From 6706c9225a8dcb976785bdf2c35eb151d54ac18c Mon Sep 17 00:00:00 2001
From: Matthew Holt <mholt@users.noreply.github.com>
Date: Tue, 18 Jun 2019 11:13:12 -0600
Subject: Implement templates handler; various minor cleanups and bug fixes

---
 modules/caddyhttp/templates/templates.go       | 146 +++++++++
 modules/caddyhttp/templates/tplcontext.go      | 413 ++++++++++++++++++++++++
 modules/caddyhttp/templates/tplcontext_test.go | 420 +++++++++++++++++++++++++
 3 files changed, 979 insertions(+)
 create mode 100644 modules/caddyhttp/templates/templates.go
 create mode 100644 modules/caddyhttp/templates/tplcontext.go
 create mode 100644 modules/caddyhttp/templates/tplcontext_test.go

(limited to 'modules/caddyhttp/templates')

diff --git a/modules/caddyhttp/templates/templates.go b/modules/caddyhttp/templates/templates.go
new file mode 100644
index 0000000..56c3b66
--- /dev/null
+++ b/modules/caddyhttp/templates/templates.go
@@ -0,0 +1,146 @@
+package templates
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"text/template"
+
+	"github.com/caddyserver/caddy"
+	"github.com/caddyserver/caddy/modules/caddyhttp"
+)
+
+func init() {
+	caddy.RegisterModule(caddy.Module{
+		Name: "http.middleware.templates",
+		New:  func() interface{} { return new(Templates) },
+	})
+}
+
+// Templates is a middleware which execute response bodies as templates.
+type Templates struct {
+	FileRoot   string   `json:"file_root,omitempty"`
+	Delimiters []string `json:"delimiters,omitempty"`
+}
+
+// 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)
+
+	wb := &responseBuffer{
+		ResponseWriterWrapper: &caddyhttp.ResponseWriterWrapper{ResponseWriter: w},
+		buf:                   buf,
+	}
+
+	err := next.ServeHTTP(wb, r)
+	if err != nil {
+		return err
+	}
+
+	err = t.executeTemplate(wb, r)
+	if err != nil {
+		return err
+	}
+
+	w.Header().Set("Content-Length", strconv.Itoa(wb.buf.Len()))
+	w.Header().Del("Accept-Ranges") // we don't know ranges for dynamically-created content
+	w.Header().Del("Etag")          // don't know a way to quickly generate etag for dynamic content
+	w.Header().Del("Last-Modified") // useless for dynamic content since it's always changing
+
+	w.WriteHeader(wb.statusCode)
+	io.Copy(w, wb.buf)
+
+	return nil
+}
+
+// executeTemplate executes the template contianed
+// in wb.buf and replaces it with the results.
+func (t *Templates) executeTemplate(wb *responseBuffer, r *http.Request) error {
+	tpl := template.New(r.URL.Path)
+
+	if len(t.Delimiters) == 2 {
+		tpl.Delims(t.Delimiters[0], t.Delimiters[1])
+	}
+
+	parsedTpl, err := tpl.Parse(wb.buf.String())
+	if err != nil {
+		return caddyhttp.Error(http.StatusInternalServerError, err)
+	}
+
+	var fs http.FileSystem
+	if t.FileRoot != "" {
+		fs = http.Dir(t.FileRoot)
+	}
+	ctx := &templateContext{
+		Root:       fs,
+		Req:        r,
+		RespHeader: tplWrappedHeader{wb.Header()},
+	}
+
+	wb.buf.Reset() // reuse buffer for output
+	err = parsedTpl.Execute(wb.buf, ctx)
+	if err != nil {
+		return caddyhttp.Error(http.StatusInternalServerError, err)
+	}
+
+	return nil
+}
+
+// responseBuffer buffers the response so that it can be
+// executed as a template.
+type responseBuffer struct {
+	*caddyhttp.ResponseWriterWrapper
+	wroteHeader bool
+	statusCode  int
+	buf         *bytes.Buffer
+}
+
+func (rb *responseBuffer) WriteHeader(statusCode int) {
+	if rb.wroteHeader {
+		return
+	}
+	rb.statusCode = statusCode
+	rb.wroteHeader = true
+}
+
+func (rb *responseBuffer) Write(data []byte) (int, error) {
+	rb.WriteHeader(http.StatusOK)
+	return rb.buf.Write(data)
+}
+
+// virtualResponseWriter is used in virtualized HTTP requests.
