Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!esosun!ucsdhub!hp-sdd!artecon!tony
From: tony@artecon.artecon.UUCP (Anthony D. Parkhurst)
Newsgroups: comp.unix.questions
Subject: Another problem with recvfrom socket call
Message-ID: <438@artecon.artecon.UUCP>
Date: Tue, 5-May-87 13:50:39 EDT
Article-I.D.: artecon.438
Posted: Tue May  5 13:50:39 1987
Date-Received: Thu, 7-May-87 06:39:39 EDT
Organization: Artecon Inc., San Diego
Lines: 97
Keywords: help


Ok, I am now using SOCK_DGRAM, and the recvfrom call is successful,
except that it doesn't put the sender's address in the 'from' parameter.

Also, the manual says that if the from parameter is non-zero (not a null 
pointer), then it fills in the sender's address.  This implies that if
I don't want the address, I can just pass a NULL pointer, But, this
errors with "Bad Address".

( BTW, I am using Sun 3.2 )

(Oh, BTW, please don't tell me that this will only work with AF_INET and
NOT AF_UNIX, I would rather it work in the UNIX domain :-)

Here are the program frags:

Server:

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>

#define SOCKNAME "/tmp/tonys"

main()
{
int s,ns; /* socket descriptors */
static struct sockaddr name = {AF_UNIX,SOCKNAME};
static struct sockaddr nname;
int nnamelen;
int imsg;

if ((s=socket(AF_UNIX,SOCK_DGRAM,0)) < 0){
	perror("cant open socket");
	exit(-1);
	}

if(bind(s,&name,sizeof(name)) < 0){
	perror("cant bind to socket");
	exit(-2);
	}

nnamelen = sizeof(nname);
if(recvfrom(s,&imsg,sizeof(imsg),0,&nname,&nnamelen) < 0){
	perror("server recvfrom error");
	exit(-5);
	}

fprintf(stderr,"Recv int: %d\n",imsg);

fprintf(stderr,"Recv family: %d, nname: %s\n",nname.sa_family,nname.sa_data);

/*       Works fine to here, gets the proper message, however, the result in
    nname is :  nname.sa_family == 1, nname.sa_data == "" (no name or address */
/* SO, I can't return a message since I don't have the sender's address */

client:

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>

#define SOCKNAME "/tmp/tonys"
#define SOCKNNAME "/tmp/tonyc"

main()
{
int s,ns; /* socket descriptors */
static struct sockaddr name = {AF_UNIX,SOCKNAME};
static struct sockaddr nname = {AF_UNIX,SOCKNNAME};
int namelen;
int nnamelen;
int imsg;

if ((s=socket(AF_UNIX,SOCK_DGRAM,0)) < 0){
	perror("cant open socket");
	exit(-1);
	}

if(bind(s,&nname,sizeof(nname)) < 0){
	perror("cant bind to socket");
	exit(-2);
	}

imsg = 345; /* arbitrary */

if(sendto(s,&imsg,sizeof(imsg),0,&name,sizeof(name)) < 0){
	perror("send error");
	exit(-6);
	}

	/* works to here */
-- 
**************** Insert 'Standard' Disclaimer here:  OOP ACK! *****************
*  Tony Parkhurst -- {hplabs|sdcsvax|ncr-sd|hpfcla|ihnp4}!hp-sdd!artecon!adp  *
*                -OR-      hp-sdd!artecon!adp@nosc.ARPA                       *
*******************************************************************************