/*
* Here start with callback functions that support the ZRTP core
*/
static int32_t zrtp_sendDataZRTP(ZrtpContext* ctx, const uint8_t* data, int32_t length)
{
struct tp_zrtp *zrtp = (struct tp_zrtp*)ctx->userData;
pj_uint16_t totalLen = length + 12; /* Fixed number of bytes of ZRTP header */
pj_uint32_t crc;
pj_uint8_t* buffer = zrtp->zrtpBuffer;
pj_uint16_t* pus;
pj_uint32_t* pui;
if ((totalLen) > MAX_ZRTP_SIZE)
return 0;
/* Get some handy pointers */
pus = (pj_uint16_t*)buffer;
pui = (pj_uint32_t*)buffer;
/* set up fixed ZRTP header */
*buffer = 0x10; /* invalid RTP version - refer to ZRTP spec chap 5 */
*(buffer + 1) = 0;
pus[1] = pj_htons(zrtp->zrtpSeq++);
pui[1] = pj_htonl(ZRTP_MAGIC);
pui[2] = pj_htonl(zrtp->localSSRC); /* stored in host order */
/* Copy ZRTP message data behind the header data */
pj_memcpy(buffer+12, data, length);
/* Setup and compute ZRTP CRC */
crc = zrtp_GenerateCksum(buffer, totalLen-CRC_SIZE);
/* convert and store CRC in ZRTP packet.*/
crc = zrtp_EndCksum(crc);
*(uint32_t*)(buffer+totalLen-CRC_SIZE) = pj_htonl(crc);
/* Send the ZRTP packet using the slave transport */
return (pjmedia_transport_send_rtp(zrtp->slave_tp, buffer, totalLen) == PJ_SUCCESS) ? 1 : 0;
}
/**
* Send a ZRTP packet via RTP.
*
* ZRTP calls this method to send a ZRTP packet via the RTP session.
*
* @param ctx
* Pointer to the opaque ZrtpContext structure.
* @param data
* Points to ZRTP message to send.
* @param length
* The length in bytes of the data
* @return
* zero if sending failed, one if packet was sent
*/
static int32_t ozrtp_sendDataZRTP (ZrtpContext* ctx, const uint8_t* data, const int32_t length ){
OrtpZrtpContext *userData = user_data(ctx);
RtpSession *session = userData->session;
struct sockaddr *destaddr=(struct sockaddr*)&session->rtp.rem_addr;
socklen_t destlen=session->rtp.rem_addrlen;
ortp_socket_t sockfd=session->rtp.socket;
// Create ZRTP packet
int32_t newlength = length + 3*4; // strangely, given length includes CRC size !!!!
uint32_t* buffer32 = alloca(newlength);
uint8_t *buffer8=(uint8_t*)buffer32;
uint16_t *buffer16=(uint16_t*)buffer32;
uint16_t seqNumber=userData->last_sent_zrtp_seq_number++;
*buffer8 = 0x10;
buffer8[1]=0;
buffer16[1] = htons(seqNumber);
buffer32[1] = htonl(ZRTP_MAGIC);
buffer32[2] = htonl(session->snd.ssrc);
memcpy(buffer32+3, data, length);
uint32_t cks=zrtp_EndCksum(zrtp_GenerateCksum(buffer8, newlength-CRC_SIZE));
buffer32[newlength/4-1] = htonl(cks);
print_zrtp_packet("sent", buffer8);
// Send packet
ssize_t bytesSent = sendto(sockfd, (void*)buffer8, newlength,0,destaddr,destlen);
if (bytesSent == -1 || bytesSent < length) {
ortp_error("zrtp_sendDataZRTP: sent only %d bytes out of %d", (int)bytesSent, length);
return 0;
} else {
return 1;
}
}
