api: refactor attestationconfigapi client/fetcher

There is now one SEVSNPVersions type that has a variant
property. That property is used to build the correct JSON
path. The surrounding methods handling the version objects
are also updated to receive a variant argument and work
for multiple variants. This simplifies adding AWS support.

internal/api/attestationconfigapi/snp.go

@@ -0,0 +1,113 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package attestationconfigapi
+
+import (
+	"encoding/json"
+	"fmt"
+	"path"
+	"sort"
+	"strings"
+
+	"github.com/edgelesssys/constellation/v2/internal/attestation/variant"
+)
+
+// attestationURLPath is the URL path to the attestation versions.
+const attestationURLPath = "constellation/v1/attestation"
+
+// SEVSNPVersion tracks the latest version of each component of the Azure SEVSNP.
+type SEVSNPVersion struct {
+	// Bootloader is the latest version of the Azure SEVSNP bootloader.
+	Bootloader uint8 `json:"bootloader"`
+	// TEE is the latest version of the Azure SEVSNP TEE.
+	TEE uint8 `json:"tee"`
+	// SNP is the latest version of the Azure SEVSNP SNP.
+	SNP uint8 `json:"snp"`
+	// Microcode is the latest version of the Azure SEVSNP microcode.
+	Microcode uint8 `json:"microcode"`
+}
+
+// SEVSNPVersionAPI is the request to get the version information of the specific version in the config api.
+// Because variant is not part of the marshalled JSON, fetcher and client methods need to fill the variant property.
+// Once we switch to v2 of the API we should embed the variant in the object.
+// That would remove the possibility of some fetcher/client code forgetting to set the variant.
+type SEVSNPVersionAPI struct {
+	Version string          `json:"-"`
+	Variant variant.Variant `json:"-"`
+	SEVSNPVersion
+}
+
+// JSONPath returns the path to the JSON file for the request to the config api.
+func (i SEVSNPVersionAPI) JSONPath() string {
+	return path.Join(attestationURLPath, i.Variant.String(), i.Version)
+}
+
+// ValidateRequest validates the request.
+func (i SEVSNPVersionAPI) ValidateRequest() error {
+	if !strings.HasSuffix(i.Version, ".json") {
+		return fmt.Errorf("version has no .json suffix")
+	}
+	return nil
+}
+
+// Validate is a No-Op at the moment.
+func (i SEVSNPVersionAPI) Validate() error {
+	return nil
+}
+
+// SEVSNPVersionList is the request to list all versions in the config api.
+// Because variant is not part of the marshalled JSON, fetcher and client methods need to fill the variant property.
+// Once we switch to v2 of the API we could embed the variant in the object and remove some code from fetcher & client.
+// That would remove the possibility of some fetcher/client code forgetting to set the variant.
+type SEVSNPVersionList struct {
+	variant variant.Variant
+	list    []string
+}
+
+// MarshalJSON marshals the i's list property to JSON.
+func (i SEVSNPVersionList) MarshalJSON() ([]byte, error) {
+	return json.Marshal(i.list)
+}
+
+// UnmarshalJSON unmarshals a list of strings into i's list property.
+func (i *SEVSNPVersionList) UnmarshalJSON(data []byte) error {
+	return json.Unmarshal(data, &i.list)
+}
+
+// List returns i's list property.
+func (i SEVSNPVersionList) List() []string { return i.list }
+
+// JSONPath returns the path to the JSON file for the request to the config api.
+func (i SEVSNPVersionList) JSONPath() string {
+	return path.Join(attestationURLPath, i.variant.String(), "list")
+}
+
+// ValidateRequest is a NoOp as there is no input.
+func (i SEVSNPVersionList) ValidateRequest() error {
+	return nil
+}
+
+// SortReverse sorts the list of versions in reverse order.
+func (i *SEVSNPVersionList) SortReverse() {
+	sort.Sort(sort.Reverse(sort.StringSlice(i.list)))
+}
+
+// addVersion adds new to i's list and sorts the element in descending order.
+func (i *SEVSNPVersionList) addVersion(new string) {
+	i.list = append(i.list, new)
+	i.list = variant.RemoveDuplicate(i.list)
+
+	i.SortReverse()
+}
+
+// Validate validates the response.
+func (i SEVSNPVersionList) Validate() error {
+	if len(i.list) < 1 {
+		return fmt.Errorf("no versions found in /list")
+	}
+	return nil
+}