Syslog protocol support

VPP provides RFC5424 syslog protocol logging, which is used to transport event messages across network. VPP currently suports UDP transport based on RFC5426.

The syslog message has the following format:

• header
• structured data
• free-form message

The header contains, priority, version, timestamp, hostname, application, process id and message id. It is followed by structured data, which provides a mechanism to express event data in easily parsable format. Structured data can contain zero, one or multiple structured data elements. Structured data element contains name-value pairs. Structured data can by followed by free-form message.

Following example explains how to use the internal APIs to genrate syslog message:

#include <vnet/syslog/syslog.h>
 
...
 
syslog_msg_t syslog_msg;
 
/* Check if syslog logging is enabled */
if (!syslog_is_enabled ())
  return;
 
/* Severity filer test */
if (syslog_severity_filter_block (severity))
  return;
 
/* Initialize syslog message header */
syslog_msg_init (&syslog_msg, facility, severity, "NAT", "SADD");
 
/* Create structured data element */
syslog_msg_sd_init (&syslog_msg, "nsess");
/* Add structured data element parameters (name-value pairs) */
syslog_msg_add_sd_param (&syslog_msg, "SSUBIX", "%d", ssubix);
syslog_msg_add_sd_param (&syslog_msg, "SVLAN", "%d", svlan);
syslog_msg_add_sd_param (&syslog_msg, "IATYP", "IPv4");
syslog_msg_add_sd_param (&syslog_msg, "ISADDR", "%U",
                         format_ip4_address, isaddr);
syslog_msg_add_sd_param (&syslog_msg, "ISPORT", "%d", isport);
syslog_msg_add_sd_param (&syslog_msg, "XATYP", "IPv4");
syslog_msg_add_sd_param (&syslog_msg, "XSADDR", "%U",
                         format_ip4_address, xsaddr);
syslog_msg_add_sd_param (&syslog_msg, "XSPORT", "%d", xsport);
syslog_msg_add_sd_param (&syslog_msg, "PROTO", "%d", proto);
 
/* Send syslog message */
syslog_msg_send (&syslog_msg);

Example above produces following syslog message: <134>1 2018-11-12T11:25:30.252715Z 172.16.4.1 NAT 5901 SADD [nsess SSUBIX="0" SVLAN="0" IATYP="IPv4" ISADDR="172.16.1.2" ISPORT="6303" XATYP="IPv4" XSADDR="10.0.0.3" XSPORT="16253" PROTO="6"]

To add free-form message use:

syslog_msg_add_msg (&syslog_msg, "event log entry");