res_pjsip: Update authentication realm documentation.

Using the same auth section for inbound and outbound authentication is not
recommended.  There is a difference in meaning for an empty realm setting
between inbound and outbound authentication uses.

An empty inbound auth realm represents the global section's default_realm
value when the authentication object is used to challenge an incoming
request.  An empty outgoing auth realm is treated as a don't care wildcard
when the authentication object is used to respond to an incoming
authentication challenge.

ASTERISK-26799

Change-Id: Id3952f7cfa1b6683b9954f2c5d2352d2f11059ce

4 files changed, 86 insertions, 11 deletions

diff --git a/configs/samples/pjsip.conf.sample b/configs/samples/pjsip.conf.sample
index 2ef893384..bb2ad94f8 100644
--- a/configs/samples/pjsip.conf.sample
+++ b/configs/samples/pjsip.conf.sample
@@ -12,6 +12,12 @@
 ; If you want to see more detail please check the documentation sources
 ; mentioned at the top of this file.
 
+; ============================================================================
+; NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE
+;
+; This file does not maintain the complete option documentation.
+; ============================================================================
+
 ; Documentation
 ;
 ; The official documentation is at http://wiki.asterisk.org
@@ -759,6 +765,14 @@
 ;==========================AUTH SECTION OPTIONS=========================
 ;[auth]
 ;  SYNOPSIS: Authentication type
+;
+;  Note: Using the same auth section for inbound and outbound
+;  authentication is not recommended.  There is a difference in
+;  meaning for an empty realm setting between inbound and outbound
+;  authentication uses.  Look to the CLI config help
+;  "config show help res_pjsip auth realm" or on the wiki for the
+;  difference.
+;
 ;auth_type=userpass     ; Authentication type (default: "userpass")
 ;nonce_lifetime=32      ; Lifetime of a nonce associated with this
                         ; authentication config (default: "32")
@@ -947,9 +961,9 @@
                                 ; From header username will be set to this value if
                                 ; there is no better option (such as CallerID or
                                 ; endpoint/from_user) to be used
-;default_realm=asterisk         ; When Asterisk generates a challenge, the realm will be
-                                ; set to this value if there is no better option (such as
-                                ; auth/realm) to be used
+;default_realm=asterisk         ; When Asterisk generates a challenge, the digest realm
+                                ; will be set to this value if there is no better option
+                                ; (such as auth/realm) to be used.
 
