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// Copyright 2015 Matthew Holt and The Caddy Authors
//
// 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 caddyhttp
import (
"bufio"
"fmt"
"net"
"net/http"
"sync"
)
// httpRedirectListener is listener that checks the first few bytes
// of the request when the server is intended to accept HTTPS requests,
// to respond to an HTTP request with a redirect.
type httpRedirectListener struct {
net.Listener
}
// Accept waits for and returns the next connection to the listener,
// wrapping it with a httpRedirectConn.
func (l *httpRedirectListener) Accept() (net.Conn, error) {
c, err := l.Listener.Accept()
if err != nil {
return nil, err
}
return &httpRedirectConn{
Conn: c,
r: bufio.NewReader(c),
}, nil
}
type httpRedirectConn struct {
net.Conn
once sync.Once
r *bufio.Reader
}
// Read tries to peek at the first few bytes of the request, and if we get
// an error reading the headers, and that error was due to the bytes looking
// like an HTTP request, then we perform a HTTP->HTTPS redirect on the same
// port as the original connection.
func (c *httpRedirectConn) Read(p []byte) (int, error) {
var errReturn error
c.once.Do(func() {
firstBytes, err := c.r.Peek(5)
if err != nil {
return
}
// If the request doesn't look like HTTP, then it's probably
// TLS bytes and we don't need to do anything.
if !firstBytesLookLikeHTTP(firstBytes) {
return
}
// Parse the HTTP request, so we can get the Host and URL to redirect to.
req, err := http.ReadRequest(c.r)
if err != nil {
return
}
// Build the redirect response, using the same Host and URL,
// but replacing the scheme with https.
headers := make(http.Header)
headers.Add("Location", "https://"+req.Host+req.URL.String())
resp := &http.Response{
Proto: "HTTP/1.0",
Status: "308 Permanent Redirect",
StatusCode: 308,
ProtoMajor: 1,
ProtoMinor: 0,
Header: headers,
}
err = resp.Write(c.Conn)
if err != nil {
errReturn = fmt.Errorf("couldn't write HTTP->HTTPS redirect")
return
}
errReturn = fmt.Errorf("redirected HTTP request on HTTPS port")
c.Conn.Close()
})
if errReturn != nil {
return 0, errReturn
}
return c.r.Read(p)
}
// firstBytesLookLikeHTTP reports whether a TLS record header
// looks like it might've been a misdirected plaintext HTTP request.
func firstBytesLookLikeHTTP(hdr []byte) bool {
switch string(hdr[:5]) {
case "GET /", "HEAD ", "POST ", "PUT /", "OPTIO":
return true
}
return false
}
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