SIP PN Support: Improve Feature-Caps interpretation

Keep performing PN param-based Contact matching even when PNs are
already handled by upstream side.

Also move more common code under lib/reg

lib/reg/pn.c

@@ -183,7 +183,7 @@ enum pn_action pn_inspect_ct_params(struct sip_msg *req, const str *ct_uri)
 	struct hdr_field *fcaps;
 	fcaps_body_t *fcaps_body;
 	str_list *param;
-	int i;
+	int i, is_cap_query = 1, is_handled_upstream = 0;
 
 	if (parse_uri(ct_uri->s, ct_uri->len, &puri) != 0) {
 		LM_ERR("failed to parse URI: '%.*s'\n", ct_uri->len, ct_uri->s);
@@ -217,9 +217,10 @@ enum pn_action pn_inspect_ct_params(struct sip_msg *req, const str *ct_uri)
 
 		fcaps_body = (fcaps_body_t *)fcaps->parsed;
 		if (str_match(&fcaps_body->pns, &puri.u_val[i])) {
-			LM_DBG("the '%.*s' PNs are being handled by an upstream proxy\n",
+			LM_DBG("PNs for '%.*s' are being handled by an upstream proxy\n",
 			       fcaps_body->pns.len, fcaps_body->pns.s);
-			return PN_HANDLED_UPSTREAM;
+			is_handled_upstream = 1;
+			goto match_params;
 		}
 	}
 
@@ -236,18 +237,76 @@ enum pn_action pn_inspect_ct_params(struct sip_msg *req, const str *ct_uri)
 match_params:
 	for (param = pn_ct_params; param; param = param->next) {
 		for (int i = 0; i < puri.u_params_no; i++)
-			if (str_match(&param->s, &puri.u_name[i]))
+			if (str_match(&param->s, &puri.u_name[i])) {
+				if (!str_match(&param->s, &pn_provider_param))
+					is_cap_query = 0;
 				goto next_param;
+			}
 
-		return PN_LIST_ONE_PNS;
+		if (is_handled_upstream)
+			/* at least one required PN param is missing and PNs are already
+			 * handled upstream anyway -- just match by URI string */
+			return PN_NONE;
+		else if (!is_cap_query)
+			return PN_UNSUPPORTED_PNS;
 
 next_param:;
 	}
 
+	if (is_cap_query)
+		return PN_LIST_ONE_PNS;
+
+	if (is_handled_upstream)
+		return PN_MATCH_PN_PARAMS;
+
 	return PN_ON;
 }
 
 
+int pn_inspect_request(struct sip_msg *req, const str *ct_uri,
+                       struct save_ctx *sctx)
+{
+	if (sctx->cmatch.mode != CT_MATCH_NONE) {
+		LM_DBG("skip PN processing, matching mode already enforced\n");
+		return 0;
+	}
+
+	switch (pn_inspect_ct_params(req, ct_uri)) {
+	case PN_NONE:
+		LM_DBG("Contact URI has no PN params\n");
+		break;
+
+	case PN_ON:
+		LM_DBG("match this contact using PN params and send PN\n");
+		sctx->cmatch.mode = CT_MATCH_PARAMS;
+		sctx->cmatch.match_params = pn_ct_params;
+		sctx->flags |= REG_SAVE__PN_ON_FLAG;
+		break;
+
+	case PN_LIST_ALL_PNS:
+		LM_DBG("Contact URI includes PN capability query (all PNS)\n");
+		break;
+
+	case PN_LIST_ONE_PNS:
+		LM_DBG("Contact URI includes PN capability query (one PNS)\n");
+		break;
+
+	case PN_MATCH_PN_PARAMS:
+		LM_DBG("match this contact using PN params but don't send PN\n");
+		sctx->cmatch.mode = CT_MATCH_PARAMS;
+		sctx->cmatch.match_params = pn_ct_params;
+		break;
+
+	case PN_UNSUPPORTED_PNS:
+		LM_DBG("at least one required PN param is missing, reply with 555\n");
+		rerrno = R_PNS_UNSUP;
+		return -1;
+	}
+
+	return 0;
+}
+
+
 void pn_append_feature_caps(struct sip_msg *msg, int append_to_reply, str *hf)
 {
 	struct pn_provider *prov;

lib/reg/pn.h

@@ -30,6 +30,7 @@
 
 #include "../../modules/usrloc/ucontact.h"
 #include "regtime.h"
+#include "save_flags.h"
 
