From 269b1e9aa34b2b02911f8746e7b6a162cd8222cf Mon Sep 17 00:00:00 2001
From: Matthew Holt <mholt@users.noreply.github.com>
Date: Thu, 20 Jun 2019 20:36:29 -0600
Subject: tls: Improve (and fix) on-demand configuration

---
 modules/caddytls/acmemanager.go | 66 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 60 insertions(+), 6 deletions(-)

(limited to 'modules/caddytls/acmemanager.go')

diff --git a/modules/caddytls/acmemanager.go b/modules/caddytls/acmemanager.go
index 50f8648..871b2bf 100644
--- a/modules/caddytls/acmemanager.go
+++ b/modules/caddytls/acmemanager.go
@@ -3,6 +3,7 @@ package caddytls
 import (
 	"encoding/json"
 	"fmt"
+	"net/url"
 	"time"
 
 	"github.com/go-acme/lego/certcrypto"
@@ -30,12 +31,12 @@ func init() {
 type ACMEManagerMaker struct {
 	CA          string           `json:"ca,omitempty"`
 	Email       string           `json:"email,omitempty"`
-	RenewAhead  caddy.Duration  `json:"renew_ahead,omitempty"`
+	RenewAhead  caddy.Duration   `json:"renew_ahead,omitempty"`
 	KeyType     string           `json:"key_type,omitempty"`
-	ACMETimeout caddy.Duration  `json:"acme_timeout,omitempty"`
+	ACMETimeout caddy.Duration   `json:"acme_timeout,omitempty"`
 	MustStaple  bool             `json:"must_staple,omitempty"`
-	Challenges  ChallengesConfig `json:"challenges"`
-	OnDemand    *OnDemandConfig  `json:"on_demand,omitempty"`
+	Challenges  ChallengesConfig `json:"challenges,omitempty"`
+	OnDemand    bool             `json:"on_demand,omitempty"`
 	Storage     json.RawMessage  `json:"storage,omitempty"`
 
 	storage certmagic.Storage
@@ -109,9 +110,34 @@ func (m *ACMEManagerMaker) makeCertMagicConfig(ctx caddy.Context) certmagic.Conf
 	}
 
 	var ond *certmagic.OnDemandConfig
-	if m.OnDemand != nil {
+	if m.OnDemand {
+		var onDemand *OnDemandConfig
+		appVal, err := ctx.App("tls")
+		if err == nil {
+			onDemand = appVal.(*TLS).Automation.OnDemand
+		}
+
 		ond = &certmagic.OnDemandConfig{
-			// TODO: fill this out
+			DecisionFunc: func(name string) error {
+				if onDemand != nil {
+					if onDemand.Ask != "" {
+						err := onDemandAskRequest(onDemand.Ask, name)
+						if err != nil {
+							return err
+						}
+					}
+					// check the rate limiter last, since
+					// even checking consumes a token; so
+					// don't even bother checking if the
+					// other regulations fail anyway
+					if onDemand.RateLimit != nil {
+						if !onDemandRateLimiter.Allow() {
+							return fmt.Errorf("on-demand rate limit exceeded")
+						}
+					}
+				}
+				return nil
+			},
 		}
 	}
 
@@ -134,6 +160,34 @@ func (m *ACMEManagerMaker) makeCertMagicConfig(ctx caddy.Context) certmagic.Conf
 	}
 }
 
+// onDemandAskRequest makes a request to the ask URL
+// to see if a certificate can be obtained for name.
+// The certificate request should be denied if this
+// returns an error.
+func onDemandAskRequest(ask string, name string) error {
+	askURL, err := url.Parse(ask)
+	if err != nil {
+		return fmt.Errorf("parsing ask URL: %v", err)
+	}
+	qs := askURL.Query()
+	qs.Set("domain", name)
+	askURL.RawQuery = qs.Encode()
+
+	resp, err := onDemandAskClient.Get(askURL.String())
+	if err != nil {
+		return fmt.Errorf("error checking %v to deterine if certificate for hostname '%s' should be allowed: %v",
+			ask, name, err)
+	}
+	resp.Body.Close()
+
+	if resp.StatusCode < 200 || resp.StatusCode > 299 {
+		return fmt.Errorf("certificate for hostname '%s' not allowed; non-2xx status code %d returned from %v",
+			name, resp.StatusCode, ask)
+	}
+
+	return nil
+}
+
 // supportedCertKeyTypes is all the key types that are supported
 // for certificates that are obtained through ACME.
 var supportedCertKeyTypes = map[string]certcrypto.KeyType{
-- 
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