mid_registrar: Avoid some memory leaks on parsing errors

Also improve mri_free(): avoid redundant checks on non-NULL fields.

Suggested by Chad Attermann <attermann@gmail.com>

(cherry picked from commit 4b9f34d)

modules/mid_registrar/mid_registrar.c

@@ -422,17 +422,10 @@ void mri_free(struct mid_reg_info *mri)
 	       mri->main_reg_uri.s);
 	LM_DBG("ct_uri: '%.*s' %p\n", mri->ct_uri.len, mri->ct_uri.s, mri->ct_uri.s);
 
-	if (mri->aor.s)
-		shm_free(mri->aor.s);
-
-	if (mri->from.s)
-		shm_free(mri->from.s);
-
-	if (mri->to.s)
-		shm_free(mri->to.s);
-
-	if (mri->callid.s)
-		shm_free(mri->callid.s);
+	shm_free(mri->aor.s);
+	shm_free(mri->from.s);
+	shm_free(mri->to.s);
+	shm_free(mri->callid.s);
 
 	if (mri->main_reg_uri.s)
 		shm_free(mri->main_reg_uri.s);

modules/mid_registrar/save.c

@@ -1438,6 +1438,7 @@ static int prepare_forward(struct sip_msg *msg, udomain_t *ud,
 
 	if (parse_from_header(msg) != 0) {
 		LM_ERR("failed to parse From hf\n");
+		mri_free(mri);
 		return -1;
 	}
 
@@ -1453,6 +1454,7 @@ static int prepare_forward(struct sip_msg *msg, udomain_t *ud,
 	if (tm_api.register_tmcb(msg, NULL, TMCB_REQUEST_FWDED,
 	    mid_reg_req_fwded, mri, NULL) <= 0) {
 		LM_ERR("cannot register additional callbacks\n");
+		mri_free(mri);
 		return -1;
 	}