goget/internal/auth/netrc.go

//go:build linux || freebsd
// +build linux freebsd

package auth

import (
	"bufio"
	"os"
	"path/filepath"
	"strings"
)

// NetrcEntry holds credentials for a single machine entry in .netrc.
type NetrcEntry struct {
	Machine  string
	Login    string
	Password string
}

// LoadNetrc reads ~/.netrc and returns entries keyed by machine name.
func LoadNetrc() (map[string]*NetrcEntry, error) {
	home, err := os.UserHomeDir()
	if err != nil {
		return nil, nil
	}
	path := filepath.Join(home, ".netrc")
	file, err := os.Open(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, err
	}
	defer file.Close()

	entries := make(map[string]*NetrcEntry)
	var current *NetrcEntry

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		// Skip comments and empty lines
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		fields := strings.Fields(line)

		// "default" is also valid but we treat it as a machine
		if len(fields) >= 2 && (fields[0] == "machine" || fields[0] == "default") {
			if current != nil && current.Machine != "" {
				entries[current.Machine] = current
			}
			name := fields[1]
			if fields[0] == "default" {
				name = "default"
			}
			current = &NetrcEntry{Machine: name}
			// Rest of line may have login/password
			parseNetrcLine(fields[2:], current)
		} else if current != nil {
			parseNetrcLine(fields, current)
		}
	}
	if current != nil && current.Machine != "" {
		entries[current.Machine] = current
	}

	return entries, scanner.Err()
}

func parseNetrcLine(fields []string, entry *NetrcEntry) {
	for i := 0; i < len(fields); i++ {
		switch fields[i] {
		case "login":
			if i+1 < len(fields) {
				entry.Login = fields[i+1]
				i++
			}
		case "password":
			if i+1 < len(fields) {
				entry.Password = fields[i+1]
				i++
			}
		}
	}
}

// LookupNetrc returns credentials from .netrc for a given hostname.
func LookupNetrc(host string) (login, password string, found bool) {
	entries, err := LoadNetrc()
	if err != nil || entries == nil {
		return "", "", false
	}
	// Exact match first
	if e, ok := entries[host]; ok {
		return e.Login, e.Password, true
	}
	// Default entry
	if e, ok := entries["default"]; ok {
		return e.Login, e.Password, true
	}
	return "", "", false
}