Add webpush-go dependency

go.mod

@@ -65,6 +65,7 @@ require (
 	github.com/ncruces/go-sqlite3 v0.20.3
 	github.com/oklog/ulid v1.3.1
 	github.com/prometheus/client_golang v1.20.5
+	github.com/SherClockHolmes/webpush-go v1.3.0
 	github.com/spf13/cobra v1.8.1
 	github.com/spf13/viper v1.19.0
 	github.com/stretchr/testify v1.10.0

go.sum

@@ -88,6 +88,8 @@ github.com/Masterminds/semver/v3 v3.2.1 h1:RN9w6+7QoMeJVGyfmbcgs28Br8cvmnucEXnY0
 github.com/Masterminds/semver/v3 v3.2.1/go.mod h1:qvl/7zhW3nngYb5+80sSMF+FG2BjYrf8m9wsX0PNOMQ=
 github.com/Masterminds/sprig/v3 v3.2.3 h1:eL2fZNezLomi0uOLqjQoN6BfsDD+fyLtgbJMAj9n6YA=
 github.com/Masterminds/sprig/v3 v3.2.3/go.mod h1:rXcFaZ2zZbLRJv/xSysmlgIM1u11eBaRMhvYXJNkGuM=
+github.com/SherClockHolmes/webpush-go v1.3.0 h1:CAu3FvEE9QS4drc3iKNgpBWFfGqNthKlZhp5QpYnu6k=
+github.com/SherClockHolmes/webpush-go v1.3.0/go.mod h1:AxRHmJuYwKGG1PVgYzToik1lphQvDnqFYDqimHvwhIw=
 github.com/ajg/form v1.5.1 h1:t9c7v8JUKu/XxOGBU0yjNpaMloxGEJhUkqFRq0ibGeU=
 github.com/ajg/form v1.5.1/go.mod h1:uL1WgH+h2mgNtvBq0339dVnzXdBETtL2LeUXaIv25UY=
 github.com/andybalholm/brotli v1.0.0/go.mod h1:loMXtMfwqflxFJPmdbJO0a3KNoPuLBgiu3qAvBg8x/Y=
@@ -675,6 +677,7 @@ golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.3.0/go.mod h1:hebNnKkNXi2UzZN1eVRvBB7co0a+JxK6XbPiWVs/3J4=
+golang.org/x/crypto v0.9.0/go.mod h1:yrmDGqONDYtNj3tH8X9dzUun2m2lzPa9ngI6/RUPGR0=
 golang.org/x/crypto v0.29.0 h1:L5SG1JTTXupVV3n6sUqMTeWbjAyfPwoda2DLX8J8FrQ=
 golang.org/x/crypto v0.29.0/go.mod h1:+F4F4N5hv6v38hfeYwTdx20oUvLLc+QfrE9Ax9HtgRg=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
@@ -712,6 +715,7 @@ golang.org/x/mod v0.1.1-0.20191107180719-034126e5016b/go.mod h1:QqPTAvyqsEbceGzB
 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/mod v0.18.0 h1:5+9lSbEzPSdWkH32vYPBwEpX8KwDbM52Ud9xBUvNlb0=
 golang.org/x/mod v0.18.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -746,6 +750,8 @@ golang.org/x/net v0.0.0-20200822124328-c89045814202/go.mod h1:/O7V0waA8r7cgGh81R
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
 golang.org/x/net v0.2.0/go.mod h1:KqCZLdyyvdV855qA2rE3GC2aiw5xGR5TEjj8smXukLY=
+golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
+golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
 golang.org/x/net v0.31.0 h1:68CPQngjLL0r2AlUKiSxtQFKvzRVbnzLwMUn5SzcLHo=
 golang.org/x/net v0.31.0/go.mod h1:P4fl1q7dY2hnZFxEk4pPSkDHF+QqjitcnDjUQyMM+pM=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
@@ -765,6 +771,7 @@ golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.9.0 h1:fEo0HyrW1GIgZdpbhCRO0PkJajUS5H9IFUztCgEo2jQ=
 golang.org/x/sync v0.9.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@@ -807,11 +814,14 @@ golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.27.0 h1:wBqf8DvsY9Y/2P8gAfPDEYNuS30J4lPHJxXSb/nJZ+s=
 golang.org/x/sys v0.27.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.2.0/go.mod h1:TVmDHMZPmdnySmBfhjOoOdhjzdE1h4u1VwSiw2l1Nuc=
+golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
+golang.org/x/term v0.8.0/go.mod h1:xPskH00ivmX89bAKVGSKKtLOWNx2+17Eiy94tnKShWo=
 golang.org/x/term v0.26.0 h1:WEQa6V3Gja/BhNxg540hBip/kkaYtRg3cxg4oXSw4AU=
 golang.org/x/term v0.26.0/go.mod h1:Si5m1o57C5nBNQo5z1iq+XDijt21BDBDp2bK0QI8e3E=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -821,6 +831,8 @@ golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/text v0.4.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
 golang.org/x/text v0.20.0 h1:gK/Kv2otX8gz+wn7Rmb3vT96ZwuoxnQlY+HlJVj7Qug=
 golang.org/x/text v0.20.0/go.mod h1:D4IsuqiFMhST5bX19pQ9ikHC2GsaKyk/oF+pn3ducp4=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
@@ -868,6 +880,7 @@ golang.org/x/tools v0.0.0-20200729194436-6467de6f59a7/go.mod h1:njjCfa9FT2d7l9Bc
 golang.org/x/tools v0.0.0-20200804011535-6c149bb5ef0d/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.0.0-20200825202427-b303f430e36d/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
 golang.org/x/tools v0.22.0 h1:gqSGLZqv+AI9lIQzniJ0nZDRG5GBPsSi+DRNHWNz6yA=
 golang.org/x/tools v0.22.0/go.mod h1:aCwcsjqvq7Yqt6TNyX7QMU2enbQ/Gt0bo6krSeEri+c=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

