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server.c
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server.c
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#include<stdio.h> //For standard things
#include<stdlib.h> //malloc
#include<string.h> //memset
#include<netinet/ip_icmp.h> //Provides declarations for icmp header
#include<netinet/udp.h> //Provides declarations for udp header
#include<netinet/tcp.h> //Provides declarations for tcp header
#include<netinet/ip.h> //Provides declarations for ip header
#include<sys/socket.h>
#include<arpa/inet.h>
#include <unistd.h>
#include"ip_header.h"
#include"check_sum.h"
#include<string.h>
void ProcessPacket(unsigned char* , int);
void print_ip_header(unsigned char* , int);
void print_tcp_packet(unsigned char* , int);
void print_udp_packet(unsigned char * , int);
void PrintData (unsigned char* , int);
int sock_raw;
FILE *logfile;
int tcp=0,udp=0,icmp=0,others=0,igmp=0,total=0,i,j;
struct sockaddr_in source,dest;
int check_packet(unsigned char* Buffer,char *ip)
{
struct iphdr *iph = (struct iphdr *)Buffer;
memset(&source, 0, sizeof(source));
source.sin_addr.s_addr = iph->saddr;
memset(&dest, 0, sizeof(dest));
dest.sin_addr.s_addr = iph->daddr;
char *str;
int len=strlen(ip);
str=calloc(len+1,sizeof(char));
inet_ntop(AF_INET, &(source.sin_addr), str, INET_ADDRSTRLEN);
// printf("%s %s\n",ip,str);
if(strcmp(str,ip)==0)
{
return(1);
}else{
return(0);
}
}
int main(int argc,char *argv[])
{
int saddr_size , data_size;
struct sockaddr saddr;
struct in_addr in;
if(argc<3)
{
perror("argc error :");
exit(-1);
}
char *ip;
int len=strlen(argv[1]);
ip=calloc(len+1,sizeof(char));
strcpy(ip,argv[1]);
int port=atoi(argv[2]);
unsigned char *buffer = (unsigned char *)malloc(65536); //Its Big!
logfile=fopen("log.txt","w");
if(logfile==NULL) printf("Unable to create file.");
printf("Starting...\n");
//Create a raw socket that shall sniff
sock_raw = socket(AF_INET , SOCK_RAW , IPPROTO_TCP);
if(sock_raw < 0)
{
printf("Socket Error\n");
return 1;
}
while(1)
{
saddr_size = sizeof saddr;
//Receive a packet
data_size = recvfrom(sock_raw , buffer , 65536 , 0 , &saddr , &saddr_size);
if(data_size <0 )
{
printf("Recvfrom error , failed to get packets\n");
return 1;
}
//Now process the packet
if(check_packet(buffer,ip)){
ProcessPacket(buffer , data_size);
}
}
close(sock_raw);
printf("Finished");
return 0;
}
void ProcessPacket(unsigned char* buffer, int size)
{
//Get the IP Header part of this packet
struct ip_header *iph = (struct ip_header*)buffer;
++total;
switch (iph->protocol) //Check the Protocol and do accordingly...
{
case 6: //TCP Protocol
++tcp;
print_tcp_packet(buffer , size);
break;
default: //Some Other Protocol like ARP etc.
