Re: Question on optional connect data field

[Patrick Caulfield <patrick@pandh.demon.co.uk>]

You need to call setsockopt to add the optional data to the connect block before doing the connect. The sequence is:

socket(AF_DECnet. SOCK_SEQPACKET, DNPROTO_NSP);
setsockopt(fd. DNPROTO_NSP, SO_CONDATA, &optdata, sizeof(optdata));
connect(...)

See dnetd and libdnet_daemon for example bits of code but that should be enough to get you going.

Patrick


________________ Reply Header ________________
Subject:	Question on optional connect data field
Author:	Rob Davies <robdavies@worldnet.att.net>
Date:		 Fri,  7 Jan 2000 05:37:18 +0000

Hi all,

I'm trying to establish a DECnet connection to a remote DECnet named object. I've been looking through the phoned code, and from that I assume I should be using something along the lines of:

out_fd = socket(AF_DECnet, SOCK_SEQPACKET, DNPROTO_NSP)

out_sockaddr.sdn_family    = AF_DECnet;
out_sockaddr.sdn_flags     = 0x00;
out_sockaddr.sdn_objnum    = 0x00;
out_sockaddr.sdn_objnamel  = obj_name_len; out_sockaddr.sdn_objname   = obj_name;
out_sockaddr.sdn_add.a_len = 0x02;

out_sockaddr.sdn_add.a_addr = dest_addr;


connect(out_fd, &out_sockaddr, len_out_sockaddr)


OK, here comes the question:

I want to send up to 16 bytes of optional user data in the connect message. 
I know that *somewhere* in the code is the capability to do it, as there's a structure defined in dn.h as:

struct optdata_dn {
        unsigned short  opt_status;     /* Extended status return */ #define opt_sts opt_status
        unsigned short  opt_optl;       /* Length of user data    */
        unsigned char   opt_data[16];   /* User data              */ };


So ... where does this fit in when I'm doing a 'connect()' ? ... or is there some other secret alternative to 'connect' ?

Also, at the other end of the connection, how do I retrieve the optional user data from the connect message ? I was planning on using select() and accept() and read(), but I'm not sure where the optional data would appear? ... maybe at the accept() stage ? How do I get at it?


Thanks in advance.

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