vendor/github.com/SherClockHolmes/webpush-go/.gitignore

@@ -0,0 +1,4 @@
+vendor/**
+
+.DS_Store
+*.out

vendor/github.com/SherClockHolmes/webpush-go/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2016 Ethan Holmes
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/SherClockHolmes/webpush-go/README.md

@@ -0,0 +1,63 @@
+# webpush-go
+
+[![Go Report Card](https://goreportcard.com/badge/github.com/SherClockHolmes/webpush-go)](https://goreportcard.com/report/github.com/SherClockHolmes/webpush-go)
+[![GoDoc](https://godoc.org/github.com/SherClockHolmes/webpush-go?status.svg)](https://godoc.org/github.com/SherClockHolmes/webpush-go)
+
+Web Push API Encryption with VAPID support.
+
+```bash
+go get -u github.com/SherClockHolmes/webpush-go
+```
+
+## Example
+
+For a full example, refer to the code in the [example](example/) directory.
+
+```go
+package main
+
+import (
+	"encoding/json"
+
+	webpush "github.com/SherClockHolmes/webpush-go"
+)
+
+func main() {
+	// Decode subscription
+	s := &webpush.Subscription{}
+	json.Unmarshal([]byte("<YOUR_SUBSCRIPTION>"), s)
+
+	// Send Notification
+	resp, err := webpush.SendNotification([]byte("Test"), s, &webpush.Options{
+		Subscriber:      "example@example.com",
+		VAPIDPublicKey:  "<YOUR_VAPID_PUBLIC_KEY>",
+		VAPIDPrivateKey: "<YOUR_VAPID_PRIVATE_KEY>",
+		TTL:             30,
+	})
+	if err != nil {
+		// TODO: Handle error
+	}
+	defer resp.Body.Close()
+}
+```
+
+### Generating VAPID Keys
+
+Use the helper method `GenerateVAPIDKeys` to generate the VAPID key pair.
+
+```golang
+privateKey, publicKey, err := webpush.GenerateVAPIDKeys()
+if err != nil {
+	// TODO: Handle error
+}
+```
+
+## Development
+
+1. Install [Go 1.11+](https://golang.org/)
+2. `go mod vendor`
+3. `go test`
+
+#### For other language implementations visit:
+
+[WebPush Libs](https://github.com/web-push-libs)

