAB;
break;
}
} /* End of setProtocol() */
int EchoHeader::setPacketCount(u16 c){
switch( this->getMessageType() ){
case TYPE_NEP_PACKET_SPEC:
this->data_pspec->packet_count=htons(c);
break;
default:
return OP_FAILURE;
break;
}
return OP_SUCCESS;
} /* End of setPacketCount() */
/* On failure, it returns 0 */
u16 EchoHeader::getPacketCount(){
switch( this->getMessageType() ){
case TYPE_NEP_PACKET_SPEC:
return ntohs(this->data_pspec->packet_count);
break;
default:
return 0;
break;
}
} /* End of getPacketCount() */
int EchoHeader::getFieldLength(u8 field){
switch(field){
/* 8bit fields */
case PSPEC_IPv4_TOS:
case PSPEC_IPv4_PROTO:
case PSPEC_IPv6_FLOW:
case PSPEC_IPv6_NHDR:
case PSPEC_TCP_FLAGS:
case PSPEC_ICMP_TYPE:
case PSPEC_ICMP_CODE:
return 1;
break;
/* 16bit fields */
case PSPEC_IPv4_ID:
case PSPEC_IPv4_FRAGOFF:
case PSPEC_TCP_SPORT:
case PSPEC_TCP_DPORT:
case PSPEC_TCP_WIN:
case PSPEC_TCP_URP:
case PSPEC_UDP_SPORT:
case PSPEC_UDP_DPORT:
case PSPEC_UDP_LEN:
return 2;
break;
/* 24bit fields */
case PSPEC_IPv6_TCLASS:
return 3;
break;
/* 32bit fields */
case PSPEC_TCP_SEQ:
case PSPEC_TCP_ACK:
return 4;
break;
/* Error */
case PSPEC_PAYLOAD_MAGIC:
default:
return -1;
break;
}
} /* End of getFieldLength() */
int EchoHeader::addFieldSpec(u8 field, u8 *val){
int flen;
/* Determine the length of the field */
if( (flen=this->getFieldLength(field))==-1 || val==NULL )
return OP_FAILURE;
else{
return this->addFieldSpec(field, val, flen);
}
} /* End of addFieldSpec() */
int EchoHeader::addFieldSpec(u8 field, u8 *val, size_t flen){
if( val==NULL ){
return OP_FAILURE;
}else{
/* Store the field spec and update internal pointers and counts */
if( (this->fs_bytes+flen) < PACKETSPEC_FIELD_LEN ){
*(this->fs_off)=field;
if(field==PSPEC_PAYLOAD_MAGIC){
/* Check length again since this field requires an extra byte */
if(this->fs_bytes+flen+1 < PACKETSPEC_FIELD_LEN){
*(this->fs_off+1)=flen;
memcpy(this->fs_off+2, val, flen);
this->fs_off+=(flen+2);
this->fs_bytes+=(flen+2);
}else{
return OP_FAILURE;
}
}else{
memcpy(this->fs_off+1, val, flen);
this->fs_off+=(flen+1);
this->fs_bytes+=(flen+1);
}
}else{
return OP_FAILURE;
}
}
return OP_SUCCESS;
} /* End of addFieldSpec() */
int EchoHeader::rewindFieldSpecCounters(){
this->fs_off=(u8 *)this->data_pspec->packetspec;
this->fs_bytes=0;
return OP_SUCCESS;
} /* rewindFieldSpecCounters */
/** @warning dst_buff must be able to hold at least (PACKETSPEC_FIELD_LEN-2) bytes. */
int EchoHeader::getNextFieldSpec(u8 *field, u8 *dst_buff, size_t *final_len){
u8 nfield=0;
int nlen=0;
if(field==NULL || dst_buff==NULL || this->fs_bytes>=PACKETSPEC_FIELD_LEN)
return OP_FAILURE;
/* Determine which is the next field specifier */
nfield=*(this->fs_off);
if(nfield==PSPEC_PAYLOAD_MAGIC){
nlen=(int)*(this->fs_off+1); /* Read length from the packet */
if(nlen<=0 || nlen>(PACKETSPEC_FIELD_LEN-2) )
return OP_FAILURE;
else if( this->fs_bytes+2+nlen>PACKETSPEC_FIELD_LEN)
return OP_FAILURE;
else
memcpy(dst_buff, this->fs_off+2, nlen);
this->fs_off+=(nlen+2);
this->fs_bytes+=(nlen+2);
}else{
if((nlen=this->getFieldLength(nfield))<=0) /* Determine field length */
return OP_FAILURE;
else if(this->fs_bytes+1+nlen>PACKETSPEC_FIELD_LEN)
return OP_FAILURE;
else
memcpy(dst_buff, this->fs_off+1, nlen);
this->fs_off+=(nlen+1);