+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)
+}
+
+// Interface guards
+var (
+	_ caddy.Validator             = (*Templates)(nil)
+	_ caddyhttp.MiddlewareHandler = (*Templates)(nil)
+	_ caddyhttp.HTTPInterfaces    = (*responseBuffer)(nil)
+)
diff --git a/modules/caddyhttp/templates/tplcontext.go b/modules/caddyhttp/templates/tplcontext.go
new file mode 100644
index 0000000..7123c42
--- /dev/null
+++ b/modules/caddyhttp/templates/tplcontext.go
@@ -0,0 +1,413 @@
+package templates
+
+import (
+	"bytes"
+	"crypto/rand"
+	"fmt"
+	"io"
+	"log"
+	weakrand "math/rand"
+	"net"
+	"net/http"
+	"path"
+	"strings"
+	"sync"
+	"text/template"
+	"time"
+
+	"os"
+
+	"github.com/caddyserver/caddy/modules/caddyhttp"
+	"gopkg.in/russross/blackfriday.v2"
+)
+
+// templateContext is the templateContext with which HTTP templates are executed.
+type templateContext struct {
+	Root       http.FileSystem
+	Req        *http.Request
+	Args       []interface{} // defined by arguments to .Include
+	RespHeader tplWrappedHeader
+	server     http.Handler
+}
+
+// Include returns the contents of filename relative to the site root.
+func (c templateContext) Include(filename string, args ...interface{}) (string, error) {
+	if c.Root == nil {
+		return "", fmt.Errorf("root file system not specified")
+	}
+
+	file, err := c.Root.Open(filename)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	bodyBuf := bufPool.Get().(*bytes.Buffer)
+	bodyBuf.Reset()
+	defer bufPool.Put(bodyBuf)
+
+	_, err = io.Copy(bodyBuf, file)
+	if err != nil {
+		return "", err
+	}
+
+	c.Args = args
+
+	return c.executeTemplate(filename, bodyBuf.Bytes())
+}
+
+// HTTPInclude returns the body of a virtual (lightweight) request
+// to the given URI on the same server.
+func (c templateContext) HTTPInclude(uri string) (string, error) {
+	if c.Req.Header.Get(recursionPreventionHeader) == "1" {
+		return "", fmt.Errorf("virtual include cycle")
+	}
+
+	buf := bufPool.Get().(*bytes.Buffer)
+	buf.Reset()
+	defer bufPool.Put(buf)
+
+	virtReq, err := http.NewRequest("GET", uri, nil)
+	if err != nil {
+		return "", err
+	}
+	virtReq.Header.Set(recursionPreventionHeader, "1")
+
+	vrw := &virtualResponseWriter{body: buf, header: make(http.Header)}
+	server := c.Req.Context().Value(caddyhttp.ServerCtxKey).(http.Handler)
+
+	server.ServeHTTP(vrw, virtReq)
+	if vrw.status >= 400 {
+		return "", fmt.Errorf("http %d", vrw.status)
+	}
+
+	return c.executeTemplate(uri, buf.Bytes())
+}
+
+func (c templateContext) executeTemplate(tplName string, body []byte) (string, error) {
+	tpl, err := template.New(tplName).Parse(string(body))
+	if err != nil {
+		return "", err
+	}
+
+	buf := bufPool.Get().(*bytes.Buffer)
+	buf.Reset()
+	defer bufPool.Put(buf)
+
+	err = tpl.Execute(buf, c)
+	if err != nil {
+		return "", err
+	}
+
+	return buf.String(), nil
+}
+
+// Now returns the current timestamp.
+func (c templateContext) Now() time.Time {
+	return time.Now()
+}
+
+// Cookie gets the value of a cookie with name name.
+func (c templateContext) Cookie(name string) string {
+	cookies := c.Req.Cookies()
+	for _, cookie := range cookies {
+		if cookie.Name == name {
+			return cookie.Value
+		}
+	}
+	return ""
+}
+
+// ReqHeader gets the value of a request header with field name.
+func (c templateContext) ReqHeader(name string) string {
+	return c.Req.Header.Get(name)
+}
+
+// Hostname gets the (remote) hostname of the client making the request.
