Date: 15 Nov 1998 16:56:52 +0000 (GMT) From: sthaug@nethelp.no To: FreeBSD-gnats-submit@FreeBSD.ORG Cc: sthaug@nethelp.no Subject: bin/8698: telnet enhancement: option to prevent IP address to name lookup Message-ID: <19981115165652.21227.qmail@verdi.nethelp.no>
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>Number: 8698
>Category: bin
>Synopsis: add telnet option to prevent IP address to name lookup
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Sun Nov 15 09:00:00 PST 1998
>Last-Modified:
>Originator: Steinar Haug
>Organization:
Nethelp Consulting
>Release: FreeBSD 3.0-CURRENT i386
>Environment:
FreeBSD 3.0-CURRENT i386 (from around 24. october 1998)
>Description:
If a telnet destination host is given by IP address, telnet will
attempt a gethostbyaddr() to lookup the corresponding host name.
If the relevant name servers take a long time to answer (e.g. if
they are lame), the telnet connection attempt will take a long
time due to the name lookup.
This patch adds a -N option to prevent IP address to name lookup
when the destination host is given by IP address.
The option really should have been -n (for similarity with route,
arp, netstat etc), but the -n option is already taken. So use -N.
>How-To-Repeat:
telnet (using IP address) to a site where the relevant name servers
aren't fully functional. Observe how long the connection attempt
takes.
>Fix:
Below is a patch relative to telnet in FreeBSD 3.0-CURRENT.
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
*** commands.c.orig Fri Jun 12 14:54:53 1998
--- commands.c Sun Nov 15 16:58:10 1998
***************
*** 2186,2192 ****
if (temp != INADDR_NONE) {
sin.sin_addr.s_addr = temp;
sin.sin_family = AF_INET;
! host = gethostbyaddr((char *)&temp, sizeof(temp), AF_INET);
if (host)
(void) strncpy(_hostname, host->h_name, sizeof(_hostname));
else
--- 2186,2193 ----
if (temp != INADDR_NONE) {
sin.sin_addr.s_addr = temp;
sin.sin_family = AF_INET;
! if (doaddrlookup)
! host = gethostbyaddr((char *)&temp, sizeof(temp), AF_INET);
if (host)
(void) strncpy(_hostname, host->h_name, sizeof(_hostname));
else
*** main.c.orig Sat Mar 29 05:32:57 1997
--- main.c Sun Nov 15 17:03:33 1998
***************
*** 135,141 ****
rlogin = (strncmp(prompt, "rlog", 4) == 0) ? '~' : _POSIX_VDISABLE;
autologin = -1;
! while ((ch = getopt(argc, argv, "8EKLS:X:acde:fFk:l:n:rt:x")) != -1) {
switch(ch) {
case '8':
eight = 3; /* binary output and input */
--- 135,141 ----
rlogin = (strncmp(prompt, "rlog", 4) == 0) ? '~' : _POSIX_VDISABLE;
autologin = -1;
! while ((ch = getopt(argc, argv, "8EKLNS:X:acde:fFk:l:n:rt:x")) != -1) {
switch(ch) {
case '8':
eight = 3; /* binary output and input */
***************
*** 150,155 ****
--- 150,158 ----
break;
case 'L':
eight |= 2; /* binary output only */
+ break;
+ case 'N':
+ doaddrlookup = 0;
break;
case 'S':
{
*** telnet.c.orig Mon Jul 6 23:01:42 1998
--- telnet.c Sun Nov 15 17:03:22 1998
***************
*** 106,111 ****
--- 106,112 ----
donebinarytoggle, /* the user has put us in binary */
dontlecho, /* do we suppress local echoing right now? */
globalmode,
+ doaddrlookup = 1, /* Should we do IP address to name lookup? */
clienteof = 0;
char *prompt = 0;
*** externs.h.orig Tue Jan 7 20:47:56 1997
--- externs.h Sun Nov 15 16:56:14 1998
***************
*** 145,150 ****
--- 145,151 ----
termdata, /* Print out terminal data flow */
#endif /* defined(unix) */
debug, /* Debug level */
+ doaddrlookup, /* Should we do IP address to name lookup? */
clienteof; /* Client received EOF */
extern cc_t escape; /* Escape to command mode */
*** telnet.1.orig Sat Dec 27 19:58:27 1997
--- telnet.1 Sun Nov 15 17:30:04 1998
***************
*** 93,98 ****
--- 93,101 ----
Specifies an 8-bit data path on output. This causes the
.Dv BINARY
option to be negotiated on output.
+ .It Fl N
+ Prevents IP address to name lookup when destination host is given as an
+ IP address.
.It Fl S Ar tos
Sets the IP type-of-service (TOS) option for the telnet
connection to the value
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