host and port name lookup

R=r,presotto
DELTA=1239  (935 added, 281 deleted, 23 changed)
OCL=21041
CL=21539

1 files changed, 68 insertions, 0 deletions

diff --git a/src/lib/net/port.go b/src/lib/net/port.go
new file mode 100644
index 000000000..5ff1e5805
--- /dev/null
+++ b/src/lib/net/port.go
@@ -0,0 +1,68 @@
+// 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 port mappings from /etc/services
+
+package net
+
+import (
+	"io";
+	"net";
+	"once";
+	"os";
+	"strconv";
+)
+
+var services *map[string] *map[string] int
+
+func ReadServices() {
+	services = new(map[string] *map[string] int);
+	file := Open("/etc/services");
+	for line, ok := file.ReadLine(); ok; line, ok = file.ReadLine() {
+		// "http 80/tcp www www-http # World Wide Web HTTP"
+		if i := ByteIndex(line, '#'); i >= 0 {
+			line = line[0:i];
+		}
+		f := GetFields(line);
+		if len(f) < 2 {
+			continue;
+		}
+		portnet := f[1];	// "tcp/80"
+		port, j, ok := Dtoi(portnet, 0);
+		if !ok || port <= 0 || j >= len(portnet) || portnet[j] != '/' {
+			continue
+		}
+		netw := portnet[j+1:len(portnet)];	// "tcp"
+		m, ok1 := services[netw];
+		if !ok1 {
+			m = new(map[string] int);
+			services[netw] = m;
+		}
+		for i := 0; i < len(f); i++ {
+			if i != 1 {	// f[1] was port/net
+				m[f[i]] = port;
+			}
+		}
+	}
+	file.Close();
+}
+
+export func LookupPort(netw, name string) (port int, ok bool) {
+	once.Do(&ReadServices);
+
+	switch netw {
+	case "tcp4", "tcp6":
+		netw = "tcp";
+	case "udp4", "udp6":
+		netw = "udp";
+	}
+
+	m, mok := services[netw];
+	if !mok {
+		return
+	}
+	port, ok = m[name];
+	return
+}
+