/*
* process an IP packet destined to someone else...
* ARGUMENT: in_pkt - pointer to incoming packet
*
* Error processing: Check for conditions that generate ICMP packets.
* For example, TTL expired, redirect, mulformed packets, ...
* DF set and fragment,.. etc.
*
* Fragment processing: Check whether fragment is necessary .. condition already checked.
*
* Forward packet and fragments (could be multicasting)
*/
int IPProcessForwardingPacket(gpacket_t *in_pkt)
{
gpacket_t *pkt_frags[MAX_FRAGMENTS];
ip_packet_t *ip_pkt = (ip_packet_t *)in_pkt->data.data;
int num_frags, i, need_frag;
char tmpbuf[MAX_TMPBUF_LEN];
verbose(2, "[IPProcessForwardingPacket]:: checking for any IP errors..");
// all the validation and ICMP generation, processing is
// done in this function...
if (IPCheck4Errors(in_pkt) == EXIT_FAILURE)
return EXIT_FAILURE;
// find the route... if it does not exist, should we send a
// ICMP network/host unreachable message -- CHECK??
if (findRouteEntry(route_tbl, gNtohl(tmpbuf, ip_pkt->ip_dst),
in_pkt->frame.nxth_ip_addr,
&(in_pkt->frame.dst_interface)) == EXIT_FAILURE)
return EXIT_FAILURE;
// check for redirection?? -- the output interface is already found
// by the previous command.. if needed the following routine sends the
// redirects but the packet is sent to destination..
// TODO: Check the RFC for conformance??
IPCheck4Redirection(in_pkt);
// check for fragmentation -- this should return three conditions:
// FRAGS_NONE, FRAGS_ERROR, MORE_FRAGS
need_frag = IPCheck4Fragmentation(in_pkt);
switch (need_frag)
{
case FRAGS_NONE:
verbose(2, "[IPProcessForwardingPacket]:: sending packet to GNET..");
// compute the checksum before sending out.. the fragmentation routine does this inside it.
ip_pkt->ip_cksum = 0;
ip_pkt->ip_cksum = htons(checksum((uchar *)ip_pkt, ip_pkt->ip_hdr_len *2));
if (IPSend2Output(in_pkt) == EXIT_FAILURE)
{
verbose(1, "[IPProcessForwardingPacket]:: WARNING: IPProcessForwardingPacket(): Could not forward packets ");
return EXIT_FAILURE;
}
break;
case FRAGS_ERROR:
verbose(2, "[IPProcessForwardingPacket]:: unreachable on packet from %s",
IP2Dot(tmpbuf, gNtohl((tmpbuf+20), ip_pkt->ip_src)));
ICMPProcessFragNeeded(in_pkt);
break;
case MORE_FRAGS:
// fragment processing...
num_frags = fragmentIPPacket(in_pkt, pkt_frags);
verbose(2, "[IPProcessForwardingPacket]:: IP packet needs fragmentation");
// forward each fragment
for (i = 0; i < num_frags; i++)
{
if (IPSend2Output(pkt_frags[i]) == EXIT_FAILURE)
{
verbose(1, "[IPProcessForwardingPacket]:: processForwardIPPacket(): Could not forward packets ");
return EXIT_FAILURE;
}
}
deallocateFragments(pkt_frags, num_frags);
break;
default:
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
/*
* this function processes the IP packets that are reinjected into the
* IP layer by ICMP, UDP, and other higher-layers.
* There can be two scenarios. The packet can be a reply for an original
* query OR it can be a new one. The processing performed by this function depends
* on the packet type..
* IMPORTANT: src_prot is the source protocol number.
*/
int IPOutgoingPacket(gpacket_t *pkt, uchar *dst_ip, int size, int newflag, int src_prot)
{
ip_packet_t *ip_pkt = (ip_packet_t *)pkt->data.data;
ushort cksum;
char tmpbuf[MAX_TMPBUF_LEN];
uchar iface_ip_addr[4];
int status;
ip_pkt->ip_ttl = 64; // set TTL to default value
ip_pkt->ip_cksum = 0; // reset the checksum field
ip_pkt->ip_prot = src_prot; // set the protocol field
if (newflag == 0)
{
//if broadcast packet we set the address for 255.255.255.255
if(pkt->frame.bcast == TRUE)
{
//set ip to find route eg. 192.168.2.255
COPY_IP(ip_pkt->ip_dst, gHtonl(tmpbuf, dst_ip));
// find the nexthop and interface and fill them in the "meta" frame
// NOTE: the packet itself is not modified by this lookup!
