add OptRouter

1 files changed, 70 insertions, 0 deletions

diff --git a/dhcpv4/option_router.go b/dhcpv4/option_router.go
new file mode 100644
index 0000000..6991f89
--- /dev/null
+++ b/dhcpv4/option_router.go
@@ -0,0 +1,70 @@
+package dhcpv4
+
+import (
+	"fmt"
+	"net"
+)
+
+// This option implements the router option
+// https://tools.ietf.org/html/rfc2132
+
+// OptDomainRouter represents an option encapsulating the routers.
+type OptRouter struct {
+	Routers []net.IP
+}
+
+// ParseOptRouter returns a new OptRouter from a byte  stream, or error if any.
+func ParseOptRouter(data []byte) (*OptRouter, error) {
+	if len(data) < 2 {
+		return nil, ErrShortByteStream
+	}
+	code := OptionCode(data[0])
+	if code != OptionRouter {
+		return nil, fmt.Errorf("expected code %v, got %v", OptionRouter, code)
+	}
+	length := int(data[1])
+	if length == 0 || length%4 != 0 {
+		return nil, fmt.Errorf("Invalid length: expected multiple of 4 larger than 4, got %v", length)
+	}
+	if len(data) < 2+length {
+		return nil, ErrShortByteStream
+	}
+	routers := make([]net.IP, 0, length%4)
+	for idx := 0; idx < length; idx += 4 {
+		b := data[2+idx : 2+idx+4]
+		routers = append(routers, net.IPv4(b[0], b[1], b[2], b[3]))
+	}
+	return &OptRouter{Routers: routers}, nil
+}
+
+// Code returns the option code.
+func (o *OptRouter) Code() OptionCode {
+	return OptionRouter
+}
+
+// ToBytes returns a serialized stream of bytes for this option.
+func (o *OptRouter) ToBytes() []byte {
+	ret := []byte{byte(o.Code()), byte(o.Length())}
+	for _, router := range o.Routers {
+		ret = append(ret, router.To4()...)
+	}
+	return ret
+}
+
+// String returns a human-readable string.
+func (o *OptRouter) String() string {
+	var routers string
+	for idx, router := range o.Routers {
+		routers += router.String()
+		if idx < len(o.Routers)-1 {
+			routers += ", "
+		}
+	}
+	return fmt.Sprintf("Routers -> %v", routers)
+}
+
+// Length returns the length of the data portion (excluding option code an byte
+// length).
+func (o *OptRouter) Length() int {
+	return len(o.Routers) * 4
+}