From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Tolpin <dvd@davidashen.net>
Message-Id: <200403231536.i2NFadOX035523@adat.davidashen.net>
To: 'magic@adat.davidashen.net, -s@adat.davidashen.net,
	9fans@cse.psu.edu, numbers'@adat.davidashen.net
Content-Type: text/plain; charset=KOI8-R
Subject: [9fans] magic numbers
Date: Tue, 23 Mar 2004 19:36:39 +0400
Topicbox-Message-UUID: 3e78b428-eacd-11e9-9e20-41e7f4b1d025



I've tried to pattern a simple program I am writing after
/sys/src/cmd/ip/telnet.c; I'm lost trying to figure out 
what each of the magic numbers means.

dodial(char *dest)

defines

char name[2*NETPATHLEN] 

that is, 80 characters long. Why NETPATHLEN should be doubled?  How
is NETPATHLEN related to the length of address tuple?

Then name is used to copy the result of netmkaddr to it; but internally
the array netmkaddr stores its result in a 

static char addr[256]

and if the host name is long enough, the stack becomes corrupt.

In the same function, on the next line after char name[2*NETPATHLEN],
devdir is defined as
char devdir[40]

Is 40 in fact NETPATHLEN?

David