static inline int tftp_parsedatapacket(const uint8_t *packet, uint16_t *opcode, uint16_t *blockno)
{
*opcode = (uint16_t)packet[0] << 8 | (uint16_t)packet[1];
if (*opcode == TFTP_DATA) {
*blockno = (uint16_t)packet[2] << 8 | (uint16_t)packet[3];
return OK;
}
#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_NET_ERROR)
else if (*opcode == TFTP_ERR) {
(void)tftp_parseerrpacket(packet);
}
#endif
return ERROR;
}
static int tftp_rcvack(int sd, uint8_t *packet, struct sockaddr_in *server,
uint16_t *port, uint16_t *blockno)
{
struct sockaddr_in from; /* The address the last UDP message recv'd from */
ssize_t nbytes; /* The number of bytes received. */
uint16_t opcode; /* The received opcode */
uint16_t rblockno; /* The received block number */
int packetlen; /* Packet length */
int retry; /* Retry counter */
/* Try up to TFTP_RETRIES times */
for (retry = 0; retry < TFTP_RETRIES; retry++)
{
/* Try for until a valid ACK is received or some error occurs */
for (;;)
{
/* Receive the next UDP packet from the server */
nbytes = tftp_recvfrom(sd, packet, TFTP_IOBUFSIZE, &from);
if (nbytes < TFTP_ACKHEADERSIZE)
{
/* Failed to receive a good packet */
if (nbytes == 0)
{
ndbg("Connection lost: %d bytes\n", nbytes);
}
else if (nbytes > 0)
{
ndbg("Short packet: %d bytes\n", nbytes);
}
else
{
ndbg("Recveid failure\n");
}
/* Break out to bump up the retry count */
break;
}
else
{
/* Get the port being used by the server if that has not yet been established */
if (!*port)
{
*port = from.sin_port;
server->sin_port = from.sin_port;
}
/* Verify that the packet was received from the correct host and port */
if (server->sin_addr.s_addr != from.sin_addr.s_addr)
{
nvdbg("Invalid address in DATA\n");
continue;
}
if (*port != server->sin_port)
{
nvdbg("Invalid port in DATA\n");
packetlen = tftp_mkerrpacket(packet, TFTP_ERR_UNKID, TFTP_ERRST_UNKID);
(void)tftp_sendto(sd, packet, packetlen, server);
continue;
}
/* Parse the error message */
opcode = (uint16_t)packet[0] << 8 | (uint16_t)packet[1];
rblockno = (uint16_t)packet[2] << 8 | (uint16_t)packet[3];
/* Verify that the message that we received is an ACK for the
* expected block number.
*/
if (opcode != TFTP_ACK)
{
nvdbg("Bad opcode\n");
#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_NET)
if (opcode == TFTP_ERR)
{
(void)tftp_parseerrpacket(packet);
}
else
#endif
if (opcode > TFTP_MAXRFC1350)
{
packetlen = tftp_mkerrpacket(packet, TFTP_ERR_ILLEGALOP, TFTP_ERRST_ILLEGALOP);
(void)tftp_sendto(sd, packet, packetlen, server);
}
/* Break out an bump up the retry count */
break;
}
/* Success! */
nvdbg("Received ACK for block %d\n", rblockno);
*blockno = rblockno;
return OK;
}
}
}
/* We have tried TFTP_RETRIES times */
ndbg("Timeout, Waiting for ACK\n");
return ERROR; /* Will never get here */
}