vendor/github.com/SherClockHolmes/webpush-go/urgency.go

@@ -0,0 +1,26 @@
+package webpush
+
+// Urgency indicates to the push service how important a message is to the user.
+// This can be used by the push service to help conserve the battery life of a user's device
+// by only waking up for important messages when battery is low.
+type Urgency string
+
+const (
+	// UrgencyVeryLow requires device state: on power and Wi-Fi
+	UrgencyVeryLow Urgency = "very-low"
+	// UrgencyLow requires device state: on either power or Wi-Fi
+	UrgencyLow Urgency = "low"
+	// UrgencyNormal excludes device state: low battery
+	UrgencyNormal Urgency = "normal"
+	// UrgencyHigh admits device state: low battery
+	UrgencyHigh Urgency = "high"
+)
+
+// Checking allowable values for the urgency header
+func isValidUrgency(urgency Urgency) bool {
+	switch urgency {
+	case UrgencyVeryLow, UrgencyLow, UrgencyNormal, UrgencyHigh:
+		return true
+	}
+	return false
+}

vendor/github.com/SherClockHolmes/webpush-go/vapid.go

@@ -0,0 +1,117 @@
+package webpush
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"math/big"
+	"net/url"
+	"time"
+
+	"github.com/golang-jwt/jwt"
+)
+
+// GenerateVAPIDKeys will create a private and public VAPID key pair
+func GenerateVAPIDKeys() (privateKey, publicKey string, err error) {
+	// Get the private key from the P256 curve
+	curve := elliptic.P256()
+
+	private, x, y, err := elliptic.GenerateKey(curve, rand.Reader)
+	if err != nil {
+		return
+	}
+
+	public := elliptic.Marshal(curve, x, y)
+
+	// Convert to base64
+	publicKey = base64.RawURLEncoding.EncodeToString(public)
+	privateKey = base64.RawURLEncoding.EncodeToString(private)
+
+	return
+}
+
+// Generates the ECDSA public and private keys for the JWT encryption
+func generateVAPIDHeaderKeys(privateKey []byte) *ecdsa.PrivateKey {
+	// Public key
+	curve := elliptic.P256()
+	px, py := curve.ScalarMult(
+		curve.Params().Gx,
+		curve.Params().Gy,
+		privateKey,
+	)
+
+	pubKey := ecdsa.PublicKey{
+		Curve: curve,
+		X:     px,
+		Y:     py,
+	}
+
+	// Private key
+	d := &big.Int{}
+	d.SetBytes(privateKey)
+
+	return &ecdsa.PrivateKey{
+		PublicKey: pubKey,
+		D:         d,
+	}
+}
+
+// getVAPIDAuthorizationHeader
+func getVAPIDAuthorizationHeader(
+	endpoint,
+	subscriber,
+	vapidPublicKey,
+	vapidPrivateKey string,
+	expiration time.Time,
+) (string, error) {
+	// Create the JWT token
+	subURL, err := url.Parse(endpoint)
+	if err != nil {
+		return "", err
+	}
+
+	token := jwt.NewWithClaims(jwt.SigningMethodES256, jwt.MapClaims{
+		"aud": fmt.Sprintf("%s://%s", subURL.Scheme, subURL.Host),
+		"exp": expiration.Unix(),
+		"sub": fmt.Sprintf("mailto:%s", subscriber),
+	})
+
+	// Decode the VAPID private key
+	decodedVapidPrivateKey, err := decodeVapidKey(vapidPrivateKey)
+	if err != nil {
+		return "", err
+	}
+
+	privKey := generateVAPIDHeaderKeys(decodedVapidPrivateKey)
+
+	// Sign token with private key
+	jwtString, err := token.SignedString(privKey)
+	if err != nil {
+		return "", err
+	}
+
+	// Decode the VAPID public key
+	pubKey, err := decodeVapidKey(vapidPublicKey)
+	if err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf(
+		"vapid t=%s, k=%s",
+		jwtString,
+		base64.RawURLEncoding.EncodeToString(pubKey),
+	), nil
+}
+
+// Need to decode the vapid private key in multiple base64 formats
+// Solution from: https://github.com/SherClockHolmes/webpush-go/issues/29
+func decodeVapidKey(key string) ([]byte, error) {
+	bytes, err := base64.URLEncoding.DecodeString(key)
+	if err == nil {
+		return bytes, nil
+	}
+
+	return base64.RawURLEncoding.DecodeString(key)
+}

