Imported Upstream version 1.4upstream/1.4

1 files changed, 116 insertions, 0 deletions

diff --git a/src/net/mockicmp_test.go b/src/net/mockicmp_test.go
new file mode 100644
index 000000000..e742365ea
--- /dev/null
+++ b/src/net/mockicmp_test.go
@@ -0,0 +1,116 @@
+// 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.
+
+package net
+
+import "errors"
+
+const (
+	icmpv4EchoRequest = 8
+	icmpv4EchoReply   = 0
+	icmpv6EchoRequest = 128
+	icmpv6EchoReply   = 129
+)
+
+// icmpMessage represents an ICMP message.
+type icmpMessage struct {
+	Type     int             // type
+	Code     int             // code
+	Checksum int             // checksum
+	Body     icmpMessageBody // body
+}
+
+// icmpMessageBody represents an ICMP message body.
+type icmpMessageBody interface {
+	Len() int
+	Marshal() ([]byte, error)
+}
+
+// Marshal returns the binary enconding of the ICMP echo request or
+// reply message m.
+func (m *icmpMessage) Marshal() ([]byte, error) {
+	b := []byte{byte(m.Type), byte(m.Code), 0, 0}
+	if m.Body != nil && m.Body.Len() != 0 {
+		mb, err := m.Body.Marshal()
+		if err != nil {
+			return nil, err
+		}
+		b = append(b, mb...)
+	}
+	switch m.Type {
+	case icmpv6EchoRequest, icmpv6EchoReply:
+		return b, nil
+	}
+	csumcv := len(b) - 1 // checksum coverage
+	s := uint32(0)
+	for i := 0; i < csumcv; i += 2 {
+		s += uint32(b[i+1])<<8 | uint32(b[i])
+	}
+	if csumcv&1 == 0 {
+		s += uint32(b[csumcv])
+	}
+	s = s>>16 + s&0xffff
+	s = s + s>>16
+	// Place checksum back in header; using ^= avoids the
+	// assumption the checksum bytes are zero.
+	b[2] ^= byte(^s)
+	b[3] ^= byte(^s >> 8)
+	return b, nil
+}
+
+// parseICMPMessage parses b as an ICMP message.
+func parseICMPMessage(b []byte) (*icmpMessage, error) {
+	msglen := len(b)
+	if msglen < 4 {
+		return nil, errors.New("message too short")
+	}
+	m := &icmpMessage{Type: int(b[0]), Code: int(b[1]), Checksum: int(b[2])<<8 | int(b[3])}
+	if msglen > 4 {
+		var err error
+		switch m.Type {
+		case icmpv4EchoRequest, icmpv4EchoReply, icmpv6EchoRequest, icmpv6EchoReply:
+			m.Body, err = parseICMPEcho(b[4:])
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+	return m, nil
+}
+
+// imcpEcho represenets an ICMP echo request or reply message body.
+type icmpEcho struct {
+	ID   int    // identifier
+	Seq  int    // sequence number
+	Data []byte // data
+}
+
+func (p *icmpEcho) Len() int {
+	if p == nil {
+		return 0
+	}
+	return 4 + len(p.Data)
+}
+
+// Marshal returns the binary enconding of the ICMP echo request or
+// reply message body p.
+func (p *icmpEcho) Marshal() ([]byte, error) {
+	b := make([]byte, 4+len(p.Data))
+	b[0], b[1] = byte(p.ID>>8), byte(p.ID)
+	b[2], b[3] = byte(p.Seq>>8), byte(p.Seq)
+	copy(b[4:], p.Data)
+	return b, nil
+}
+
+// parseICMPEcho parses b as an ICMP echo request or reply message
+// body.
+func parseICMPEcho(b []byte) (*icmpEcho, error) {
+	bodylen := len(b)
+	p := &icmpEcho{ID: int(b[0])<<8 | int(b[1]), Seq: int(b[2])<<8 | int(b[3])}
+	if bodylen > 4 {
+		p.Data = make([]byte, bodylen-4)
+		copy(p.Data, b[4:])
+	}
+	return p, nil
+}