socket.c

#include <arpa/inet.h>
#include <assert.h>
#include <netinet/ip.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

int main() {
  char buf[1024];
  int err, num, numleft, sockfd, newsockfd;
  unsigned int client_len;
  struct sockaddr_in client_addr;
  struct sockaddr_in serv_addr;
  uint16_t port = 8080;

  memset(&serv_addr, 0, sizeof(serv_addr));
  memset(&client_addr, 0, sizeof(client_addr));
  client_len = sizeof(client_addr);
  strcpy(buf, "Hello world!\n");
  
  serv_addr.sin_family = AF_INET;
  serv_addr.sin_port = htons(port);
  serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);

  sockfd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);                         assert(sockfd != -1);
  err = bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr));       assert(err == 0);
  err = listen(sockfd, 10);                                                   assert(err == 0);

  printf("Listening on %s:%d\n", inet_ntoa(serv_addr.sin_addr), port);

  for(;;) {
    newsockfd = accept(sockfd, (struct sockaddr *)&client_addr, &client_len); assert(newsockfd != -1);
    printf("Connection from %s\n", inet_ntoa(client_addr.sin_addr));
    numleft = strlen(buf);
    while(numleft > 0) { 
      num = write(newsockfd, buf, strlen(buf));                               assert(num >= 0);
      numleft -= num;
    }
    close(newsockfd);
  }

  return 0;
}