segmentation fault - socket programming - c

Question

I'm having a problem with running a small block of code. This is regarding socket programming in C. What I'm trying to do is have a client communicate to a server on two different ports. But when i'm trying to compile the client code, i get 'segmentation fault'. I'm giving my client code here. Please let me know what's going wrong.
#include<stdio.h>
#include<stdbool.h>
#include<string.h>
#include<stdlib.h>
#include<time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
int main(int argc,char *argv[])
{
int sockfd,newsockfd,sockfd_infinite,sockfd_kitchen,portno,portno1,n,no_of_tables;
struct sockaddr_in serv_addr,kitchen_addr;
struct hostent *server,*kitchen;
struct timeval time_out;
time_out.tv_sec = 15; // 15 seconds
time_out.tv_usec = 0; // 0 milliseconds
// server=gethostbyname(argv[1]);
// char buffer[256];
portno=atoi(argv[2]);
portno1=atoi(argv[4]);
sockfd=socket(AF_INET,SOCK_STREAM,0);
if(sockfd==-1)
error("\nError creating socket");
server=gethostbyname(argv[1]);
serv_addr.sin_family=AF_INET;
serv_addr.sin_port=htons(portno);
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,
server->h_length);
sockfd_kitchen=socket(AF_INET,SOCK_STREAM,0);
if(sockfd_kitchen==-1)
error("\nError creating socket");
kitchen=gethostbyname(argv[3]);
kitchen_addr.sin_family=AF_INET;
kitchen_addr.sin_port=htons(portno1);
bcopy((char *)kitchen->h_addr,
(char *)&kitchen_addr.sin_addr.s_addr,
kitchen->h_length);
n=connect(sockfd_kitchen,(struct sockaddr *)&kitchen_addr,sizeof(kitchen_addr));
if(n==-1)
error("\nError connecting to kitchen");
n=connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr));
if(n==-1)
error("\nError connecting to server");
return 0;
}
So the idea behind this code is - there is a client and there is a server. This client wants to communicate with the server on two different ports as if the client is talking to two different servers. I'm doing this on my laptop giving in the server names as 'localhost' for both the server names and different port numbers. Like you see in my code, I have two pointer variables for the two servers namely, *server and *kitchen.
Eg:
./thiscode localhost 15535 localhost 12345
In the example I've mentioned, this is how I'm compiling my client code. argv[1] is the first "localhost" (server name) and argv[2] is the port number of the first server. The second "localhost" and '12345' are the second server's name and port number.
Like I've said before, I'm trying to have three windows on my laptop running three different codes (one for client and two for servers). My two server codes compile without any problem but my client code gets this 'segmentation' fault. Please let me know where I'm going wrong.
Thanks.

Answer 1

For a start, you should be checking the return values from gethostbyname:
The gethostbyname() and gethostbyaddr() functions return the hostent structure or a NULL pointer if an error occurs. On error, the h_errno variable holds an error number.

Answer 2

It seems that the problem is in bcopy() function call.
You have not declared space for the variable before copying stuff into it, and hence you saw a segmentation fault.
Enter the following code before the bcopy() statement to remove the Seg-fault:
serv_addr.sin_addr.s_addr=malloc(sizeof(unsigned long));