lib, bgp: add initial support for asdot format

AS number can be defined as an unsigned long number, or
two uint16 values separated by a period (.). The possible
valus are:
- usual 32 bit values : [1;2^32 -1]
- <1.65535>.<0.65535> for dot notation
- <0.65535>.<0.65535> for dot+ notation.

The 0.0 value is forbidden when configuring BGP instances
or peer configurations.

A new ASN type is added for parsing in the vty.
The following commands use that new identifier:
- router bgp ..
- bgp confederation ..
- neighbor <> remote-as <>
- neighbor <> local-as <>
- clear ip bgp <>
- route-map / set as-path <>

An asn library is available in lib/ and provides some
services:
- convert an as string into an as number.
- parse an as path list string and extract a number.
- convert an as number into a string.

Also, the bgp tests forge an as_zero_path, and to do that,
an API to relax the possibility to have a 0 as value is
specifically called from the tests.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/command.h b/lib/command.h
index 8f5d96053c..0ee45cee55 100644
--- a/lib/command.h
+++ b/lib/command.h
@@ -403,7 +403,8 @@ struct cmd_node {
 #define DEBUG_STR "Debugging functions\n"
 #define UNDEBUG_STR "Disable debugging functions (see also 'debug')\n"
 #define ROUTER_STR "Enable a routing process\n"
-#define AS_STR "AS number\n"
+#define AS_STR                                                                 \
+	"AS number in plain  <1-4294967295> or dotted <0-65535>.<0-65535> format\n"
 #define MAC_STR "MAC address\n"
 #define MBGP_STR "MBGP information\n"
 #define MATCH_STR "Match values from routing table\n"