void NAT_ALG_TCP_checksum
(
IP_HEADER_PTR ip_header_ptr /* [IN] pointer to IP header */
)
{ /* Body */
TRANSPORT_UNION transport;
uint16_t checksum;
uint16_t protocol;
uint16_t iplen = IPH_LEN(ip_header_ptr);
uint16_t len = mqx_ntohs(ip_header_ptr->LENGTH) - iplen;
/* Get TCP header */
transport.PTR = TRANSPORT_PTR(ip_header_ptr);
mqx_htons(transport.TCP_PTR->checksum, 0); /* Clear checksum field */
protocol = mqx_ntohc(ip_header_ptr->PROTOCOL); /* PROTOCOL */
checksum = (uint16_t) _mem_sum_ip(protocol, 8, ip_header_ptr->SOURCE); /* IP SRC and DST ADDR */
checksum = (uint16_t) _mem_sum_ip(checksum, len, transport.PTR);
/* TCP LENGTH */
checksum = IP_Sum_immediate(checksum, len);
checksum = IP_Sum_invert(checksum);
mqx_htons(transport.TCP_PTR->checksum, checksum);
} /* Endbody */
DNAT_RULE_STRUCT_PTR DNAT_lookup_rule
(
NAT_CFG_STRUCT_PTR nat_cfg_ptr,
IP_HEADER_PTR ip_header_ptr,
bool pub_to_prv
)
{ /* Body */
TRANSPORT_UNION transport;
DNAT_ELEMENT_STRUCT_PTR element_ptr;
_ip_address source_ip = mqx_ntohl(ip_header_ptr->SOURCE);
uint32_t ip_protocol;
uint16_t source_port, destination_port; /* source port and destination port */
transport.PTR = TRANSPORT_PTR(ip_header_ptr);
ip_protocol = mqx_ntohc(ip_header_ptr->PROTOCOL);
/* NAT spports ICMP, UDP and TCP transport layer protocols */
switch (ip_protocol) {
case IPPROTO_TCP:
destination_port = mqx_ntohs(transport.TCP_PTR->dest_port);
source_port = mqx_ntohs(transport.TCP_PTR->source_port);
break;
case IPPROTO_UDP:
destination_port = mqx_ntohs(transport.UDP_PTR->DEST_PORT);
source_port = mqx_ntohs(transport.UDP_PTR->SRC_PORT);
break;
case IPPROTO_ICMP:
/* Allow all ICMP request/reply */
return NULL;
} /* Endswitch */
element_ptr = (DNAT_ELEMENT_STRUCT_PTR) _queue_head(&nat_cfg_ptr->RULE_QUEUE);
/*
** Check for the target port and then forward the packet to the corresponding
** DNAT rule target ip.
*/
while (element_ptr != NULL) {
if (element_ptr->RULE.IP_PROTOCOL == ip_protocol) {
if (pub_to_prv) {
if ((destination_port >= element_ptr->RULE.PUBLIC_START_PORT) &&
(destination_port <= element_ptr->RULE.PUBLIC_END_PORT)) {
break;
}
} else {
if ((source_ip == element_ptr->RULE.PRIVATE_IP) &&
(source_port >= element_ptr->RULE.PRIVATE_START_PORT) &&
(source_port <= element_ptr->RULE.PRIVATE_END_PORT)) {
break;
}
}
}
element_ptr = (DNAT_ELEMENT_STRUCT_PTR) _queue_next(&nat_cfg_ptr->RULE_QUEUE, &element_ptr->ELEMENT);
} /* Endwhile */
if (element_ptr!=NULL) {
return &element_ptr->RULE;
} else {
return NULL;
}
}/* Endbody */
uint_32 NAT_ALG_tftp_apply
(
RTCSPCB_PTR _PTR_ pcb_ptr_ptr, /* [IN/OUT] PCB containing packet */
boolean pub_to_prv, /* [IN] Direction of packet */
pointer alg_cfg_ptr, /* [IN] Pointer to TFTP config */
pointer _PTR_ session_ptr_ptr /* [OUT] Pointer to session */
)
{ /* Body */
NAT_SESSION_STRUCT_PTR nat_session_ptr = *((NAT_SESSION_STRUCT_PTR *)session_ptr_ptr);
uchar_ptr data_ptr = (pointer)RTCSPCB_DATA(*pcb_ptr_ptr);
IP_HEADER_PTR ip_header_ptr = (IP_HEADER_PTR)(pointer)data_ptr;
TRANSPORT_UNION transport;
TFTP_HEADER_PTR tftp_header_ptr;
uint_16 opcode, block;
if (nat_session_ptr == NULL) {
return RTCS_OK;
} /* Endif */
/* TFTP uses UDP */
if (ntohc(ip_header_ptr->PROTOCOL) != IPPROTO_UDP) {
return RTCS_OK;
} /* Endif */
transport.PTR = TRANSPORT_PTR(ip_header_ptr);
/* The UDP length should be long enough to contain a TFTP header */
if (ntohs(transport.UDP_PTR->LENGTH) < sizeof(UDP_HEADER) + sizeof(TFTP_HEADER)) {
return RTCS_OK;
} /* Endif */
tftp_header_ptr = (TFTP_HEADER_PTR)(pointer)(transport.UDP_PTR + 1);
opcode = ntohs(tftp_header_ptr->OP);
block = ntohs(tftp_header_ptr->BLOCK);
/*
** A normal reply should have: OP 3 (DATA) and BLOCK 1 (first block) or
** an OP 4 and BLOCK 0. Error replies should have: OP 5, and a variable
** error code
*/
if ((opcode != 3 || block != 1) &&
(opcode != 4 || block != 0) &&
(opcode != 5))
{
return RTCS_OK;
} /* Endif */
if (nat_session_ptr->SNAT_OR_DNAT == SNAT) {
/* We only need to consider the first packet returned by the server */
if (!pub_to_prv) {
return RTCS_OK;
} /* Endif */
/* Make sure port number is the TFTP port number */
if (nat_session_ptr->PUB_PORT != IPPORT_TFTP) {
return RTCS_OK;
} /* Endif */
/* Set new server port number */
nat_session_ptr->PUB_PORT = ntohs(transport.UDP_PTR->SRC_PORT);
} else {
/* We only need to consider the first packet returned by the server */
if (pub_to_prv){
return RTCS_OK;
} /* Endif */
/* Make sure port number is the TFTP port number */
if (nat_session_ptr->PRV_PORT != IPPORT_TFTP) {
return RTCS_OK;
} /* Endif */
/* Set new server port number */
nat_session_ptr->PRV_PORT = ntohs(transport.UDP_PTR->SRC_PORT);
} /* Endif */
return RTCS_OK;
} /* Endbody */
