// Copyright 2012 Google Inc. All Rights Reserved.
//
// 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 main
import (
"bufio"
"errors"
"fmt"
"net"
"net/url"
"os"
"os/exec"
"strings"
"syscall"
"time"
)
type Client struct {
ProxyBin string
Args []string
insecure bool
}
func (c *Client) Run() error {
if err := c.resolveArgs(); err != nil {
return fmt.Errorf("resolveArgs() got error: %v", err)
}
// Connect to the proxy.
uconn, hconn, addr, err := c.connect()
if err != nil {
return fmt.Errorf("connect() got error: %v", err)
}
// Keep the unix socket connection open for the duration of the request.
defer uconn.Close()
// Keep a connection to the HTTP server open, so no other user can
// bind on the same address so long as the process is running.
defer hconn.Close()
// Start the git-remote-http subprocess.
cargs := []string{"-c", fmt.Sprintf("http.proxy=%v", addr), "remote-http"}
cargs = append(cargs, c.Args...)
cmd := exec.Command("git", cargs...)
for _, v := range os.Environ() {
if !strings.HasPrefix(v, "GIT_PERSISTENT_HTTPS_SECURE=") {
cmd.Env = append(cmd.Env, v)
}
}
// Set the GIT_PERSISTENT_HTTPS_SECURE environment variable when
// the proxy is using a SSL connection. This allows credential helpers
// to identify secure proxy connections, despite being passed an HTTP
// scheme.
if !c.insecure {
cmd.Env = append(cmd.Env, "GIT_PERSISTENT_HTTPS_SECURE=1")
}
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
if err := cmd.Run(); err != nil {
if eerr, ok := err.(*exec.ExitError); ok {
if stat, ok := eerr.ProcessState.Sys().(syscall.WaitStatus); ok && stat.ExitStatus() != 0 {
os.Exit(stat.ExitStatus())
}
}
return fmt.Errorf("git-remote-http subprocess got error: %v", err)
}
return nil
}
func (c *Client) connect() (uconn net.Conn, hconn net.Conn, addr string, err error) {
uconn, err = DefaultSocket.Dial()
if err != nil {
if e, ok := err.(*net.OpError); ok && (os.IsNotExist(e.Err) || e.Err == syscall.ECONNREFUSED) {
if err = c.startProxy(); err == nil {
uconn, err = DefaultSocket.Dial()
}
}
if err != nil {
return
}
}
if addr, err = c.readAddr(uconn); err != nil {
return
}
// Open a tcp connection to the proxy.
if hconn, err = net.Dial("tcp", addr); err != nil {
return
}
// Verify the address hasn't changed ownership.
var addr2 string
if addr2, err = c.readAddr(uconn); err != nil {
return
} else if addr != addr2 {
err = fmt.Errorf("address changed after connect. got %q, want %q", addr2, addr)
return
}
return
}
func (c *Client) readAddr(conn net.Conn) (string, error) {
conn.SetDeadline(time.Now().Add(5 * time.Second))
data := make([]byte, 100)
n, err := conn.Read(data)
if err != nil {
return "", fmt.Errorf("error reading unix socket: %v", err)
} else if n == 0 {
return "", errors.New("empty data response")
}
conn.Write([]byte{1}) // Ack
var addr string
if addrs := strings.Split(string(data[:n]), "\n"); len(addrs) != 2 {
return "", fmt.Errorf("got %q, wanted 2 addresses", data[:n])
} else if c.insecure {
addr = addrs[1]
} else {
addr = addrs[0]
}
return addr, nil
}
func (c *Client) startProxy() error {
cmd := exec.Command(c.ProxyBin)
cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
stdout, err := cmd.StdoutPipe()
if err != nil {
return err
}
defer stdout.Close()
if err := cmd.Start(); err != nil {
return err
}
result := make(chan error)
go func() {
bytes, _, err := bufio.NewReader(stdout).ReadLine()
if line := string(bytes); err == nil && line != "OK" {
err = fmt.Errorf("proxy returned %q, want \"OK\"", line)
}
result <- err
}()
select {
case err := <-result:
return err
case <-time.After(5 * time.Second):
return errors.New("timeout waiting for proxy to start")
}
panic("not reachable")
}
func (c *Client) resolveArgs() error {
if nargs := len(c.Args); nargs == 0 {
return errors.New("remote needed")
} else if nargs > 2 {
return fmt.Errorf("want at most 2 args, got %v", c.Args)
}
// Rewrite the url scheme to be http.
idx := len(c.Args) - 1
rawurl := c.Args[idx]
rurl, err := url.Parse(rawurl)
if err != nil {
return fmt.Errorf("invalid remote: %v", err)
}
c.insecure = rurl.Scheme == "persistent-http"
rurl.Scheme = "http"
c.Args[idx] = rurl.String()
if idx != 0 && c.Args[0] == rawurl {
c.Args[0] = c.Args[idx]
}
return nil
}
