summaryrefslogtreecommitdiff
path: root/modules/caddyhttp/templates/templates.go
blob: 05a2f633a705863365020a004633d5a0d9e794d1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package templates

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"strconv"
	"strings"

	"github.com/caddyserver/caddy/v2"
	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
)

func init() {
	caddy.RegisterModule(Templates{})
}

// Templates is a middleware which execute response bodies as templates.
type Templates struct {
	IncludeRoot string   `json:"include_root,omitempty"`
	MIMETypes   []string `json:"mime_types,omitempty"`
	Delimiters  []string `json:"delimiters,omitempty"`
}

// CaddyModule returns the Caddy module information.
func (Templates) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		Name: "http.handlers.templates",
		New:  func() caddy.Module { return new(Templates) },
	}
}

// Provision provisions t.
func (t *Templates) Provision(ctx caddy.Context) error {
	if t.MIMETypes == nil {
		t.MIMETypes = defaultMIMETypes
	}
	if t.IncludeRoot == "" {
		t.IncludeRoot = "{http.vars.root}"
	}
	return nil
}

// Validate ensures t has a valid configuration.
func (t *Templates) Validate() error {
	if len(t.Delimiters) != 0 && len(t.Delimiters) != 2 {
		return fmt.Errorf("delimiters must consist of exactly two elements: opening and closing")
	}
	return nil
}

func (t *Templates) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
	buf := bufPool.Get().(*bytes.Buffer)
	buf.Reset()
	defer bufPool.Put(buf)

	// shouldBuf determines whether to execute templates on this response,
	// since generally we will not want to execute for images or CSS, etc.
	shouldBuf := func(status int) bool {
		ct := w.Header().Get("Content-Type")
		for _, mt := range t.MIMETypes {
			if strings.Contains(ct, mt) {
				return true
			}
		}
		return false
	}

	rec := caddyhttp.NewResponseRecorder(w, buf, shouldBuf)

	err := next.ServeHTTP(rec, r)
	if err != nil {
		return err
	}
	if !rec.Buffered() {
		return nil
	}

	err = t.executeTemplate(rec, r)
	if err != nil {
		return err
	}

	w.Header().Set("Content-Length", strconv.Itoa(buf.Len()))
	w.Header().Del("Accept-Ranges") // we don't know ranges for dynamically-created content
	w.Header().Del("Last-Modified") // useless for dynamic content since it's always changing

	// we don't know a way to guickly generate etag for dynamic content,
	// but we can convert this to a weak etag to kind of indicate that
	if etag := w.Header().Get("ETag"); etag != "" {
		w.Header().Set("ETag", "W/"+etag)
	}

	w.WriteHeader(rec.Status())
	io.Copy(w, buf)

	return nil
}

// executeTemplate executes the template contained in wb.buf and replaces it with the results.
func (t *Templates) executeTemplate(rr caddyhttp.ResponseRecorder, r *http.Request) error {
	var fs http.FileSystem
	if t.IncludeRoot != "" {
		repl := r.Context().Value(caddy.ReplacerCtxKey).(caddy.Replacer)
		fs = http.Dir(repl.ReplaceAll(t.IncludeRoot, "."))
	}

	ctx := &templateContext{
		Root:       fs,
		Req:        r,
		RespHeader: tplWrappedHeader{rr.Header()},
		config:     t,
	}

	err := ctx.executeTemplateInBuffer(r.URL.Path, rr.Buffer())
	if err != nil {
		return caddyhttp.Error(http.StatusInternalServerError, err)
	}

	return nil
}

// virtualResponseWriter is used in virtualized HTTP requests
// that templates may execute.
type virtualResponseWriter struct {
	status int
	header http.Header
	body   *bytes.Buffer
}

func (vrw *virtualResponseWriter) Header() http.Header {
	return vrw.header
}

func (vrw *virtualResponseWriter) WriteHeader(statusCode int) {
	vrw.status = statusCode
}

func (vrw *virtualResponseWriter) Write(data []byte) (int, error) {
	return vrw.body.Write(data)
}

var defaultMIMETypes = []string{
	"text/html",
	"text/plain",
	"text/markdown",
}

// Interface guards
var (
	_ caddy.Provisioner           = (*Templates)(nil)
	_ caddy.Validator             = (*Templates)(nil)
	_ caddyhttp.MiddlewareHandler = (*Templates)(nil)
)