+func (c templateContext) Hostname() string {
+	ip := c.IP()
+
+	hostnameList, err := net.LookupAddr(ip)
+	if err != nil || len(hostnameList) == 0 {
+		return c.Req.RemoteAddr
+	}
+
+	return hostnameList[0]
+}
+
+// Env gets a map of the environment variables.
+func (c templateContext) Env() map[string]string {
+	osEnv := os.Environ()
+	envVars := make(map[string]string, len(osEnv))
+	for _, env := range osEnv {
+		data := strings.SplitN(env, "=", 2)
+		if len(data) == 2 && len(data[0]) > 0 {
+			envVars[data[0]] = data[1]
+		}
+	}
+	return envVars
+}
+
+// IP gets the (remote) IP address of the client making the request.
+func (c templateContext) IP() string {
+	ip, _, err := net.SplitHostPort(c.Req.RemoteAddr)
+	if err != nil {
+		return c.Req.RemoteAddr
+	}
+	return ip
+}
+
+// Host returns the hostname portion of the Host header
+// from the HTTP request.
+func (c templateContext) Host() (string, error) {
+	host, _, err := net.SplitHostPort(c.Req.Host)
+	if err != nil {
+		if !strings.Contains(c.Req.Host, ":") {
+			// common with sites served on the default port 80
+			return c.Req.Host, nil
+		}
+		return "", err
+	}
+	return host, nil
+}
+
+// Truncate truncates the input string to the given length.
+// If length is negative, it returns that many characters
+// starting from the end of the string. If the absolute value
+// of length is greater than len(input), the whole input is
+// returned.
+func (c templateContext) Truncate(input string, length int) string {
+	if length < 0 && len(input)+length > 0 {
+		return input[len(input)+length:]
+	}
+	if length >= 0 && len(input) > length {
+		return input[:length]
+	}
+	return input
+}
+
+// StripHTML returns s without HTML tags. It is fairly naive
+// but works with most valid HTML inputs.
+func (c templateContext) StripHTML(s string) string {
+	var buf bytes.Buffer
+	var inTag, inQuotes bool
+	var tagStart int
+	for i, ch := range s {
+		if inTag {
+			if ch == '>' && !inQuotes {
+				inTag = false
+			} else if ch == '<' && !inQuotes {
+				// false start
+				buf.WriteString(s[tagStart:i])
+				tagStart = i
+			} else if ch == '"' {
+				inQuotes = !inQuotes
+			}
+			continue
+		}
+		if ch == '<' {
+			inTag = true
+			tagStart = i
+			continue
+		}
+		buf.WriteRune(ch)
+	}
+	if inTag {
+		// false start
+		buf.WriteString(s[tagStart:])
+	}
+	return buf.String()
+}
+
+// Markdown renders the markdown body as HTML.
+func (c templateContext) Markdown(body string) string {
+	return string(blackfriday.Run([]byte(body)))
+}
+
+// Ext returns the suffix beginning at the final dot in the final
+// slash-separated element of the pathStr (or in other words, the
+// file extension).
+func (c templateContext) Ext(pathStr string) string {
+	return path.Ext(pathStr)
+}
+
+// StripExt returns the input string without the extension,
+// which is the suffix starting with the final '.' character
+// but not before the final path separator ('/') character.
+// If there is no extension, the whole input is returned.
+func (c templateContext) StripExt(path string) string {
+	for i := len(path) - 1; i >= 0 && path[i] != '/'; i-- {
+		if path[i] == '.' {
+			return path[:i]
+		}
+	}
+	return path
+}
+
+// Replace replaces instances of find in input with replacement.
+func (c templateContext) Replace(input, find, replacement string) string {
+	return strings.Replace(input, find, replacement, -1)
+}
+
+// HasPrefix returns true if s starts with prefix.
+func (c templateContext) HasPrefix(s, prefix string) bool {
+	return strings.HasPrefix(s, prefix)
+}
+
+// ToLower will convert the given string to lower case.
+func (c templateContext) ToLower(s string) string {
+	return strings.ToLower(s)
+}
+
+// ToUpper will convert the given string to upper case.
+func (c templateContext) ToUpper(s string) string {
+	return strings.ToUpper(s)
+}
+
+// Split is a pass-through to strings.Split. It will split
+// the first argument at each instance of the separator and
+// return a slice of strings.
