SimpleServer.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

const char APRESSMESSAGE[] = "APRESS - For Professionals, By Professionals!\n";
int main(int argc, char *argv[]) {
    int simpleSocket = 0;
    int simplePort = 0;
    int returnStatus = 0;
    struct sockaddr_in simpleServer;
    if (2 != argc) {
	fprintf(stderr, "Usage: %s <port>\n", argv[0]);
	exit(1);
    }
    simpleSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (simpleSocket == -1) {
	fprintf(stderr, "Could not create a socket!\n");
	exit(1);
    }
    else {
	fprintf(stderr, "Socket created!\n");
    }
    /* retrieve the port number for listening */
    simplePort = atoi(argv[1]);
    /* set up the address structure */
    /* use INADDR_ANY to bind to all local addresses */
    bzero(&simpleServer, sizeof(simpleServer));
    simpleServer.sin_family = AF_INET;
    simpleServer.sin_addr.s_addr = htonl(INADDR_ANY);
    simpleServer.sin_port = htons(simplePort);
    /* bind to the address and port with our socket */
    returnStatus = bind(simpleSocket,
	    (struct sockaddr *)&simpleServer,
	    sizeof(simpleServer));
    if (returnStatus == 0) {
	fprintf(stderr, "Bind completed!\n");
    }
    else {
	fprintf(stderr, "Could not bind to address!\n");
	close(simpleSocket);
	exit(1);
    }/* let's listen on the socket for connections */
    returnStatus = listen(simpleSocket, 5);
    if (returnStatus == -1) {
	fprintf(stderr, "Cannot listen on socket!\n");
	close(simpleSocket);
	exit(1);
    }
    while (1)
    {
	struct sockaddr_in clientName = { 0 };
	int simpleChildSocket = 0;
	int clientNameLength = sizeof(clientName);
	/* wait here */
	simpleChildSocket = accept(simpleSocket,
		(struct sockaddr *)&clientName,
		&clientNameLength);
	if (simpleChildSocket == -1) {
	    fprintf(stderr, "Cannot accept connections!\n");
	    close(simpleSocket);
	    exit(1);
	}
	/* handle the new connection request */
	/* write out our message to the client */
	write(simpleChildSocket, APRESSMESSAGE, strlen(APRESSMESSAGE));
	close(simpleChildSocket);
    }
    close(simpleSocket);
    return 0;
}