Add MTU field to route type definition

SPEC.md

@@ -489,6 +489,7 @@ Plugins must output a JSON object with the following keys upon a successful `ADD
 - `routes`: Routes created by this attachment:
     - `dst`: The destination of the route, in CIDR notation
     - `gw`: The next hop address. If unset, a value in `gateway` in the `ips` array may be used.
+    - `mtu`: The MTU for this route. If unset, the MTU for the interface indicated by `interface` in the `ips` array may be used.
 - `dns`: a dictionary consisting of DNS configuration information
     - `nameservers` (list of strings): list of a priority-ordered list of DNS nameservers that this network is aware of. Each entry in the list is a string containing either an IPv4 or an IPv6 address.
     - `domain` (string): the local domain used for short hostname lookups.

pkg/types/020/types_test.go

@@ -17,13 +17,13 @@ package types020_test
 import (
 	"encoding/json"
 	"fmt"
+	types020 "github.com/containernetworking/cni/pkg/types/020"
 	"net"
 
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 
 	"github.com/containernetworking/cni/pkg/types"
-	"github.com/containernetworking/cni/pkg/types/020"
 	"github.com/containernetworking/cni/pkg/types/create"
 )
 

pkg/types/100/types.go

@@ -83,11 +83,11 @@ func NewResultFromResult(result types.Result) (*Result, error) {
 
 // Result is what gets returned from the plugin (via stdout) to the caller
 type Result struct {
-	CNIVersion string         `json:"cniVersion,omitempty"`
-	Interfaces []*Interface   `json:"interfaces,omitempty"`
-	IPs        []*IPConfig    `json:"ips,omitempty"`
-	Routes     []*types.Route `json:"routes,omitempty"`
-	DNS        types.DNS      `json:"dns,omitempty"`
+	CNIVersion string       `json:"cniVersion,omitempty"`
+	Interfaces []*Interface `json:"interfaces,omitempty"`
+	IPs        []*IPConfig  `json:"ips,omitempty"`
+	Routes     []*Route     `json:"routes,omitempty"`
+	DNS        types.DNS    `json:"dns,omitempty"`
 }
 
 func convertFrom02x(from types.Result, toVersion string) (types.Result, error) {
@@ -127,7 +127,7 @@ func convertFrom04x(from types.Result, toVersion string) (types.Result, error) {
 	toResult := &Result{
 		CNIVersion: toVersion,
 		DNS:        *fromResult.DNS.Copy(),
-		Routes:     []*types.Route{},
+		Routes:     []*Route{},
 	}
 	for _, fromIntf := range fromResult.Interfaces {
 		toResult.Interfaces = append(toResult.Interfaces, convertInterfaceFrom040(fromIntf))
@@ -136,7 +136,7 @@ func convertFrom04x(from types.Result, toVersion string) (types.Result, error) {
 		toResult.IPs = append(toResult.IPs, convertIPConfigFrom040(fromIPC))
 	}
 	for _, fromRoute := range fromResult.Routes {
-		toResult.Routes = append(toResult.Routes, fromRoute.Copy())
+		toResult.Routes = append(toResult.Routes, convertRouteFrom040(fromRoute))
 	}
 	return toResult, nil
 }
@@ -180,7 +180,7 @@ func convertTo04x(from types.Result, toVersion string) (types.Result, error) {
 		toResult.IPs = append(toResult.IPs, convertIPConfigTo040(fromIPC))
 	}
 	for _, fromRoute := range fromResult.Routes {
-		toResult.Routes = append(toResult.Routes, fromRoute.Copy())
+		toResult.Routes = append(toResult.Routes, fromRoute.convertTo040())
 	}
 	return toResult, nil
 }
@@ -305,3 +305,52 @@ func (c *IPConfig) UnmarshalJSON(data []byte) error {
 	c.Gateway = ipc.Gateway
 	return nil
 }
+
+type Route struct {
+	Dst net.IPNet
+	GW  net.IP
+	MTU int
+}
+
+func (r *Route) String() string {
+	return fmt.Sprintf("%+v", *r)
+}
+
+func (r *Route) Copy() *Route {
+	if r == nil {
+		return nil
+	}
+	newRoute := *r
+	return &newRoute
+}
+
+func (r *Route) convertTo040() *types.Route {
+	return &types.Route{
+		Dst: net.IPNet(types.IPNet(r.Dst)),
+		GW:  r.GW,
+	}
+}
+
+func convertRouteFrom040(from *types.Route) *Route {
+	return &Route{
+		Dst: from.Dst,
+		GW:  from.GW,
+	}
+}
+
+// JSON (un)marshallable types
+type route struct {
+	Dst types.IPNet `json:"dst"`
+	GW  net.IP      `json:"gw,omitempty"`
+	MTU int         `json:"mtu,omitempty"`
+}
+
+func (r *Route) MarshalJSON() ([]byte, error) {
+	rt := route{
+		Dst: types.IPNet(r.Dst),
+		GW:  r.GW,
+		MTU: r.MTU,
+	}
+
+	return json.Marshal(rt)
+}