+func (c templateContext) Split(s string, sep string) []string {
+	return strings.Split(s, sep)
+}
+
+// Join is a pass-through to strings.Join. It will join the
+// first argument slice with the separator in the second
+// argument and return the result.
+func (c templateContext) Join(a []string, sep string) string {
+	return strings.Join(a, sep)
+}
+
+// Slice will convert the given arguments into a slice.
+func (c templateContext) Slice(elems ...interface{}) []interface{} {
+	return elems
+}
+
+// Dict will convert the arguments into a dictionary (map). It expects
+// alternating keys and values of string types. This is useful since you
+// cannot express map literals directly in Go templates.
+func (c templateContext) Dict(values ...interface{}) (map[string]interface{}, error) {
+	if len(values)%2 != 0 {
+		return nil, fmt.Errorf("expected even number of arguments")
+	}
+	dict := make(map[string]interface{}, len(values)/2)
+	for i := 0; i < len(values); i += 2 {
+		key, ok := values[i].(string)
+		if !ok {
+			return nil, fmt.Errorf("argument %d: map keys must be strings", i)
+		}
+		dict[key] = values[i+1]
+	}
+	return dict, nil
+}
+
+// ListFiles reads and returns a slice of names from the given
+// directory relative to the root of c.
+func (c templateContext) ListFiles(name string) ([]string, error) {
+	if c.Root == nil {
+		return nil, fmt.Errorf("root file system not specified")
+	}
+
+	dir, err := c.Root.Open(path.Clean(name))
+	if err != nil {
+		return nil, err
+	}
+	defer dir.Close()
+
+	stat, err := dir.Stat()
+	if err != nil {
+		return nil, err
+	}
+	if !stat.IsDir() {
+		return nil, fmt.Errorf("%v is not a directory", name)
+	}
+
+	dirInfo, err := dir.Readdir(0)
+	if err != nil {
+		return nil, err
+	}
+
+	names := make([]string, len(dirInfo))
+	for i, fileInfo := range dirInfo {
+		names[i] = fileInfo.Name()
+	}
+
+	return names, nil
+}
+
+// RandomString generates a random string of random length given
+// length bounds. Thanks to http://stackoverflow.com/a/35615565/1048862
+// for the clever technique that is fairly fast, secure, and maintains
+// proper distributions over the dictionary.
+func (c templateContext) RandomString(minLen, maxLen int) string {
+	const (
+		letterBytes   = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+		letterIdxBits = 6                    // 6 bits to represent 64 possibilities (indexes)
+		letterIdxMask = 1<<letterIdxBits - 1 // all 1-bits, as many as letterIdxBits
+	)
+
+	if minLen < 0 || maxLen < 0 || maxLen < minLen {
+		return ""
+	}
+
+	n := weakrand.Intn(maxLen-minLen+1) + minLen // choose actual length
+
+	// secureRandomBytes returns a number of bytes using crypto/rand.
+	secureRandomBytes := func(numBytes int) []byte {
+		randomBytes := make([]byte, numBytes)
+		if _, err := rand.Read(randomBytes); err != nil {
+			// TODO: what to do with the logs (throughout whole file) (could return as error? might get rendered though...)
+			log.Println("[ERROR] failed to read bytes: ", err)
+		}
+		return randomBytes
+	}
+
+	result := make([]byte, n)
+	bufferSize := int(float64(n) * 1.3)
+	for i, j, randomBytes := 0, 0, []byte{}; i < n; j++ {
+		if j%bufferSize == 0 {
+			randomBytes = secureRandomBytes(bufferSize)
+		}
+		if idx := int(randomBytes[j%n] & letterIdxMask); idx < len(letterBytes) {
+			result[i] = letterBytes[idx]
+			i++
+		}
+	}
+
+	return string(result)
+}
+
+// tplWrappedHeader wraps niladic functions so that they
+// can be used in templates. (Template functions must
+// return a value.)
+type tplWrappedHeader struct{ http.Header }
+
+// Add adds a header field value, appending val to
+// existing values for that field. It returns an
+// empty string.
+func (h tplWrappedHeader) Add(field, val string) string {
+	h.Header.Add(field, val)
+	return ""
+}
+
+// Set sets a header field value, overwriting any
+// other values for that field. It returns an
+// empty string.
