More useful message upon Validation Challenge failure.

Format the problem document if the JSON has an “error” key.  Cf. section
7 “Identifier Validation Challenges”.

1 files changed, 9 insertions, 2 deletions

diff --git a/client b/client
index 2566c9b..46f388f 100755
--- a/client
+++ b/client
@@ -284,10 +284,17 @@ elsif ($COMMAND eq 'new-cert') {
             keyAuthorization => $keyAuthorization
         });
         # wait until the status become 'valid'
-        for ( my $i = 0, my $status;
-              $status = request_json_decode($r)->{status} // 'pending',
+        for ( my $i = 0, my $content, my $status;
+              $content = request_json_decode($r),
+              $status = $content->{status} // 'pending',
               $status ne 'valid';
               $r = request('GET' => $challenge->{uri}), $i++ ) {
+            if (defined (my $problem = $content->{error})) { # problem document (RFC 7807)
+                my $msg = $problem->{status};
+                $msg .= " " .$problem->{title}      if defined $problem->{title};
+                $msg .= " (".$problem->{detail}.")" if defined $problem->{detail};
+                die $msg, "\n";
+            }
             die "Error: Invalid challenge for $domain (status: ".$status.")\n" if $status ne 'pending';
             die "Timeout exceeded while waiting for challenge to pass ($domain)\n"
                 if $i >= ($CONFIG->{timeout} // 10);