// Set local PeerID and sequence number (required to complete auth protocol)
static void authSetLocalData(struct s_auth_state *authstate, const int peerid, const int64_t seq, const int64_t flags) {
authstate->local_peerid = peerid;
cryptoRand(authstate->local_keygen_nonce, auth_NONCESIZE);
cryptoRand(authstate->s4msg_nonce, auth_NONCESIZE);
utilWriteInt64(authstate->local_seq, seq);
utilWriteInt64(authstate->local_flags, flags);
authstate->local_cneg_set = 1;
authGenMsg(authstate);
}
// encode packet
static int packetEncode(unsigned char *pbuf, const int pbuf_size, const struct s_packet_data *data, struct s_crypto *ctx) {
unsigned char dec_buf[packet_CRHDR_SIZE + data->pl_buf_size];
int32_t *scr_peerid = ((int32_t *)pbuf);
int32_t ne_peerid;
int len;
// check if enough space is available for the operation
if(data->pl_length > data->pl_buf_size) { return 0; }
// prepare buffer
utilWriteInt64(&dec_buf[packet_CRHDR_SEQ_START], data->seq);
utilWriteInt16(&dec_buf[packet_CRHDR_PLLEN_START], data->pl_length);
dec_buf[packet_CRHDR_PLTYPE_START] = data->pl_type;
dec_buf[packet_CRHDR_PLOPT_START] = data->pl_options;
memcpy(&dec_buf[packet_CRHDR_SIZE], data->pl_buf, data->pl_length);
// encrypt buffer
len = cryptoEnc(ctx, &pbuf[packet_PEERID_SIZE], (pbuf_size - packet_PEERID_SIZE), dec_buf, (packet_CRHDR_SIZE + data->pl_length), packet_HMAC_SIZE, packet_IV_SIZE);
if(len < (packet_HMAC_SIZE + packet_IV_SIZE + packet_CRHDR_SIZE)) { return 0; }
// write the scrambled peer ID
utilWriteInt32((unsigned char *)&ne_peerid, data->peerid);
scr_peerid[0] = (ne_peerid ^ (scr_peerid[1] ^ scr_peerid[2]));
// return length of encoded packet
return (packet_PEERID_SIZE + len);
}