if (findRouteEntry(route_tbl, gNtohl(tmpbuf, ip_pkt->ip_dst),
pkt->frame.nxth_ip_addr, &(pkt->frame.dst_interface)) == EXIT_FAILURE)
return EXIT_FAILURE;
//find interface IP
if ((status = findInterfaceIP(MTU_tbl, pkt->frame.dst_interface,
iface_ip_addr)) == EXIT_FAILURE) {
error("[IPOutgoingPacket]:: couldn't find interface ");
return EXIT_FAILURE;
}
// the outgoing packet should have the interface IP as source
COPY_IP(ip_pkt->ip_src, gHtonl(tmpbuf, iface_ip_addr));
//set broadcast IP = 255.255.255.255
uchar bcast_ip[] = IP_BCAST_ADDR;
COPY_IP(ip_pkt->ip_dst, gHtonl(tmpbuf, bcast_ip));
} else {
COPY_IP(ip_pkt->ip_dst, ip_pkt->ip_src); // set dst to original src
COPY_IP(ip_pkt->ip_src, gHtonl(tmpbuf, pkt->frame.src_ip_addr)); // set src to me
// find the nexthop and interface and fill them in the "meta" frame
// NOTE: the packet itself is not modified by this lookup!
if (findRouteEntry(route_tbl, gNtohl(tmpbuf, ip_pkt->ip_dst),
pkt->frame.nxth_ip_addr, &(pkt->frame.dst_interface)) == EXIT_FAILURE)
return EXIT_FAILURE;
}
}
else if (newflag == 1)
{
// non REPLY PACKET -- this is a new packet; set all fields
ip_pkt->ip_version = 4;
ip_pkt->ip_hdr_len = 5;
ip_pkt->ip_tos = 0;
ip_pkt->ip_identifier = IP_OFFMASK & random();
RESET_DF_BITS(ip_pkt->ip_frag_off);
RESET_MF_BITS(ip_pkt->ip_frag_off);
ip_pkt->ip_frag_off = 0;
COPY_IP(ip_pkt->ip_dst, gHtonl(tmpbuf, dst_ip));
ip_pkt->ip_pkt_len = htons(size + ip_pkt->ip_hdr_len * 4);
//printGPacket(pkt, 3, "IP_ROUTINE"); //for debug
verbose(2, "[IPOutgoingPacket]:: lookup next hop ");
// find the nexthop and interface and fill them in the "meta" frame
// NOTE: the packet itself is not modified by this lookup!
if (findRouteEntry(route_tbl, gNtohl(tmpbuf, ip_pkt->ip_dst),
pkt->frame.nxth_ip_addr, &(pkt->frame.dst_interface)) == EXIT_FAILURE) {
error("[IPOutgoingPacket]:: couldn't find route entry ");
return EXIT_FAILURE;
}
verbose(2, "[IPOutgoingPacket]:: lookup MTU of nexthop");
// lookup the IP address of the destination interface..
if ((status = findInterfaceIP(MTU_tbl, pkt->frame.dst_interface,
iface_ip_addr)) == EXIT_FAILURE) {
error("[IPOutgoingPacket]:: couldn't find interface ");
return EXIT_FAILURE;
}
// the outgoing packet should have the interface IP as source
COPY_IP(ip_pkt->ip_src, gHtonl(tmpbuf, iface_ip_addr));
//if broadcast packet we set the address for 255.255.255.255
if(pkt->frame.bcast == TRUE)
{
//set broadcast IP =
uchar bcast_ip[] = IP_BCAST_ADDR;
COPY_IP(ip_pkt->ip_dst, gHtonl(tmpbuf, bcast_ip));
}
verbose(2, "[IPOutgoingPacket]:: almost one processing the IP header.");
} else
{
error("[IPOutgoingPacket]:: unknown outgoing packet action.. packet discarded ");
return EXIT_FAILURE;
}
// compute the new checksum
cksum = checksum((uchar *)ip_pkt, ip_pkt->ip_hdr_len*2);
ip_pkt->ip_cksum = htons(cksum);
pkt->data.header.prot = htons(IP_PROTOCOL);
//FOR DEBUG
if(src_prot == OSPF_PROTOCOL) //specific modifications for OSPF_PROTOCOL
{
ospfhdr_t *ospfhdr = (ospfhdr_t *)((uchar *)ip_pkt + ip_pkt->ip_hdr_len*4);
if (ospfhdr->type == OSPF_LINK_STATUS_UPDATE &&
(COMPARE_IP(ospfhdr->ip_src, gHtonl(tmpbuf, iface_ip_addr))) == 0) {
printGPacket(pkt, 3, "IP_ROUTINE");
verbose(2,"[DEBUG] Retransmission of LSA pkt, not broadcasting\n");
//return EXIT_SUCCESS;
}
}
IPSend2Output(pkt);
verbose(2, "[IPOutgoingPacket]:: IP packet sent to output queue.. ");
return EXIT_SUCCESS;
}
/*
* this function processes the IP packets that are reinjected into the
* IP layer by ICMP, UDP, and other higher-layers.
