Add sso token provider

CHANGELOG_PENDING.md

@@ -3,3 +3,5 @@
 ### SDK Enhancements
 
 ### SDK Bugs
+* `aws/credentials/ssocreds`: Implement SSO token provider to support for `sso-session` in AWS shared config.
+  * Fixes [4649](https://github.com/aws/aws-sdk-go/issues/4649)

aws/auth/bearer/token.go

@@ -0,0 +1,49 @@
+package bearer
+
+import (
+	"github.com/aws/aws-sdk-go/aws"
+	"time"
+)
+
+type Token struct {
+	Value string
+
+	CanExpire bool
+	Expires   time.Time
+}
+
+// Expired returns if the token's Expires time is before or equal to the time
+// provided. If CanExpires is false, Expired will always return false.
+func (t Token) Expired(now time.Time) bool {
+	if !t.CanExpire {
+		return false
+	}
+	now = now.Round(0)
+	return now.Equal(t.Expires) || now.After(t.Expires)
+}
+
+// TokenProvider provides interface for retrieving bearer tokens.
+type TokenProvider interface {
+	RetrieveBearerToken(aws.Context) (Token, error)
+}
+
+// TokenProviderFunc provides a helper utility to wrap a function as a type
+// that implements the TokenProvider interface.
+type TokenProviderFunc func(aws.Context) (Token, error)
+
+// RetrieveBearerToken calls the wrapped function, returning the Token or
+// error.
+func (fn TokenProviderFunc) RetrieveBearerToken(ctx aws.Context) (Token, error) {
+	return fn(ctx)
+}
+
+// StaticTokenProvider provides a utility for wrapping a static bearer token
+// value within an implementation of a token provider.
+type StaticTokenProvider struct {
+	Token Token
+}
+
+// RetrieveBearerToken returns the static token specified.
+func (s StaticTokenProvider) RetrieveBearerToken(aws.Context) (Token, error) {
+	return s.Token, nil
+}

aws/credentials/ssocreds/provider.go

@@ -4,7 +4,6 @@ import (
 	"crypto/sha1"
 	"encoding/hex"
 	"encoding/json"
-	"fmt"
 	"io/ioutil"
 	"path/filepath"
 	"strings"
@@ -123,25 +122,6 @@ func getCacheFileName(url string) (string, error) {
 	return strings.ToLower(hex.EncodeToString(hash.Sum(nil))) + ".json", nil
 }
 
-type rfc3339 time.Time
-
-func (r *rfc3339) UnmarshalJSON(bytes []byte) error {
-	var value string
-
-	if err := json.Unmarshal(bytes, &value); err != nil {
-		return err
-	}
-
-	parse, err := time.Parse(time.RFC3339, value)
-	if err != nil {
-		return fmt.Errorf("expected RFC3339 timestamp: %v", err)
-	}
-
-	*r = rfc3339(parse)
-
-	return nil
-}
-
 type token struct {
 	AccessToken string  `json:"accessToken"`
 	ExpiresAt   rfc3339 `json:"expiresAt"`

