On Sat, Dec 22 2018, "Ted Unangst" <[email protected]> wrote:
> Daniel Jakots wrote:
>> Hi,
>>
>> With nc(1) you can do:
>> nc -zv example.com 80
>> or
>> nc -zv example.com http
>> which does the same. This works well unless the service name has a dash:
>> $ nc -zv example.com syslog-tls
>> nc: service "tls" unknown
>>
>> This is because nc(1) is able to do some port scanning and the
>> delimiter used for the range is the dash. When it sees a dash, it
>> thinks it's a port range.
>>
>> nc(1) is not the only software that takes an input that can be a port,
>> a range or a service name: pf is in this case too. In pf the delimiter
>> used is ":" so this works fine.
>>
>> Here's a diff that change the delimiter to ":". This breaks existing
>> scripts but it would make the syntax like pf.conf instead of using
>> another symbol for a port range.
>>
>> If you have a better idea how to solve this problem, please share!
>
> This preserves the low-high syntax, adds low:high syntax, and also tries to be
> smarter about service-name.
>
> First look for :. That's a range.
> Next look for -. Then check it's not a service name. That's a range.
> Otherwise it's a port.
Looks like the nicest way to handle it.
> It may work, but needs testing.
Diff below hopefully has the same behavior, but with less churn and no goto.
Index: netcat.c
===================================================================
RCS file: /cvs/src/usr.bin/nc/netcat.c,v
retrieving revision 1.199
diff -u -p -p -u -r1.199 netcat.c
--- netcat.c 29 Nov 2018 14:25:06 -0000 1.199
+++ netcat.c 23 Dec 2018 00:02:03 -0000
@@ -1427,7 +1427,15 @@ build_ports(char *p)
int hi, lo, cp;
int x = 0;
- if ((n = strchr(p, '-')) != NULL) {
+ if ((n = strchr(p, ':')) == NULL) {
+ if ((n = strchr(p, '-')) != NULL &&
+ getservbyname(p, uflag ? "udp" : "tcp") != NULL) {
+ /* Really a service name, not a "lo-hi" port range. */
+ n = NULL;
+ }
+ }
+
+ if (n != NULL) {
*n = '\0';
n++;
--
jca | PGP : 0x1524E7EE / 5135 92C1 AD36 5293 2BDF DDCC 0DFA 74AE 1524 E7EE