pkg/types/100/types_test.go

@@ -68,9 +68,9 @@ func testResult() *current.Result {
 				Gateway:   net.ParseIP("abcd:1234:ffff::1"),
 			},
 		},
-		Routes: []*types.Route{
-			{Dst: *routev4, GW: routegwv4},
-			{Dst: *routev6, GW: routegwv6},
+		Routes: []*current.Route{
+			{Dst: *routev4, GW: routegwv4, MTU: 1024},
+			{Dst: *routev6, GW: routegwv6, MTU: 1024},
 		},
 		DNS: types.DNS{
 			Nameservers: []string{"1.2.3.4", "1::cafe"},
@@ -124,11 +124,13 @@ var _ = Describe("Current types operations", func() {
     "routes": [
         {
             "dst": "15.5.6.0/24",
-            "gw": "15.5.6.8"
+            "gw": "15.5.6.8",
+			"mtu": 1024
         },
         {
             "dst": "1111:dddd::/80",
-            "gw": "1111:dddd::aaaa"
+            "gw": "1111:dddd::aaaa",
+			"mtu": 1024
         }
     ],
     "dns": {

pkg/types/types_test.go

@@ -87,14 +87,15 @@ var _ = Describe("Types", func() {
 					IP:   net.ParseIP("1.2.3.0"),
 					Mask: net.CIDRMask(24, 32),
 				},
-				GW: net.ParseIP("1.2.3.1"),
+				GW:  net.ParseIP("1.2.3.1"),
+				MTU: 1024,
 			}
 		})
 
 		It("marshals and unmarshals to JSON", func() {
 			jsonBytes, err := json.Marshal(example)
 			Expect(err).NotTo(HaveOccurred())
-			Expect(jsonBytes).To(MatchJSON(`{ "dst": "1.2.3.0/24", "gw": "1.2.3.1" }`))
+			Expect(jsonBytes).To(MatchJSON(`{ "dst": "1.2.3.0/24", "gw": "1.2.3.1", "mtu": 1024 }`))
 
 			var unmarshaled types.Route
 			Expect(json.Unmarshal(jsonBytes, &unmarshaled)).To(Succeed())
@@ -104,13 +105,13 @@ var _ = Describe("Types", func() {
 		Context("when the json data is not valid", func() {
 			Specify("UnmarshalJSON returns an error", func() {
 				route := new(types.Route)
-				err := route.UnmarshalJSON([]byte(`{ "dst": "1.2.3.0/24", "gw": "1.2.3.x" }`))
+				err := route.UnmarshalJSON([]byte(`{ "dst": "1.2.3.0/24", "gw": "1.2.3.x", "mtu": 1024 }`))
 				Expect(err).To(MatchError("invalid IP address: 1.2.3.x"))
 			})
 		})
 
 		It("formats as a string with a hex mask", func() {
-			Expect(example.String()).To(Equal(`{Dst:{IP:1.2.3.0 Mask:ffffff00} GW:1.2.3.1}`))
+			Expect(example.String()).To(Equal(`{Dst:{IP:1.2.3.0 Mask:ffffff00} GW:1.2.3.1 MTU:1024}`))
 		})
 	})