showtable.c

Linux下server与client的通信实现。Server支持多线程。附有makefile可供编译。Linux下调试通过。

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

#define TRUE 1
#define FALSE 0

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


char *readfromSocket (int sockfd, char *buffer, int length) {

  static int outstanding = 0;
  static char *pos;

  char *tmp;


  while (1) {
    
    if (outstanding == 0) {
      bzero (buffer, length);
      outstanding = read (sockfd, buffer, BUFFERLENGTH);
      printf ("Reading %d characters from socket: %s\n", outstanding, buffer);
      if (outstanding < 0) 
	error("ERROR reading from socket");
      pos = buffer;
    }

    if (outstanding == 0) {
	perror ("Reading results failed.\n");
      }
      while ((*buffer != '\0') && (outstanding > 0)) {
	outstanding--;
	buffer++;
      }
      if (*buffer == '\0') {
	outstanding--;
	buffer++;
	tmp = pos;
	pos = buffer;
	return tmp;
      }	
  }
  /* NOT REACHED */
}


void printResult (char command, char *output, char *buffer) {

  if (buffer[0] != command) {
    fprintf (stderr, "Expected part %c, got %c", command, buffer[0]);
    exit (1);
  }

  printf (output);
  printf ("%s\n", &(buffer[1]));
}

int main(int argc, char *argv[])
{
    int sockfd, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;
    char * position;
    char *endptr;
    int count, tmp, portno;
    
    if (argc != 3) {
      fprintf (stderr, "usage: %s hostname port \n", argv[0]);
      exit (1);
    }
    
    portno = strtol (argv[2],  &endptr, 10);
    if ((portno == 0 ) || (endptr == NULL) || (*endptr != '\0')) {
      fprintf (stderr, "%s: invalid port number!\n", argv[0]);
      exit (1);
    }


    char buffer[BUFFERLENGTH];
    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");

    /* Now fill the buffer with the arguments */
    
    bzero(buffer,BUFFERLENGTH);
    position = buffer;
    /* skip program name */
    argc --;
    argv ++;

    /* put command in first character */
    buffer[0] = SHOW_TABLE;
    count = BUFFERLENGTH - 2;
    position = buffer + 1;
    
    while (argc) {
      tmp = strlen (*argv);
      if (tmp > count) {
	fprintf (stderr, "Maximal string length exceeded!\n");
	exit (1);
      }
      position = memcpy (position, *argv, tmp);
      position += tmp;
      
      argc --;
      argv ++;
      
      count = count - tmp;
    }
    
    /* add the final null character */
    *position = '\0';
    position++;

    n = write (sockfd, buffer, position - buffer);
    if (n < 0) 
         error("ERROR writing to socket");

    return 0;
}