Ticket History #113: telnet should provide the IP address connected to

From jhawk@bbnplanet.com Tue Oct 15 20:20:31 1996
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Date: Tue, 15 Oct 1996 20:20:23 -0400 (EDT)
From: John Hawkinson <jhawk@bbnplanet.com>
To: krb5-bugs@MIT.EDU
Subject: telnet should provide the IP address connected to

BBN Planet
System: SunOS all-purpo 4.1.4 4 sun4m
Architecture: sun4


When telnetting to multiple-interfaced hosts (i.e. round robin
A records), it's sometimes useful to know which one you've
landed on.

The current interface can give you this information at connect
time, but generally you're more interested in getting it
much later.

This patch adds support to telnet for keeping track of
the current IP address outside of the scope of the tn() function
(just like it currently does with "hostname"), and displaying
it respone to the "status" command.


umm, scratch your head wondering what IP address you've managed to
connect to and decide that running "netstat" is too much trouble or
not deterministic enough.


*** commands.c 1996/10/06 23:21:52 1.2
--- commands.c 1996/10/16 00:01:59 1.3
***************
*** 96,101 ****
--- 96,102 ----

char *hostname;
static char _hostname[MAXDNAME];
+ struct in_addr hostaddr;

extern char *getenv();

***************
*** 103,108 ****
--- 104,111 ----
extern char **genget();
extern int Ambiguous();

+ extern char *inet_ntoa();
+
static call();

typedef struct {
***************
*** 2156,2162 ****
char *argv[];
{
if (connected) {
! printf("Connected to %s.\r\n", hostname);
if ((argc < 2) || strcmp(argv[1], "notmuch")) {
int mode = getconnmode();

--- 2159,2165 ----
char *argv[];
{
if (connected) {
! printf("Connected to %s (%s).\r\n", hostname, inet_ntoa(hostaddr));
if ((argc < 2) || strcmp(argv[1], "notmuch")) {
int mode = getconnmode();

***************
*** 2240,2246 ****
struct sockaddr_in sin;
struct servent *sp = 0;
unsigned long temp;
- extern char *inet_ntoa();
#if defined(IP_OPTIONS) && defined(IPPROTO_IP)
char *srp = 0;
unsigned long sourceroute(), srlen;
--- 2243,2248 ----
***************
*** 2348,2353 ****
--- 2350,2356 ----
#if defined(IP_OPTIONS) && defined(IPPROTO_IP)
}
#endif
+ hostaddr.s_addr = sin.sin_addr.s_addr;
if (portp) {
if (*portp == '-') {
portp++;

From: John Hawkinson <jhawk@MIT.EDU>
To: hartmans@MIT.EDU
Cc: krb5-bugs@MIT.EDU
Subject: Re: telnet/113: telnet should provide the IP address connected to
Date: Sat, 19 Oct 1996 11:00:35 -0400 (EDT)

Incidently, Sam asked why this was interesting.
Here is an example (please ignore the idiocy that results
in this A name binding to multiple ifaces rather than a loopback,
though):

---cut
[all-purpose-gunk!jhawk] ~> telnet denver-cr1
Trying 4.0.208.249...
telnet: connect to address 4.0.208.249: Host is unreachable
telnet: connect to address 4.0.208.245: Host is unreachable
telnet: connect to address 4.0.208.97: Host is unreachable
telnet: connect to address 4.0.208.101: Host is unreachable
telnet: connect to address 4.0.208.105: Host is unreachable
telnet: connect to address 4.0.208.109: Host is unreachable
telnet: connect to address 4.0.208.113: Host is unreachable
telnet: connect to address 4.0.208.117: Host is unreachable
telnet: connect to address 4.0.208.121: Host is unreachable
telnet: connect to address 4.0.208.125: Host is unreachable
Encryption is verbose
Connected to denver-cr1.bbnplanet.net (4.0.208.249).
Escape character is '^]'.
---cut

Please note this is with my patch applied. The original telnet code
tells you the first IP address it tries, and each failure thereafter,
but does not tell you where you have connected to originally (my patch
has the side effect of repeating the IP address at you after
connection, as the same code is used there as in the "status"
command).

Arguably the interface should be changed so it prints a Trying
a.b.c.d... line prior to each attempt. At this point, I think that
would be slightly suboptimal since it would double the lines
of output.

Perhaps Trying should not print a newline and then the connect() error
could be shortened to something not including the ipaddr... I'd still
like my patch applied, however, since my desire is to find out the
other side's address sometime *after* the initial connection and thus
the "Trying..." lines have scrolled off.

--jhawk

From: John Hawkinson <jhawk@bbnplanet.com>
To: krb5-bugs@MIT.EDU
Cc: krb5-prs@RT-11.MIT.EDU
Subject: Re: telnet/113: telnet should provide the IP address connected to
Date: Tue, 29 Oct 1996 23:14:41 -0500

My earlier patch missed the case where
connect() fails and telnet moves on to a new IP address -- in that
case hostaddr does not get (re-)set so it indicates the IP address
first attempted.

Here's an addition to my previous patch.

*** commands.c 1996/10/16 00:01:59 1.3
--- commands.c 1996/10/30 04:12:43 1.4
***************
*** 2427,2432 ****
--- 2427,2434 ----
host->h_addr_list++;
memcpy((caddr_t)&sin.sin_addr,
host->h_addr_list[0], host->h_length);
+ memcpy((caddr_t)&hostaddr,
+ host->h_addr_list[0], host->h_length);
(void) NetClose(net);
continue;
}

--jhawk
State-Changed-From-To: open-closed
State-Changed-By: hartmans
State-Changed-When: Sun Nov 10 21:13:44 EST 1996
State-Changed-Why:
Applied patch