*: reflect SPEC's DNS changes in implementation

* DNS is now a type which will result in a JSON dictionary in
  configurations and results
* Minor refactoring, making use of type embedding

pkg/types/types.go

@@ -61,13 +61,14 @@ type NetConf struct {
 	IPAM struct {
 		Type string `json:"type,omitempty"`
 	} `json:"ipam,omitempty"`
+	DNS DNS `json:"dns"`
 }
 
 // Result is what gets returned from the plugin (via stdout) to the caller
 type Result struct {
 	IP4 *IPConfig `json:"ip4,omitempty"`
 	IP6 *IPConfig `json:"ip6,omitempty"`
-	DNS []string  `json:"dns,omitempty"`
+	DNS DNS       `json:"dns,omitempty"`
 }
 
 func (r *Result) Print() error {
@@ -81,6 +82,14 @@ type IPConfig struct {
 	Routes  []Route
 }
 
+// DNS contains values interesting for DNS resolvers
+type DNS struct {
+	Nameservers []string `json:"nameservers,omitempty"`
+	Domain      string   `json:"domain,omitempty"`
+	Search      []string `json:"search,omitempty"`
+	Options     []string `json:"options,omitempty"`
+}
+
 type Route struct {
 	Dst net.IPNet
 	GW  net.IP

plugins/main/bridge/bridge.go

@@ -39,7 +39,6 @@ type NetConf struct {
 	IsGW   bool   `json:"isGateway"`
 	IPMasq bool   `json:"ipMasq"`
 	MTU    int    `json:"mtu"`
-	DNS    []string `json:"dns"`
 }
 
 func init() {

plugins/main/ipvlan/ipvlan.go

@@ -34,7 +34,6 @@ type NetConf struct {
 	Master string `json:"master"`
 	Mode   string `json:"mode"`
 	MTU    int    `json:"mtu"`
-	DNS    []string `json:"dns"`
 }
 
 func init() {

plugins/main/macvlan/macvlan.go

@@ -34,7 +34,6 @@ type NetConf struct {
 	Master string `json:"master"`
 	Mode   string `json:"mode"`
 	MTU    int    `json:"mtu"`
-	DNS    []string `json:"dns"`
 }
 
 func init() {

plugins/main/ptp/ptp.go

@@ -43,7 +43,6 @@ type NetConf struct {
 	types.NetConf
 	IPMasq bool `json:"ipMasq"`
 	MTU    int  `json:"mtu"`
-	DNS    []string `json:"dns"`
 }
 
 func setupContainerVeth(netns, ifName string, mtu int, pr *types.Result) (string, error) {