++others;
break;
}
printf("TCP : %d Others : %d Total : %d\r",tcp,others,total);
}
void print_ip_header(unsigned char* Buffer, int Size)
{
unsigned short iphdrlen;
struct ip_header *iph = (struct ip_header *)Buffer;
iphdrlen =5*4;
memset(&source, 0, sizeof(source));
source.sin_addr.s_addr = iph->src_addr;
memset(&dest, 0, sizeof(dest));
dest.sin_addr.s_addr = iph->dest_addr;
fprintf(logfile,"\n");
fprintf(logfile,"IP Header\n");
fprintf(logfile," |-IP Version : %d\n",(unsigned int)iph->header_ver);
fprintf(logfile," |-IP Header Length : %d DWORDS or %d Bytes\n",(unsigned int)iph->header_len,((unsigned int)(iph->header_len))*4);
fprintf(logfile," |-Type Of Service : %d\n",(unsigned int)iph->service_esn);
fprintf(logfile," |-IP Total Length : %d Bytes(Size of Packet)\n",ntohs(iph->total_length));
fprintf(logfile," |-Identification : %d\n",ntohs(iph->ident));
fprintf(logfile," |-TTL : %d\n",(unsigned int)iph->ttl);
fprintf(logfile," |-Protocol : %d\n",(unsigned int)iph->protocol);
fprintf(logfile," |-Checksum : %d\n",ntohs(iph->checksum));
fprintf(logfile," |-Source IP : %s\n",inet_ntoa(source.sin_addr));
fprintf(logfile," |-Destination IP : %s\n",inet_ntoa(dest.sin_addr));
}
void print_tcp_packet(unsigned char* Buffer, int Size)
{
unsigned short iphdrlen;
struct ip_header *iph = (struct ip_header *)Buffer;
iphdrlen = 5*4;
struct tcp_header *tcph=(struct tcp_header*)(Buffer + iphdrlen);
fprintf(logfile,"\n\n***********************TCP Packet*************************\n");
print_ip_header(Buffer,Size);
fprintf(logfile,"\n");
fprintf(logfile,"TCP Header\n");
fprintf(logfile," |-Source Port : %u\n",ntohs(tcph->source_port));
fprintf(logfile," |-Destination Port : %u\n",ntohs(tcph->dest_port));
fprintf(logfile," |-Sequence Number : %u\n",ntohl(tcph->sequ_number));
fprintf(logfile," |-Acknowledge Number : %u\n",ntohl(tcph->ack_number));
fprintf(logfile," |-Urgent Flag : %d\n",(unsigned int)tcph->bit_urg);
fprintf(logfile," |-Acknowledgement Flag : %d\n",(unsigned int)tcph->bit_ack);
fprintf(logfile," |-Push Flag : %d\n",(unsigned int)tcph->bit_psh);
fprintf(logfile," |-Reset Flag : %d\n",(unsigned int)tcph->bit_rsh);
fprintf(logfile," |-Synchronise Flag : %d\n",(unsigned int)tcph->bit_sin);
fprintf(logfile," |-Finish Flag : %d\n",(unsigned int)tcph->bit_fin);
fprintf(logfile," |-Window : %d\n",ntohs(tcph->window_size));
fprintf(logfile," |-Checksum : %d\n",ntohs(tcph->checksum));
fprintf(logfile," |-Urgent Pointer : %d\n",tcph->urgent_pointer);
fprintf(logfile,"\n");
fprintf(logfile," DATA Dump ");
fprintf(logfile,"\n");
fprintf(logfile,"IP Header\n");
PrintData(Buffer,iphdrlen);
fprintf(logfile,"TCP Header\n");
/* PrintData(Buffer+iphdrlen,tcph->doff*4);
fprintf(logfile,"Data Payload\n");
PrintData(Buffer + iphdrlen + tcph->doff*4 , (Size - tcph->doff*4-iph->ihl*4) );
fprintf(logfile,"\n###########################################################");
*/
}
void PrintData (unsigned char* data , int Size)
{
for(i=0 ; i < Size ; i++)
{
if( i!=0 && i%16==0) //if one line of hex printing is complete...
{
fprintf(logfile," ");
for(j=i-16 ; j<i ; j++)
{
if(data[j]>=32 && data[j]<=128)
fprintf(logfile,"%c",(unsigned char)data[j]); //if its a number or alphabet
else fprintf(logfile,"."); //otherwise print a dot
}
fprintf(logfile,"\n");
}
if(i%16==0) fprintf(logfile," ");
fprintf(logfile," %02X",(unsigned int)data[i]);
if( i==Size-1) //print the last spaces
{
for(j=0;j<15-i%16;j++) fprintf(logfile," "); //extra spaces
fprintf(logfile," ");
for(j=i-i%16 ; j<=i ; j++)
{
if(data[j]>=32 && data[j]<=128) fprintf(logfile,"%c",(unsigned char)data[j]);
else fprintf(logfile,".");
}
fprintf(logfile,"\n");
}
}
}