vendor/github.com/SherClockHolmes/webpush-go/webpush.go

@@ -0,0 +1,287 @@
+package webpush
+
+import (
+	"bytes"
+	"context"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/binary"
+	"errors"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"golang.org/x/crypto/hkdf"
+)
+
+const MaxRecordSize uint32 = 4096
+
+var ErrMaxPadExceeded = errors.New("payload has exceeded the maximum length")
+
+// saltFunc generates a salt of 16 bytes
+var saltFunc = func() ([]byte, error) {
+	salt := make([]byte, 16)
+	_, err := io.ReadFull(rand.Reader, salt)
+	if err != nil {
+		return salt, err
+	}
+
+	return salt, nil
+}
+
+// HTTPClient is an interface for sending the notification HTTP request / testing
+type HTTPClient interface {
+	Do(*http.Request) (*http.Response, error)
+}
+
+// Options are config and extra params needed to send a notification
+type Options struct {
+	HTTPClient      HTTPClient // Will replace with *http.Client by default if not included
+	RecordSize      uint32     // Limit the record size
+	Subscriber      string     // Sub in VAPID JWT token
+	Topic           string     // Set the Topic header to collapse a pending messages (Optional)
+	TTL             int        // Set the TTL on the endpoint POST request
+	Urgency         Urgency    // Set the Urgency header to change a message priority (Optional)
+	VAPIDPublicKey  string     // VAPID public key, passed in VAPID Authorization header
+	VAPIDPrivateKey string     // VAPID private key, used to sign VAPID JWT token
+	VapidExpiration time.Time  // optional expiration for VAPID JWT token (defaults to now + 12 hours)
+}
+
+// Keys are the base64 encoded values from PushSubscription.getKey()
+type Keys struct {
+	Auth   string `json:"auth"`
+	P256dh string `json:"p256dh"`
+}
+
+// Subscription represents a PushSubscription object from the Push API
+type Subscription struct {
+	Endpoint string `json:"endpoint"`
+	Keys     Keys   `json:"keys"`
+}
+
+// SendNotification calls SendNotificationWithContext with default context for backwards-compatibility
+func SendNotification(message []byte, s *Subscription, options *Options) (*http.Response, error) {
+	return SendNotificationWithContext(context.Background(), message, s, options)
+}
+
+// SendNotificationWithContext sends a push notification to a subscription's endpoint
+// Message Encryption for Web Push, and VAPID protocols.
+// FOR MORE INFORMATION SEE RFC8291: https://datatracker.ietf.org/doc/rfc8291
+func SendNotificationWithContext(ctx context.Context, message []byte, s *Subscription, options *Options) (*http.Response, error) {
+	// Authentication secret (auth_secret)
+	authSecret, err := decodeSubscriptionKey(s.Keys.Auth)
+	if err != nil {
+		return nil, err
+	}
+
+	// dh (Diffie Hellman)
+	dh, err := decodeSubscriptionKey(s.Keys.P256dh)
+	if err != nil {
+		return nil, err
+	}
+
+	// Generate 16 byte salt
+	salt, err := saltFunc()
+	if err != nil {
+		return nil, err
+	}
+
+	// Create the ecdh_secret shared key pair
+	curve := elliptic.P256()
+
+	// Application server key pairs (single use)
+	localPrivateKey, x, y, err := elliptic.GenerateKey(curve, rand.Reader)
+	if err != nil {
+		return nil, err
+	}
+
+	localPublicKey := elliptic.Marshal(curve, x, y)
+
+	// Combine application keys with receiver's EC public key
+	sharedX, sharedY := elliptic.Unmarshal(curve, dh)
+	if sharedX == nil {
+		return nil, errors.New("Unmarshal Error: Public key is not a valid point on the curve")
+	}
+
+	// Derive ECDH shared secret
+	sx, sy := curve.ScalarMult(sharedX, sharedY, localPrivateKey)
+	if !curve.IsOnCurve(sx, sy) {
+		return nil, errors.New("Encryption error: ECDH shared secret isn't on curve")
+	}
+	mlen := curve.Params().BitSize / 8
+	sharedECDHSecret := make([]byte, mlen)
+	sx.FillBytes(sharedECDHSecret)
+
+	hash := sha256.New
+
+	// ikm
+	prkInfoBuf := bytes.NewBuffer([]byte("WebPush: info\x00"))