+func (h tplWrappedHeader) Set(field, val string) string {
+	h.Header.Set(field, val)
+	return ""
+}
+
+// Del deletes a header field. It returns an empty string.
+func (h tplWrappedHeader) Del(field string) string {
+	h.Header.Del(field)
+	return ""
+}
+
+var bufPool = sync.Pool{
+	New: func() interface{} {
+		return new(bytes.Buffer)
+	},
+}
+
+const recursionPreventionHeader = "Caddy-Templates-Include"
diff --git a/modules/caddyhttp/templates/tplcontext_test.go b/modules/caddyhttp/templates/tplcontext_test.go
new file mode 100644
index 0000000..af4ad4e
--- /dev/null
+++ b/modules/caddyhttp/templates/tplcontext_test.go
@@ -0,0 +1,420 @@
+// Copyright 2015 Light Code Labs, LLC
+//
+// 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/ioutil"
+	"net/http"
+	"os"
+	"path/filepath"
+	"reflect"
+	"sort"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestMarkdown(t *testing.T) {
+	context := getContextOrFail(t)
+
+	for i, test := range []struct {
+		body   string
+		expect string
+	}{
+		{
+			body:   "- str1\n- str2\n",
+			expect: "<ul>\n<li>str1</li>\n<li>str2</li>\n</ul>\n",
+		},
+	} {
+		result := context.Markdown(test.body)
+		if result != test.expect {
+			t.Errorf("Test %d: expected '%s' but got '%s'", i, test.expect, result)
+		}
+	}
+}
+
+func TestCookie(t *testing.T) {
+	for i, test := range []struct {
+		cookie     *http.Cookie
+		cookieName string
+		expect     string
+	}{
+		{
+			// happy path
+			cookie:     &http.Cookie{Name: "cookieName", Value: "cookieValue"},
+			cookieName: "cookieName",
+			expect:     "cookieValue",
+		},
+		{
+			// try to get a non-existing cookie
+			cookie:     &http.Cookie{Name: "cookieName", Value: "cookieValue"},
+			cookieName: "notExisting",
+			expect:     "",
+		},
+		{
+			// partial name match
+			cookie:     &http.Cookie{Name: "cookie", Value: "cookieValue"},
+			cookieName: "cook",
+			expect:     "",
+		},
+		{
+			// cookie with optional fields
+			cookie:     &http.Cookie{Name: "cookie", Value: "cookieValue", Path: "/path", Domain: "https://localhost", Expires: (time.Now().Add(10 * time.Minute)), MaxAge: 120},
+			cookieName: "cookie",
+			expect:     "cookieValue",
+		},
+	} {
+		context := getContextOrFail(t)
+		context.Req.AddCookie(test.cookie)
+		actual := context.Cookie(test.cookieName)
+		if actual != test.expect {
+			t.Errorf("Test %d: Expected cookie value '%s' but got '%s' for cookie with name '%s'",
+				i, test.expect, actual, test.cookieName)
+		}
+	}
+}
+
+func TestCookieMultipleCookies(t *testing.T) {
+	context := getContextOrFail(t)
+
+	cookieNameBase, cookieValueBase := "cookieName", "cookieValue"
+
+	for i := 0; i < 10; i++ {
+		context.Req.AddCookie(&http.Cookie{
+			Name:  fmt.Sprintf("%s%d", cookieNameBase, i),
+			Value: fmt.Sprintf("%s%d", cookieValueBase, i),
+		})
+	}
+
+	for i := 0; i < 10; i++ {
+		expectedCookieVal := fmt.Sprintf("%s%d", cookieValueBase, i)
+		actualCookieVal := context.Cookie(fmt.Sprintf("%s%d", cookieNameBase, i))
+		if actualCookieVal != expectedCookieVal {
+			t.Errorf("Expected cookie value %s, found %s", expectedCookieVal, actualCookieVal)
+		}
+	}
+}
+
+func TestEnv(t *testing.T) {
+	context := getContextOrFail(t)
+
+	name := "ENV_TEST_NAME"
+	testValue := "TEST_VALUE"
+	os.Setenv(name, testValue)
+
+	notExisting := "ENV_TEST_NOT_EXISTING"
+	os.Unsetenv(notExisting)
+
+	invalidName := "ENV_TEST_INVALID_NAME"
+	os.Setenv("="+invalidName, testValue)
+
+	env := context.Env()
