sever client exercise

client.c

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

void error(const char *msg){
  perror(msg);
  exit(0);
}

int main(int argc, char *argv[]){
  int sockfd, portno, n;
  struct sockaddr_in serv_addr;
  struct hostent *server;
  char *buffer;
  FILE *fp;

  if (argc < 3) {
     fprintf(stderr,"usage %s hostname port\n", argv[0]);
     exit(0);
  }

  portno = atoi(argv[2]);
  sockfd = socket(AF_INET, SOCK_STREAM, 0);
  if (sockfd < 0) error("ERROR opening socket");

  server = gethostbyname(argv[1]);
  if (server == NULL) {
    fprintf(stderr,"ERROR, no such host\n");
    exit(0);
  }

  bzero((char *) &serv_addr, sizeof(serv_addr));
  serv_addr.sin_family = AF_INET;
  bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);
  serv_addr.sin_port = htons(portno);

  if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) 
    error("ERROR connecting");

  printf("Sending data.");
  if((fp = fopen("text.dat", "r")) == NULL) {
    printf("file open error!!\n");
    exit(0);
  }

  buffer = (char *) malloc(1024);
  while (fgets(buffer, 1024, fp) != NULL){
    write(sockfd, buffer, strlen(buffer));
  }
  free(buffer);
  fclose(fp);

  bzero(buffer,256);
  n = read(sockfd,buffer,255);
  if (n < 0) error("ERROR reading from socket");

  printf("%s\n",buffer);
  close(sockfd);
  return 0;
}

sever.c

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

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

void dostuff(int sock){
  int n;
  char *buffer;

  buffer = (char *) malloc(1024);   
  n = read(sock, buffer, 1024);
  if(n < 0) error("ERROR reading from socket");

  printf("Here is the message: %s\n",buffer);
  n = write(sock, "I got your message", 18);
  if(n < 0) error("ERROR writing to socket");
  free(buffer);
}

int main(int argc, char *argv[]){
  int sockfd, newsockfd, portno, pid;
  socklen_t clilen;
  struct sockaddr_in serv_addr, cli_addr;

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

  sockfd = socket(AF_INET, SOCK_STREAM, 0);
  if (sockfd < 0) error("ERROR opening socket");

  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);
  if(bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
    error("ERROR on binding");

  listen(sockfd,5);
  clilen = sizeof(cli_addr);
  while(1){
    newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);
    if(newsockfd < 0) error("ERROR on accept");

    pid = fork();
    if(pid < 0) error("ERROR on fork");

    if(pid == 0){
     close(sockfd);
     dostuff(newsockfd);
     exit(0);
    } else {
     close(newsockfd);
    }
  }

  close(sockfd);
  return 0;
}

from Tokyo Zone a to b:

[ec2-user@ip-10-160-41-240 ~]$ time ./client 176.34.63.81 80
Sending data... I got your message.

real    0m0.005s
user    0m0.000s
sys     0m0.002s

from Tokyo to Virginia:

[ec2-user@ip-10-80-207-28 ~]$ time ./client 176.34.63.81 80
Sending data... I got your message.

real    0m0.408s
user    0m0.001s
sys     0m0.002s