Client socket won't open using socket() function in a chat client - c

Question

So this is a work in progress right now, but when I run the commands:
./server 4444
and from a different terminal window, ./client localhost 4444
The client stops at the "Error opening socket."
I have no idea why, and any advice will be greatly appreciated. I am fully aware this code is buggy and incomplete, but I cannot move forward without first getting my client and server to connect properly.
Here is my code:
client.c
#include "../lib/sockettalk.h"
#include "../lib/my.h"
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string.h>
#include <stdio.h>
//#define MAX_SIZE=255
int main(int argc, char **argv)
{
int sockfd = socket(AF_INET, SOCK_STREAM, 0);//only need one socket since you are the only one connecting
int n;
char buffer[MAX_SIZE];
struct sockaddr_in serv_addr;
struct hostent *server;
int portnum = atoi(argv[2]);
if(argc < 3)
{
printf("Check your arguments.");
exit(0);
}
//printf("%d", portnum);
if(portnum < 2000 || portnum > 65535)//must be greater than 5000 to avoid conflictin ports
{
printf("Error, port number is out of bounds. Must be >2000 AND <65535.");
printf("Please enter a valid port number next time.");
exit(0);
}
if(sockfd < 0);
printf("Error opening socket. \n");
else
printf("Opened socket directly. \n");
if((server = gethostbyname(argv[1])) == 0)
{
printf("Error, no host. \n");
exit(0);
}
//memset(&serv_addr, '0', sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htonl(portnum);
if((connect(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr))) < 0)
{
printf("Error connecting. \n");
}
while(1)
{
//clear and write a message
memset(buffer, '0', sizeof(buffer));
if((n = write(sockfd, buffer, my_strlen(buffer))) < 0)
{
printf("Error writing to server. \n");
exit(1);
}
printf("Client: ");
printf("%s", buffer);
printf(" \n");
//clear and read
memset(buffer, '0', sizeof(buffer));
if((n = read(sockfd, buffer, MAX_SIZE)) < 0)
{
printf("Error reading from server. \n");
exit(1);
}
printf("Server: ");
printf("%s", buffer);
printf(" \n");
}
return 0;
}
server.c
#include "../lib/my.h"
#include "../lib/sockettalk.h"
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <string.h>
#include <stdio.h>
int main(int argc, char **argv)
{
int port = atoi(argv[1]);
int pid;
int n; //to read and write
char buffer[MAX_BUFFER_SIZE];
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
int newsockfd;
int clilen; //to be used in accept step as a dummy, need size of bytes
struct sockaddr_in cli_addr, serv_addr;
memset(&serv_addr, 0, sizeof(serv_addr));
if (sockfd<0)
printf("Problem openning socket.\n");
else
{
printf("Openned socket successfully.\n");
}
serv_addr.sin_family = AF_INET; //address family
serv_addr.sin_port = port; //IP port
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); //IP address, INADDR_ANY allows program to work without knowing the IP address of machine it is running on.
if(bind(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0)//assigns a name to a socket. we must also cast serv_addr to a pointer to a struct socketDDR
{
printf("Error binding socket. \n");
exit(1);
}
else
{
printf("Bound socket successfully. \n");
}
if(listen(sockfd, 5) < 0) //should be an already bound socket. 5 is the number of clients that can connect at once
{
printf("Error listning.\n");
exit(1);
}
while(1) //place into loop so that process can repeat for every new connection
{
//now a newsockfd needs to be created so that it gives every new client a unique identifir
newsockfd = accept(sockfd,(struct sockaddr*) &cli_addr, &clilen);
if(newsockfd < 0)
{
printf("Error accepting\n");
exit(1);
}
else
{
printf("Client is connected.\n");
}
if ((pid = fork()) < 0) //problem
{
printf("Error forking. \n");
exit(1);
}
else if(pid == 0) //forking is sucessful, is a child
{
close(sockfd); //closes from the child side
while(1)
{
memset(buffer, 0, sizeof(buffer));
n = read(newsockfd, buffer, MAX_BUFFER_SIZE);
if (n < 0)
{
printf("Error reading from client.\n");
exit(1);
}
printf("%s", buffer);
printf("\n");
memset(buffer, 0, sizeof(buffer));
fgets(buffer, 254, stdin);
n = write(newsockfd, buffer, strlen(buffer));
if(n < 0)
{
printf("Error writing to client.\n");
exit(1);
}
printf("Server: ");
printf("%s", buffer);
printf("\n");
}
close(sockfd);
}
}
return 0;
}

Answer 1

In the client, you aren't actually using the result of server = gethostbyname(...) anywhere. Indeed, you're leaving serv_addr.sin_addr uninitialized, so you're trying to connect to some random IP address (probably 0.0.0.0), which is of course failing.