+	if value := env[name]; value != testValue {
+		t.Errorf("Expected env-variable %s value '%s', found '%s'",
+			name, testValue, value)
+	}
+
+	if value, ok := env[notExisting]; ok {
+		t.Errorf("Expected empty env-variable %s, found '%s'",
+			notExisting, value)
+	}
+
+	for k, v := range env {
+		if strings.Contains(k, invalidName) {
+			t.Errorf("Expected invalid name not to be included in Env %s, found in key '%s'", invalidName, k)
+		}
+		if strings.Contains(v, invalidName) {
+			t.Errorf("Expected invalid name not be be included in Env %s, found in value '%s'", invalidName, v)
+		}
+	}
+
+	os.Unsetenv("=" + invalidName)
+}
+
+func TestIP(t *testing.T) {
+	context := getContextOrFail(t)
+	for i, test := range []struct {
+		inputRemoteAddr string
+		expect          string
+	}{
+		{"1.1.1.1:1111", "1.1.1.1"},
+		{"1.1.1.1", "1.1.1.1"},
+		{"[::1]:11", "::1"},
+		{"[2001:db8:a0b:12f0::1]", "[2001:db8:a0b:12f0::1]"},
+		{`[fe80:1::3%eth0]:44`, `fe80:1::3%eth0`},
+	} {
+		context.Req.RemoteAddr = test.inputRemoteAddr
+		if actual := context.IP(); actual != test.expect {
+			t.Errorf("Test %d: Expected %s but got %s", i, test.expect, actual)
+		}
+	}
+}
+
+func TestTruncate(t *testing.T) {
+	context := getContextOrFail(t)
+
+	for i, test := range []struct {
+		input  string
+		length int
+		expect string
+	}{
+		{
+			input:  "string",
+			length: 1,
+			expect: "s",
+		},
+		{
+			input:  "string",
+			length: 6,
+			expect: "string",
+		},
+		{
+			input:  "string",
+			length: 10,
+			expect: "string",
+		},
+		{
+			input:  "string",
+			length: 0,
+			expect: "",
+		},
+		{
+			input:  "string",
+			length: -5,
+			expect: "tring",
+		},
+		{
+			input:  "string",
+			length: -6,
+			expect: "string",
+		},
+		{
+			input:  "string",
+			length: -7,
+			expect: "string",
+		},
+	} {
+		actual := context.Truncate(test.input, test.length)
+		if actual != test.expect {
+			t.Errorf("Test %d: Expected '%s' but got '%s'", i, test.expect, actual)
+		}
+	}
+}
+
+func TestStripHTML(t *testing.T) {
+	context := getContextOrFail(t)
+
+	for i, test := range []struct {
+		input  string
+		expect string
+	}{
+		{
+			// no tags
+			input:  `h1`,
+			expect: `h1`,
+		},
+		{
+			// happy path
+			input:  `<h1>h1</h1>`,
+			expect: `h1`,
+		},
+		{
+			// tag in quotes
+			input:  `<h1">">h1</h1>`,
+			expect: `h1`,
+		},
+		{
+			// multiple tags
+			input:  `<h1><b>h1</b></h1>`,
+			expect: `h1`,
+		},
+		{
+			// tags not closed
+			input:  `<h1`,
+			expect: `<h1`,
+		},
+		{
+			// false start
+			input:  `<h1<b>hi`,
+			expect: `<h1hi`,
+		},
+	} {
+		actual := context.StripHTML(test.input)
+		if actual != test.expect {
+			t.Errorf("Test %d: Expected %s, found %s. Input was StripHTML(%s)", i, test.expect, actual, test.input)
+		}
+	}
+}
+
+func TestStripExt(t *testing.T) {
+	context := getContextOrFail(t)
+	tests := []struct {
+		input  string
+		expect string
+	}{
+		{
+			input:  "",
+			expect: "",
+		},
+		{
+			input:  "file.ext",
+			expect: "file",
+		},
+		{
+			input:  "file",
+			expect: "file",
+		},
+		{
+			input:  "/file",
+			expect: "/file",
+		},
+		{
+			input:  "/file.ext",
+			expect: "/file",
+		},
+		{
+			input:  "/dir.ext/",
+			expect: "/dir.ext/",
+		},
+		{
+			input:  "/dir.ext/file.ext",
+			expect: "/dir.ext/file",
+		},
+	}
+
+	for i, test := range tests {
+		actual := context.StripExt(test.input)
+		if actual != test.expect {
