contrib/persistent-https/socket.go

   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
  15 package main
  16
  17 import (
  18         "fmt"
  19         "log"
  20         "net"
  21         "os"
  22         "path/filepath"
  23         "syscall"
  24 )
  25
  26 // A Socket is a wrapper around a Unix socket that verifies directory
  27 // permissions.
  28 type Socket struct {
  29         Dir string
  30 }
  31
  32 func defaultDir() string {
  33         sockPath := ".git-credential-cache"
  34         if home := os.Getenv("HOME"); home != "" {
  35                 return filepath.Join(home, sockPath)
  36         }
  37         log.Printf("socket: cannot find HOME path. using relative directory %q for socket", sockPath)
  38         return sockPath
  39 }
  40
  41 // DefaultSocket is a Socket in the $HOME/.git-credential-cache directory.
  42 var DefaultSocket = Socket{Dir: defaultDir()}
  43
  44 // Listen announces the local network address of the unix socket. The
  45 // permissions on the socket directory are verified before attempting
  46 // the actual listen.
  47 func (s Socket) Listen() (net.Listener, error) {
  48         network, addr := "unix", s.Path()
  49         if err := s.mkdir(); err != nil {
  50                 return nil, &net.OpError{Op: "listen", Net: network, Addr: &net.UnixAddr{Name: addr, Net: network}, Err: err}
  51         }
  52         return net.Listen(network, addr)
  53 }
  54
  55 // Dial connects to the unix socket. The permissions on the socket directory
  56 // are verified before attempting the actual dial.
  57 func (s Socket) Dial() (net.Conn, error) {
  58         network, addr := "unix", s.Path()
  59         if err := s.checkPermissions(); err != nil {
  60                 return nil, &net.OpError{Op: "dial", Net: network, Addr: &net.UnixAddr{Name: addr, Net: network}, Err: err}
  61         }
  62         return net.Dial(network, addr)
  63 }
  64
  65 // Path returns the fully specified file name of the unix socket.
  66 func (s Socket) Path() string {
  67         return filepath.Join(s.Dir, "persistent-https-proxy-socket")
  68 }
  69
  70 func (s Socket) mkdir() error {
  71         if err := s.checkPermissions(); err == nil {
  72                 return nil
  73         } else if !os.IsNotExist(err) {
  74                 return err
  75         }
  76         if err := os.MkdirAll(s.Dir, 0700); err != nil {
  77                 return err
  78         }
  79         return s.checkPermissions()
  80 }
  81
  82 func (s Socket) checkPermissions() error {
  83         fi, err := os.Stat(s.Dir)
  84         if err != nil {
  85                 return err
  86         }
  87         if !fi.IsDir() {
  88                 return fmt.Errorf("socket: got file, want directory for %q", s.Dir)
  89         }
  90         if fi.Mode().Perm() != 0700 {
  91                 return fmt.Errorf("socket: got perm %o, want 700 for %q", fi.Mode().Perm(), s.Dir)
  92         }
  93         if st := fi.Sys().(*syscall.Stat_t); int(st.Uid) != os.Getuid() {
  94                 return fmt.Errorf("socket: got uid %d, want %d for %q", st.Uid, os.Getuid(), s.Dir)
  95         }
  96         return nil
  97 }