From c6746425a3bc7ae390a87a8b717ac0fc4bd914b5 Mon Sep 17 00:00:00 2001
From: Mariano Cano <mariano@smallstep.com>
Date: Fri, 24 Jul 2020 17:09:29 -0700
Subject: [PATCH] Add methods to initialize ssh templates in provisioners.

---
 authority/provisioner/ssh_options.go | 107 +++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 authority/provisioner/ssh_options.go

diff --git a/authority/provisioner/ssh_options.go b/authority/provisioner/ssh_options.go
new file mode 100644
index 00000000..784b0958
--- /dev/null
+++ b/authority/provisioner/ssh_options.go
@@ -0,0 +1,107 @@
+package provisioner
+
+import (
+	"encoding/json"
+	"strings"
+
+	"github.com/pkg/errors"
+	"github.com/smallstep/certificates/sshutil"
+)
+
+// CertificateOptions is an interface that returns a list of options passed when
+// creating a new certificate.
+type SSHCertificateOptions interface {
+	Options(SignSSHOptions) []sshutil.Option
+}
+
+type sshCertificateOptionsFunc func(SignSSHOptions) []sshutil.Option
+
+func (fn sshCertificateOptionsFunc) Options(so SignSSHOptions) []sshutil.Option {
+	return fn(so)
+}
+
+// SSHOptions are a collection of custom options that can be added to each
+// provisioner.
+type SSHOptions struct {
+	// Template contains an SSH certificate template. It can be a JSON template
+	// escaped in a string or it can be also encoded in base64.
+	Template string `json:"template,omitempty"`
+
+	// TemplateFile points to a file containing a SSH certificate template.
+	TemplateFile string `json:"templateFile,omitempty"`
+
+	// TemplateData is a JSON object with variables that can be used in custom
+	// templates.
+	TemplateData json.RawMessage `json:"templateData,omitempty"`
+}
+
+// HasTemplate returns true if a template is defined in the provisioner options.
+func (o *SSHOptions) HasTemplate() bool {
+	return o != nil && (o.Template != "" || o.TemplateFile != "")
+}
+
+// SSHTemplateOptions generates a CertificateOptions with the template and data
+// defined in the ProvisionerOptions, the provisioner generated data, and the
+// user data provided in the request. If no template has been provided,
+// x509util.DefaultLeafTemplate will be used.
+func TemplateSSHOptions(o *SSHOptions, data sshutil.TemplateData) (SSHCertificateOptions, error) {
+	return CustomSSHTemplateOptions(o, data, sshutil.DefaultCertificate)
+}
+
+// CustomTemplateOptions generates a CertificateOptions with the template, data
+// defined in the ProvisionerOptions, the provisioner generated data and the
+// user data provided in the request. If no template has been provided in the
+// ProvisionerOptions, the given template will be used.
+func CustomSSHTemplateOptions(o *SSHOptions, data sshutil.TemplateData, defaultTemplate string) (SSHCertificateOptions, error) {
+	if o != nil {
+		if data == nil {
+			data = sshutil.NewTemplateData()
+		}
+
+		// Add template data if any.
+		if len(o.TemplateData) > 0 {
+			if err := json.Unmarshal(o.TemplateData, &data); err != nil {
+				return nil, errors.Wrap(err, "error unmarshaling template data")
+			}
+		}
+	}
+
+	return sshCertificateOptionsFunc(func(so SignSSHOptions) []sshutil.Option {
+		// We're not provided user data without custom templates.
+		if !o.HasTemplate() {
+			return []sshutil.Option{
+				sshutil.WithTemplate(defaultTemplate, data),
+			}
+		}
+
+		// Add user provided data.
+		if len(so.TemplateData) > 0 {
+			userObject := make(map[string]interface{})
+			if err := json.Unmarshal(so.TemplateData, &userObject); err != nil {
+				data.SetUserData(map[string]interface{}{})
+			} else {
+				data.SetUserData(userObject)
+			}
+		}
+
+		// Load a template from a file if Template is not defined.
+		if o.Template == "" && o.TemplateFile != "" {
+			return []sshutil.Option{
+				sshutil.WithTemplateFile(o.TemplateFile, data),
+			}
+		}
+
+		// Load a template from the Template fields
+		// 1. As a JSON in a string.
+		template := strings.TrimSpace(o.Template)
+		if strings.HasPrefix(template, "{") {
+			return []sshutil.Option{
+				sshutil.WithTemplate(template, data),
+			}
+		}
+		// 2. As a base64 encoded JSON.
+		return []sshutil.Option{
+			sshutil.WithTemplateBase64(template, data),
+		}
+	}), nil
+}