+			t.Errorf("Test %d: Expected %s but got %s", i, test.expect, actual)
+		}
+	}
+}
+
+func TestFileListing(t *testing.T) {
+	for i, test := range []struct {
+		fileNames []string
+		inputBase string
+		shouldErr bool
+		verifyErr func(error) bool
+	}{
+		{
+			// directory and files exist
+			fileNames: []string{"file1", "file2"},
+			shouldErr: false,
+		},
+		{
+			// directory exists, no files
+			fileNames: []string{},
+			shouldErr: false,
+		},
+		{
+			// file or directory does not exist
+			fileNames: nil,
+			inputBase: "doesNotExist",
+			shouldErr: true,
+			verifyErr: os.IsNotExist,
+		},
+		{
+			// directory and files exist, but path to a file
+			fileNames: []string{"file1", "file2"},
+			inputBase: "file1",
+			shouldErr: true,
+			verifyErr: func(err error) bool {
+				return strings.HasSuffix(err.Error(), "is not a directory")
+			},
+		},
+		{
+			// try to escape Context Root
+			fileNames: nil,
+			inputBase: filepath.Join("..", "..", "..", "..", "..", "etc"),
+			shouldErr: true,
+			verifyErr: os.IsNotExist,
+		},
+	} {
+		context := getContextOrFail(t)
+		var dirPath string
+		var err error
+
+		// create files for test case
+		if test.fileNames != nil {
+			dirPath, err = ioutil.TempDir(fmt.Sprintf("%s", context.Root), "caddy_ctxtest")
+			if err != nil {
+				t.Fatalf("Test %d: Expected no error creating directory, got: '%s'", i, err.Error())
+			}
+			for _, name := range test.fileNames {
+				absFilePath := filepath.Join(dirPath, name)
+				if err = ioutil.WriteFile(absFilePath, []byte(""), os.ModePerm); err != nil {
+					os.RemoveAll(dirPath)
+					t.Fatalf("Test %d: Expected no error creating file, got: '%s'", i, err.Error())
+				}
+			}
+		}
+
+		// perform test
+		input := filepath.ToSlash(filepath.Join(filepath.Base(dirPath), test.inputBase))
+		actual, err := context.ListFiles(input)
+		if err != nil {
+			if !test.shouldErr {
+				t.Errorf("Test %d: Expected no error, got: '%s'", i, err)
+			} else if !test.verifyErr(err) {
+				t.Errorf("Test %d: Could not verify error content, got: '%s'", i, err)
+			}
+		} else if test.shouldErr {
+			t.Errorf("Test %d: Expected error but had none", i)
+		} else {
+			numFiles := len(test.fileNames)
+			// reflect.DeepEqual does not consider two empty slices to be equal
+			if numFiles == 0 && len(actual) != 0 {
+				t.Errorf("Test %d: Expected files %v, got: %v",
+					i, test.fileNames, actual)
+			} else {
+				sort.Strings(actual)
+				if numFiles > 0 && !reflect.DeepEqual(test.fileNames, actual) {
+					t.Errorf("Test %d: Expected files %v, got: %v",
+						i, test.fileNames, actual)
+				}
+			}
+		}
+
+		if dirPath != "" {
+			if err := os.RemoveAll(dirPath); err != nil && !os.IsNotExist(err) {
+				t.Fatalf("Test %d: Expected no error removing temporary test directory, got: %v", i, err)
+			}
+		}
+	}
+}
+
+func getContextOrFail(t *testing.T) templateContext {
+	context, err := initTestContext()
+	if err != nil {
+		t.Fatalf("failed to prepare test context: %v", err)
+	}
+	return context
+}
+
+func initTestContext() (templateContext, error) {
+	body := bytes.NewBufferString("request body")
+	request, err := http.NewRequest("GET", "https://example.com/foo/bar", body)
+	if err != nil {
+		return templateContext{}, err
+	}
+	return templateContext{
+		Root:       http.Dir(os.TempDir()),
+		Req:        request,
+		RespHeader: tplWrappedHeader{make(http.Header)},
+	}, nil
+}
-- 
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