* There can be two scenarios. The packet can be a reply for an original
* query OR it can be a new one. The processing performed by this function depends
* on the packet type..
* IMPORTANT: src_prot is the source protocol number.
*/
int IPOutgoingPacket(gpacket_t *pkt, uchar *dst_ip, int size, int newflag, int src_prot)
{
ip_packet_t *ip_pkt = (ip_packet_t *)pkt->data.data;
ushort cksum;
char tmpbuf[MAX_TMPBUF_LEN];
uchar iface_ip_addr[4];
int status;
ip_pkt->ip_ttl = 64; // set TTL to default value
ip_pkt->ip_cksum = 0; // reset the checksum field
ip_pkt->ip_prot = src_prot; // set the protocol field
if (newflag == 0)
{
COPY_IP(ip_pkt->ip_dst, ip_pkt->ip_src); // set dst to original src
COPY_IP(ip_pkt->ip_src, gHtonl(tmpbuf, pkt->frame.src_ip_addr)); // set src to me
// find the nexthop and interface and fill them in the "meta" frame
// NOTE: the packet itself is not modified by this lookup!
if (findRouteEntry(route_tbl, gNtohl(tmpbuf, ip_pkt->ip_dst),
pkt->frame.nxth_ip_addr, &(pkt->frame.dst_interface)) == EXIT_FAILURE)
return EXIT_FAILURE;
} else if (newflag == 1)
{
// non REPLY PACKET -- this is a new packet; set all fields
ip_pkt->ip_version = 4;
ip_pkt->ip_hdr_len = 5;
ip_pkt->ip_tos = 0;
ip_pkt->ip_identifier = IP_OFFMASK & random();
RESET_DF_BITS(ip_pkt->ip_frag_off);
RESET_MF_BITS(ip_pkt->ip_frag_off);
ip_pkt->ip_frag_off = 0;
COPY_IP(ip_pkt->ip_dst, gHtonl(tmpbuf, dst_ip));
ip_pkt->ip_pkt_len = htons(size + ip_pkt->ip_hdr_len * 4);
verbose(2, "[IPOutgoingPacket]:: lookup next hop ");
// find the nexthop and interface and fill them in the "meta" frame
// NOTE: the packet itself is not modified by this lookup!
if (findRouteEntry(route_tbl, gNtohl(tmpbuf, ip_pkt->ip_dst),
pkt->frame.nxth_ip_addr, &(pkt->frame.dst_interface)) == EXIT_FAILURE)
return EXIT_FAILURE;
verbose(2, "[IPOutgoingPacket]:: lookup MTU of nexthop");
// lookup the IP address of the destination interface..
if ((status = findInterfaceIP(MTU_tbl, pkt->frame.dst_interface,
iface_ip_addr)) == EXIT_FAILURE)
return EXIT_FAILURE;
// the outgoing packet should have the interface IP as source
COPY_IP(ip_pkt->ip_src, gHtonl(tmpbuf, iface_ip_addr));
verbose(2, "[IPOutgoingPacket]:: almost one processing the IP header.");
} else
{
error("[IPOutgoingPacket]:: unknown outgoing packet action.. packet discarded ");
return EXIT_FAILURE;
}
// compute the new checksum
cksum = checksum((uchar *)ip_pkt, ip_pkt->ip_hdr_len*2);
ip_pkt->ip_cksum = htons(cksum);
pkt->data.header.prot = htons(IP_PROTOCOL);
IPSend2Output(pkt);
verbose(2, "[IPOutgoingPacket]:: IP packet sent to output queue.. ");
return EXIT_SUCCESS;
}
