server.c

UNIX/Linux环境下使用UNIX domain协议实现的客户端和服务器端程序

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

#define LISTENQ	5

int main(int argc, char **argv)
{
  int fd;

  if (argc < 2)
  {
    fprintf(stdout, "Usage: %s <path>\n", argv[0]);
    exit(1);
  }

  // XXX: step 1, socket();
  //int socket(int domain, int type, int protocol);
  if ((fd = socket(PF_LOCAL, SOCK_STREAM, 0)) < 0)
  {
    fprintf(stderr, "socket() failed: %s\n", strerror(errno));
    exit(1);
  }

  unlink(argv[1]);

  // XXX: step 2, bind() (optional)
  struct sockaddr_un local_address;

  memset(&local_address, 0, sizeof(local_address));
  local_address.sun_family = PF_LOCAL;
  memcpy(local_address.sun_path, argv[1], strlen(argv[1]));

  //int bind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen);
  if (bind(fd, (struct sockaddr *) &local_address, sizeof(local_address)) < 0)
  {
    fprintf(stderr, "bind() failed: %s\n", strerror(errno));
    // FIXME:
    close(fd);
    exit(1);
  }

  // XXX: step 3, listen();
  // int listen(int s, int backlog);
  if (listen(fd, LISTENQ) < 0)
  {
    fprintf(stderr, "listen() failed: %s\n", strerror(errno));
    // FIXME:
    close(fd);
    exit(1);
  }

  // XXX: step 4, accept();
  int new_accepted_socket;
  struct sockaddr_un peer_address;
  socklen_t peer_address_length;

  ssize_t written;
  char *welcome_message = "welcome to unix domain programming.";

  for (;;)
  {
    peer_address_length = sizeof(peer_address);

    //int accept(int s, struct sockaddr *addr, socklen_t *addrlen);
    if ((new_accepted_socket = accept(fd, (struct sockaddr *) &peer_address, &peer_address_length)) < 0)
    {
      fprintf(stderr, "accept() failed: %s\n", strerror(errno));
      // FIXME:
      close(fd);
      exit(1);
    }

    fprintf(stdout, "Accepted new connection %d from %s.\n", new_accepted_socket, peer_address.sun_path);

    // XXX: step 4, r/w
    // FIXME: maybe we should use a loop to write all data to client
    //ssize_t write(int fd, const void *buf, size_t count);
    if ((written = write(new_accepted_socket, welcome_message, strlen(welcome_message))) < 0)
    {
      fprintf(stderr, "write() failed: %s\n", strerror(errno));
      // FIXME:
      close(new_accepted_socket);
      close(fd);
      exit(1);
    }
    else
    {
      fprintf(stdout, "written %d bytes to %d.\n", written, new_accepted_socket);
    }

    close(new_accepted_socket);
  }

  // XXX: step 5, close()
  close(fd);

  return 0;
}