client.c

一个C编写网络广播的程序

/* client.c -- main client source code
 *  
 * This file is part of 'netcast' program, released under BSD License. 
 * (c) 2001-2002 Stanis砤w Pa秌o <[e-mail]>. All rights reserved. 
 */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include "mdist.h"
#include "mdtcp.h"
#include "mcast.h"
#include "util.h"

int main(int argc, char *argv[]) {
  int ms,ts;                                      /* multicast/tcp sockets */
  struct mdmsg *pkt,*tmp;                         /* receive buffers */
  int i,c,r,z;                                    /* counters */
  uint32_t l;                                     /* repeat block num */
  fd_set rfds;                                    /* 4 select */
  struct timeval tv;
  long rep=0,tot=0;                               /* stats */
  long long size=0;
  uint8_t byt;                                    /* single-byte messages */
  u_short port=0;                                 /* server port */
  struct mdreq *req;                              /* request head */
  uint32_t *rqb;                                  /* request body */
  char rqbuf[sizeof(struct mdreq)+ROUND*sizeof(uint32_t)];  /* request - buf*/
  
  if (argc<2) {
    printf("Usage: client IP [port]\n");
    return 0;
  }
  if (argc>2) port=atoi(argv[2]);  
 
  /* Connect to server, get multicast group & port, open multicast socket */
  ts = mdtcp_open_client(argv[1],port);
  md_init();
  if (read_all(ts,&mdini,sizeof(struct mdinit))!=sizeof(struct mdinit))
    ERROR("error while reading initial data");
  ms = init_mcast_socket(&mdini.group);
  /*  set_nonblock(ms); */
  /* Init buffers */
  pkt = (struct mdmsg *) malloc(MMSIZE);
  req=(struct mdreq *) rqbuf;
  rqb=(uint32_t *) (rqbuf+sizeof(struct mdreq));  
  tmp = pkt;
  i = ts; if (i<ms) i=ms;
  i++;
  FD_ZERO(&rfds);

  do {
    /* Start a segment */
    if (read_all(ts,&mdhead,sizeof(struct mdctl))<sizeof(struct mdctl)) 
      ERROR("Error reading segment header");
    byt=CLIENT_READY;
    write(ts,&byt,1);
    c=0;
    z=1;
    if (mdhead.pkt) do {    
      /* Read packets from multicast and check tcp for end mark */
      FD_SET(ts,&rfds);FD_SET(ms,&rfds);
      tv.tv_sec=6;tv.tv_usec=0;
      if ((r=select(i,&rfds,0,0,&tv))<0) ERROR("select error");
      if (r>0) {
        /* Read multicast packet */
        if (FD_ISSET(ms,&rfds)) {
          if (tmp) pkt = tmp;
          r=recv(ms,pkt,MMSIZE,0);
          if (r<=0) ERROR("error on multicast socket"); 
          if (r<sizeof(struct mdmsg) ) {
            MSG(7,"Truncated packet received (%d bytes)",r);
          } else {
            if (r!=pkt->siz+sizeof(struct mdmsg)) {
              MSG(7,"Truncated packet received (%d of %d bytes)",r,pkt->siz+sizeof(struct mdmsg)); 
            } else {
              tmp = md_put(pkt);
              if (!tmp) MSG(5,"Malformed packet");
              if (tmp && !tmp->siz) c++;
            }
          } 
        /* Check tcp, only if there was no data on multicast - there may be more */
        } else if (FD_ISSET(ts,&rfds)) {
          /* no more data */
          MSG(6,"No more data");
          if (read(ts,&byt,1)<1)
            ERROR("Error on TCP synchronization");
          r=0;z=0;
        }
      }
    } while (r>0 && c<mdhead.pkt);
    if (c==mdhead.pkt) MSG(6,"All packets received");
    if (z && read(ts,&byt,1)<1) 
      ERROR("Error on TCP synchronization");
    req->ack=mdhead.blk;
    req->rqc=0;
    /* Construct request */
    if (c<mdhead.pkt) {
      for (l=0;l<mdhead.pkt;l++) if (!mdbuf[l]->siz) {
        MSG(6,"Requesting packet %u",l+mdhead.base);
        rqb[req->rqc]=l+mdhead.base;
        req->rqc++;
      }
    }
    /* Send request */
    if (req->rqc>0) {
      byt=CLIENT_REQ;
      write(ts,&byt,1);
      write(ts,req,sizeof(struct mdreq)+(req->rqc)*sizeof(uint32_t));
      /* read repeated blocks via TCP */
      for (l=0;l<req->rqc;l++) {
        if (tmp) pkt = tmp;
        r=read_all(ts,pkt,sizeof(struct mdmsg));
        if (r!=sizeof(struct mdmsg)) ERROR("Error on tcp socket");
        r=read_all(ts,((char *) pkt )+sizeof(struct mdmsg),pkt->siz);
        if (r!=pkt->siz) ERROR("Error on tcp socket received %d of %d",r,pkt->siz);
        tmp = md_put(pkt);
        if (!tmp) ERROR("Malformed packet on tcp socket");
        MSG(6,"Received packet %u",pkt->seq);
      } 
      rep+=req->rqc;
    }
    tot+=mdhead.pkt;size+=mdhead.siz;
//    MSG(4,"Received segment: %d bytes in %d packets",mdhead.siz,mdhead.pkt);
    fprintf(stderr,"\rnetcast: received %lld bytes in %ld packets %ld repeats",size,tot,rep);
    /* Write data to stdout */
    if (mdhead.pkt) md_flush(1);
    byt=CLIENT_START;
    write(ts,&byt,1);
  } while (mdhead.pkt); 
  shutdown(ts,2);
  fprintf(stderr,"\nnetcast: done.\n");
//  MSG(4,"Total %ld packets %ld repeated",tot,rep);  
  return 0;
}