Merge branch 'jk/list-objects-optim-wo-trees'
[git/git.git] / contrib / persistent-https / client.go
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1// Copyright 2012 Google Inc. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package main
16
17import (
18 "bufio"
19 "errors"
20 "fmt"
21 "net"
22 "net/url"
23 "os"
24 "os/exec"
25 "strings"
26 "syscall"
27 "time"
28)
29
30type Client struct {
31 ProxyBin string
32 Args []string
33
34 insecure bool
35}
36
37func (c *Client) Run() error {
38 if err := c.resolveArgs(); err != nil {
39 return fmt.Errorf("resolveArgs() got error: %v", err)
40 }
41
42 // Connect to the proxy.
43 uconn, hconn, addr, err := c.connect()
44 if err != nil {
45 return fmt.Errorf("connect() got error: %v", err)
46 }
47 // Keep the unix socket connection open for the duration of the request.
48 defer uconn.Close()
49 // Keep a connection to the HTTP server open, so no other user can
50 // bind on the same address so long as the process is running.
51 defer hconn.Close()
52
53 // Start the git-remote-http subprocess.
54 cargs := []string{"-c", fmt.Sprintf("http.proxy=%v", addr), "remote-http"}
55 cargs = append(cargs, c.Args...)
56 cmd := exec.Command("git", cargs...)
57
58 for _, v := range os.Environ() {
59 if !strings.HasPrefix(v, "GIT_PERSISTENT_HTTPS_SECURE=") {
60 cmd.Env = append(cmd.Env, v)
61 }
62 }
63 // Set the GIT_PERSISTENT_HTTPS_SECURE environment variable when
64 // the proxy is using a SSL connection. This allows credential helpers
65 // to identify secure proxy connections, despite being passed an HTTP
66 // scheme.
67 if !c.insecure {
68 cmd.Env = append(cmd.Env, "GIT_PERSISTENT_HTTPS_SECURE=1")
69 }
70
71 cmd.Stdin = os.Stdin
72 cmd.Stdout = os.Stdout
73 cmd.Stderr = os.Stderr
74 if err := cmd.Run(); err != nil {
75 if eerr, ok := err.(*exec.ExitError); ok {
76 if stat, ok := eerr.ProcessState.Sys().(syscall.WaitStatus); ok && stat.ExitStatus() != 0 {
77 os.Exit(stat.ExitStatus())
78 }
79 }
80 return fmt.Errorf("git-remote-http subprocess got error: %v", err)
81 }
82 return nil
83}
84
85func (c *Client) connect() (uconn net.Conn, hconn net.Conn, addr string, err error) {
86 uconn, err = DefaultSocket.Dial()
87 if err != nil {
88 if e, ok := err.(*net.OpError); ok && (os.IsNotExist(e.Err) || e.Err == syscall.ECONNREFUSED) {
89 if err = c.startProxy(); err == nil {
90 uconn, err = DefaultSocket.Dial()
91 }
92 }
93 if err != nil {
94 return
95 }
96 }
97
98 if addr, err = c.readAddr(uconn); err != nil {
99 return
100 }
101
102 // Open a tcp connection to the proxy.
103 if hconn, err = net.Dial("tcp", addr); err != nil {
104 return
105 }
106
107 // Verify the address hasn't changed ownership.
108 var addr2 string
109 if addr2, err = c.readAddr(uconn); err != nil {
110 return
111 } else if addr != addr2 {
112 err = fmt.Errorf("address changed after connect. got %q, want %q", addr2, addr)
113 return
114 }
115 return
116}
117
118func (c *Client) readAddr(conn net.Conn) (string, error) {
119 conn.SetDeadline(time.Now().Add(5 * time.Second))
120 data := make([]byte, 100)
121 n, err := conn.Read(data)
122 if err != nil {
123 return "", fmt.Errorf("error reading unix socket: %v", err)
124 } else if n == 0 {
125 return "", errors.New("empty data response")
126 }
127 conn.Write([]byte{1}) // Ack
128
129 var addr string
130 if addrs := strings.Split(string(data[:n]), "\n"); len(addrs) != 2 {
131 return "", fmt.Errorf("got %q, wanted 2 addresses", data[:n])
132 } else if c.insecure {
133 addr = addrs[1]
134 } else {
135 addr = addrs[0]
136 }
137 return addr, nil
138}
139
140func (c *Client) startProxy() error {
141 cmd := exec.Command(c.ProxyBin)
142 cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
143 stdout, err := cmd.StdoutPipe()
144 if err != nil {
145 return err
146 }
147 defer stdout.Close()
148 if err := cmd.Start(); err != nil {
149 return err
150 }
151 result := make(chan error)
152 go func() {
153 bytes, _, err := bufio.NewReader(stdout).ReadLine()
154 if line := string(bytes); err == nil && line != "OK" {
155 err = fmt.Errorf("proxy returned %q, want \"OK\"", line)
156 }
157 result <- err
158 }()
159 select {
160 case err := <-result:
161 return err
162 case <-time.After(5 * time.Second):
163 return errors.New("timeout waiting for proxy to start")
164 }
165 panic("not reachable")
166}
167
168func (c *Client) resolveArgs() error {
169 if nargs := len(c.Args); nargs == 0 {
170 return errors.New("remote needed")
171 } else if nargs > 2 {
172 return fmt.Errorf("want at most 2 args, got %v", c.Args)
173 }
174
175 // Rewrite the url scheme to be http.
176 idx := len(c.Args) - 1
177 rawurl := c.Args[idx]
178 rurl, err := url.Parse(rawurl)
179 if err != nil {
180 return fmt.Errorf("invalid remote: %v", err)
181 }
182 c.insecure = rurl.Scheme == "persistent-http"
183 rurl.Scheme = "http"
184 c.Args[idx] = rurl.String()
185 if idx != 0 && c.Args[0] == rawurl {
186 c.Args[0] = c.Args[idx]
187 }
188 return nil
189}