+	prkInfoBuf.Write(dh)
+	prkInfoBuf.Write(localPublicKey)
+
+	prkHKDF := hkdf.New(hash, sharedECDHSecret, authSecret, prkInfoBuf.Bytes())
+	ikm, err := getHKDFKey(prkHKDF, 32)
+	if err != nil {
+		return nil, err
+	}
+
+	// Derive Content Encryption Key
+	contentEncryptionKeyInfo := []byte("Content-Encoding: aes128gcm\x00")
+	contentHKDF := hkdf.New(hash, ikm, salt, contentEncryptionKeyInfo)
+	contentEncryptionKey, err := getHKDFKey(contentHKDF, 16)
+	if err != nil {
+		return nil, err
+	}
+
+	// Derive the Nonce
+	nonceInfo := []byte("Content-Encoding: nonce\x00")
+	nonceHKDF := hkdf.New(hash, ikm, salt, nonceInfo)
+	nonce, err := getHKDFKey(nonceHKDF, 12)
+	if err != nil {
+		return nil, err
+	}
+
+	// Cipher
+	c, err := aes.NewCipher(contentEncryptionKey)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(c)
+	if err != nil {
+		return nil, err
+	}
+
+	// Get the record size
+	recordSize := options.RecordSize
+	if recordSize == 0 {
+		recordSize = MaxRecordSize
+	}
+
+	recordLength := int(recordSize) - 16
+
+	// Encryption Content-Coding Header
+	recordBuf := bytes.NewBuffer(salt)
+
+	rs := make([]byte, 4)
+	binary.BigEndian.PutUint32(rs, recordSize)
+
+	recordBuf.Write(rs)
+	recordBuf.Write([]byte{byte(len(localPublicKey))})
+	recordBuf.Write(localPublicKey)
+
+	// Data
+	dataBuf := bytes.NewBuffer(message)
+
+	// Pad content to max record size - 16 - header
+	// Padding ending delimeter
+	dataBuf.Write([]byte("\x02"))
+	if err := pad(dataBuf, recordLength-recordBuf.Len()); err != nil {
+		return nil, err
+	}
+
+	// Compose the ciphertext
+	ciphertext := gcm.Seal([]byte{}, nonce, dataBuf.Bytes(), nil)
+	recordBuf.Write(ciphertext)
+
+	// POST request
+	req, err := http.NewRequest("POST", s.Endpoint, recordBuf)
+	if err != nil {
+		return nil, err
+	}
+
+	if ctx != nil {
+		req = req.WithContext(ctx)
+	}
+
+	req.Header.Set("Content-Encoding", "aes128gcm")
+	req.Header.Set("Content-Length", strconv.Itoa(len(ciphertext)))
+	req.Header.Set("Content-Type", "application/octet-stream")
+	req.Header.Set("TTL", strconv.Itoa(options.TTL))
+
+	// Сheck the optional headers
+	if len(options.Topic) > 0 {
+		req.Header.Set("Topic", options.Topic)
+	}
+
+	if isValidUrgency(options.Urgency) {
+		req.Header.Set("Urgency", string(options.Urgency))
+	}
+
+	expiration := options.VapidExpiration
+	if expiration.IsZero() {
+		expiration = time.Now().Add(time.Hour * 12)
+	}
+
+	// Get VAPID Authorization header
+	vapidAuthHeader, err := getVAPIDAuthorizationHeader(
+		s.Endpoint,
+		options.Subscriber,
+		options.VAPIDPublicKey,
+		options.VAPIDPrivateKey,
+		expiration,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("Authorization", vapidAuthHeader)
+
+	// Send the request
+	var client HTTPClient
+	if options.HTTPClient != nil {
+		client = options.HTTPClient
+	} else {
+		client = &http.Client{}
+	}
+
+	return client.Do(req)
+}
+
+// decodeSubscriptionKey decodes a base64 subscription key.
+// if necessary, add "=" padding to the key for URL decode
+func decodeSubscriptionKey(key string) ([]byte, error) {
+	// "=" padding
+	buf := bytes.NewBufferString(key)
+	if rem := len(key) % 4; rem != 0 {
+		buf.WriteString(strings.Repeat("=", 4-rem))
+	}
+
+	bytes, err := base64.StdEncoding.DecodeString(buf.String())
+	if err == nil {
+		return bytes, nil
+	}
+
+	return base64.URLEncoding.DecodeString(buf.String())
+}
+
+// Returns a key of length "length" given an hkdf function
+func getHKDFKey(hkdf io.Reader, length int) ([]byte, error) {
+	key := make([]byte, length)
+	n, err := io.ReadFull(hkdf, key)
+	if n != len(key) || err != nil {
+		return key, err
+	}
+
+	return key, nil
+}
+
+func pad(payload *bytes.Buffer, maxPadLen int) error {
+	payloadLen := payload.Len()
+	if payloadLen > maxPadLen {
+		return ErrMaxPadExceeded
+	}
+
+	padLen := maxPadLen - payloadLen
+
+	padding := make([]byte, padLen)
+	payload.Write(padding)
+
+	return nil
+}

