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miniflux/http/response/builder.go

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2018-10-07 21:42:43 -04:00
// Copyright 2018 Frédéric Guillot. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.
package response // import "miniflux.app/http/response"
import (
"compress/flate"
"compress/gzip"
"fmt"
"io"
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"net/http"
"strings"
"time"
)
const compressionThreshold = 1024
// Builder generates HTTP responses.
type Builder struct {
w http.ResponseWriter
r *http.Request
statusCode int
headers map[string]string
enableCompression bool
body interface{}
}
// WithStatus uses the given status code to build the response.
func (b *Builder) WithStatus(statusCode int) *Builder {
b.statusCode = statusCode
return b
}
// WithHeader adds the given HTTP header to the response.
func (b *Builder) WithHeader(key, value string) *Builder {
b.headers[key] = value
return b
}
// WithBody uses the given body to build the response.
func (b *Builder) WithBody(body interface{}) *Builder {
b.body = body
return b
}
// WithAttachment forces the document to be downloaded by the web browser.
func (b *Builder) WithAttachment(filename string) *Builder {
b.headers["Content-Disposition"] = fmt.Sprintf("attachment; filename=%s", filename)
return b
}
// WithoutCompression disables HTTP compression.
func (b *Builder) WithoutCompression() *Builder {
b.enableCompression = false
return b
}
// WithCaching adds caching headers to the response.
func (b *Builder) WithCaching(etag string, duration time.Duration, callback func(*Builder)) {
b.headers["ETag"] = etag
b.headers["Cache-Control"] = "public"
b.headers["Expires"] = time.Now().Add(duration).Format(time.RFC1123)
if etag == b.r.Header.Get("If-None-Match") {
b.statusCode = http.StatusNotModified
b.body = nil
b.Write()
} else {
callback(b)
}
}
// Write generates the HTTP response.
func (b *Builder) Write() {
if b.body == nil {
b.writeHeaders()
return
}
switch v := b.body.(type) {
case []byte:
b.compress(v)
case string:
b.compress([]byte(v))
case error:
b.compress([]byte(v.Error()))
case io.Reader:
// Compression not implemented in this case
b.writeHeaders()
io.Copy(b.w, v)
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}
}
func (b *Builder) writeHeaders() {
b.headers["X-XSS-Protection"] = "1; mode=block"
b.headers["X-Content-Type-Options"] = "nosniff"
b.headers["X-Frame-Options"] = "DENY"
b.headers["Content-Security-Policy"] = "default-src 'self'; img-src *; media-src *; frame-src *; child-src *"
for key, value := range b.headers {
b.w.Header().Set(key, value)
}
b.w.WriteHeader(b.statusCode)
}
func (b *Builder) compress(data []byte) {
if b.enableCompression && len(data) > compressionThreshold {
acceptEncoding := b.r.Header.Get("Accept-Encoding")
switch {
case strings.Contains(acceptEncoding, "gzip"):
b.headers["Content-Encoding"] = "gzip"
b.writeHeaders()
gzipWriter := gzip.NewWriter(b.w)
defer gzipWriter.Close()
gzipWriter.Write(data)
return
case strings.Contains(acceptEncoding, "deflate"):
b.headers["Content-Encoding"] = "deflate"
b.writeHeaders()
flateWriter, _ := flate.NewWriter(b.w, -1)
defer flateWriter.Close()
flateWriter.Write(data)
return
}
}
b.writeHeaders()
b.w.Write(data)
}
// New creates a new response builder.
func New(w http.ResponseWriter, r *http.Request) *Builder {
return &Builder{w: w, r: r, statusCode: http.StatusOK, headers: make(map[string]string), enableCompression: true}
}