x509crl: add OpenSSL::X509::CRL#by_serial

ext/openssl/ossl_x509crl.c

@@ -297,6 +297,44 @@ ossl_x509crl_get_revoked(VALUE self)
     return ary;
 }
 
+/*
+ * call-seq:
+ *    crl.by_serial(serial) -> OpenSSL::X509::Revoked or nil
+ *
+ * Looks up the certificate _serial_ (an Integer or OpenSSL::BN) in the CRL and
+ * returns the matching OpenSSL::X509::Revoked entry, or +nil+ if that serial is
+ * not listed.
+ *
+ * Unlike iterating over #revoked, this does not instantiate the entire
+ * revocation list: it performs a sorted lookup (wrapping the OpenSSL function
+ * +X509_CRL_get0_by_serial+), which is significantly faster and uses far less
+ * memory for large CRLs.
+ *
+ *    crl.by_serial(cert.serial)        #=> #<OpenSSL::X509::Revoked> or nil
+ *    crl.by_serial(cert.serial)&.time  #=> revocation time, if revoked
+ */
+static VALUE
+ossl_x509crl_by_serial(VALUE self, VALUE serial)
+{
+    X509_CRL *crl;
+    X509_REVOKED *rev = NULL;
+    ASN1_INTEGER *asn1_serial;
+    int found;
+
+    GetX509CRL(self, crl);
+    asn1_serial = num_to_asn1integer(serial, NULL);
+
+    /* 0 = not found, 1 = found, 2 = found with reason removeFromCRL */
+    found = X509_CRL_get0_by_serial(crl, &rev, asn1_serial);
+    ASN1_INTEGER_free(asn1_serial);
+
+    if (found == 0)
+        return Qnil;
+
+    /* ossl_x509revoked_new dups, so the result outlives the CRL safely */
+    return ossl_x509revoked_new(rev);
+}
+
 static VALUE
 ossl_x509crl_set_revoked(VALUE self, VALUE ary)
 {
@@ -525,6 +563,7 @@ Init_ossl_x509crl(void)
     rb_define_method(cX509CRL, "next_update=", ossl_x509crl_set_next_update, 1);
     rb_define_method(cX509CRL, "revoked", ossl_x509crl_get_revoked, 0);
     rb_define_method(cX509CRL, "revoked=", ossl_x509crl_set_revoked, 1);
+    rb_define_method(cX509CRL, "by_serial", ossl_x509crl_by_serial, 1);
     rb_define_method(cX509CRL, "add_revoked", ossl_x509crl_add_revoked, 1);
     rb_define_method(cX509CRL, "sign", ossl_x509crl_sign, 2);
     rb_define_method(cX509CRL, "verify", ossl_x509crl_verify, 1);

test/openssl/test_x509crl.rb

@@ -105,6 +105,44 @@ def test_revoked
     assert_equal(revoked.map(&:serial), revoked2.map(&:serial))
   end
 
+  def test_by_serial
+    now = Time.at(Time.now.to_i)
+    revoke_info = [
+      [1, Time.at(0),          1], # keyCompromise
+      [2, Time.at(0x7fffffff), 2], # cACompromise
+      [3, now,                 3], # affiliationChanged
+    ]
+    cert = issue_cert(@ca, @rsa1, 1, [], nil, nil)
+    crl = issue_crl(revoke_info, 1, Time.now, Time.now+1600, [],
+                    cert, @rsa1, "SHA256")
+
+    # Returns the matching Revoked entry for a listed serial
+    rev = crl.by_serial(2)
+    assert_instance_of(OpenSSL::X509::Revoked, rev)
+    assert_equal(2, rev.serial)
+    assert_equal(Time.at(0x7fffffff), rev.time)
+    assert_equal("CRLReason", rev.extensions[0].oid)
+    assert_equal("CA Compromise", rev.extensions[0].value)
+
+    # Accepts an OpenSSL::BN as well as an Integer
+    assert_equal(3, crl.by_serial(OpenSSL::BN.new(3)).serial)
+
+    # Returns nil for a serial that is not listed
+    assert_nil(crl.by_serial(42))
+
+    # Same answers after a DER round-trip, and consistent with #revoked
+    crl = OpenSSL::X509::CRL.new(crl.to_der)
+    revoke_info.each do |serial, time, _reason|
+      by_serial = crl.by_serial(serial)
+      from_list = crl.revoked.find {|r| r.serial == serial }
+      assert_equal(by_serial, from_list)
+      assert_equal(time, by_serial.time)
+    end
+
+    # Rejects values that can't be an integer serial
+    assert_raise(TypeError) { crl.by_serial(nil) }
+  end
+
   def test_extension
     cert_exts = [
       ["basicConstraints", "CA:TRUE", true],