152 lines
4 KiB
Go
152 lines
4 KiB
Go
/*
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*
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* Copyright 2017 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package grpc
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import (
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"bufio"
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"context"
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"encoding/base64"
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"errors"
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"fmt"
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"io"
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"net"
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"net/http"
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"net/http/httputil"
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"net/url"
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)
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const proxyAuthHeaderKey = "Proxy-Authorization"
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var (
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// errDisabled indicates that proxy is disabled for the address.
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errDisabled = errors.New("proxy is disabled for the address")
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// The following variable will be overwritten in the tests.
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httpProxyFromEnvironment = http.ProxyFromEnvironment
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)
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func mapAddress(ctx context.Context, address string) (*url.URL, error) {
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req := &http.Request{
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URL: &url.URL{
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Scheme: "https",
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Host: address,
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},
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}
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url, err := httpProxyFromEnvironment(req)
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if err != nil {
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return nil, err
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}
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if url == nil {
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return nil, errDisabled
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}
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return url, nil
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}
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// To read a response from a net.Conn, http.ReadResponse() takes a bufio.Reader.
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// It's possible that this reader reads more than what's need for the response and stores
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// those bytes in the buffer.
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// bufConn wraps the original net.Conn and the bufio.Reader to make sure we don't lose the
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// bytes in the buffer.
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type bufConn struct {
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net.Conn
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r io.Reader
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}
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func (c *bufConn) Read(b []byte) (int, error) {
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return c.r.Read(b)
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}
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func basicAuth(username, password string) string {
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auth := username + ":" + password
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return base64.StdEncoding.EncodeToString([]byte(auth))
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}
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func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr string, proxyURL *url.URL) (_ net.Conn, err error) {
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defer func() {
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if err != nil {
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conn.Close()
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}
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}()
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req := &http.Request{
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Method: http.MethodConnect,
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URL: &url.URL{Host: backendAddr},
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Header: map[string][]string{"User-Agent": {grpcUA}},
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}
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if t := proxyURL.User; t != nil {
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u := t.Username()
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p, _ := t.Password()
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req.Header.Add(proxyAuthHeaderKey, "Basic "+basicAuth(u, p))
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}
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if err := sendHTTPRequest(ctx, req, conn); err != nil {
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return nil, fmt.Errorf("failed to write the HTTP request: %v", err)
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}
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r := bufio.NewReader(conn)
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resp, err := http.ReadResponse(r, req)
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if err != nil {
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return nil, fmt.Errorf("reading server HTTP response: %v", err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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dump, err := httputil.DumpResponse(resp, true)
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if err != nil {
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return nil, fmt.Errorf("failed to do connect handshake, status code: %s", resp.Status)
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}
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return nil, fmt.Errorf("failed to do connect handshake, response: %q", dump)
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}
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return &bufConn{Conn: conn, r: r}, nil
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}
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// newProxyDialer returns a dialer that connects to proxy first if necessary.
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// The returned dialer checks if a proxy is necessary, dial to the proxy with the
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// provided dialer, does HTTP CONNECT handshake and returns the connection.
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func newProxyDialer(dialer func(context.Context, string) (net.Conn, error)) func(context.Context, string) (net.Conn, error) {
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return func(ctx context.Context, addr string) (conn net.Conn, err error) {
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var newAddr string
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proxyURL, err := mapAddress(ctx, addr)
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if err != nil {
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if err != errDisabled {
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return nil, err
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}
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newAddr = addr
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} else {
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newAddr = proxyURL.Host
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}
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conn, err = dialer(ctx, newAddr)
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if err != nil {
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return
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}
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if proxyURL != nil {
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// proxy is disabled if proxyURL is nil.
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conn, err = doHTTPConnectHandshake(ctx, conn, addr, proxyURL)
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}
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return
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}
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}
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func sendHTTPRequest(ctx context.Context, req *http.Request, conn net.Conn) error {
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req = req.WithContext(ctx)
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if err := req.Write(conn); err != nil {
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return fmt.Errorf("failed to write the HTTP request: %v", err)
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}
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return nil
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}
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