feat: Support v2 storage and send notification for each token

README.md

@@ -58,6 +58,12 @@ where usrname='hemlock' and s.name='hemlock.push_notification_data';
 (1 row)
 ```
 
+NOTE: As of v2, the token may be a bare token or a base64url-encoded set of tokens.  If the value starts with "eyJl"
+it is likely base64url-encoded.  You can decode and pretty-print the contents with this command:
+```bash
+echo "$token" | basenc --base64url -d | jq .
+```
+
 Collecting Metrics
 ------------------
 GET /metrics

buildinfo.go

@@ -30,7 +30,10 @@ func readBuildInfo() (string, error) {
 	}
 	programName := filepath.Base(execPath)
 
-	if builtBy != "goreleaser" {
+	if builtBy == "goreleaser" {
+		commit = safeSubstr(commit, 8)
+		date = safeSubstr(date, 10)
+	} else {
 		info, ok := debug.ReadBuildInfo()
 		if !ok {
 			return "", fmt.Errorf("ReadBuildInfo failed")

go.mod

@@ -1,4 +1,4 @@
-module kenstir.net/hemlock-sendmsg
+module github.com/kenstir/hemlock-sendmsg
 
 go 1.22.2
 
@@ -8,6 +8,8 @@ require (
 	google.golang.org/api v0.170.0
 )
 
+require github.com/google/go-cmp v0.6.0
+
 require (
 	cloud.google.com/go v0.112.1 // indirect
 	cloud.google.com/go/compute v1.24.0 // indirect

sendmsg.go

@@ -2,12 +2,14 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log/slog"
 	"net/http"
 	"os"
 	"sort"
 	"strings"
+	"time"
 
 	firebase "firebase.google.com/go/v4"
 	"firebase.google.com/go/v4/errorutils"
@@ -23,6 +25,9 @@ import (
 const HemlockNotificationTypeKey = "hemlock.t"
 const HemlockNotificationUsernameKey = "hemlock.u"
 
+// Cutoff time for tokens; if a token was added before this time, we consider it expired
+const TokenExpirationCutoff = 365 * 24 * time.Hour
+
 // NB: This list of notification types (Android notification channelIds) must be kept in sync in 3 places:
 // * hemlock (android): core/src/main/java/org/evergreen_ils/data/PushNotification.kt
 // * hemlock-ios:       Source/Models/PushNotification.swift
@@ -35,49 +40,61 @@ var HemlockNotificationTypes = map[string]bool{
 	"pmc":       true,
 }
 
+var (
+	ErrEmptyToken   = fmt.Errorf("empty token")
+	ErrExpiredToken = fmt.Errorf("token too old")
+)
+
 type ServiceData struct {
 	fcmClient *messaging.Client
 
 	notificationsSent *prometheus.CounterVec
 }
 
-// categorize the result of sendMessage and record metric
-func (srv *ServiceData) trackSendMessage(token string, err error) (string, int) {
-	httpStatusCode := http.StatusOK
-	result := "ok"
-	if token == "" {
-		httpStatusCode = http.StatusBadRequest
-		result = "EmptyToken"
-	} else if err != nil {
-		httpStatusCode = http.StatusInternalServerError
-		if resp := errorutils.HTTPResponse(err); resp != nil {
-			httpStatusCode = resp.StatusCode
-		}
-		result = ""
-		if messaging.IsUnregistered(err) {
-			result = "Unregistered"
-			// should remove token from db
-		} else if errorutils.IsUnavailable(err) {
-			result = "Unavailable"
-			// should retry in an hour
-		} else if messaging.IsInternal(err) {
-			result = "InternalError"
-		} else if messaging.IsInvalidArgument(err) {
-			result = "InvalidArgument"
-		} else {
-			result = "UnknownError"
-		}
+// determine the HTTP status code for the response, and a result label for the measurement
+func (srv *ServiceData) resultAndCodeFromError(err error) (result string, httpStatusCode int) {
+	// handle local errors
+	if err == nil {
+		return "ok", http.StatusOK
+	} else if errors.Is(err, ErrEmptyToken) {
+		return "EmptyToken", http.StatusBadRequest
+	} else if errors.Is(err, ErrExpiredToken) {
+		return "ExpiredToken", http.StatusBadRequest
+	}
+
+	// it's an FCM error; use the FCM response status code if available
+	httpStatusCode = http.StatusInternalServerError
+	if resp := errorutils.HTTPResponse(err); resp != nil {
+		httpStatusCode = resp.StatusCode
+	}
+
+	// determine appropriate result label for metrics
+	if messaging.IsUnregistered(err) {
+		result = "Unregistered"
+		// should remove token from db
+	} else if errorutils.IsUnavailable(err) {
+		result = "Unavailable"
+		// should retry in an hour
+	} else if messaging.IsInternal(err) {
+		result = "InternalError"
+	} else if messaging.IsInvalidArgument(err) {
+		result = "InvalidArgument"
+	} else {
+		result = "UnknownError"
 	}
-	srv.notificationsSent.WithLabelValues(result).Inc()
 	return result, httpStatusCode
 }
 
-// send a notification
-func (srv *ServiceData) sendMessage(token string, title string, body string, notificationType string, username string) (string, string, int, error) {
-	// send the message
+// send one notification
+func (srv *ServiceData) sendMessage(entry TokenEntry, title string, body string, notificationType string, username string) (string, string, int, error) {
 	response := ""
 	var err error = nil
-	if token != "" {
+	cutoff := time.Now().UTC().Add(-TokenExpirationCutoff).Unix()
+	if entry.Token == "" {
+		err = ErrEmptyToken
+	} else if entry.AddedAt < cutoff {
+		err = ErrExpiredToken
+	} else {
