Connection working, auth received, control packets parsed. TODO: Cleanup/filesplit and create login + terminal code.

1 files changed, 47 insertions, 0 deletions

diff --git a/udp.c b/udp.c
index b4bfb34..96fd906 100644
--- a/udp.c
+++ b/udp.c
@@ -10,6 +10,51 @@
 #include <linux/if_arp.h>
 #include <stdio.h>
 
+unsigned short udp_sum_calc(unsigned short len_udp, unsigned char src_addr[],unsigned char dest_addr[], unsigned char buff[]) {
+	unsigned short prot_udp=17;
+	unsigned short padd=0;
+	unsigned short word16;
+	unsigned long sum;
+	int i;	
+	
+	// Find out if the length of data is even or odd number. If odd,
+	// add a padding byte = 0 at the end of packet
+	if (len_udp % 2 == 1){
+		padd=1;
+		buff[len_udp]=0;
+	}
+	
+	//initialize sum to zero
+	sum=0;
+	
+	// make 16 bit words out of every two adjacent 8 bit words and 
+	// calculate the sum of all 16 vit words
+	for (i=0;i<len_udp+padd;i=i+2){
+		word16 =((buff[i]<<8)&0xFF00)+(buff[i+1]&0xFF);
+		sum = sum + (unsigned long)word16;
+	}	
+	// add the UDP pseudo header which contains the IP source and destinationn addresses
+	for (i=0;i<4;i=i+2){
+		word16 =((src_addr[i]<<8)&0xFF00)+(src_addr[i+1]&0xFF);
+		sum=sum+word16;	
+	}
+	for (i=0;i<4;i=i+2){
+		word16 =((dest_addr[i]<<8)&0xFF00)+(dest_addr[i+1]&0xFF);
+		sum=sum+word16; 	
+	}
+	// the protocol number and the length of the UDP packet
+	sum = sum + prot_udp + len_udp;
+
+	// keep only the last 16 bits of the 32 bit calculated sum and add the carries
+    	while (sum>>16)
+		sum = (sum & 0xFFFF)+(sum >> 16);
+		
+	// Take the one's complement of sum
+	sum = ~sum;
+
+	return ((unsigned short) sum);
+}
+
 //#define ETH_FRAME_LEN 1518
 unsigned short in_cksum(unsigned short *addr, int len)
 {
@@ -114,7 +159,9 @@ int sendCustomUDP(const int socket, const char *sourcemac, const char *destmac,
 	// UDP Header
 	udp->source = htons(20561);
 	udp->dest = htons(20561);
+	udp->check = 0;
 	udp->len = htons(sizeof(struct udphdr) + datalen);
+	//udp->check = udp_sum_calc(datalen+8, (unsigned char *)&(ip->saddr), (unsigned char *)&(ip->daddr), (unsigned char *)udp);
 
 	memcpy(resten, data, datalen);