bool build_handshake_packet(nabto_connect* con, uint8_t* buffer, size_t bufferLength, size_t* packetLength) {
uint8_t* packetPtr;
/*
* type, 1 bytes
* flags, 1 bytes
* nsi cp, 4 bytes
* nsi sp, 4 bytes
* nsi co, 4 bytes
* id, 20 bytes
*/
size_t nonceLength = 38;
uint8_t nonce[38];
uint8_t* noncePtr = nonce;
packetPtr = insert_header(buffer, con->cpnsi, con->spnsi, NP_PACKET_HDR_TYPE_GW_CONN_U, false, 0, 0, con->consi);
//NOTE: These type and flags must match the connection attributes set
//in the unabto_tcp_fallback_connect_thread when a connection is
//established.
WRITE_U8(noncePtr, NP_GW_CONN_U_TYPE_TCP); noncePtr+=1;
WRITE_U8(noncePtr, NP_GW_CONN_U_FLAG_RELIABLE); noncePtr+=1;
WRITE_U32(noncePtr, con->cpnsi); noncePtr+=4;
WRITE_U32(noncePtr, con->spnsi); noncePtr+=4;
memcpy(noncePtr, con->consi, 8); noncePtr+=8;
memcpy(noncePtr, con->gatewayId, 20);
packetPtr = insert_payload(packetPtr, NP_PAYLOAD_TYPE_NONCE, nonce, nonceLength);
*packetLength = packetPtr - buffer;
insert_length(buffer, *packetLength);
return true;
}
/* Reconstruct nabto header with crypto payload header. */
uint8_t* reconstruct_header(uint8_t* buf, const nabto_packet_header * hdr)
{
uint8_t* ptr;
// insert copy of request header (Length will be inserted later)
ptr = buf;
/* Write fixed part of packet header */
WRITE_U32(ptr, hdr->nsi_cp); ptr += 4;
WRITE_U32(ptr, hdr->nsi_sp); ptr += 4;
WRITE_U8(ptr, hdr->type); ptr += 1;
WRITE_U8(ptr, hdr->version); ptr += 1;
WRITE_U8(ptr, hdr->rsvd); ptr += 1;
WRITE_U8(ptr, hdr->flags | NP_PACKET_HDR_FLAG_RESPONSE); ptr += 1;
WRITE_U16(ptr, hdr->seq); ptr += 2;
/*WRITE_U16(ptr, len);*/ ptr += 2; /* Length to be packed later */
/* Write NSI.co to packet header (optional) */
if (hdr->flags & NP_PACKET_HDR_FLAG_NSI_CO) {
memcpy(ptr, (const void*) hdr->nsi_co, 8); ptr += 8;
}
/* Write tag to packet header (optional) */
if (hdr->flags & NP_PACKET_HDR_FLAG_TAG) {
WRITE_U16(ptr, hdr->tag); ptr += 2;
}
{
ptrdiff_t diff = ptr - buf;
if (hdr->hlen != (uint16_t)(diff)) {
NABTO_LOG_ERROR(("header length mismatch: %" PRIu16 " != %" PRIptrdiff " !!!!!!!!!!!!!!!!!!!", hdr->hlen, diff));
return NULL;
}
}
// insert crypto header (len and code will be inserted later)
WRITE_U8(ptr, NP_PAYLOAD_TYPE_CRYPTO); ptr += 1;
WRITE_U8(ptr, NP_PAYLOAD_HDR_FLAG_NONE); /*ptr += 1;
WRITE_U16(ptr, len); ptr += 2;
WRITE_U16(ptr, code); ptr += 2;*/
/* len and code is patched by unabto_encrypt() */ ptr += 5;
return ptr; /* return end of packet (so far) */
}