X-Git-Url: http://sjero.net/git/?p=ltp2tcp;a=blobdiff_plain;f=encap.c;h=c841ba29e5d76098a67f3bf2b26af1626a22b4a4;hp=2f08235931d94854adc8663a8859d3a8b83def2d;hb=HEAD;hpb=415ee2322fe2a27adcd10e5db2871699fc4f4f07

diff --git a/encap.c b/encap.c
index 2f08235..c841ba2 100644
--- a/encap.c
+++ b/encap.c
@@ -28,6 +28,7 @@ Notes:
 	2)Uses some special types from Linux (u_char, u_int32_t)
 ******************************************************************************/
 #include "ltp2tcp.h"
+#include "checksums.h"
 
 
 
@@ -74,6 +75,7 @@ int fill_eip4_encap(struct eip4_en_p *eip, const u_char* data, int dlen, struct
 /* encapsulation manipulation after conversion */
 int eip4_post(struct eip4_en_p *eip, int tlen, u_char* data){
 	struct iphdr *iph;
+	struct tcphdr *tcph;
 
 	/* Move data pointer to start of IPv4 header*/
 	data+=sizeof(struct ether_header);
@@ -86,7 +88,17 @@ int eip4_post(struct eip4_en_p *eip, int tlen, u_char* data){
 
 	/*Adjust IPv4 header to account for packet's total length*/
 	iph=(struct iphdr*)data;
-	iph->tot_len=htons(sizeof(struct iphdr)+tlen);
+	iph->tot_len=htons(iph->ihl*4+tlen);
+
+	/*Compute IPv4 Checksum*/
+	iph->check=0;
+	iph->check=ipv4_chksum(data,iph->ihl*4);
+
+	/*Compute TCP Checksum*/
+	data+=iph->ihl*4;
+	tcph=(struct tcphdr*)data;
+	tcph->check=0;
+	tcph->check=ipv4_pseudohdr_chksum(data, tlen, (u_char*)&iph->daddr, (u_char*)&iph->saddr, iph->protocol);
 	return 0;
 }
 
@@ -135,6 +147,10 @@ int eip4_handshake(struct eip4_en_p *eip, struct pcap_pkthdr *h){
 		iph->check=htonl(0);
 		iph->tot_len=htons(sizeof(struct iphdr)+sizeof(struct tcphdr)+4);
 
+		/*Compute IPv4 Checksum*/
+		iph->check=0;
+		iph->check=ipv4_chksum((u_char*)iph,iph->ihl*4);
+
 		/*Build TCP header*/
 		ptr+=sizeof(struct ether_header)+ sizeof(struct iphdr);
 		tcph=(struct tcphdr*)ptr;
@@ -161,6 +177,11 @@ int eip4_handshake(struct eip4_en_p *eip, struct pcap_pkthdr *h){
 		ptr++;
 		*ptr=2;
 
+		/*Compute TCP Checksum*/
+		tcph->check=0;
+		tcph->check=ipv4_pseudohdr_chksum((u_char*)tcph,tcph->doff*4,
+										(u_char*)&iph->daddr, (u_char*)&iph->saddr, iph->protocol);
+
 		/*Save To Packet Capture*/
 		pcap_dump((u_char*)state.out,&nh, data);
 
@@ -188,6 +209,10 @@ int eip4_handshake(struct eip4_en_p *eip, struct pcap_pkthdr *h){
 		iph->daddr=temp;
 		iph->tot_len=htons(sizeof(struct iphdr)+sizeof(struct tcphdr)+4);
 
+		/*Compute IPv4 Checksum*/
+		iph->check=0;
+		iph->check=ipv4_chksum((u_char*)iph,iph->ihl*4);
+
 		/*Build TCP header*/
 		ptr+=sizeof(struct ether_header)+ sizeof(struct iphdr);
 		tcph=(struct tcphdr*)ptr;
@@ -214,6 +239,11 @@ int eip4_handshake(struct eip4_en_p *eip, struct pcap_pkthdr *h){
 		ptr++;
 		*ptr=2;
 
+		/*Compute TCP Checksum*/
+		tcph->check=0;
+		tcph->check=ipv4_pseudohdr_chksum((u_char*)tcph,tcph->doff*4 ,
+									(u_char*)&iph->daddr, (u_char*)&iph->saddr, iph->protocol);
+
 		/*Save To Packet Capture*/
 		pcap_dump((u_char*)state.out,&nh, data);
 
@@ -237,6 +267,10 @@ int eip4_handshake(struct eip4_en_p *eip, struct pcap_pkthdr *h){
 		iph->check=htonl(0);
 		iph->tot_len=htons(sizeof(struct iphdr)+sizeof(struct tcphdr));
 
