1 files changed, 226 insertions, 0 deletions
diff --git a/src/pkg/net/lookup_plan9.go b/src/pkg/net/lookup_plan9.go
new file mode 100644
index 0000000000..37d6b8e315
--- /dev/null
+++ b/src/pkg/net/lookup_plan9.go
@@ -0,0 +1,226 @@
+// Copyright 2011 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.
+
+package net
+
+import (
+	"os"
+)
+
+func query(filename, query string, bufSize int) (res []string, err os.Error) {
+	file, err := os.OpenFile(filename, os.O_RDWR, 0)
+	if err != nil {
+		return
+	}
+	defer file.Close()
+
+	_, err = file.WriteString(query)
+	if err != nil {
+		return
+	}
+	_, err = file.Seek(0, 0)
+	if err != nil {
+		return
+	}
+	buf := make([]byte, bufSize)
+	for {
+		n, _ := file.Read(buf)
+		if n <= 0 {
+			break
+		}
+		res = append(res, string(buf[:n]))
+	}
+	return
+}
+
+func queryCS(net, host, service string) (res []string, err os.Error) {
+	switch net {
+	case "tcp4", "tcp6":
+		net = "tcp"
+	case "udp4", "udp6":
+		net = "udp"
+	}
+	if host == "" {
+		host = "*"
+	}
+	return query("/net/cs", net+"!"+host+"!"+service, 128)
+}
+
+func queryCS1(net string, ip IP, port int) (clone, dest string, err os.Error) {
+	ips := "*"
+	if !ip.IsUnspecified() {
+		ips = ip.String()
+	}
+	lines, err := queryCS(net, ips, itoa(port))
+	if err != nil {
+		return
+	}
+	f := getFields(lines[0])
+	if len(f) < 2 {
+		return "", "", os.NewError("net: bad response from ndb/cs")
+	}
+	clone, dest = f[0], f[1]
+	return
+}
+
+func queryDNS(addr string, typ string) (res []string, err os.Error) {
+	return query("/net/dns", addr+" "+typ, 1024)
+}
+
+// LookupHost looks up the given host using the local resolver.
+// It returns an array of that host's addresses.
+func LookupHost(host string) (addrs []string, err os.Error) {
+	// Use /net/cs insead of /net/dns because cs knows about
+	// host names in local network (e.g. from /lib/ndb/local)
+	lines, err := queryCS("tcp", host, "1")
+	if err != nil {
+		return
+	}
+	for _, line := range lines {
+		f := getFields(line)
+		if len(f) < 2 {
+			continue
+		}
+		addr := f[1]
+		if i := byteIndex(addr, '!'); i >= 0 {
+			addr = addr[:i] // remove port
+		}
+		if ParseIP(addr) == nil {
+			continue
+		}
+		addrs = append(addrs, addr)
+	}
+	return
+}
+
+// LookupIP looks up host using the local resolver.
+// It returns an array of that host's IPv4 and IPv6 addresses.
+func LookupIP(host string) (ips []IP, err os.Error) {
+	addrs, err := LookupHost(host)
+	if err != nil {
+		return
+	}
+	for _, addr := range addrs {
+		if ip := ParseIP(addr); ip != nil {
+			ips = append(ips, ip)
+		}
+	}
+	return
+}
+
+// LookupPort looks up the port for the given network and service.
+func LookupPort(network, service string) (port int, err os.Error) {
+	switch network {
+	case "tcp4", "tcp6":
+		network = "tcp"
+	case "udp4", "udp6":
+		network = "udp"
+	}
+	lines, err := queryCS(network, "127.0.0.1", service)
+	if err != nil {
+		return
+	}
+	unknownPortError := &AddrError{"unknown port", network + "/" + service}
+	if len(lines) == 0 {
+		return 0, unknownPortError
+	}
+	f := getFields(lines[0])
+	if len(f) < 2 {
+		return 0, unknownPortError
+	}
+	s := f[1]
+	if i := byteIndex(s, '!'); i >= 0 {
+		s = s[i+1:] // remove address
+	}
+	if n, _, ok := dtoi(s, 0); ok {
+		return n, nil
+	}
+	return 0, unknownPortError
+}
+
+// LookupCNAME returns the canonical DNS host for the given name.
+// Callers that do not care about the canonical name can call
+// LookupHost or LookupIP directly; both take care of resolving
+// the canonical name as part of the lookup.
+func LookupCNAME(name string) (cname string, err os.Error) {
+	lines, err := queryDNS(name, "cname")
+	if err != nil {
+		return
+	}
+	if len(lines) > 0 {
+		if f := getFields(lines[0]); len(f) >= 3 {
+			return f[2] + ".", nil
+		}
+	}
+	return "", os.NewError("net: bad response from ndb/dns")
+}
+
+// LookupSRV tries to resolve an SRV query of the given service,
+// protocol, and domain name, as specified in RFC 2782. In most cases
+// the proto argument can be the same as the corresponding
+// Addr.Network(). The returned records are sorted by priority 
+// and randomized by weight within a priority.
+func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err os.Error) {
+	target := "_" + service + "._" + proto + "." + name
+	lines, err := queryDNS(target, "srv")
+	if err != nil {
+		return
+	}
+	for _, line := range lines {
+		f := getFields(line)
+		if len(f) < 6 {
+			continue
+		}
+		port, _, portOk := dtoi(f[2], 0)
+		priority, _, priorityOk := dtoi(f[3], 0)
+		weight, _, weightOk := dtoi(f[4], 0)
+		if !(portOk && priorityOk && weightOk) {
+			continue
+		}
+		addrs = append(addrs, &SRV{f[5], uint16(port), uint16(priority), uint16(weight)})
+		cname = f[0]
+	}
+	byPriorityWeight(addrs).sort()
+	return
+}
+
+// LookupMX returns the DNS MX records for the given domain name sorted by preference.
+func LookupMX(name string) (mx []*MX, err os.Error) {
+	lines, err := queryDNS(name, "mx")
+	if err != nil {
+		return
+	}
+	for _, line := range lines {
+		f := getFields(line)
+		if len(f) < 4 {
+			continue
+		}
+		if pref, _, ok := dtoi(f[2], 0); ok {
+			mx = append(mx, &MX{f[3], uint16(pref)})
+		}
+	}
+	byPref(mx).sort()
+	return
+}
+
+// LookupAddr performs a reverse lookup for the given address, returning a list
+// of names mapping to that address.
+func LookupAddr(addr string) (name []string, err os.Error) {
+	arpa, err := reverseaddr(addr)
+	if err != nil {
+		return
+	}
+	lines, err := queryDNS(arpa, "ptr")
+	if err != nil {
+		return
+	}
+	for _, line := range lines {
+		f := getFields(line)
+		if len(f) < 3 {
+			continue
+		}
+		name = append(name, f[2])
+	}
+	return
+}