 		response, err = srv.fcmClient.Send(context.Background(), &messaging.Message{
 			Data: map[string]string{
 				HemlockNotificationTypeKey:     notificationType,
@@ -92,10 +109,11 @@ func (srv *ServiceData) sendMessage(token string, title string, body string, not
 					ChannelID: notificationType,
 				},
 			},
-			Token: token,
+			Token: entry.Token,
 		})
 	}
-	result, httpStatusCode := srv.trackSendMessage(token, err)
+	result, httpStatusCode := srv.resultAndCodeFromError(err)
+	srv.notificationsSent.WithLabelValues(result).Inc()
 	return response, result, httpStatusCode, err
 }
 
@@ -122,9 +140,9 @@ func (srv *ServiceData) sendHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// token is "required", but we want to keep track of requests made without one,
-	// to count users without the mobile app
-	token := r.FormValue("token")
+	// tokenData is "required", but we don't require it because we want to track
+	// EmptyToken requests, i.e. notifications for users without the mobile app
+	tokenData := r.FormValue("token")
 
 	// should be required
 	username := r.FormValue("username")
@@ -155,16 +173,34 @@ func (srv *ServiceData) sendHandler(w http.ResponseWriter, r *http.Request) {
 		logLevel = slog.LevelInfo
 	}
 
-	// send the message
-	response, result, httpStatusCode, err := srv.sendMessage(token, title, body, notificationType, username)
-	if err != nil {
-		slog.Error("Failed to send notification", "result", result, "code", httpStatusCode, "err", err)
-		w.WriteHeader(httpStatusCode)
-		fmt.Fprintf(w, "%s\n", err.Error())
-	} else {
-		fmt.Fprintf(w, "%s\n", response)
+	// v2: handle either a single token or a JSON object with multiple tokens
+	tokenStore := NewTokenStoreFromString(tokenData)
+
+	// send a message for each token
+	var responseBody strings.Builder
+	hasError := false
+	errorStatusCode := http.StatusInternalServerError
+	for _, entry := range tokenStore.Entries {
+		response, result, httpStatusCode, err := srv.sendMessage(entry, title, body, notificationType, username)
+		if err != nil {
+			slog.Error("Failed to send notification", "result", result, "code", httpStatusCode, "err", err)
+			if !hasError {
+				hasError = true
+				errorStatusCode = httpStatusCode
+			}
+			fmt.Fprintf(&responseBody, "%s\n", err.Error())
+		} else {
+			fmt.Fprintf(&responseBody, "%s\n", response)
+		}
+		slog.Log(r.Context(), logLevel, fmt.Sprintf("%s %s", r.Method, r.URL.Path),
+			"result", result, "code", httpStatusCode, "username", username,
+			"title", title, "type", notificationType, "body", body, "token", entry.Token)
+	}
+
+	if hasError {
+		w.WriteHeader(errorStatusCode)
 	}
-	slog.Log(r.Context(), logLevel, fmt.Sprintf("%s %s", r.Method, r.URL.Path), "result", result, "code", httpStatusCode, "username", username, "title", title, "type", notificationType, "body", body, "token", token)
+	fmt.Fprint(w, responseBody.String())
 }
 
 func createServiceData(credentialsFile string) (*ServiceData, error) {

token_store.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"strings"
+	"time"
+)
+
+const MaxEntries = 3
+
+// decoder/encoder for v2 tokens, declared here so they can be tested as compatible
+var V2DecodeString = base64.RawURLEncoding.DecodeString
+var V2EncodeString = base64.RawURLEncoding.EncodeToString
+
+// prefix on all v2 base64url-encoded tokens, which when decoded is `{"entries":[`
+const V2EncodedTokenPrefix = "eyJlbnRyaWVzIjpb"
+
+type TokenEntry struct {
+	Token   string `json:"token"`
+	AddedAt int64  `json:"added_at"`
+}
+
+type TokenStore struct {
+	Entries []TokenEntry `json:"entries"`
+}
+
+func NewTokenStore() *TokenStore {
+	return &TokenStore{
+		Entries: make([]TokenEntry, 0, MaxEntries),
+	}
+}
+
+func NewTokenStoreFromString(str string) *TokenStore {
+	ts := NewTokenStore()
+	ts.FromString(str)
+	return ts
+}
+
+func (ts *TokenStore) AddToken(token string) {
+	ts.AddTokenEntry(TokenEntry{
+		Token:   token,
+		AddedAt: time.Now().Unix(),
+	})
+}
+
+func (ts *TokenStore) AddTokenEntry(entry TokenEntry) {
+	if len(ts.Entries) >= MaxEntries {
+		ts.Entries = ts.Entries[1:]
+	}
+	ts.Entries = append(ts.Entries, entry)
+}
+
+func (ts *TokenStore) FindToken(token string) *TokenEntry {
+	for i := len(ts.Entries) - 1; i >= 0; i-- {
+		if ts.Entries[i].Token == token {
+			return &ts.Entries[i]
+		}
+	}
+	return nil
+}
+
+func (ts *TokenStore) ToJSON() ([]byte, error) {
+	return json.Marshal(ts)
+}
+
+func (ts *TokenStore) FromJSON(data []byte) error {
+	return json.Unmarshal(data, ts)
+}
+
+// FromString creates a TokenStore from a string, either a plain PN token (v1) or a base64url-encoded JSON TS object (v2).
+func (ts *TokenStore) FromString(str string) {
+	// if it looks like a v2 encoded object, try to parse it
+	if strings.HasPrefix(str, V2EncodedTokenPrefix) {
+		decoded, err := V2DecodeString(str)
+		if err == nil {
+			err = ts.FromJSON(decoded)
+			if err == nil {
+				return
+			}
+		}
+	}
+
+	// treat it as a single token string
+	ts.AddToken(str)
+}