/* minazuki1-linux.c - Don Yang (uguu.org)

   07/03/02
                                                                           */

#include<pthread.h>
#include<arpa/inet.h>
#include<netinet/in.h>
#include<sys/socket.h>
#include<sys/time.h>
#include<sys/types.h>
#include<errno.h>
#include<fcntl.h>
#include<netdb.h>
#include<signal.h>
#include<unistd.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

static int writer_active;
static int sock, s2;
static struct sockaddr_in a1, a2;

static void createsocket(unsigned int ip, unsigned short port)
{
   sock = socket(PF_INET, SOCK_STREAM, 0);
   a2.sin_family = AF_INET;
   a2.sin_port = htons(port);
   a2.sin_addr.s_addr = htonl(ip);
   if( bind(sock, (struct sockaddr*)&a2, sizeof(struct sockaddr_in)) == -1 )
   {
      printf("%d: bind() failed: %d\n", __LINE__, errno);
      sock = -1;
      return;
   }
}

static void *write_loop(void *arg)
{
   static char writebuffer[1025];

   writebuffer[1024] = '\0';
   while( writer_active )
   {
      printf("> ");
      fgets(writebuffer, 1024, stdin);
      if( feof(stdin) )
         break;
      send(sock, writebuffer, strlen(writebuffer), 0);
         /* send() probably won't fail, since it's more likely in a chat
            situation that recv fails (because writer terminates connection
            first) rather than send fails (reader terminate in middle of
            receive).                                                       */
   }

   writer_active = 0;
   return NULL;
}

static void message_loop(int sock)
{
   static char readbuffer[1025];
   fd_set sset, rset;
   pthread_t wthread;
   struct timeval timeout;
   int size;

   writer_active = 1;
   pthread_create(&wthread, NULL, write_loop, NULL);
      /* We only have two threads in this process, so threads
         will probably be created successfully.               */

   FD_ZERO(&sset);
   FD_SET(sock, &sset);
   while( writer_active )
   {
      memcpy(&rset, &sset, sizeof(fd_set));
      timeout.tv_sec = 1;
      timeout.tv_usec = 0;
      select(FD_SETSIZE, &rset, NULL, NULL, &timeout);
         /* select() rarely fails */
      if( FD_ISSET(sock, &rset) )
      {
         size = recv(sock, readbuffer, 1024, 0);
         if( size <= 0 )
         {
            writer_active = 0;
            return;
         }

         readbuffer[size] = '\0';
         printf("\r  \r%s> ", readbuffer);
         fflush(stdout);
      }
   }
}

int main(int argc, char **argv)
{
   struct hostent *hostinfo;
   unsigned short port;
   fd_set sset;
   socklen_t size;

   if( argc < 3 )
      return printf("%s <remote host> <port>\n", *argv);

   if( (hostinfo = gethostbyname(argv[1])) == NULL )
   {
      if( (a1.sin_addr.s_addr = inet_addr(argv[1])) == INADDR_NONE )
         return printf("%d: inet_addr() failed: %d\n", __LINE__, errno);
   }
   else
   {
      a1.sin_addr = *(struct in_addr*)hostinfo->h_addr;
   }
   a1.sin_family = AF_INET;
   a1.sin_port = htons(port = (unsigned short)atoi(argv[2]));

   createsocket(INADDR_ANY, 0);
   if( sock == -1 )
      return 1;

   if( connect(sock, (struct sockaddr*)&a1, sizeof(struct sockaddr_in))
         == -1 )
   {
      close(sock);
      createsocket(INADDR_ANY, port);
      if( sock == -1 )
         return 1;
      if( listen(sock, 1) == -1 )
      {
         close(sock);
         return printf("%d: listen() failed: %d\n", __LINE__, errno);
      }

      FD_ZERO(&sset);
      FD_SET(sock, &sset);
      select(FD_SETSIZE, &sset, NULL, NULL, NULL);
         /* select() rarely fails */
      size = sizeof(struct sockaddr_in);
      s2 = accept(sock, (struct sockaddr*)&a1, &size);
      close(sock);
      if( s2 == -1 )
         return printf("%d: accept() failed: %d\n", __LINE__, errno);
      size = sizeof(struct sockaddr_in);
      getpeername(s2, (struct sockaddr*)&a1, &size);
         /* getpeername() rarely fails */
      printf("Server: accepted connection from %s:%hd\n",
         inet_ntoa(a1.sin_addr), ntohs(a1.sin_port));
      sock = s2;
   }
   else
   {
      printf("Client: connected to %s:%hd\n",
         inet_ntoa(a1.sin_addr), ntohs(a1.sin_port));
   }

   message_loop(sock);
   shutdown(sock, 2);
   close(sock);
   putchar('\n');
   return 0;
}