add dhcpv4.GetOption and dhcpv4.GetSingleOption methods (#63)

GetOption and GetOneOption are convenience methods for getting a DHCPv4
option from its Option Code.

GetOption returns a list of options that match since the DHCP RFC allows
for an option to be present multiple times with its values appended
together.  (Note: I am not sure I've ever seen this done and it's not clear if
how option parsing would work for more complex values.  Is appending
done at the byte level? )

GetOneOption will return the first found option that matches a code.

1 files changed, 25 insertions, 0 deletions

diff --git a/dhcpv4/dhcpv4.go b/dhcpv4/dhcpv4.go
index 3deda86..226c077 100644
--- a/dhcpv4/dhcpv4.go
+++ b/dhcpv4/dhcpv4.go
@@ -511,6 +511,31 @@ func (d *DHCPv4) Options() []Option {
 	return d.options
 }
 
+// GetOption will attempt to get all options that match a DHCPv4 option
+// from its OptionCode.  If the option was not found it will return an
+// empty list.
+func (d *DHCPv4) GetOption(code OptionCode) []Option {
+	opts := []Option{}
+	for _, opt := range d.Options() {
+		if opt.Code() == code {
+			opts = append(opts, opt)
+		}
+	}
+	return opts
+}
+
+// GetOneOption will attempt to get an  option that match a Option code.
+// If there are multiple options with the same OptionCode it will only return
+// the first one found.  If no matching option is found nil will be returned.
+func (d *DHCPv4) GetOneOption(code OptionCode) Option {
+	for _, opt := range d.Options() {
+		if opt.Code() == code {
+			return opt
+		}
+	}
+	return nil
+}
+
 // StrippedOptions works like Options, but it does not return anything after the
 // End option.
 func (d *DHCPv4) StrippedOptions() []Option {