Problems with sockets: need help

[lia!nieh at cs.utexas.edu]

I am having problem with the TCP/UDP facilities. What I want to do is to
have a server process permanently listen to two ports one created as a UPD
port and the other as a TCP port. The server will receive UPD and/or TCP
packets asynchronously. The following program is written in Sun/C++ on
SunOs-4.0.3.

The symptom are:

1. If several processes send UPD packets to the server, it works
2. If several processes send TCP packets to the server, it works
3. If several processes send UPD packets first then
   other processes send TCP packets, the sever will not receive
   the TCP packets.
4. If several processes send TCP packets first then
   other processes send UDP packets, the sever will not receive
   the UDP packets.

I need your help.  If you can figure out the problem from the following
code please e-mail me your solution.  If you need to see the rest of the
code please let me know I can send it to you.

Ko-Haw Nieh

// This is a server
// class TcpChannel and UdpChannel are C++ classes build on top of socket

#include "tcp_udp_channel.h"
#include <osfcn.h>

main(int ii,char **argv){

   TcpChannel tconnection,*tx;
   UdpChannel uconnection;
   int    tfd,ufd;
   fd_set fdset,xxfdset;
   char buf[1000];
   int size;
   int width;
   int xx;
   // argv[1] contains the host name
   uconnection.CreateService(argv[1],3503);  // listen to this udp channel
   tconnection.CreateService(argv[1],3502);  // listen to this tcp channel
   ufd = uconnection.Descriptor();	     // get the udp descriptor
   tfd = tconnection.Descriptor();	     // get the tcp descriptor
   FD_ZERO(&fdset);		
   FD_SET(ufd,&fdset);
   FD_SET(tfd,&fdset);
   width = getdtablesize();
   for(int j=0;;j++){                        // main loop
     buf[0] = '\0';
     if(select(width,&fdset,0,0,NULL) < 0){ // multiplex on udp and tcp channel
       perror("select error\n");
       exit(1);
     }
     if(FD_ISSET(ufd,&fdset)){    // a udp packet is ready
       size = read(ufd,buf,500);
       buf[size] = '\0';
       printf("UDP: %d:read %d characters, content = %s\n",j,size,buf);
       printf("------------------------\n");
     }
     else{                       // a tcp packet is ready
       if(FD_ISSET(tfd,&fdset)){
	 tx = tconnection.AcceptClient();  // returns a TcpChannel
	 xx = tx->Descriptor();            // get the descriptor of the Channel
	 FD_ZERO(&xxfdset);
         FD_SET(xx,&xxfdset);
	 if(select(width,&xxfdset,&xxfdset,0,NULL) < 0){
	   perror("select error\n");
	   exit(1);
	 }
	 size = read(xx,buf,500);
	 buf[size] = '\0';
	 printf("TCP: %d:read %d characters, content = %s\n",j,size,buf);
	 printf("------------------------\n");
	 delete tx;      // delete (close) the TcpChannel as well as its descriptor
       }
       else
       printf("a wrong descriptor is ready\n");
     }
   }
 }


-----------tcp_udp_channel.h------------------------

#ifndef tcp_udp_Channel_h
#define tcp_udp_Channel_h

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/un.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <libc.h>
#include <osfcn.h>

typedef unsigned boolean;

//static const boolean false = 0;
//static const boolean true = 1;

class TcpChannel {
public:
    TcpChannel();
    ~TcpChannel();
    void CreateService(char* host, int port);  // called by server
    boolean OpenService(char* host, int port); // called by client
    TcpChannel* AcceptClient();
    int Read(void*, int);
    int Write(void*, int);
    int Descriptor () { return fd; }
    void Close();
protected:
    int fd;      // file descriptor for read/write to the TcpChannel
    int domain;  // UNIX domain or Internet domain
    char* name;  // service name -- server site
                 // host name    -- client site
    int port;    // Internet prot number, not used for UNIX domain

};

class UdpChannel {
public:
    UdpChannel();
    ~UdpChannel();
    void CreateService(char* host, int port);    // called by server
    int OpenServiceAndSend(char* host, int port,char *buf,int z);
    int Read(void*, int);
    int Write(void*, int);
    int Descriptor () { return fd; }
    void Close();
protected:
    int fd;      // file descriptor for read/write to the UdpChannel
    int domain;  // UNIX domain or Internet domina
    char* name;  // service name -- server site
                 // host name    -- client site
    int port;    // Internet prot number, not used for UNIX domain
};

#endif

Ko-Haw Nieh,   Litton/Industrial Automation
1301 Harbor Bay Parkway, P.O. Box 4004, Alameda, CA 94501-0404
uunet!fernwood!lia!nieh      nieh at lia.com
FAX  :  415-521-5499                 Tele :  415-769-5640