Add RFC 3327 Path header support to chan_sip

This patch adds support for RFC 3327 "Path" headers. This can be enabled in
sip.conf using the 'supportpath' setting, either on a global basis or on a
peer basis. This setting enables Asterisk to route outgoing out-of-dialog
requests via a set of proxies by using a pre-loaded route-set defined by the
Path headers in the REGISTER request. This patch also adds Realtime support
for dynamically updating the Path information for a peer.

A huge thank-you to Klaus Darillion and Olle E Johansson for their efforts
in writing this patch.

Review: https://reviewboard.asterisk.org/r/2235/
Review: https://reviewboard.asterisk.org/r/991/

(closes issue ASTERISK-16884)
Reported by: klaus3000
Tested by: klaus3000, oej, mjordan
patches:
  path-1.8.0-patch.txt uploaded by klaus3000 (License 5054)
  oolong-path-support-trunk in team branch by oej (License 5267)



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@382440 65c4cc65-6c06-0410-ace0-fbb531ad65f3

contrib/realtime/mysql/sippeers.sql

@@ -79,6 +79,7 @@ CREATE TABLE IF NOT EXISTS `sippeers` (
       `callingpres` enum('allowed_not_screened','allowed_passed_screen','allowed_failed_screen','allowed','prohib_not_screened','prohib_passed_screen','prohib_failed_screen','prohib') DEFAULT NULL,
       `mohinterpret` varchar(40) DEFAULT NULL,
       `mohsuggest` varchar(40) DEFAULT NULL,
+      `path` varchar(256) DEFAULT NULL,
       `parkinglot` varchar(40) DEFAULT NULL,
       `hasvoicemail` enum('yes','no') DEFAULT NULL,
       `subscribemwi` enum('yes','no') DEFAULT NULL,
@@ -90,6 +91,7 @@ CREATE TABLE IF NOT EXISTS `sippeers` (
       `ignoresdpversion` enum('yes','no') DEFAULT NULL,
       `allowtransfer` enum('yes','no') DEFAULT NULL,
       `dynamic` enum('yes','no') DEFAULT NULL,
+      `supportpath` enum('yes','no') DEFAULT NULL,
       PRIMARY KEY (`id`),
       UNIQUE KEY `name` (`name`),
       KEY `ipaddr` (`ipaddr`,`port`),