feat: gitea client

vendor/cloud.google.com/go/auth/credentials/selfsignedjwt.go

@@ -0,0 +1,81 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package credentials
+
+import (
+	"context"
+	"crypto/rsa"
+	"fmt"
+	"strings"
+	"time"
+
+	"cloud.google.com/go/auth"
+	"cloud.google.com/go/auth/internal"
+	"cloud.google.com/go/auth/internal/credsfile"
+	"cloud.google.com/go/auth/internal/jwt"
+)
+
+var (
+	// for testing
+	now func() time.Time = time.Now
+)
+
+// configureSelfSignedJWT uses the private key in the service account to create
+// a JWT without making a network call.
+func configureSelfSignedJWT(f *credsfile.ServiceAccountFile, opts *DetectOptions) (auth.TokenProvider, error) {
+	pk, err := internal.ParseKey([]byte(f.PrivateKey))
+	if err != nil {
+		return nil, fmt.Errorf("credentials: could not parse key: %w", err)
+	}
+	return &selfSignedTokenProvider{
+		email:    f.ClientEmail,
+		audience: opts.Audience,
+		scopes:   opts.scopes(),
+		pk:       pk,
+		pkID:     f.PrivateKeyID,
+	}, nil
+}
+
+type selfSignedTokenProvider struct {
+	email    string
+	audience string
+	scopes   []string
+	pk       *rsa.PrivateKey
+	pkID     string
+}
+
+func (tp *selfSignedTokenProvider) Token(context.Context) (*auth.Token, error) {
+	iat := now()
+	exp := iat.Add(time.Hour)
+	scope := strings.Join(tp.scopes, " ")
+	c := &jwt.Claims{
+		Iss:   tp.email,
+		Sub:   tp.email,
+		Aud:   tp.audience,
+		Scope: scope,
+		Iat:   iat.Unix(),
+		Exp:   exp.Unix(),
+	}
+	h := &jwt.Header{
+		Algorithm: jwt.HeaderAlgRSA256,
+		Type:      jwt.HeaderType,
+		KeyID:     string(tp.pkID),
+	}
+	msg, err := jwt.EncodeJWS(h, c, tp.pk)
+	if err != nil {
+		return nil, fmt.Errorf("credentials: could not encode JWT: %w", err)
+	}
+	return &auth.Token{Value: msg, Type: internal.TokenTypeBearer, Expiry: exp}, nil
+}