aws/credentials/ssocreds/sso_cached_token.go

@@ -0,0 +1,229 @@
+package ssocreds
+
+import (
+	"crypto/sha1"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"github.com/aws/aws-sdk-go/internal/shareddefaults"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var resolvedOsUserHomeDir = shareddefaults.UserHomeDir
+
+// StandardCachedTokenFilepath returns the filepath for the cached SSO token file, or
+// error if unable get derive the path. Key that will be used to compute a SHA1
+// value that is hex encoded.
+//
+// Derives the filepath using the Key as:
+//
+//	~/.aws/sso/cache/<sha1-hex-encoded-key>.json
+func StandardCachedTokenFilepath(key string) (string, error) {
+	homeDir := resolvedOsUserHomeDir()
+	if len(homeDir) == 0 {
+		return "", fmt.Errorf("unable to get USER's home directory for cached token")
+	}
+	hash := sha1.New()
+	if _, err := hash.Write([]byte(key)); err != nil {
+		return "", fmt.Errorf("unable to compute cached token filepath key SHA1 hash, %v", err)
+	}
+
+	cacheFilename := strings.ToLower(hex.EncodeToString(hash.Sum(nil))) + ".json"
+
+	return filepath.Join(homeDir, ".aws", "sso", "cache", cacheFilename), nil
+}
+
+type tokenKnownFields struct {
+	AccessToken string   `json:"accessToken,omitempty"`
+	ExpiresAt   *rfc3339 `json:"expiresAt,omitempty"`
+
+	RefreshToken string `json:"refreshToken,omitempty"`
+	ClientID     string `json:"clientId,omitempty"`
+	ClientSecret string `json:"clientSecret,omitempty"`
+}
+
+type cachedToken struct {
+	tokenKnownFields
+	UnknownFields map[string]interface{} `json:"-"`
+}
+
+func (t cachedToken) MarshalJSON() ([]byte, error) {
+	fields := map[string]interface{}{}
+
+	setTokenFieldString(fields, "accessToken", t.AccessToken)
+	setTokenFieldRFC3339(fields, "expiresAt", t.ExpiresAt)
+
+	setTokenFieldString(fields, "refreshToken", t.RefreshToken)
+	setTokenFieldString(fields, "clientId", t.ClientID)
+	setTokenFieldString(fields, "clientSecret", t.ClientSecret)
+
+	for k, v := range t.UnknownFields {
+		if _, ok := fields[k]; ok {
+			return nil, fmt.Errorf("unknown token field %v, duplicates known field", k)
+		}
+		fields[k] = v
+	}
+
+	return json.Marshal(fields)
+}
+
+func setTokenFieldString(fields map[string]interface{}, key, value string) {
+	if value == "" {
+		return
+	}
+	fields[key] = value
+}
+func setTokenFieldRFC3339(fields map[string]interface{}, key string, value *rfc3339) {
+	if value == nil {
+		return
+	}
+	fields[key] = value
+}
+
+func (t *cachedToken) UnmarshalJSON(b []byte) error {
+	var fields map[string]interface{}
+	if err := json.Unmarshal(b, &fields); err != nil {
+		return nil
+	}
+
+	t.UnknownFields = map[string]interface{}{}
+
+	for k, v := range fields {
+		var err error
+		switch k {
+		case "accessToken":
+			err = getTokenFieldString(v, &t.AccessToken)
+		case "expiresAt":
+			err = getTokenFieldRFC3339(v, &t.ExpiresAt)
+		case "refreshToken":
+			err = getTokenFieldString(v, &t.RefreshToken)
+		case "clientId":
+			err = getTokenFieldString(v, &t.ClientID)
+		case "clientSecret":
+			err = getTokenFieldString(v, &t.ClientSecret)
+		default:
+			t.UnknownFields[k] = v
+		}
+
+		if err != nil {
+			return fmt.Errorf("field %q, %v", k, err)
+		}
+	}
+
+	return nil
+}
+
+func getTokenFieldString(v interface{}, value *string) error {
+	var ok bool
+	*value, ok = v.(string)
+	if !ok {
+		return fmt.Errorf("expect value to be string, got %T", v)
+	}
+	return nil
+}
+
+func getTokenFieldRFC3339(v interface{}, value **rfc3339) error {
+	var stringValue string
+	if err := getTokenFieldString(v, &stringValue); err != nil {
+		return err
+	}
+
+	timeValue, err := parseRFC3339(stringValue)
+	if err != nil {
+		return err
+	}
+
+	*value = &timeValue
+	return nil
+}
+
+func loadCachedToken(filename string) (cachedToken, error) {
+	fileBytes, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return cachedToken{}, fmt.Errorf("failed to read cached SSO token file, %v", err)
+	}
+
+	var t cachedToken
+	if err := json.Unmarshal(fileBytes, &t); err != nil {
+		return cachedToken{}, fmt.Errorf("failed to parse cached SSO token file, %v", err)
+	}
+
+	if len(t.AccessToken) == 0 || t.ExpiresAt == nil || time.Time(*t.ExpiresAt).IsZero() {
+		return cachedToken{}, fmt.Errorf(
+			"cached SSO token must contain accessToken and expiresAt fields")
+	}
+
+	return t, nil
+}
+
+func storeCachedToken(filename string, t cachedToken, fileMode os.FileMode) (err error) {
+	tmpFilename := filename + ".tmp-" + strconv.FormatInt(nowTime().UnixNano(), 10)
+	if err := writeCacheFile(tmpFilename, fileMode, t); err != nil {
+		return err
+	}
+
+	if err := os.Rename(tmpFilename, filename); err != nil {
+		return fmt.Errorf("failed to replace old cached SSO token file, %v", err)
+	}
+
+	return nil
+}
+
+func writeCacheFile(filename string, fileMode os.FileMode, t cachedToken) (err error) {
+	var f *os.File
+	f, err = os.OpenFile(filename, os.O_CREATE|os.O_TRUNC|os.O_RDWR, fileMode)
+	if err != nil {
+		return fmt.Errorf("failed to create cached SSO token file %v", err)
+	}
+
+	defer func() {
+		closeErr := f.Close()
+		if err == nil && closeErr != nil {
+			err = fmt.Errorf("failed to close cached SSO token file, %v", closeErr)
+		}
+	}()
+
+	encoder := json.NewEncoder(f)
+
+	if err = encoder.Encode(t); err != nil {
+		return fmt.Errorf("failed to serialize cached SSO token, %v", err)
+	}
+
+	return nil
+}
+
+type rfc3339 time.Time
+
+func (r *rfc3339) UnmarshalJSON(bytes []byte) error {
+	var value string
+	var err error
+
+	if err = json.Unmarshal(bytes, &value); err != nil {
+		return err
+	}
+
+	*r, err = parseRFC3339(value)
+	return err
+}
+
+func parseRFC3339(v string) (rfc3339, error) {
+	parsed, err := time.Parse(time.RFC3339, v)
+	if err != nil {
+		return rfc3339{}, fmt.Errorf("expected RFC3339 timestamp: %v", err)
+	}
+
+	return rfc3339(parsed), nil
+}
+
+func (r *rfc3339) MarshalJSON() ([]byte, error) {
+	value := time.Time(*r).Format(time.RFC3339)
+
+	// Use JSON unmarshal to unescape the quoted value making use of JSON's
+	// quoting rules.
+	return json.Marshal(value)
+}