vendor/golang.org/x/crypto/hkdf/hkdf.go

@@ -0,0 +1,95 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package hkdf implements the HMAC-based Extract-and-Expand Key Derivation
+// Function (HKDF) as defined in RFC 5869.
+//
+// HKDF is a cryptographic key derivation function (KDF) with the goal of
+// expanding limited input keying material into one or more cryptographically
+// strong secret keys.
+package hkdf
+
+import (
+	"crypto/hmac"
+	"errors"
+	"hash"
+	"io"
+)
+
+// Extract generates a pseudorandom key for use with Expand from an input secret
+// and an optional independent salt.
+//
+// Only use this function if you need to reuse the extracted key with multiple
+// Expand invocations and different context values. Most common scenarios,
+// including the generation of multiple keys, should use New instead.
+func Extract(hash func() hash.Hash, secret, salt []byte) []byte {
+	if salt == nil {
+		salt = make([]byte, hash().Size())
+	}
+	extractor := hmac.New(hash, salt)
+	extractor.Write(secret)
+	return extractor.Sum(nil)
+}
+
+type hkdf struct {
+	expander hash.Hash
+	size     int
+
+	info    []byte
+	counter byte
+
+	prev []byte
+	buf  []byte
+}
+
+func (f *hkdf) Read(p []byte) (int, error) {
+	// Check whether enough data can be generated
+	need := len(p)
+	remains := len(f.buf) + int(255-f.counter+1)*f.size
+	if remains < need {
+		return 0, errors.New("hkdf: entropy limit reached")
+	}
+	// Read any leftover from the buffer
+	n := copy(p, f.buf)
+	p = p[n:]
+
+	// Fill the rest of the buffer
+	for len(p) > 0 {
+		if f.counter > 1 {
+			f.expander.Reset()
+		}
+		f.expander.Write(f.prev)
+		f.expander.Write(f.info)
+		f.expander.Write([]byte{f.counter})
+		f.prev = f.expander.Sum(f.prev[:0])
+		f.counter++
+
+		// Copy the new batch into p
+		f.buf = f.prev
+		n = copy(p, f.buf)
+		p = p[n:]
+	}
+	// Save leftovers for next run
+	f.buf = f.buf[n:]
+
+	return need, nil
+}
+
+// Expand returns a Reader, from which keys can be read, using the given
+// pseudorandom key and optional context info, skipping the extraction step.
+//
+// The pseudorandomKey should have been generated by Extract, or be a uniformly
+// random or pseudorandom cryptographically strong key. See RFC 5869, Section
+// 3.3. Most common scenarios will want to use New instead.
+func Expand(hash func() hash.Hash, pseudorandomKey, info []byte) io.Reader {
+	expander := hmac.New(hash, pseudorandomKey)
+	return &hkdf{expander, expander.Size(), info, 1, nil, nil}
+}
+
+// New returns a Reader, from which keys can be read, using the given hash,
+// secret, salt and context info. Salt and info can be nil.
+func New(hash func() hash.Hash, secret, salt, info []byte) io.Reader {
+	prk := Extract(hash, secret, salt)
+	return Expand(hash, prk, info)
+}

vendor/modules.txt

@@ -84,6 +84,9 @@ github.com/Masterminds/semver/v3
 # github.com/Masterminds/sprig/v3 v3.2.3
 ## explicit; go 1.13
 github.com/Masterminds/sprig/v3
+# github.com/SherClockHolmes/webpush-go v1.3.0
+## explicit; go 1.13
+github.com/SherClockHolmes/webpush-go
 # github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2
 ## explicit; go 1.13
 github.com/asaskevich/govalidator
@@ -1081,6 +1084,7 @@ golang.org/x/crypto/blowfish
 golang.org/x/crypto/chacha20
 golang.org/x/crypto/curve25519
 golang.org/x/crypto/ed25519
+golang.org/x/crypto/hkdf
 golang.org/x/crypto/internal/alias
 golang.org/x/crypto/internal/poly1305
 golang.org/x/crypto/pbkdf2