 struct pn_provider {
 	str name;
@@ -41,11 +42,22 @@ struct pn_provider {
 
 enum pn_action {
 	PN_NONE,             /* no 'pn-provider' was given */
-	PN_HANDLED_UPSTREAM, /* a Feature-Caps hf is present, so PNs are handled */
 	PN_UNSUPPORTED_PNS,  /* the given 'pn-provider' value is not supported */
+
+	/* Query Network PNS Capabilities */
 	PN_LIST_ALL_PNS,     /* cap query: only 'pn-provider' given, no value */
 	PN_LIST_ONE_PNS,     /* cap query: a known 'pn-provider' value was given */
-	PN_ON,               /* enable PN: all required 'pn-*' params are present */
+
+	/* while the 'pn-*' params are present and the contact must be matched
+	 * using them, we must _not_ send any Push Notifications, since an upstream
+	 * proxy has already indicated that it is doing so */
+	PN_MATCH_PN_PARAMS,
+
+	/* fully enable PN:
+	 *    1. all required 'pn-*' params are present -- match these exclusively
+	 *    2. generate PNs to this contact as required
+	 */
+	PN_ON,
 };
 
 /* common registrar PN modparams */
@@ -85,6 +97,16 @@ extern str_list *pn_ct_params;  /* list of parsed match params */
 int pn_init(void);
 
 
+/**
+ * Perform any required RFC 8599 processing for a SIP request, including
+ * handling for Feature-Caps headers arriving from upstream.
+ *
+ * Return: 0 on success, -1 on failure and should reply immediately
+ */
+int pn_inspect_request(struct sip_msg *req, const str *ct_uri,
+                       struct save_ctx *sctx);
+
+
 /**
  * Look for any RFC 8599 URI parameters and take the appropriate action
  */

modules/mid_registrar/save.c

@@ -2498,34 +2498,9 @@ int mid_reg_save(struct sip_msg *msg, udomain_t *d, str *flags_str,
 		goto quick_reply;
 	}
 
-	if (pn_enable && sctx.cmatch.mode == CT_MATCH_NONE) {
-		switch (pn_inspect_ct_params(msg, &c->uri)) {
-		case PN_NONE:
-			LM_DBG("Contact URI has no PN params\n");
-			break;
-
-		case PN_ON:
-			LM_DBG("Contact URI includes all required PN params\n");
-			sctx.cmatch.mode = CT_MATCH_PARAMS;
-			sctx.cmatch.match_params = pn_ct_params;
-			sctx.flags |= REG_SAVE__PN_ON_FLAG;
-			break;
-
-		case PN_LIST_ALL_PNS:
-			LM_DBG("Contact URI includes PN capability query (all PNS)\n");
-			break;
-
-		case PN_LIST_ONE_PNS:
-			LM_DBG("Contact URI includes PN capability query (one PNS)\n");
-			break;
-
-		case PN_HANDLED_UPSTREAM:
-			break;
-
-		case PN_UNSUPPORTED_PNS:
-			rerrno = R_PNS_UNSUP;
-			goto quick_reply;
-		}
+	if (pn_enable && pn_inspect_request(msg, &c->uri, &sctx) != 0) {
+		LM_DBG("SIP PN processing failed\n");
+		goto quick_reply;
 	}
 
 	/* mid-registrar always rewrites the Contact, so any Path hf must go! */

modules/registrar/save.c

@@ -642,34 +642,9 @@ int save_aux(struct sip_msg* _m, str* forced_binding, void* _d, str* flags_s,
 		c = get_first_contact(_m);
 	}
 
-	if (pn_enable && sctx.cmatch.mode == CT_MATCH_NONE) {
-		switch (pn_inspect_ct_params(_m, &c->uri)) {
-		case PN_NONE:
-			LM_DBG("Contact URI has no PN params\n");
-			break;
-
-		case PN_ON:
-			LM_DBG("Contact URI includes all required PN params\n");
-			sctx.cmatch.mode = CT_MATCH_PARAMS;
-			sctx.cmatch.match_params = pn_ct_params;
-			sctx.flags |= REG_SAVE__PN_ON_FLAG;
-			break;
-
-		case PN_LIST_ALL_PNS:
-			LM_DBG("Contact URI includes PN capability query (all PNS)\n");
-			break;
-
-		case PN_LIST_ONE_PNS:
-			LM_DBG("Contact URI includes PN capability query (one PNS)\n");
-			break;
-
-		case PN_HANDLED_UPSTREAM:
-			break;
-
-		case PN_UNSUPPORTED_PNS:
-			rerrno = R_PNS_UNSUP;
-			goto error;
-		}
+	if (pn_enable && pn_inspect_request(_m, &c->uri, &sctx) != 0) {
+		LM_DBG("SIP PN processing failed\n");
+		goto error;
 	}
 
 	update_act_time();