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/*
*
* Copyright 2017 gRPC 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 grpc
import (
"bufio"
"context"
"encoding/base64"
"errors"
"fmt"
"io"
"net"
"net/http"
"net/http/httputil"
"net/url"
)
const proxyAuthHeaderKey = "Proxy-Authorization"
var (
// errDisabled indicates that proxy is disabled for the address.
errDisabled = errors.New("proxy is disabled for the address")
// The following variable will be overwritten in the tests.
httpProxyFromEnvironment = http.ProxyFromEnvironment
)
func mapAddress(ctx context.Context, address string) (*url.URL, error) {
req := &http.Request{
URL: &url.URL{
Scheme: "https",
Host: address,
},
}
url, err := httpProxyFromEnvironment(req)
if err != nil {
return nil, err
}
if url == nil {
return nil, errDisabled
}
return url, nil
}
// To read a response from a net.Conn, http.ReadResponse() takes a bufio.Reader.
// It's possible that this reader reads more than what's need for the response and stores
// those bytes in the buffer.
// bufConn wraps the original net.Conn and the bufio.Reader to make sure we don't lose the
// bytes in the buffer.
type bufConn struct {
net.Conn
r io.Reader
}
func (c *bufConn) Read(b []byte) (int, error) {
return c.r.Read(b)
}
func basicAuth(username, password string) string {
auth := username + ":" + password
return base64.StdEncoding.EncodeToString([]byte(auth))
}
func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr string, proxyURL *url.URL) (_ net.Conn, err error) {
defer func() {
if err != nil {
conn.Close()
}
}()
req := &http.Request{
Method: http.MethodConnect,
URL: &url.URL{Host: backendAddr},
Header: map[string][]string{"User-Agent": {grpcUA}},
}
if t := proxyURL.User; t != nil {
u := t.Username()
p, _ := t.Password()
req.Header.Add(proxyAuthHeaderKey, "Basic "+basicAuth(u, p))
}
if err := sendHTTPRequest(ctx, req, conn); err != nil {
return nil, fmt.Errorf("failed to write the HTTP request: %v", err)
}
r := bufio.NewReader(conn)
resp, err := http.ReadResponse(r, req)
if err != nil {
return nil, fmt.Errorf("reading server HTTP response: %v", err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
dump, err := httputil.DumpResponse(resp, true)
if err != nil {
return nil, fmt.Errorf("failed to do connect handshake, status code: %s", resp.Status)
}
return nil, fmt.Errorf("failed to do connect handshake, response: %q", dump)
}
return &bufConn{Conn: conn, r: r}, nil
}
// newProxyDialer returns a dialer that connects to proxy first if necessary.
// The returned dialer checks if a proxy is necessary, dial to the proxy with the
// provided dialer, does HTTP CONNECT handshake and returns the connection.
func newProxyDialer(dialer func(context.Context, string) (net.Conn, error)) func(context.Context, string) (net.Conn, error) {
return func(ctx context.Context, addr string) (conn net.Conn, err error) {
var newAddr string
proxyURL, err := mapAddress(ctx, addr)
if err != nil {
if err != errDisabled {
return nil, err
}
newAddr = addr
} else {
newAddr = proxyURL.Host
}
conn, err = dialer(ctx, newAddr)
if err != nil {
return
}
if proxyURL != nil {
// proxy is disabled if proxyURL is nil.
conn, err = doHTTPConnectHandshake(ctx, conn, addr, proxyURL)
}
return
}
}
func sendHTTPRequest(ctx context.Context, req *http.Request, conn net.Conn) error {
req = req.WithContext(ctx)
if err := req.Write(conn); err != nil {
return fmt.Errorf("failed to write the HTTP request: %v", err)
}
return nil
}