From:	SMTP%"RELAY-INFO-VAX@CRVAX.SRI.COM"  5-MAY-1993 16:56:51.66
To:	EVERHART
CC:	
Subj:	Re: Need help with Multinet & TCP/IP Programming

X-Newsgroups: comp.lang.c,comp.os.vms,comp.dcom.lans.misc,vmsnet.networks.tcp-ip.multinet
From: adelman@tgv.com (Kenneth Adelman)
Subject: Re: Need help with Multinet & TCP/IP Programming
Message-Id: <4MAY199320203295@tgv.com>
Summary: help with tcp/ip
News-Software: VAX/VMS VNEWS 1.41    
Keywords: tcp/ip, recvfrom()
Sender: usenet@news.arc.nasa.gov
Organization: TGV, Incorporated (Santa Cruz, CA, USA)
Date: Wed, 5 May 1993 03:20:00 GMT
Lines: 42
To: Info-VAX@kl.sri.com
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In article <1s6i35$c8c@zip.eecs.umich.edu>, macika@emunix.emich.edu (Dominic Macika (Ass. Lab Supervisor)) writes...
>Howdy.  We recently had Multinet installed on our Vax 4000's and
>I'm exploring some tcp/ip programming.  I've hit a snag and can't
>seem to find any answer for it.  I'm simply trying to send a data
>gram from our unix system to our vax system.  The server program
>I've written for the vax end hangs at the recvfrom() function.
>I assume it's not receiving the data I'm sending it.  Any and
>all comments, suggestions and answers (heck,  I'll even accept flames
>at this point, as long as they lead to something useful) will
>be greatly appreciated.  Please resond via email and I will
>post a summary, etc.
>
>
>  if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
>    barf("error opening socket\n");
>  }
>
>  barf("socket open\n");
>
>  len = sizeof(sin);
>  barf("going into recvfrom\n");
>
>/* this is the last message that makes it to my errorlog */
>
>  n = recvfrom(s, buf, sizeof(buf), 0, &sin, &len);
>  if (n < 0) {
>    barf("recvform\n");
>  }
>  barf("Data received, heading for the file.\n");

    You need to do a bind() operation on the socket to tell the
network what port you want to accept packets on. Something like:

    bzero((char *) &sin, sizeof(sin));
    sin.sin_family = AF_INET;
    sin.sin_port = htons(PORT);
    n = bind(s, &sin, sizeof(sin));
    if (n < 0) {
	barf("bind");
    }

						    Ken