netrc.go

     1  // Copyright 2019 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package auth
     6  
     7  import (
     8  	"os"
     9  	"path/filepath"
    10  	"runtime"
    11  	"strings"
    12  	"sync"
    13  )
    14  
    15  type netrcLine struct {
    16  	machine  string
    17  	login    string
    18  	password string
    19  }
    20  
    21  var (
    22  	netrcOnce sync.Once
    23  	netrc     []netrcLine
    24  	netrcErr  error
    25  )
    26  
    27  func parseNetrc(data string) []netrcLine {
    28  	// See https://www.gnu.org/software/inetutils/manual/html_node/The-_002enetrc-file.html
    29  	// for documentation on the .netrc format.
    30  	var nrc []netrcLine
    31  	var l netrcLine
    32  	inMacro := false
    33  	for _, line := range strings.Split(data, "\n") {
    34  		if inMacro {
    35  			if line == "" {
    36  				inMacro = false
    37  			}
    38  			continue
    39  		}
    40  
    41  		f := strings.Fields(line)
    42  		i := 0
    43  		for ; i < len(f)-1; i += 2 {
    44  			// Reset at each "machine" token.
    45  			// “The auto-login process searches the .netrc file for a machine token
    46  			// that matches […]. Once a match is made, the subsequent .netrc tokens
    47  			// are processed, stopping when the end of file is reached or another
    48  			// machine or a default token is encountered.”
    49  			switch f[i] {
    50  			case "machine":
    51  				l = netrcLine{machine: f[i+1]}
    52  			case "default":
    53  				break
    54  			case "login":
    55  				l.login = f[i+1]
    56  			case "password":
    57  				l.password = f[i+1]
    58  			case "macdef":
    59  				// “A macro is defined with the specified name; its contents begin with
    60  				// the next .netrc line and continue until a null line (consecutive
    61  				// new-line characters) is encountered.”
    62  				inMacro = true
    63  			}
    64  			if l.machine != "" && l.login != "" && l.password != "" {
    65  				nrc = append(nrc, l)
    66  				l = netrcLine{}
    67  			}
    68  		}
    69  
    70  		if i < len(f) && f[i] == "default" {
    71  			// “There can be only one default token, and it must be after all machine tokens.”
    72  			break
    73  		}
    74  	}
    75  
    76  	return nrc
    77  }
    78  
    79  func netrcPath() (string, error) {
    80  	if env := os.Getenv("NETRC"); env != "" {
    81  		return env, nil
    82  	}
    83  	dir, err := os.UserHomeDir()
    84  	if err != nil {
    85  		return "", err
    86  	}
    87  	base := ".netrc"
    88  	if runtime.GOOS == "windows" {
    89  		base = "_netrc"
    90  	}
    91  	return filepath.Join(dir, base), nil
    92  }
    93  
    94  func readNetrc() {
    95  	path, err := netrcPath()
    96  	if err != nil {
    97  		netrcErr = err
    98  		return
    99  	}
   100  
   101  	data, err := os.ReadFile(path)
   102  	if err != nil {
   103  		if !os.IsNotExist(err) {
   104  			netrcErr = err
   105  		}
   106  		return
   107  	}
   108  
   109  	netrc = parseNetrc(string(data))
   110  }
   111
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