add OptRelayAgentInformation (#193)

1 files changed, 74 insertions, 0 deletions

diff --git a/dhcpv4/option_relay_agent_information.go b/dhcpv4/option_relay_agent_information.go
new file mode 100644
index 0000000..447783e
--- /dev/null
+++ b/dhcpv4/option_relay_agent_information.go
@@ -0,0 +1,74 @@
+package dhcpv4
+
+import "fmt"
+
+// This option implements the relay agent information option
+// https://tools.ietf.org/html/rfc3046
+
+// OptRelayAgentInformation is a "container" option for specific agent-supplied
+// sub-options.
+type OptRelayAgentInformation struct {
+	Options []Option
+}
+
+// ParseOptRelayAgentInformation returns a new OptRelayAgentInformation from a
+// byte stream, or error if any.
+func ParseOptRelayAgentInformation(data []byte) (*OptRelayAgentInformation, error) {
+	if len(data) < 4 {
+		return nil, ErrShortByteStream
+	}
+	code := OptionCode(data[0])
+	if code != OptionRelayAgentInformation {
+		return nil, fmt.Errorf("expected code %v, got %v", OptionRelayAgentInformation, code)
+	}
+	length := int(data[1])
+	if len(data) < 2+length {
+		return nil, ErrShortByteStream
+	}
+	options, err := OptionsFromBytesWithParser(data[2:length+2], relayParseOption)
+	if err != nil {
+		return nil, err
+	}
+	return &OptRelayAgentInformation{Options: options}, nil
+}
+
+func relayParseOption(data []byte) (Option, error) {
+	if len(data) < 2 {
+		return nil, ErrShortByteStream
+	}
+	code := OptionCode(data[0])
+	length := int(data[1])
+	if len(data) < 2+length {
+		return nil, ErrShortByteStream
+	}
+	return &OptionGeneric{OptionCode: code, Data: data[2:length+2]}, nil
+}
+
+// Code returns the option code.
+func (o *OptRelayAgentInformation) Code() OptionCode {
+	return OptionRelayAgentInformation
+}
+
+// ToBytes returns a serialized stream of bytes for this option.
+func (o *OptRelayAgentInformation) ToBytes() []byte {
+	ret := []byte{byte(o.Code()), byte(o.Length())}
+	for _, opt := range o.Options {
+		ret = append(ret, opt.ToBytes()...)
+	}
+	return ret
+}
+
+// String returns a human-readable string for this option.
+func (o *OptRelayAgentInformation) String() string {
+	return fmt.Sprintf("Relay Agent Information -> %v", o.Options)
+}
+
+// Length returns the length of the data portion (excluding option code and byte
+// for length, if any).
+func (o *OptRelayAgentInformation) Length() int {
+	l := 0
+	for _, opt := range o.Options {
+		l += 2 + opt.Length()
+	}
+	return l
+}