As mentioned previously, there's only one caller that uses this, all
others can't.

Index: cert.c
===================================================================
RCS file: /cvs/src/usr.sbin/rpki-client/cert.c,v
diff -u -p -r1.133 cert.c
--- cert.c	3 Jun 2024 12:58:39 -0000	1.133
+++ cert.c	3 Jun 2024 14:48:56 -0000
@@ -529,7 +529,7 @@ sbgp_sia(const char *fn, struct cert *ce
 		oid = ad->method;
 
 		if (OBJ_cmp(oid, carepo_oid) == 0) {
-			if (!x509_location(fn, "SIA: caRepository", NULL,
+			if (!x509_location(fn, "SIA: caRepository",
 			    ad->location, &carepo))
 				goto out;
 			if (cert->repo == NULL && strncasecmp(carepo,
@@ -544,7 +544,7 @@ sbgp_sia(const char *fn, struct cert *ce
 			free(carepo);
 			carepo = NULL;
 		} else if (OBJ_cmp(oid, manifest_oid) == 0) {
-			if (!x509_location(fn, "SIA: rpkiManifest", NULL,
+			if (!x509_location(fn, "SIA: rpkiManifest",
 			    ad->location, &rpkimft))
 				goto out;
 			if (cert->mft == NULL && strncasecmp(rpkimft,
@@ -560,8 +560,14 @@ sbgp_sia(const char *fn, struct cert *ce
 			rpkimft = NULL;
 		} else if (OBJ_cmp(oid, notify_oid) == 0) {
 			if (!x509_location(fn, "SIA: rpkiNotify",
-			    HTTPS_PROTO, ad->location, &cert->notify))
+			    ad->location, &cert->notify))
 				goto out;
+			if (strncasecmp(cert->notify, HTTPS_PROTO,
+			    HTTPS_PROTO_LEN) != 0) {
+				warnx("%s: non-https uri in rpkiNotify: %s",
+				    fn, cert->notify);
+				goto out;
+			}
 		}
 	}
 
Index: extern.h
===================================================================
RCS file: /cvs/src/usr.sbin/rpki-client/extern.h,v
diff -u -p -r1.220 extern.h
--- extern.h	31 May 2024 02:45:15 -0000	1.220
+++ extern.h	3 Jun 2024 13:02:03 -0000
@@ -913,8 +913,8 @@ char		*x509_pubkey_get_ski(X509_PUBKEY *
 enum cert_purpose	 x509_get_purpose(X509 *, const char *);
 int		 x509_get_time(const ASN1_TIME *, time_t *);
 char		*x509_convert_seqnum(const char *, const ASN1_INTEGER *);
-int		 x509_location(const char *, const char *, const char *,
-		    GENERAL_NAME *, char **);
+int		 x509_location(const char *, const char *, GENERAL_NAME *,
+		    char **);
 int		 x509_inherits(X509 *);
 int		 x509_any_inherits(X509 *);
 int		 x509_valid_name(const char *, const char *, const X509_NAME *);
Index: x509.c
===================================================================
RCS file: /cvs/src/usr.sbin/rpki-client/x509.c,v
diff -u -p -r1.91 x509.c
--- x509.c	3 Jun 2024 12:58:39 -0000	1.91
+++ x509.c	3 Jun 2024 14:47:48 -0000
@@ -456,7 +456,7 @@ x509_get_aia(X509 *x, const char *fn, ch
 		goto out;
 	}
 
-	if (!x509_location(fn, "AIA: caIssuers", NULL, ad->location, aia))
+	if (!x509_location(fn, "AIA: caIssuers", ad->location, aia))
 		goto out;
 
 	rc = 1;
@@ -522,9 +522,7 @@ x509_get_sia(X509 *x, const char *fn, ch
 			goto out;
 		}
 
-		/* Don't fail on non-rsync URI, so check this afterward. */
-		if (!x509_location(fn, "SIA: signedObject", NULL, ad->location,
-		    sia))
+		if (!x509_location(fn, "SIA: signedObject", ad->location, sia))
 			goto out;
 
 		if (rsync_found)
@@ -764,9 +762,7 @@ x509_get_crl(X509 *x, const char *fn, ch
 	for (i = 0; i < sk_GENERAL_NAME_num(names); i++) {
 		name = sk_GENERAL_NAME_value(names, i);
 
-		/* Don't fail on non-rsync URI, so check this afterward. */
-		if (!x509_location(fn, "CRL distribution point", NULL, name,
-		    crl))
+		if (!x509_location(fn, "CRL distribution point", name, crl))
 			goto out;
 
 		if (strncasecmp(*crl, RSYNC_PROTO, RSYNC_PROTO_LEN) == 0) {
@@ -812,8 +808,8 @@ x509_get_time(const ASN1_TIME *at, time_
  * Returns 0 on failure and 1 on success.
  */
 int
-x509_location(const char *fn, const char *descr, const char *proto,
-    GENERAL_NAME *location, char **out)
+x509_location(const char *fn, const char *descr, GENERAL_NAME *location,
+    char **out)
 {
 	ASN1_IA5STRING	*uri;
 
@@ -824,7 +820,7 @@ x509_location(const char *fn, const char
 
 	uri = location->d.uniformResourceIdentifier;
 
-	if (!valid_uri(uri->data, uri->length, proto)) {
+	if (!valid_uri(uri->data, uri->length, NULL)) {
 		warnx("%s: RFC 6487 section 4.8: %s bad location", fn, descr);
 		return 0;
 	}