Girish Gowdra | 6450343 | 2020-01-07 10:59:10 +0530 | [diff] [blame^] | 1 | /* |
| 2 | * |
| 3 | * Copyright 2017 gRPC authors. |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | * |
| 17 | */ |
| 18 | |
| 19 | package grpc |
| 20 | |
| 21 | import ( |
| 22 | "bufio" |
| 23 | "context" |
| 24 | "encoding/base64" |
| 25 | "errors" |
| 26 | "fmt" |
| 27 | "io" |
| 28 | "net" |
| 29 | "net/http" |
| 30 | "net/http/httputil" |
| 31 | "net/url" |
| 32 | ) |
| 33 | |
| 34 | const proxyAuthHeaderKey = "Proxy-Authorization" |
| 35 | |
| 36 | var ( |
| 37 | // errDisabled indicates that proxy is disabled for the address. |
| 38 | errDisabled = errors.New("proxy is disabled for the address") |
| 39 | // The following variable will be overwritten in the tests. |
| 40 | httpProxyFromEnvironment = http.ProxyFromEnvironment |
| 41 | ) |
| 42 | |
| 43 | func mapAddress(ctx context.Context, address string) (*url.URL, error) { |
| 44 | req := &http.Request{ |
| 45 | URL: &url.URL{ |
| 46 | Scheme: "https", |
| 47 | Host: address, |
| 48 | }, |
| 49 | } |
| 50 | url, err := httpProxyFromEnvironment(req) |
| 51 | if err != nil { |
| 52 | return nil, err |
| 53 | } |
| 54 | if url == nil { |
| 55 | return nil, errDisabled |
| 56 | } |
| 57 | return url, nil |
| 58 | } |
| 59 | |
| 60 | // To read a response from a net.Conn, http.ReadResponse() takes a bufio.Reader. |
| 61 | // It's possible that this reader reads more than what's need for the response and stores |
| 62 | // those bytes in the buffer. |
| 63 | // bufConn wraps the original net.Conn and the bufio.Reader to make sure we don't lose the |
| 64 | // bytes in the buffer. |
| 65 | type bufConn struct { |
| 66 | net.Conn |
| 67 | r io.Reader |
| 68 | } |
| 69 | |
| 70 | func (c *bufConn) Read(b []byte) (int, error) { |
| 71 | return c.r.Read(b) |
| 72 | } |
| 73 | |
| 74 | func basicAuth(username, password string) string { |
| 75 | auth := username + ":" + password |
| 76 | return base64.StdEncoding.EncodeToString([]byte(auth)) |
| 77 | } |
| 78 | |
| 79 | func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr string, proxyURL *url.URL) (_ net.Conn, err error) { |
| 80 | defer func() { |
| 81 | if err != nil { |
| 82 | conn.Close() |
| 83 | } |
| 84 | }() |
| 85 | |
| 86 | req := &http.Request{ |
| 87 | Method: http.MethodConnect, |
| 88 | URL: &url.URL{Host: backendAddr}, |
| 89 | Header: map[string][]string{"User-Agent": {grpcUA}}, |
| 90 | } |
| 91 | if t := proxyURL.User; t != nil { |
| 92 | u := t.Username() |
| 93 | p, _ := t.Password() |
| 94 | req.Header.Add(proxyAuthHeaderKey, "Basic "+basicAuth(u, p)) |
| 95 | } |
| 96 | |
| 97 | if err := sendHTTPRequest(ctx, req, conn); err != nil { |
| 98 | return nil, fmt.Errorf("failed to write the HTTP request: %v", err) |
| 99 | } |
| 100 | |
| 101 | r := bufio.NewReader(conn) |
| 102 | resp, err := http.ReadResponse(r, req) |
| 103 | if err != nil { |
| 104 | return nil, fmt.Errorf("reading server HTTP response: %v", err) |
| 105 | } |
| 106 | defer resp.Body.Close() |
| 107 | if resp.StatusCode != http.StatusOK { |
| 108 | dump, err := httputil.DumpResponse(resp, true) |
| 109 | if err != nil { |
| 110 | return nil, fmt.Errorf("failed to do connect handshake, status code: %s", resp.Status) |
| 111 | } |
| 112 | return nil, fmt.Errorf("failed to do connect handshake, response: %q", dump) |
| 113 | } |
| 114 | |
| 115 | return &bufConn{Conn: conn, r: r}, nil |
| 116 | } |
| 117 | |
| 118 | // newProxyDialer returns a dialer that connects to proxy first if necessary. |
| 119 | // The returned dialer checks if a proxy is necessary, dial to the proxy with the |
| 120 | // provided dialer, does HTTP CONNECT handshake and returns the connection. |
| 121 | func newProxyDialer(dialer func(context.Context, string) (net.Conn, error)) func(context.Context, string) (net.Conn, error) { |
| 122 | return func(ctx context.Context, addr string) (conn net.Conn, err error) { |
| 123 | var newAddr string |
| 124 | proxyURL, err := mapAddress(ctx, addr) |
| 125 | if err != nil { |
| 126 | if err != errDisabled { |
| 127 | return nil, err |
| 128 | } |
| 129 | newAddr = addr |
| 130 | } else { |
| 131 | newAddr = proxyURL.Host |
| 132 | } |
| 133 | |
| 134 | conn, err = dialer(ctx, newAddr) |
| 135 | if err != nil { |
| 136 | return |
| 137 | } |
| 138 | if proxyURL != nil { |
| 139 | // proxy is disabled if proxyURL is nil. |
| 140 | conn, err = doHTTPConnectHandshake(ctx, conn, addr, proxyURL) |
| 141 | } |
| 142 | return |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | func sendHTTPRequest(ctx context.Context, req *http.Request, conn net.Conn) error { |
| 147 | req = req.WithContext(ctx) |
| 148 | if err := req.Write(conn); err != nil { |
| 149 | return fmt.Errorf("failed to write the HTTP request: %v", err) |
| 150 | } |
| 151 | return nil |
| 152 | } |