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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 MOJAVE

in

in.h(3HEAD)							      Headers							       in.h(3HEAD)

NAME

       in.h, in - Internet Protocol family

SYNOPSIS

       #include <netinet/in.h>

DESCRIPTION

       The <netinet/in.h> header defines the following types through typedef:

       in_port_t       An unsigned integral type of exactly 16 bits.

       in_addr_t       An  unsigned  integral  type  of exactly 32 bits. The <netinet/in.h> header defines the in_addr structure that includes the
		       following member:

       The <netinet/in.h> header defines the in_addr structure that includes the following member:

       in_addr_t       s_addr

       The <netinet/in.h> header defines the type sa_family_t as described in socket.h(3HEAD).

       The <netinet/in.h> header defines the following macros for use as values of the level argument of getsockopt() and setsockopt():

       IPPROTO_IP	       Dummy for  IP

       IPPROTO_ICMP	       Control message protocol

       IPPROTO_TCP	       TCP

       IPPROTO_UDP	       User datagram protocol The <netinet/in.h> header defines the following macros for use as destination addresses  for
			       connect(), sendmsg(), and sendto():

       INADDR_ANY	       Local host address

       INADDR_BROADCAST        Broadcast address

       The  <netinet/in.h>  header  defines the sockaddr_in structure that is used to store addresses for the Internet protocol family.  Values of
       this type must be cast to struct sockaddr for use with the socket interfaces.

   Default
       For applications that do not require standard-conforming behavior (those that use the socket interfaces described in section(3SOCKET)	of
       the reference manual; see Intro(3) and standards(5)), the <netinet/in.h> header defines the sockaddr_in structure that includes the follow-
       ing members:

       sa_family_t     sin_family
       in_port_t       sin_port
       struct in_addr  sin_addr
       char	       sin_zero[8]

   Standard conforming
       For applications that require standard-conforming behavior (those that use the socket interfaces described in section(3XNET) of the refer-
       ence  manual;  see Intro(3) and standards(5)), the <netinet/in.h> header defines the sockaddr_in structure that includes the following mem-
       bers:

       sa_family_t     sin_family
       in_port_t       sin_port
       struct in_addr  sin_addr
       unsigned char   sin_zero[8]

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       Intro(3), connect(3SOCKET), connect(3XNET),  getsockopt(3SOCKET),  getsockopt(3XNET),  sendmsg(3SOCKET),  sendmsg(3XNET),  sendto(3SOCKET),
       sendto(3XNET), setsockopt(3SOCKET), setsockopt(3XNET), socket.h(3HEAD), attributes(5), standards(5)

SunOS 5.10							    30 Aug 2002 						       in.h(3HEAD)
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