rpki-client: reject bad URLs in cert files

[Claudio Jeker]

Be stricter in what we accept as URL. Nobody should use silly encodings
like UTF-8 or other crap in the embedded URLs. I also consider any kind of
space as a failure (use %20 instead if that is really needed).

This makes later handling of URLs a lot safer (e.g. rpki-client prints
part of URLs in log messages).

OK?
-- 
:wq Claudio

Index: cert.c
===================================================================
RCS file: /cvs/src/usr.sbin/rpki-client/cert.c,v
retrieving revision 1.19
diff -u -p -r1.19 cert.c
--- cert.c      24 Oct 2020 08:09:39 -0000      1.19
+++ cert.c      2 Dec 2020 13:59:48 -0000
@@ -19,6 +19,7 @@
 
 #include <arpa/inet.h>
 #include <assert.h>
+#include <ctype.h>
 #include <err.h>
 #include <inttypes.h>
 #include <stdarg.h>
@@ -141,6 +142,8 @@ static int
 sbgp_sia_resource_notify(struct parse *p,
        const unsigned char *d, size_t dsz)
 {
+       size_t i;
+
        if (p->res->notify != NULL) {
                warnx("%s: RFC 6487 section 4.8.8: SIA: "
                    "Notify location already specified", p->fn);
@@ -153,6 +156,14 @@ sbgp_sia_resource_notify(struct parse *p
                    p->fn);
                return 0;
        }
+       /* make sure only US-ASCII chars are in the URL */
+       for (i = 0; i < dsz; i++) {
+               if (isalnum(d[i]) || ispunct(d[i]))
+                       continue;
+               warnx("%s: invalid URI", p->fn);
+               return 0;
+       }
+
 
        if ((p->res->notify = strndup((const char *)d, dsz)) == NULL)
                err(1, NULL);
@@ -168,6 +179,8 @@ static int
 sbgp_sia_resource_mft(struct parse *p,
        const unsigned char *d, size_t dsz)
 {
+       size_t i;
+
        if (p->res->mft != NULL) {
                warnx("%s: RFC 6487 section 4.8.8: SIA: "
                    "MFT location already specified", p->fn);
@@ -185,7 +198,13 @@ sbgp_sia_resource_mft(struct parse *p,
                    "invalid rsync URI suffix", p->fn);
                return 0;
        }
-
+       /* make sure only US-ASCII chars are in the URL */
+       for (i = 0; i < dsz; i++) {
+               if (isalnum(d[i]) || ispunct(d[i]))
+                       continue;
+               warnx("%s: invalid URI", p->fn);
+               return 0;
+       }
 
        if ((p->res->mft = strndup((const char *)d, dsz)) == NULL)
                err(1, NULL);