state, filter: Do not panic on interpretation of ifaces names

In scenarios where an interface name is composed of numbers in
scientific notation without a dot, the application panics with a failure
to extract a string type from a Go interface (which is actually a float64).

In order to fix the problem, the parsing of the interface name is performed
using a dedicated interface-state structure.

Note: this change does not solve the problem of incorrectly representing
valid scientific numeric values like `10e+02` as strings (they are now
represented back as full integers: "1000").
This is due to the YAML-to-JSON conversion which does not obey to
the defined member type.

ref: yaml/pyyaml#173

Signed-off-by: Edward Haas <edwardh@redhat.com>

pkg/state/filter.go

@@ -73,12 +73,11 @@ func filterOutDynamicAttributes(iface map[string]interface{}) {
 	delete(options, "hello-timer")
 }
 
-func filterOutInterfaces(ifaces []interface{}, interfacesFilterGlob glob.Glob) []interface{} {
-	filteredInterfaces := []interface{}{}
-	for _, iface := range ifaces {
-		name := iface.(map[string]interface{})["name"]
-		if !interfacesFilterGlob.Match(name.(string)) {
-			filterOutDynamicAttributes(iface.(map[string]interface{}))
+func filterOutInterfaces(ifacesState []interfaceState, interfacesFilterGlob glob.Glob) []interfaceState {
+	filteredInterfaces := []interfaceState{}
+	for _, iface := range ifacesState {
+		if !interfacesFilterGlob.Match(iface.Name) {
+			filterOutDynamicAttributes(iface.Data)
 			filteredInterfaces = append(filteredInterfaces, iface)
 		}
 	}
@@ -87,8 +86,7 @@ func filterOutInterfaces(ifaces []interface{}, interfacesFilterGlob glob.Glob) [
 
 func filterOut(currentState shared.State, interfacesFilterGlob glob.Glob) (shared.State, error) {
 	var state rootState
-	err := yaml.Unmarshal(currentState.Raw, &state)
-	if err != nil {
+	if err := yaml.Unmarshal(currentState.Raw, &state); err != nil {
 		return currentState, err
 	}
 

pkg/state/filter_test.go

@@ -359,4 +359,29 @@ interfaces:
 			Expect(returnedState).To(MatchYAML(filteredState))
 		})
 	})
+
+	// See https://github.com/yaml/pyyaml/issues/173 for why this scenario is checked.
+	Context("when the interfaces names have numbers in scientific notation without dot", func() {
+		BeforeEach(func() {
+			state = nmstate.NewState(`
+interfaces:
+- name: eth0
+- name: 10e+02
+- name: 60e+02
+`)
+			filteredState = nmstate.NewState(`
+interfaces:
+- name: eth0
+- name: "1000"
+- name: "6000"
+`)
+			interfacesFilterGlob = glob.MustCompile("10e*")
+		})
+
+		It("does not filter out interfaces correctly and does not represent them correctly", func() {
+			returnedState, err := filterOut(state, interfacesFilterGlob)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(returnedState).To(MatchYAML(filteredState))
+		})
+	})
 })

pkg/state/type.go

@@ -1,11 +1,47 @@
 package state
 
+import (
+	"encoding/json"
+	"fmt"
+
+	"sigs.k8s.io/yaml"
+)
+
 type rootState struct {
-	Interfaces []interface{} `json:"interfaces"`
-	Routes     *routesState  `json:"routes,omitempty"`
+	Interfaces []interfaceState `json:"interfaces"`
+	Routes     *routesState     `json:"routes,omitempty"`
 }
 
 type routesState struct {
 	Config  []interface{} `json:"config"`
 	Running []interface{} `json:"running"`
 }
+
+type interfaceState struct {
+	interfaceFields
+	Data map[string]interface{}
+}
+
+// interfaceFields allows unmarshaling directly into the defined fields
+type interfaceFields struct {
+	Name string `json:"name"`
+}
+
+func (i interfaceState) MarshalJSON() (output []byte, err error) {
+	i.Data["name"] = i.Name
+	return json.Marshal(i.Data)
+}
+
+func (i *interfaceState) UnmarshalJSON(b []byte) error {
+	if err := yaml.Unmarshal(b, &i.Data); err != nil {
+		return fmt.Errorf("failed Unmarshaling b: %w", err)
+	}
+
+	var ifaceFields interfaceFields
+	if err := yaml.Unmarshal(b, &ifaceFields); err != nil {
+		return fmt.Errorf("failed Unmarshaling raw: %w", err)
+	}
+	i.Data["name"] = ifaceFields.Name
+	i.Name = ifaceFields.Name
+	return nil
+}