ip-whois.c

/*
 * @brief
 * Whois client program
 * 
 * @details
 * This program shall fetch whois data for a IPv4 address.
 * 
 * @author Silver Moon ( m00n.silv3r@gmail.com )
 * http://www.binarytides.com/c-code-to-perform-ip-whois/
 * */

#include<stdio.h>	//scanf , printf
#include<string.h>	//strtok
#include<stdlib.h>	//realloc
#include<sys/socket.h>	//socket
#include<netinet/in.h> //sockaddr_in
#include<arpa/inet.h>	//getsockname
#include<netdb.h>	//hostent
#include<unistd.h>	//close

int main(int argc , char *argv[])
{
	char ip[100] , *data = NULL;
	
	printf("Enter ip address to whois : ");
	scanf("%s" , ip);
	
	get_whois(ip , &data);
	printf("\n\n");
	puts(data);
	
	free(data);
	return 0;
}

/**
	Get the whois content of an ip
	by selecting the correct server
*/
void get_whois(char *ip , char **data) 
{
	char *wch = NULL, *pch , *response = NULL;
	
	if(whois_query("whois.iana.org" , ip , &response))
	{
		printf("Whois query failed");
	}
	
	pch = strtok(response , "\n");
	
	while(pch != NULL)
	{
		//Check if whois line
		wch = strstr(pch , "whois.");
		if(wch != NULL)
		{
			break;
		}

		//Next line please
		pch = strtok(NULL , "\n");
	}
	
	if(wch != NULL)
	{
		printf("\nWhois server is : %s" , wch);
		whois_query(wch , ip , data);
	}
	else
	{
		*data = malloc(100);
		strcpy(*data , "No whois data");
	}
	
	return;
}

/*
 * Perform a whois query to a server and record the response
 * */
int whois_query(char *server , char *query , char **response)
{
	char ip[32] , message[100] , buffer[1500];
	int sock , read_size , total_size = 0;
	struct sockaddr_in dest;
	 
	sock = socket(AF_INET , SOCK_STREAM , IPPROTO_TCP);
     
    //Prepare connection structures :)
    memset( &dest , 0 , sizeof(dest) );
    dest.sin_family = AF_INET;
     
	printf("\nResolving %s..." , server);
	if(hostname_to_ip(server , ip))
	{
		printf("Failed");
		return 1;
	}
	printf("%s" , ip);    
	dest.sin_addr.s_addr = inet_addr( ip );
	dest.sin_port = htons( 43 );

	//Now connect to remote server
	if(connect( sock , (const struct sockaddr*) &dest , sizeof(dest) ) < 0)
	{
		perror("connect failed");
	}
	
	//Now send some data or message
	printf("\nQuerying for ... %s ..." , query);
	sprintf(message , "%s\r\n" , query);
	if( send(sock , message , strlen(message) , 0) < 0)
	{
		perror("send failed");
	}
	
	//Now receive the response
	while( (read_size = recv(sock , buffer , sizeof(buffer) , 0) ) )
	{
		*response = realloc(*response , read_size + total_size);
		if(*response == NULL)
		{
			printf("realloc failed");
		}
		memcpy(*response + total_size , buffer , read_size);
		total_size += read_size;
	}
	printf("Done");
	fflush(stdout);
	
	*response = realloc(*response , total_size + 1);
	*(*response + total_size) = '\0';
	
	close(sock);
	return 0;
}

/*
 * @brief
 * Get the ip address of a given hostname
 * 
 * */
int hostname_to_ip(char * hostname , char* ip)
{
	struct hostent *he;
	struct in_addr **addr_list;
	int i;
		
	if ( (he = gethostbyname( hostname ) ) == NULL) 
	{
		// get the host info
		herror("gethostbyname");
		return 1;
	}

	addr_list = (struct in_addr **) he->h_addr_list;
	
	for(i = 0; addr_list[i] != NULL; i++) 
	{
		//Return the first one;
		strcpy(ip , inet_ntoa(*addr_list[i]) );
		return 0;
	}
	
	return 0;
}