rr: Add new return value for preloaded route set to loose_route()

Instead of returning just -1 (error), return a dedicated value. Now it is
possible to detect from the script if a preloaded Route header was removed
that pointed at the local proxy.

The new return code is kept negative, so all code checking for failure response
keeps working.

(cherry picked from commit c5b8e5b3a82ac0f61a059f69921866952405ffe5)

src/modules/rr/doc/rr_admin.xml

@@ -364,7 +364,7 @@ modparam("rr", "ignore_sips", 1)
 
         <listitem>
           <para><emphasis>2</emphasis> - route calculation based on
-	  flow-token has been successful</para>
+          flow-token has been successful</para>
         </listitem>
 
         <listitem>
@@ -376,6 +376,11 @@ modparam("rr", "ignore_sips", 1)
           <para><emphasis>-2</emphasis> - outbound flow-token shows evidence
           of tampering</para>
         </listitem>
+
+        <listitem>
+          <para><emphasis>-3</emphasis> - next hop is taken from
+          a preloaded route set</para>
+        </listitem>
       </itemizedlist>
 
       <para>This function can be used from REQUEST_ROUTE.</para>

src/modules/rr/loose.c

@@ -48,6 +48,7 @@
 #define RR_OB_DRIVEN 2		/*!< The next hop is determined from the route set based on flow-token */
 #define NOT_RR_DRIVEN -1	/*!< The next hop is not determined from the route set */
 #define FLOW_TOKEN_BROKEN -2	/*!< Outbound flow-token shows evidence of tampering */
+#define RR_PRELOADED -3		/*!< The next hop is determined from a preloaded route set */
 
 #define RR_ROUTE_PREFIX ROUTE_PREFIX "<"
 #define RR_ROUTE_PREFIX_LEN (sizeof(RR_ROUTE_PREFIX)-1)
@@ -840,7 +841,7 @@ static inline int after_loose(struct sip_msg* _m, int preloaded)
 			}
 			if (res > 0) { /* No next route found */
 				LM_DBG("No next URI found\n");
-				status = (preloaded ? NOT_RR_DRIVEN : RR_DRIVEN);
+				status = (preloaded ? RR_PRELOADED : RR_DRIVEN);
 				goto done;
 			}
 			rt = (rr_t*)hdr->parsed;
@@ -873,7 +874,7 @@ static inline int after_loose(struct sip_msg* _m, int preloaded)
 					}
 				if (res > 0) { /* No next route found */
 					LM_DBG("no next URI found\n");
-					status = (preloaded ? NOT_RR_DRIVEN : RR_DRIVEN);
+					status = (preloaded ? RR_PRELOADED : RR_DRIVEN);
 					goto done;
 				}
 				rt = (rr_t*)hdr->parsed;