Rewrite katello-certs-check to Ruby

This makes it easier to maintain because the Ruby API is easier to
handle than "parsing" the OpenSSL command line output.

bin/katello-certs-check.rb

@@ -0,0 +1,164 @@
+#!/usr/bin/env ruby
+require 'openssl'
+require 'optparse'
+
+class FailedCheck < Exception
+end
+
+def check(message, code=1)
+  # TODO: no line end
+  puts message
+  begin
+    result = yield
+  rescue FailedCheck => e
+    # TODO: fail in a cleaner way
+    $stderr.puts e
+    exit code
+  rescue Exception => e
+    # TODO: fail in a cleaner way
+    fail "Failed: #{e}"
+    exit code
+  else
+    # TODO markup
+    puts "[OK]"
+  end
+  result
+end
+
+cert_path = nil
+key_path = nil
+bundle_path = nil
+
+parser = OptionParser.new do |opts|
+  opts.on('-t [SERVER|PROXY]', String, 'Target') do |v|
+    # TODO store?
+  end
+
+  opts.on('-c [CERTIFICATE]', String, 'Path to certificate file') do |path|
+    unless File.exist?(path)
+      fail "Path '#{path}' does not exist"
+    end
+    cert_path = path
+  end
+
+  opts.on('-k [KEY]', String, 'Path to private key file') do |path|
+    unless File.exist?(path)
+      fail "Path '#{path}' does not exist"
+    end
+    key_path = path
+  end
+
+  opts.on('-b [BUNDLE]', String, 'Path to Certificate Authority bundle file') do |path|
+    unless File.exist?(path)
+      fail "Path '#{path}' does not exist"
+    end
+    bundle_path = path
+  end
+end
+
+parser.parse!
+
+if [cert_path, key_path, bundle_path].include?(nil)
+  # TODO: print usage
+  fail "Missing cert, key or bundle option"
+end
+
+cert = check("Reading certificate file '#{cert_path}'") do
+  OpenSSL::X509::Certificate.new(File.read(cert_path))
+rescue Exception => e
+  raise FailedCheck, "Failed to read certificate: #{e}"
+  # TODO: check if file is DER encoded
+end
+
+key = check("Reading private key '#{key_path}'") do
+  OpenSSL::PKey.read(File.read(key_path))
+rescue Exception => e
+  # TODO: check if there's a password?
+  raise FailedCheck, "Failed to read private key: #{e}"
+end
+
+bundle = check("Reading CA certificate '#{bundle_path}'") do
+  OpenSSL::X509::Certificate.new(File.read(bundle_path))
+rescue Exception => e
+  raise FailedCheck, "Failed to read CA certificate: #{e}"
+end
+
+check('Checking certificate expiration') do
+  now = Time.now
+  if cert.not_before > now
+    raise FailedCheck, "Certificate not valid yet: #{cert.not_before} is in the future"
+  end
+
+  if cert.not_after < now
+    raise FailedCheck, "Certificate no longer valid: #{cert.not_after} is in the past"
+  end
+end
+
+check('Checking CA bundle expiration') do
+  now = Time.now
+  if bundle.not_before > now
+    raise FailedCheck, "Certificate not valid yet: #{bundle.not_before} is in the future"
+  end
+
+  if bundle.not_after < now
+    raise FailedCheck, "Certificate no longer valid: #{bundle.not_after} is in the past"
+  end
+end
+
+check('Verifying if private key matches certificate') do
+  unless cert.check_private_key(key)
+    raise FailedCheck, "Certificate '#{cert_path}' is not signed by '#{key_path}"
+  end
+end
+
+store = OpenSSL::X509::Store.new
+# TODO: also for clients?
+store.purpose = OpenSSL::X509::PURPOSE_SSL_SERVER
+store.add_file(bundle_path)
+
+chain = check('Verify certificate is singed by bundle') do
+  unless store.verify(cert)
+    raise FailedCheck, "Certificate is not signed by bundle: #{store.error_string}"
+  end
+  store.chain
+end
+
+# TODO
+check('Verifying root is included in bundle has CA:TRUE') do
+  # TODO: oid for basicConstraints?
+  basicConstraints = chain.last.extensions.find { |ext| ext.oid == 'basicConstraints' }
+  unless basicConstraints
+    raise FailedCheck, 'No basicConstraints extension on root'
+  end
+
+  unless basicConstraints.value == 'CA:TRUE'
+    raise FailedCheck, "basicConstraints extension has value '#{basicConstraints.value}' instead of CA:TRUE"
+  end
+end
+
+# TODO: check if there aren't more than 32 certs in the store
+# TODO: verify if there aren't TRUSTED certificates in the store
+
+check('Verifying if subjectAltName extension is valid') do
+  # TODO oid for subjectAltName?
+  subjectAltName = cert.extensions.find { |ext| ext.oid == 'subjectAltName' }
+  unless subjectAltName
+    # Common Name is deprecated, use Subject Alt Name instead. See: https://tools.ietf.org/html/rfc2818#section-3.1"
+    raise FailedCheck, 'No subjectAltName extension on certificate'
+  end
+
+  cn = cert.subject.to_a.find { |name, _data, _type| name == 'CN' }
+  unless cn
+    raise FailedCheck, 'Unable to determine CN on certificate'
+  end
+  cn_value = cn[1]
+  unless cn_value.include?('.')
+    raise FailedCheck, "commonName on #{cert_path} is set to a shortname while an FQDN is expected"
+  end
+
+  unless subjectAltName.value.include?("DNS:#{cn_value}")
+    raise FailedCheck, "subjectAltName on certificate doesn't include commonName '#{cn_value}'"
+  end
+end
+
+# TODO: check key usage includes Key Encipherment on cert