diff options
Diffstat (limited to 'libgo/go/net/dnsconfig_unix.go')
| -rw-r--r-- | libgo/go/net/dnsconfig_unix.go | 101 |
1 files changed, 77 insertions, 24 deletions
diff --git a/libgo/go/net/dnsconfig_unix.go b/libgo/go/net/dnsconfig_unix.go index 6073fdb6d8..9c8108d11c 100644 --- a/libgo/go/net/dnsconfig_unix.go +++ b/libgo/go/net/dnsconfig_unix.go @@ -8,36 +8,54 @@ package net -var defaultNS = []string{"127.0.0.1", "::1"} +import ( + "os" + "sync/atomic" + "time" +) + +var ( + defaultNS = []string{"127.0.0.1:53", "[::1]:53"} + getHostname = os.Hostname // variable for testing +) type dnsConfig struct { - servers []string // servers to use - search []string // suffixes to append to local name - ndots int // number of dots in name to trigger absolute lookup - timeout int // seconds before giving up on packet - attempts int // lost packets before giving up on server - rotate bool // round robin among servers - unknownOpt bool // anything unknown was encountered - lookup []string // OpenBSD top-level database "lookup" order - err error // any error that occurs during open of resolv.conf + servers []string // server addresses (in host:port form) to use + search []string // rooted suffixes to append to local name + ndots int // number of dots in name to trigger absolute lookup + timeout time.Duration // wait before giving up on a query, including retries + attempts int // lost packets before giving up on server + rotate bool // round robin among servers + unknownOpt bool // anything unknown was encountered + lookup []string // OpenBSD top-level database "lookup" order + err error // any error that occurs during open of resolv.conf + mtime time.Time // time of resolv.conf modification + soffset uint32 // used by serverOffset } // See resolv.conf(5) on a Linux machine. -// TODO(rsc): Supposed to call uname() and chop the beginning -// of the host name to get the default search domain. func dnsReadConfig(filename string) *dnsConfig { conf := &dnsConfig{ ndots: 1, - timeout: 5, + timeout: 5 * time.Second, attempts: 2, } file, err := open(filename) if err != nil { conf.servers = defaultNS + conf.search = dnsDefaultSearch() conf.err = err return conf } defer file.close() + if fi, err := file.file.Stat(); err == nil { + conf.mtime = fi.ModTime() + } else { + conf.servers = defaultNS + conf.search = dnsDefaultSearch() + conf.err = err + return conf + } for line, ok := file.readLine(); ok; line, ok = file.readLine() { if len(line) > 0 && (line[0] == ';' || line[0] == '#') { // comment. @@ -51,43 +69,45 @@ func dnsReadConfig(filename string) *dnsConfig { case "nameserver": // add one name server if len(f) > 1 && len(conf.servers) < 3 { // small, but the standard limit // One more check: make sure server name is - // just an IP address. Otherwise we need DNS + // just an IP address. Otherwise we need DNS // to look it up. if parseIPv4(f[1]) != nil { - conf.servers = append(conf.servers, f[1]) + conf.servers = append(conf.servers, JoinHostPort(f[1], "53")) } else if ip, _ := parseIPv6(f[1], true); ip != nil { - conf.servers = append(conf.servers, f[1]) + conf.servers = append(conf.servers, JoinHostPort(f[1], "53")) } } case "domain": // set search path to just this domain if len(f) > 1 { - conf.search = []string{f[1]} + conf.search = []string{ensureRooted(f[1])} } case "search": // set search path to given servers conf.search = make([]string, len(f)-1) for i := 0; i < len(conf.search); i++ { - conf.search[i] = f[i+1] + conf.search[i] = ensureRooted(f[i+1]) } case "options": // magic options for _, s := range f[1:] { switch { case hasPrefix(s, "ndots:"): - n, _, _ := dtoi(s, 6) - if n < 1 { - n = 1 + n, _, _ := dtoi(s[6:]) + if n < 0 { + n = 0 + } else if n > 15 { + n = 15 } conf.ndots = n case hasPrefix(s, "timeout:"): - n, _, _ := dtoi(s, 8) + n, _, _ := dtoi(s[8:]) if n < 1 { n = 1 } - conf.timeout = n + conf.timeout = time.Duration(n) * time.Second case hasPrefix(s, "attempts:"): - n, _, _ := dtoi(s, 9) + n, _, _ := dtoi(s[9:]) if n < 1 { n = 1 } @@ -112,9 +132,42 @@ func dnsReadConfig(filename string) *dnsConfig { if len(conf.servers) == 0 { conf.servers = defaultNS } + if len(conf.search) == 0 { + conf.search = dnsDefaultSearch() + } return conf } +// serverOffset returns an offset that can be used to determine +// indices of servers in c.servers when making queries. +// When the rotate option is enabled, this offset increases. +// Otherwise it is always 0. +func (c *dnsConfig) serverOffset() uint32 { + if c.rotate { + return atomic.AddUint32(&c.soffset, 1) - 1 // return 0 to start + } + return 0 +} + +func dnsDefaultSearch() []string { + hn, err := getHostname() + if err != nil { + // best effort + return nil + } + if i := byteIndex(hn, '.'); i >= 0 && i < len(hn)-1 { + return []string{ensureRooted(hn[i+1:])} + } + return nil +} + func hasPrefix(s, prefix string) bool { return len(s) >= len(prefix) && s[:len(prefix)] == prefix } + +func ensureRooted(s string) string { + if len(s) > 0 && s[len(s)-1] == '.' { + return s + } + return s + "." +} |