Implement templates handler; various minor cleanups and bug fixes

1 files changed, 413 insertions, 0 deletions

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"