                     ; Asterisk Task Processor Queue Size
                     ; On heavy loaded system with DB storage you may need to increase
diff --git a/res/res_pjsip.c b/res/res_pjsip.c
index 9b9905826..2390bc041 100644
--- a/res/res_pjsip.c
+++ b/res/res_pjsip.c
@@ -112,9 +112,15 @@
 						This is a comma-delimited list of <replaceable>auth</replaceable> sections defined
 						in <filename>pjsip.conf</filename> to be used to verify inbound connection attempts.
 						</para><para>
-						Endpoints without an <literal>authentication</literal> object
-						configured will allow connections without vertification.
-					</para></description>
+						Endpoints without an authentication object
+						configured will allow connections without verification.</para>
+						<note><para>
+						Using the same auth section for inbound and outbound
+						authentication is not recommended.  There is a difference in
+						meaning for an empty realm setting between inbound and outbound
+						authentication uses.  See the auth realm description for details.
+						</para></note>
+					</description>
 				</configOption>
 				<configOption name="callerid">
 					<synopsis>CallerID information for the endpoint</synopsis>
@@ -329,7 +335,18 @@
 					<synopsis>Default Music On Hold class</synopsis>
 				</configOption>
 				<configOption name="outbound_auth">
-					<synopsis>Authentication object used for outbound requests</synopsis>
+					<synopsis>Authentication object(s) used for outbound requests</synopsis>
+					<description><para>
+						This is a comma-delimited list of <replaceable>auth</replaceable>
+						sections defined in <filename>pjsip.conf</filename> used to respond
+						to outbound connection authentication challenges.</para>
+						<note><para>
+						Using the same auth section for inbound and outbound
+						authentication is not recommended.  There is a difference in
+						meaning for an empty realm setting between inbound and outbound
+						authentication uses.  See the auth realm description for details.
+						</para></note>
+					</description>
 				</configOption>
 				<configOption name="outbound_proxy">
 					<synopsis>Proxy through which to send requests, a full SIP URI must be provided</synopsis>
@@ -961,8 +978,30 @@
 					<synopsis>PlainText password used for authentication.</synopsis>
 					<description><para>Only used when auth_type is <literal>userpass</literal>.</para></description>
 				</configOption>
-				<configOption name="realm" default="asterisk">
+				<configOption name="realm">
 					<synopsis>SIP realm for endpoint</synopsis>
+					<description><para>
+						The treatment of this value depends upon how the authentication
+						object is used.
+						</para><para>
+						When used as an inbound authentication object, the realm is sent
+						as part of the challenge so the peer can know which key to use
+						when responding.  An empty value will use the
+						<replaceable>global</replaceable> section's
+						<literal>default_realm</literal> value when issuing a challenge.
+						</para><para>
+						When used as an outbound authentication object, the realm is
+						matched with the received challenge realm to determine which
+						authentication object to use when responding to the challenge.  An
+						empty value matches any challenging realm when determining
+						which authentication object matches a received challenge.
+						</para>
+						<note><para>
+						Using the same auth section for inbound and outbound
+						authentication is not recommended.  There is a difference in
+						meaning for an empty realm setting between inbound and outbound
+						authentication uses.</para></note>
+					</description>
 				</configOption>
 				<configOption name="type">
 					<synopsis>Must be 'auth'</synopsis>
@@ -1506,7 +1545,7 @@
 						used.</synopsis>
 				</configOption>
 				<configOption name="default_realm" default="asterisk">
-					<synopsis>When Asterisk generates an challenge, the digest will be
+					<synopsis>When Asterisk generates a challenge, the digest realm will be
 						set to this value if there is no better option (such as auth/realm) to be
 						used.</synopsis>
 				</configOption>
diff --git a/res/res_pjsip_outbound_publish.c b/res/res_pjsip_outbound_publish.c
index 35eedf0d2..3afa41307 100644
--- a/res/res_pjsip_outbound_publish.c
+++ b/res/res_pjsip_outbound_publish.c
@@ -54,7 +54,18 @@
 					<synopsis>Expiration time for publications in seconds</synopsis>
 				</configOption>
 				<configOption name="outbound_auth" default="">
-					<synopsis>Authentication object to be used for outbound publishes.</synopsis>
+					<synopsis>Authentication object(s) to be used for outbound publishes.</synopsis>
+					<description><para>
+						This is a comma-delimited list of <replaceable>auth</replaceable>
+						sections defined in <filename>pjsip.conf</filename> used to respond
+						to outbound authentication challenges.</para>
+						<note><para>
+						Using the same auth section for inbound and outbound
+						authentication is not recommended.  There is a difference in
+						meaning for an empty realm setting between inbound and outbound
+						authentication uses.  See the auth realm description for details.
+						</para></note>
+					</description>
 				</configOption>
 				<configOption name="outbound_proxy" default="">
 					<synopsis>SIP URI of the outbound proxy used to send publishes</synopsis>
diff --git a/res/res_pjsip_outbound_registration.c b/res/res_pjsip_outbound_registration.c
index da15f19f5..bfb327c75 100644
--- a/res/res_pjsip_outbound_registration.c
+++ b/res/res_pjsip_outbound_registration.c
@@ -82,7 +82,18 @@
 					<synopsis>Maximum number of registration attempts.</synopsis>
 				</configOption>
 				<configOption name="outbound_auth" default="">
-					<synopsis>Authentication object to be used for outbound registrations.</synopsis>
+					<synopsis>Authentication object(s) to be used for outbound registrations.</synopsis>
+					<description><para>
+						This is a comma-delimited list of <replaceable>auth</replaceable>
+						sections defined in <filename>pjsip.conf</filename> used to respond
+						to outbound authentication challenges.</para>
+						<note><para>
+						Using the same auth section for inbound and outbound
+						authentication is not recommended.  There is a difference in
+						meaning for an empty realm setting between inbound and outbound
+						authentication uses.  See the auth realm description for details.
+						</para></note>
+					</description>
 				</configOption>
 				<configOption name="outbound_proxy" default="">
 					<synopsis>Outbound Proxy used to send registrations</synopsis>