+		/*Compute IPv4 Checksum*/
+		iph->check=0;
+		iph->check=ipv4_chksum((u_char*)iph,iph->ihl*4);
+
 		/*Build TCP header*/
 		ptr+=sizeof(struct ether_header)+ sizeof(struct iphdr);
 		tcph=(struct tcphdr*)ptr;
@@ -257,6 +291,11 @@ int eip4_handshake(struct eip4_en_p *eip, struct pcap_pkthdr *h){
 		tcph->ack_seq=htonl(state.ack_num);
 		tcph->window=htons(WIN_FACTOR);
 
+		/*Compute TCP Checksum*/
+		tcph->check=0;
+		tcph->check=ipv4_pseudohdr_chksum((u_char*)tcph,tcph->doff*4,
+								(u_char*)&iph->daddr, (u_char*)&iph->saddr, iph->protocol);
+
 		/*Save To Packet Capture*/
 		pcap_dump((u_char*)state.out,&nh, data);
 	return 0;
@@ -307,6 +346,10 @@ int eip4_fin(struct eip4_en_p *eip){
 		iph->check=htonl(0);
 		iph->tot_len=htons(sizeof(struct iphdr)+sizeof(struct tcphdr));
 
+		/*Compute IPv4 Checksum*/
+		iph->check=0;
+		iph->check=ipv4_chksum((u_char*)iph,iph->ihl*4);
+
 		/*Build TCP header*/
 		ptr+=sizeof(struct ether_header)+ sizeof(struct iphdr);
 		tcph=(struct tcphdr*)ptr;
@@ -330,6 +373,11 @@ int eip4_fin(struct eip4_en_p *eip){
 		/*Update Sequence Number to include the fin packet in the sequence number space*/
 		state.seq_num++;
 
+		/*Compute TCP Checksum*/
+		tcph->check=0;
+		tcph->check=ipv4_pseudohdr_chksum((u_char*)tcph,tcph->doff*4,
+								(u_char*)&iph->daddr, (u_char*)&iph->saddr, iph->protocol);
+
 		/* Save To Packet Capture*/
 		pcap_dump((u_char*)state.out,&nh, data);
 
@@ -356,6 +404,10 @@ int eip4_fin(struct eip4_en_p *eip){
 		iph->daddr=temp;
 		iph->tot_len=htons(sizeof(struct iphdr)+sizeof(struct tcphdr));
 
+		/*Compute IPv4 Checksum*/
+		iph->check=0;
+		iph->check=ipv4_chksum((u_char*)iph,iph->ihl*4);
+
 		/*Build TCP header*/
 		ptr+=sizeof(struct ether_header)+ sizeof(struct iphdr);
 		tcph=(struct tcphdr*)ptr;
@@ -376,6 +428,11 @@ int eip4_fin(struct eip4_en_p *eip){
 		tcph->ack_seq=htonl(state.seq_num);
 		tcph->window=htons(WIN_FACTOR);
 
+		/*Compute TCP Checksum*/
+		tcph->check=0;
+		tcph->check=ipv4_pseudohdr_chksum((u_char*)tcph,sizeof(struct tcphdr),
+								(u_char*)&iph->daddr, (u_char*)&iph->saddr, iph->protocol);
+
 		/*Save To Packet Capture*/
 		pcap_dump((u_char*)state.out,&nh, data);
 
@@ -399,6 +456,10 @@ int eip4_fin(struct eip4_en_p *eip){
 		iph->check=htonl(0);
 		iph->tot_len=htons(sizeof(struct iphdr)+sizeof(struct tcphdr));
 
+		/*Compute IPv4 Checksum*/
+		iph->check=0;
+		iph->check=ipv4_chksum((u_char*)iph,iph->ihl*4);
+
 		/*Build TCP header*/
 		ptr+=sizeof(struct ether_header)+ sizeof(struct iphdr);
 		tcph=(struct tcphdr*)ptr;
@@ -419,6 +480,11 @@ int eip4_fin(struct eip4_en_p *eip){
 		tcph->ack_seq=htonl(state.ack_num);
 		tcph->window=htons(WIN_FACTOR);
 
+		/*Compute TCP Checksum*/
+		tcph->check=0;
+		tcph->check=ipv4_pseudohdr_chksum((u_char*)tcph,tcph->doff*4,
+								(u_char*)&iph->daddr, (u_char*)&iph->saddr, iph->protocol);
+
 		/*Save To Packet Capture*/
 		pcap_dump((u_char*)state.out,&nh, data);
 	return 0;