Child Process code help

[geewhan]

Hey guys, I am writing a code for a server where it would recognize multiple clients. So far the code runs, but does not recognize the child. Does anyone know the reason why?

Thank you for your time


/* A simple server in the internet domain using TCP
The port number is passed as an argument */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

#include <sys/wait.h>

void error(const char *msg)
{
perror(msg);
exit(1);
}

int main(int argc, char *argv[])
{
int sockfd, newsockfd, portno;
socklen_t clilen;
char buffer[256];
char tmp[256];
char * ptr;
struct sockaddr_in serv_addr, cli_addr;
int n, sent, length;
pid_t processid;
int childcount = 0;

if (argc < 2) {
fprintf(stderr,"ERROR, no port provided\n");
exit(1);
}

//Step 1: Create a socket
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");

//Step 2: Setup Address structure
bzero((char *) &serv_addr, sizeof(serv_addr));
portno = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);

//Step 3: Bind the socket to the port
if (bind(sockfd, (struct sockaddr *) &serv_addr,
sizeof(serv_addr)) < 0)
error("ERROR on binding");

//Step 4:Listen to the socket
listen(sockfd,5);

//Step 5: Setup an infinite loop to make connections
while(1){
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd,
(struct sockaddr *) &cli_addr,
&clilen);
if (newsockfd < 0)
error("ERROR on accept");

printf("Client Accepted!");

//fork this process into a child and parent
processid = fork();
printf("Child! %d", processid);
//Check the return value given by fork(), if negative then error,
//if 0 then it is the child.
if ( processid == -1){
error("fork()");
}else if (processid == 0){
/*Child Process*/

close(sockfd);
//loop until client closes
while (1){
//read string from client
bzero(buffer,256);
do{
bzero(tmp,256);
tmp[n] = '\0';
n = read(newsockfd,tmp,255);
if (n < 0) error("ERROR reading from socket");
if (n == 0) break;
strncat(buffer, tmp, n-1);
buffer[n-1] = ' ';
}while (tmp[n-1] != '\n');
buffer[ strlen(buffer) ] = '\n';

if (n == 0) break;

//write string back to client
sent = 0;
ptr = buffer;
length = strlen(buffer);
while (sent < length ){
n = write(newsockfd, ptr, strlen(ptr) );
if (n < 0) error("ERROR writing to socket");
sent += n;
ptr += n;
}
}
close(newsockfd);
//Child Exits
exit(0);
}//End of if statement processid

//Parent Process
printf("Child process spawned with id number: %d\n",processid);

//increment the number of children processes
childcount++;

while(childcount){
processid = waitpid( (pid_t) - 1, NULL, WNOHANG );
if (processid < 0) error("waitpid()");
else if (processid == 0) break;
else childcount--;
}

}//End of Main While loop
close(sockfd);
exit(0);
}