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Full Discussion: UDP sockets
Special Forums IP Networking UDP sockets Post 102173 by Rakesh Ranjan on Thursday 16th of March 2006 06:22:14 AM
Old 03-16-2006
Hi strider u made few small mistakes in ur program that I'm listing down:

1) U need not convert INADDR_ANY to network long
2) In client side u may use inet_aton() to convert client IP address (that u have taken as 127.0.0.1) to in_addr struct

Apart from above I would also like to suggest u two more things that might b helpful

1) In ur server side prog u have used server structure (sockaddr_in server) to store server address as well as the address of connecting clients in 2nd last arg of recvfrom()
2) U can avoid warnings if u type cast pointer to sockaddr_in structure to sockaddr* in bind,sendto and recvfrom.

Now I enlist the rectified code

Code:
//server
main()
{
        int   sd;
        struct   sockaddr_in server,clients;
        char buf[512];
        int rc,len;

        server.sin_family = AF_INET;
        server.sin_addr.s_addr = INADDR_ANY;
        server.sin_port = htons(1234);

        sd = socket (AF_INET,SOCK_DGRAM,0);

        if(bind ( sd, (struct sockaddr*)&server, sizeof(server))==-1)
                printf("error\n");
        else
                printf("ok\n");

        len=sizeof(clients);
        printf("check\n");

        printf("check1\n");
        rc = recvfrom (sd, &buf, 2, 0,(struct sockaddr*)&clients, &len);
        printf("check2\n");
        buf[rc]= '\0';
        printf("Received: %s\n", buf);
        return 0;
}


//client
main()
{

        int     sd,a;
        struct  sockaddr_in server;

        sd = socket (AF_INET,SOCK_DGRAM,0);

        server.sin_family = AF_INET;
        inet_aton("127.0.0.1",&(server.sin_addr));
        server.sin_port = htons(1234);

        a=sendto(sd, "HI",2, 0,(struct sockaddr*)&server, sizeof(server));
        printf("sent=%d\n",a);
        exit(0);

}

Tell me if this worked for u or not esp. because i've tested it on Linux.
 

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LEARN ABOUT SUNOS

in.echod

in.echod(1M)						  System Administration Commands					      in.echod(1M)

NAME

       in.echod - UDP or TCP echo protocol service daemon

SYNOPSIS

       in.echod

       FMRI
       svc:/internet/echo:default

DESCRIPTION

       FMRI  stands  for  Fault  Management  Resource  Identifier.  It is used to identify resources managed by the Fault Manager. See fmd(1M) and
       smf(5).

       The in.echod service provides the server-side of the echo protocol. This protocol is used for debugging and bandwidth  measurement  and	is
       available on both TCP and UDP transports, through port 7.

       The in.echod service is an inetd(1M) smf(5) delegated service. The in.echod detects which transport is requested by examining the socket it
       is passed by the inetd daemon.

       TCP-based service

	   Once a connection is established, the in.echod echoes any data received from the client back to the	client.  The  server  echoes  data
	   until the client program terminates the connection.

       UDP-based service

	   The	in.echod listens for UDP datagrams. When a datagram is received, the server creates a UDP datagram containing the data it received
	   and sends it to the client.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNW			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       inetd(1M), attributes(5), smf(5)

       RFC 862

SunOS 5.10							    23 Aug 2004 						      in.echod(1M)
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