1 files changed, 120 insertions, 0 deletions
diff --git a/libgo/go/net/dnsconfig.go b/libgo/go/net/dnsconfig.go
new file mode 100644
index 0000000000..26f0e04e90
--- /dev/null
+++ b/libgo/go/net/dnsconfig.go
@@ -0,0 +1,120 @@
+// Copyright 2009 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.
+
+// Read system DNS config from /etc/resolv.conf
+
+package net
+
+import "os"
+
+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
+}
+
+var dnsconfigError os.Error
+
+type DNSConfigError struct {
+	Error os.Error
+}
+
+func (e *DNSConfigError) String() string {
+	return "error reading DNS config: " + e.Error.String()
+}
+
+func (e *DNSConfigError) Timeout() bool   { return false }
+func (e *DNSConfigError) Temporary() bool { return false }
+
+
+// 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.
+// We assume it's in resolv.conf anyway.
+func dnsReadConfig() (*dnsConfig, os.Error) {
+	file, err := open("/etc/resolv.conf")
+	if err != nil {
+		return nil, &DNSConfigError{err}
+	}
+	conf := new(dnsConfig)
+	conf.servers = make([]string, 3)[0:0] // small, but the standard limit
+	conf.search = make([]string, 0)
+	conf.ndots = 1
+	conf.timeout = 5
+	conf.attempts = 2
+	conf.rotate = false
+	for line, ok := file.readLine(); ok; line, ok = file.readLine() {
+		f := getFields(line)
+		if len(f) < 1 {
+			continue
+		}
+		switch f[0] {
+		case "nameserver": // add one name server
+			a := conf.servers
+			n := len(a)
+			if len(f) > 1 && n < cap(a) {
+				// One more check: make sure server name is
+				// just an IP address.  Otherwise we need DNS
+				// to look it up.
+				name := f[1]
+				switch len(ParseIP(name)) {
+				case 16:
+					name = "[" + name + "]"
+					fallthrough
+				case 4:
+					a = a[0 : n+1]
+					a[n] = name
+					conf.servers = a
+				}
+			}
+
+		case "domain": // set search path to just this domain
+			if len(f) > 1 {
+				conf.search = make([]string, 1)
+				conf.search[0] = f[1]
+			} else {
+				conf.search = make([]string, 0)
+			}
+
+		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]
+			}
+
+		case "options": // magic options
+			for i := 1; i < len(f); i++ {
+				s := f[i]
+				switch {
+				case len(s) >= 6 && s[0:6] == "ndots:":
+					n, _, _ := dtoi(s, 6)
+					if n < 1 {
+						n = 1
+					}
+					conf.ndots = n
+				case len(s) >= 8 && s[0:8] == "timeout:":
+					n, _, _ := dtoi(s, 8)
+					if n < 1 {
+						n = 1
+					}
+					conf.timeout = n
+				case len(s) >= 8 && s[0:9] == "attempts:":
+					n, _, _ := dtoi(s, 9)
+					if n < 1 {
+						n = 1
+					}
+					conf.attempts = n
+				case s == "rotate":
+					conf.rotate = true
+				}
+			}
+		}
+	}
+	file.close()
+
+	return conf, nil
+}