Major rewrite

* use dep for vendoring
* lets encrypt
* moved web to transfer.sh-web repo
* single command install
* added first tests

vendor/github.com/golang/gddo/httputil/buster.go

@@ -0,0 +1,95 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd.
+
+package httputil
+
+import (
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+)
+
+type busterWriter struct {
+	headerMap http.Header
+	status    int
+	io.Writer
+}
+
+func (bw *busterWriter) Header() http.Header {
+	return bw.headerMap
+}
+
+func (bw *busterWriter) WriteHeader(status int) {
+	bw.status = status
+}
+
+// CacheBusters maintains a cache of cache busting tokens for static resources served by Handler.
+type CacheBusters struct {
+	Handler http.Handler
+
+	mu     sync.Mutex
+	tokens map[string]string
+}
+
+func sanitizeTokenRune(r rune) rune {
+	if r <= ' ' || r >= 127 {
+		return -1
+	}
+	// Convert percent encoding reserved characters to '-'.
+	if strings.ContainsRune("!#$&'()*+,/:;=?@[]", r) {
+		return '-'
+	}
+	return r
+}
+
+// Get returns the cache busting token for path. If the token is not already
+// cached, Get issues a HEAD request on handler and uses the response ETag and
+// Last-Modified headers to compute a token.
+func (cb *CacheBusters) Get(path string) string {
+	cb.mu.Lock()
+	if cb.tokens == nil {
+		cb.tokens = make(map[string]string)
+	}
+	token, ok := cb.tokens[path]
+	cb.mu.Unlock()
+	if ok {
+		return token
+	}
+
+	w := busterWriter{
+		Writer:    ioutil.Discard,
+		headerMap: make(http.Header),
+	}
+	r := &http.Request{URL: &url.URL{Path: path}, Method: "HEAD"}
+	cb.Handler.ServeHTTP(&w, r)
+
+	if w.status == 200 {
+		token = w.headerMap.Get("Etag")
+		if token == "" {
+			token = w.headerMap.Get("Last-Modified")
+		}
+		token = strings.Trim(token, `" `)
+		token = strings.Map(sanitizeTokenRune, token)
+	}
+
+	cb.mu.Lock()
+	cb.tokens[path] = token
+	cb.mu.Unlock()
+
+	return token
+}
+
+// AppendQueryParam appends the token as a query parameter to path.
+func (cb *CacheBusters) AppendQueryParam(path string, name string) string {
+	token := cb.Get(path)
+	if token == "" {
+		return path
+	}
+	return path + "?" + name + "=" + token
+}