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- // Copyright 2015 The Go Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- //go:build aix || darwin || dragonfly || freebsd || hurd || linux || netbsd || openbsd || solaris
- package net
- import (
- "errors"
- "internal/bytealg"
- "io"
- "os"
- )
- // nssConf represents the state of the machine's /etc/nsswitch.conf file.
- type nssConf struct {
- err error // any error encountered opening or parsing the file
- sources map[string][]nssSource // keyed by database (e.g. "hosts")
- }
- type nssSource struct {
- source string // e.g. "compat", "files", "mdns4_minimal"
- criteria []nssCriterion
- }
- // standardCriteria reports all specified criteria have the default
- // status actions.
- func (s nssSource) standardCriteria() bool {
- for i, crit := range s.criteria {
- if !crit.standardStatusAction(i == len(s.criteria)-1) {
- return false
- }
- }
- return true
- }
- // nssCriterion is the parsed structure of one of the criteria in brackets
- // after an NSS source name.
- type nssCriterion struct {
- negate bool // if "!" was present
- status string // e.g. "success", "unavail" (lowercase)
- action string // e.g. "return", "continue" (lowercase)
- }
- // standardStatusAction reports whether c is equivalent to not
- // specifying the criterion at all. last is whether this criteria is the
- // last in the list.
- func (c nssCriterion) standardStatusAction(last bool) bool {
- if c.negate {
- return false
- }
- var def string
- switch c.status {
- case "success":
- def = "return"
- case "notfound", "unavail", "tryagain":
- def = "continue"
- default:
- // Unknown status
- return false
- }
- if last && c.action == "return" {
- return true
- }
- return c.action == def
- }
- func parseNSSConfFile(file string) *nssConf {
- f, err := os.Open(file)
- if err != nil {
- return &nssConf{err: err}
- }
- defer f.Close()
- return parseNSSConf(f)
- }
- func parseNSSConf(r io.Reader) *nssConf {
- slurp, err := readFull(r)
- if err != nil {
- return &nssConf{err: err}
- }
- conf := new(nssConf)
- conf.err = foreachLine(slurp, func(line []byte) error {
- line = trimSpace(removeComment(line))
- if len(line) == 0 {
- return nil
- }
- colon := bytealg.IndexByte(line, ':')
- if colon == -1 {
- return errors.New("no colon on line")
- }
- db := string(trimSpace(line[:colon]))
- srcs := line[colon+1:]
- for {
- srcs = trimSpace(srcs)
- if len(srcs) == 0 {
- break
- }
- sp := bytealg.IndexByte(srcs, ' ')
- var src string
- if sp == -1 {
- src = string(srcs)
- srcs = nil // done
- } else {
- src = string(srcs[:sp])
- srcs = trimSpace(srcs[sp+1:])
- }
- var criteria []nssCriterion
- // See if there's a criteria block in brackets.
- if len(srcs) > 0 && srcs[0] == '[' {
- bclose := bytealg.IndexByte(srcs, ']')
- if bclose == -1 {
- return errors.New("unclosed criterion bracket")
- }
- var err error
- criteria, err = parseCriteria(srcs[1:bclose])
- if err != nil {
- return errors.New("invalid criteria: " + string(srcs[1:bclose]))
- }
- srcs = srcs[bclose+1:]
- }
- if conf.sources == nil {
- conf.sources = make(map[string][]nssSource)
- }
- conf.sources[db] = append(conf.sources[db], nssSource{
- source: src,
- criteria: criteria,
- })
- }
- return nil
- })
- return conf
- }
- // parses "foo=bar !foo=bar"
- func parseCriteria(x []byte) (c []nssCriterion, err error) {
- err = foreachField(x, func(f []byte) error {
- not := false
- if len(f) > 0 && f[0] == '!' {
- not = true
- f = f[1:]
- }
- if len(f) < 3 {
- return errors.New("criterion too short")
- }
- eq := bytealg.IndexByte(f, '=')
- if eq == -1 {
- return errors.New("criterion lacks equal sign")
- }
- lowerASCIIBytes(f)
- c = append(c, nssCriterion{
- negate: not,
- status: string(f[:eq]),
- action: string(f[eq+1:]),
- })
- return nil
- })
- return
- }
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