this->fs_bytes+=(nlen+2);
}
/* Store data */
*field=nfield;
if(final_len!=NULL)
*final_len=nlen;
return OP_SUCCESS;
} /* End of getNextFieldSpec() */
/******************************************************************************/
/* NEP_PACKET_ECHO methods */
/******************************************************************************/
int EchoHeader::setDLT(u16 dlt){
this->data_echo->dlt_type=htons(dlt);
return OP_SUCCESS;
} /* End of setDLT() */
u16 EchoHeader::getDLT(){
return ntohs(this->data_echo->dlt_type);
} /* End of getDLT() */
int EchoHeader::setPacketLength(u16 len){
this->data_echo->packet_len=htons(len);
return OP_SUCCESS;
} /* End of setPacketLength() */
u16 EchoHeader::getPacketLength(){
return ntohs(this->data_echo->packet_len);
} /* End of setPacketLength() */
int EchoHeader::setEchoedPacket(const u8 *pkt, size_t pktlen){
int padding=0;
if(pkt==NULL)
return OP_FAILURE;
if(pktlen>MAX_ECHOED_PACKET_LEN){
pktlen=MAX_ECHOED_PACKET_LEN;
}
memcpy(this->data_echo->payload_and_mac, pkt, pktlen);
if((pktlen+4)%16!=0){
padding=16-((pktlen+4)%16);
memset(this->data_echo->payload_and_mac+pktlen, 0, padding);
}
this->echo_bytes=pktlen+padding;
this->echo_mac+=pktlen+padding;
/* Set the packet length field automatically */
this->setPacketLength((u16)pktlen);
this->length = STD_NEP_HEADER_LEN + 4 + this->echo_bytes + MAC_LENGTH;
assert(this->length%16==0);
return OP_SUCCESS;
} /* End of setEchoedPacket() */
/* @warning value stored in final_len is not exactly the actual length of the
* returned buffer but the value stored in the "Packet Length" field of the
* NEP_ECHO message. The caller is supposed to validate received packets before
* trusting that length */
u8 *EchoHeader::getEchoedPacket(u16 *final_len){
if(final_len!=NULL)
*final_len=this->getPacketLength();
return this->data_echo->payload_and_mac;
} /* End of getEchoedPacket() */
u8 *EchoHeader::getEchoedPacket(){
return this->getEchoedPacket(NULL);
} /* End of getEchoedPacket() */
/** This method tries to update the object's internal counters for a NEP_ECHO
* packet. This should be used when storing a received NEP_ECHO message in
* the object. In that case, the internal pointers will not be set up
* correctly, as the object did not construct the message. Calling this method
* should fix the internal state of the object and make things like
* verifyMessageAuthenticationCode() work. */
int EchoHeader::updateEchoInternals(){
if( this->getMessageType()!=TYPE_NEP_ECHO )
return OP_FAILURE;
/* Fix echo bytes length */
this->echo_bytes=this->getPacketLength();
if((this->echo_bytes+4)%16!=0){
this->echo_bytes+=16-((this->echo_bytes+4)%16);
}
/* Fix MAC offset */
this->echo_mac=((u8 *)this->data_echo->payload_and_mac)+this->echo_bytes;
return OP_SUCCESS;
} /* End of updateEchoInternals() */
/******************************************************************************/
/* NEP_ERROR methods */
/******************************************************************************/
/** @warning error strings longer than MAX_NEP_ERROR_MSG_LEN-1 will be truncated */
int EchoHeader::setErrorMessage(const char *err){
if(err==NULL){
return OP_FAILURE;
}else{
strncpy((char *)this->data_error->errmsg, err, ERROR_MSG_LEN);
this->data_error->errmsg[ERROR_MSG_LEN-1]='\0';
}
