1 files changed, 200 insertions, 0 deletions
diff --git a/xau/xau.go b/xau/xau.go
new file mode 100644
index 0000000..2f3ec9a
--- /dev/null
+++ b/xau/xau.go
@@ -0,0 +1,200 @@
+package xau
+
+import (
+	"bytes"
+	"io"
+	"os"
+)
+
+const (
+	FamilyLocal         uint16 = 256 /* not part of X standard (i.e. X.h) */
+	FamilyWild                 = 65535
+	FamilyNetname              = 254 /* not part of X standard */
+	FamilyKrb5Principal        = 253 /* Kerberos 5 principal name */
+	FamilyLocalHost            = 252 /* for local non-net authentication */
+)
+
+type Xauth struct {
+	Family  uint16
+	Address []byte
+	Number  []byte
+	Name    string
+	Data    []byte
+}
+
+func fileName() string {
+	const slashDotXauthority = "/.Xauthority"
+
+	name := os.Getenv("XAUTHORITY")
+	if name != "" {
+		return name
+	}
+
+	name = os.Getenv("HOME")
+	if name == "" {
+		dir := os.Getenv("USERNAME")
+		if dir == "" {
+			return ""
+		}
+		name = "/users/" + dir
+	}
+
+	if len(name) < 2 {
+		return name + slashDotXauthority[1:]
+	}
+	return name + slashDotXauthority
+}
+
+func GetAuthByAddr(family uint16, address []byte, number []byte, name string) *Xauth {
+	auth_name := fileName()
+	if auth_name == "" {
+		return nil
+	}
+
+	auth_file, err := os.Open(auth_name)
+	if err != nil {
+		return nil
+	}
+	defer auth_file.Close()
+
+	var entry *Xauth
+	for {
+		entry = readAuth(auth_file)
+		if entry == nil {
+			break
+		}
+		/*
+		 * Match when:
+		 *   either family or entry->family are FamilyWild or
+		 *    family and entry->family are the same and
+		 *     address and entry->address are the same
+		 *  and
+		 *   either number or entry->number are empty or
+		 *    number and entry->number are the same
+		 *  and
+		 *   either name or entry->name are empty or
+		 *    name and entry->name are the same
+		 */
+
+		if (family == FamilyWild || entry.Family == FamilyWild ||
+			(entry.Family == family &&
+				bytes.Equal(address, entry.Address))) &&
+			(len(number) == 0 || len(entry.Number) == 0 ||
+				bytes.Equal(number, entry.Number)) &&
+			(len(name) == 0 || len(entry.Name) == 0 ||
+				entry.Name == name) {
+			break
+		}
+	}
+	return entry
+}
+
+func GetBestAuthByAddr(family uint16, address []byte, number []byte, types []string) *Xauth {
+	auth_name := fileName()
+	if auth_name == "" {
+		return nil
+	}
+
+	auth_file, err := os.Open(auth_name)
+	if err != nil {
+		return nil
+	}
+	defer auth_file.Close()
+
+	var best *Xauth
+	best_type := len(types)
+	for {
+		entry := readAuth(auth_file)
+		if entry == nil {
+			break
+		}
+		/*
+		 * Match when:
+		 *   either family or entry->family are FamilyWild or
+		 *    family and entry->family are the same and
+		 *     address and entry->address are the same
+		 *  and
+		 *   either number or entry->number are empty or
+		 *    number and entry->number are the same
+		 *  and
+		 *   either name or entry->name are empty or
+		 *    name and entry->name are the same
+		 */
+
+		if (family == FamilyWild || entry.Family == FamilyWild ||
+			(entry.Family == family && bytes.Equal(entry.Address, address))) &&
+			(len(number) == 0 || len(entry.Number) == 0 ||
+				bytes.Equal(number, entry.Number)) {
+			if best_type == 0 {
+				best = entry
+				break
+			}
+			for i := 0; i < best_type; i++ {
+				if types[i] == entry.Name {
+					best = entry
+					best_type = i
+					break
+				}
+				if best_type == 0 {
+					break
+				}
+				continue
+			}
+		}
+	}
+	return best
+}
+
+func readShort(file *os.File) (uint16, error) {
+	var buf [2]byte
+	_, err := io.ReadFull(file, buf[:])
+
+	if err != nil {
+		return 0, err
+	}
+	return uint16(buf[0])*256 + uint16(buf[1]), nil
+}
+
+func readCountedString(file *os.File) ([]byte, error) {
+	len, err := readShort(file)
+	if err != nil {
+		return nil, err
+	}
+
+	buf := make([]byte, len)
+	_, err = io.ReadFull(file, buf)
+	if err != nil {
+		return nil, err
+	}
+
+	return buf, nil
+}
+
+func readAuth(auth_file *os.File) *Xauth {
+	var local Xauth
+
+	var err error
+	local.Family, err = readShort(auth_file)
+	if err != nil {
+		return nil
+	}
+	local.Address, err = readCountedString(auth_file)
+	if err != nil {
+		return nil
+	}
+	local.Number, err = readCountedString(auth_file)
+	if err != nil {
+		return nil
+	}
+	name, err := readCountedString(auth_file)
+	if err != nil {
+		return nil
+	}
+	local.Name = string(name)
+	local.Data, err = readCountedString(auth_file)
+	if err != nil {
+		return nil
+	}
+
+	return &local
+}