Mya Pitzeruse
02d115f682
This change refactors a handful of components to make them reusable across pageview and session tracking endpoints. Resolves https://github.com/mjpitz/pages/issues/2
125 lines
3.2 KiB
Go
125 lines
3.2 KiB
Go
// Copyright (C) 2022 The pages authors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//
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package session
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import (
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"bytes"
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"fmt"
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"net/http"
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"strconv"
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"strings"
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"github.com/gorilla/mux"
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"github.com/mjpitz/pages/internal/excludes"
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)
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func script(path string) string {
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return fmt.Sprintf(`<script async type='text/javascript' src='%s'></script>`, path)
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}
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type opt struct {
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jsPath string
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excludes []excludes.Exclusion
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}
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// Option provides a way to configure elements of the Middleware.
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type Option func(*opt)
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// JavaScriptPath configures the URL for the JS snippet.
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func JavaScriptPath(path string) Option {
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return func(o *opt) {
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o.jsPath = path
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}
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}
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// Exclusions appends the provided rules to the excludes list. Any path that matches an exclusion will not be measured.
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func Exclusions(exclusions ...excludes.Exclusion) Option {
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return func(o *opt) {
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o.excludes = append(o.excludes, exclusions...)
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}
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}
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// Middleware injects a JavaScript snippet that establishes a session with the server.
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func Middleware(opts ...Option) mux.MiddlewareFunc {
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o := opt{}
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for _, opt := range opts {
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opt(&o)
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}
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exclude := excludes.AnyExclusion(o.excludes...)
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injection := script(o.jsPath)
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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if exclude(r.URL.Path) {
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next.ServeHTTP(w, r)
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return
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}
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buffer := &bufferedResponseWriter{
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header: http.Header{},
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status: http.StatusOK,
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buffer: bytes.NewBuffer(nil),
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}
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next.ServeHTTP(buffer, r)
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for key := range buffer.header {
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w.Header().Set(key, buffer.header.Get(key))
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}
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contents := buffer.buffer.Bytes()
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if strings.Contains(buffer.header.Get("Content-Type"), "text/html") {
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contents = bytes.TrimSpace(contents)
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contents = bytes.TrimSuffix(contents, []byte("</html>"))
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contents = bytes.TrimSpace(contents)
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contents = bytes.TrimSuffix(contents, []byte("</body>"))
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contents = append(contents, []byte(injection)...)
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contents = append(contents, []byte("</body></html>")...)
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}
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w.Header().Set("Content-Length", strconv.Itoa(len(contents)))
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w.WriteHeader(buffer.status)
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_, _ = w.Write(contents)
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})
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}
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}
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type bufferedResponseWriter struct {
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header http.Header
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status int
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buffer *bytes.Buffer
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}
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func (w *bufferedResponseWriter) Header() http.Header {
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return w.header
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}
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func (w *bufferedResponseWriter) WriteHeader(statusCode int) {
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w.status = statusCode
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}
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func (w *bufferedResponseWriter) Write(data []byte) (n int, err error) {
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return w.buffer.Write(data)
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}
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var _ http.ResponseWriter = &bufferedResponseWriter{}
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