Decode BGP Shutdown Communication messages (RFC 8203)
Job Snijders
job at ntt.net
Thu Jul 27 17:55:40 CEST 2017
Hi all,
Here is a patch to decode received BGP shutdown communication messages
as specified in RFC 8203. In the following example scenario I'm sending
a shutdown communication with openbgpd:
$ bgpctl neighbor 94.142.241.204 down "TICKET-2331 we are upgrading, back in 30 min"
request processed
And can subsequently observe the message via logging and via 'show protocols all':
job at irime:~/source/bird$ sudo ./bird -s test.sock -d -c bird2.conf
bird: Started
bird: bgp1: Received: Administrative shutdown: "TICKET-2331 we are upgrading, back in 30 min"
job at irime:~/source/bird$ sudo ./birdc -s test.sock show protocols all
....
BGP state: Active
Neighbor address: 165.254.255.26
Neighbor AS: 15562
Connect delay: 3/5
Last error: Received: Administrative shutdown
Message: "TICKET-2331 we are upgrading, back in 30 min"
As for the remaining RFC 8203 work:
I could use some help with _sending_ bgp shutdown communication
messages. It is not clear to me where I should hook the message into
the config/cli infrastructure. Ideally you can do things like:
$ birdc disable bgp1 "hi, we will upgrade to bird 1.6.4"
or via the configuration (also during reconfigure):
protocol bgp {
disabled "shutdown due to maintenance ticket 2424";
description "My BGP uplink";
local 94.142.241.204 as 65000;
neighbor 165.254.255.26 as 15562;
}
Thoughts?
Kind regards,
Job
---
proto/bgp/bgp.c | 13 ++++++++++
proto/bgp/bgp.h | 2 ++
proto/bgp/packets.c | 73 ++++++++++++++++++++++++++++++++++-------------------
3 files changed, 62 insertions(+), 26 deletions(-)
diff --git a/proto/bgp/bgp.c b/proto/bgp/bgp.c
index f706e76..551b156 100644
--- a/proto/bgp/bgp.c
+++ b/proto/bgp/bgp.c
@@ -1487,6 +1487,16 @@ bgp_last_errmsg(struct bgp_proto *p)
}
static const char *
+bgp_last_shutmsg(struct bgp_proto *p)
+{
+ unsigned len;
+ char *buf = calloc (128, sizeof (char));
+ len = p->last_received_shutmsg[0];
+ bsnprintf(buf, len, "%s", p->last_received_shutmsg+1);
+ return(buf);
+}
+
+static const char *
bgp_state_dsc(struct bgp_proto *p)
{
if (p->p.proto_state == PS_DOWN)
@@ -1580,7 +1590,10 @@ bgp_show_proto_info(struct proto *P)
{
const char *err1 = bgp_err_classes[p->last_error_class];
const char *err2 = bgp_last_errmsg(p);
+ const char *msg = bgp_last_shutmsg(p);
cli_msg(-1006, " Last error: %s%s", err1, err2);
+ if (p->last_received_shutmsg[0] > 0)
+ cli_msg(-1006, " Message: \"%s\"", msg);
}
}
diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h
index e47a0eb..d958716 100644
--- a/proto/bgp/bgp.h
+++ b/proto/bgp/bgp.h
@@ -157,6 +157,8 @@ struct bgp_proto {
u8 last_error_class; /* Error class of last error */
u32 last_error_code; /* Error code of last error. BGP protocol errors
are encoded as (bgp_err_code << 16 | bgp_err_subcode) */
+ byte last_received_shutmsg[129]; /* RFC 8203 */
+
#ifdef IPV6
byte *mp_reach_start, *mp_unreach_start; /* Multiprotocol BGP attribute notes */
unsigned mp_reach_len, mp_unreach_len;
diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index ab87bdc..1a021dd 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -1460,9 +1460,9 @@ static struct {
{ 5, 3, "Unexpected message in Established state" },
{ 6, 0, "Cease" }, /* Subcodes are according to [RFC4486] */
{ 6, 1, "Maximum number of prefixes reached" },
- { 6, 2, "Administrative shutdown" },
+ { 6, 2, "Administrative shutdown" }, /* RFC 8203 can follow */
{ 6, 3, "Peer de-configured" },
- { 6, 4, "Administrative reset" },
+ { 6, 4, "Administrative reset" }, /* RFC 8203 can follow */
{ 6, 5, "Connection rejected" },
{ 6, 6, "Other configuration change" },
{ 6, 7, "Connection collision resolution" },
@@ -1497,35 +1497,56 @@ bgp_error_dsc(unsigned code, unsigned subcode)
void
bgp_log_error(struct bgp_proto *p, u8 class, char *msg, unsigned code, unsigned subcode, byte *data, unsigned len)
{
- const byte *name;
- byte *t, argbuf[36];
- unsigned i;
+ const byte *name;
+ byte *t, argbuf[256];
+ unsigned i;
+ unsigned shutdown_comm_length;
- /* Don't report Cease messages generated by myself */
- if (code == 6 && class == BE_BGP_TX)
- return;
+ /* Don't report Cease messages generated by myself */
+ if (code == 6 && class == BE_BGP_TX)
+ return;
+
+ name = bgp_error_dsc(code, subcode);
+ t = argbuf;
+ memset(p->last_received_shutmsg, 0, 129); // clear old RFC 8203 messages
- name = bgp_error_dsc(code, subcode);
- t = argbuf;
- if (len)
+ if (len)
{
- *t++ = ':';
- *t++ = ' ';
+ *t++ = ':';
+ *t++ = ' ';
- if ((code == 2) && (subcode == 2) && ((len == 2) || (len == 4)))
- {
- /* Bad peer AS - we would like to print the AS */
- t += bsprintf(t, "%d", (len == 2) ? get_u16(data) : get_u32(data));
- goto done;
- }
- if (len > 16)
- len = 16;
- for (i=0; i<len; i++)
- t += bsprintf(t, "%02x", data[i]);
+ if ((code == 2) && (subcode == 2) && ((len == 2) || (len == 4)))
+ {
+ /* Bad peer AS - we would like to print the AS */
+ t += bsprintf(t, "%d", (len == 2) ? get_u16(data) : get_u32(data));
+ goto done;
+ }
+ /* RFC 8203 */
+ if ((code == 6) && ((subcode == 2 || subcode == 4)) && (len <= 129))
+ {
+ shutdown_comm_length = data[0];
+ if ((shutdown_comm_length <= 128) && (len == shutdown_comm_length + 1))
+ {
+ t += bsprintf(t, "\"");
+ for (i=1; i<len; i++)
+ t += bsprintf(t, "%c", data[i]);
+ t += bsprintf(t, "\"");
+ memcpy(p->last_received_shutmsg, data, shutdown_comm_length + 1);
+ goto done;
+ }
+ }
+ else
+ {
+ if (len > 16)
+ len = 16;
+ for (i=0; i<len; i++)
+ t += bsprintf(t, "%02x", data[i]);
+ }
}
- done:
- *t = 0;
- log(L_REMOTE "%s: %s: %s%s", p->p.name, msg, name, argbuf);
+
+ done:
+ *t = 0;
+ log(L_REMOTE "%s: %s: %s%s", p->p.name, msg, name, argbuf);
}
static void
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