return OP_SUCCESS;
} /* End of setErrorMessage() */
/* @warning Returned pointer, points to the start of the "Error Message" field
* of the NEP_ERROR message. When receiving this kind of messages, there is no
* guarantee that the field contains printable characters, or that it is NULL
* terminated. The caller should validate it's contents. It is safe to read
* MAX_NEP_ERROR_MSG_LEN bytes from the start of the returned buffer pointer. */
char *EchoHeader::getErrorMessage(){
return (char *)this->data_error->errmsg;
} /* End of getErrorMessage() */
/******************************************************************************/
/* CRYPTOGRAPHY */
/******************************************************************************/
u8 *EchoHeader::getCiphertextBounds(size_t *final_len){
return this->getCiphertextBounds(final_len, this->getMessageType());
}
u8 *EchoHeader::getCiphertextBounds(size_t *final_len, int message_type){
u8 *start=NULL;
size_t len=0;
switch( message_type ){
case TYPE_NEP_HANDSHAKE_SERVER: /* this msg is never transmitted encrypted */
len=0;
start=(u8 *)&this->h;
break;
case TYPE_NEP_HANDSHAKE_CLIENT:
start=this->data_hsclnt->partner_ip;
len=32;
break;
case TYPE_NEP_HANDSHAKE_FINAL:
start=this->data_hsfinal->partner_ip;
len=32;
break;
case TYPE_NEP_PACKET_SPEC:
start=(u8 *)(&this->h);
len=NEP_PACKETSPEC_LEN-MAC_LENGTH;
break;
case TYPE_NEP_READY:
start=(u8 *)(&this->h);
len=NEP_READY_LEN-MAC_LENGTH;
break;
case TYPE_NEP_ECHO:
start=(u8 *)(&this->h);
len=this->length-MAC_LENGTH;
break;
case TYPE_NEP_ERROR:
start=(u8 *)(&this->h);
len=NEP_ERROR_LEN-MAC_LENGTH;
break;
default:
return NULL;
break;
}
if(final_len!=NULL)
*final_len=len;
return start;
} /* End of getCiphertextBounds() */
/** Encrypts the NEP message using the supplied key and initialization vector.
* On success it returns a pointer to the beginning of the last ciphertext
* block. This should be stored by the caller and used as the IV for the
* next encrypted data. It returns NULL in case of error. */
u8 *EchoHeader::encrypt(u8 *key, size_t key_len, u8 *iv){
nping_print(DBG_4, "%s(%p, %lu, %p)", __func__, key, (long unsigned)key_len, iv);
u8 *start=NULL;
size_t len=0;
if(key==NULL || key_len==0 || iv==NULL)
return NULL;
if((start=this->getCiphertextBounds(&len))==NULL)
return NULL;
if(len>=CIPHER_BLOCK_SIZE){
if( Crypto::aes128_cbc_encrypt(start, len, (u8 *)(&this->h_tmp), key, key_len, iv) != OP_SUCCESS )
return NULL;
else{
memcpy(start, &this->h_tmp, len);
return (start+(len-CIPHER_BLOCK_SIZE));
}
}else{
return NULL;
}
} /* End of encrypt() */
u8 *EchoHeader::decrypt(u8 *key, size_t key_len, u8 *iv, int message_type){
nping_print(DBG_4, "%s(%p, %lu, %p)", __func__, key, (long unsigned)key_len, iv);
u8 *start=NULL;
size_t len=0;
static u8 lastblock[CIPHER_BLOCK_SIZE];
if(key==NULL || key_len==0 || iv==NULL)
return NULL;
if((start=this->getCiphertextBounds(&len, message_type))==NULL)
return NULL;
if(len>=CIPHER_BLOCK_SIZE){
/* Keep a copy of the last ciphertext block */
memcpy(lastblock, start+len-CIPHER_BLOCK_SIZE, CIPHER_BLOCK_SIZE);
if( Crypto::aes128_cbc_decrypt(start, len, (u8 *)(&this->h_tmp), key, key_len, iv) != OP_SUCCESS )
return NULL;
else{
memcpy(start, &this->h_tmp, len);
return lastblock;
}
}else{
return NULL;
}
} /* End of decrypt() */