Show an event's entrypoint and request headers (closes #389)

An expanded event in the event log and the event's own page now show
the entrypoint the event arrived at (its description, "Entrypoint"
when it has none, or "deleted entrypoint"; never its URL), or for a
resubmitted copy the one its original arrived at, and the request
headers, one per line, sorted by name, whitespace kept. The event log
leaves out headers that hold more than the body's 32 KiB limit, stored
or as lines, and links to the event's page, which shows them all.
Both pages draw them through one shared template, event_request.html,
and read the webhook's entrypoints once per page.

Model: opus-5-5

internal/handlers/event_detail.go

@@ -1,6 +1,7 @@
 package handlers
 
 import (
+	"math"
 	"net/http"
 
 	"github.com/go-chi/chi"
@@ -59,8 +60,9 @@ func (h *Handlers) HandleEventDetail() http.HandlerFunc {
 			return
 		}
 
+		// The page shows every request header.
 		views, ok := h.eventLogViews(
-			w, r, webhookDB, webhook.ID, rows, targets,
+			w, r, webhookDB, webhook.ID, rows, targets, math.MaxInt,
 		)
 		if !ok {
 			return

internal/handlers/event_log_view.go

@@ -1,10 +1,14 @@
 package handlers
 
 import (
+	"encoding/json"
+	"net/http"
+	"slices"
 	"time"
 	"unicode/utf8"
 
 	"github.com/dustin/go-humanize"
+	"sneak.berlin/go/webhooker/internal/database"
 )
 
 // eventLogColumns is the event log's projection. The casts to
@@ -12,16 +16,20 @@ import (
 // bytes rather than characters, so the cap bounds the page in
 // bytes whatever the payload's encoding. Cutting in SQLite
 // rather than in Go is the point of the projection — an
-// oversized body never becomes a Go string at all.
+// oversized body or set of request headers never becomes a Go
+// string at all.
 const eventLogColumns = "id, created_at, method, content_type, " +
-	"resubmitted_from_id, " +
+	"resubmitted_from_id, entrypoint_id, " +
+	"substr(cast(headers as blob), 1, ?) AS headers, " +
+	"length(cast(headers as blob)) AS headers_bytes, " +
 	"substr(cast(body as blob), 1, ?) AS body, " +
 	"length(cast(body as blob)) AS body_bytes"
 
 // eventColumns is eventLogColumns for the event's own page, which
-// shows the whole body.
+// shows the whole body and every request header.
 const eventColumns = "id, created_at, method, content_type, " +
-	"resubmitted_from_id, " +
+	"resubmitted_from_id, entrypoint_id, headers, " +
+	"length(cast(headers as blob)) AS headers_bytes, " +
 	"cast(body as blob) AS body, " +
 	"length(cast(body as blob)) AS body_bytes"
 
@@ -40,6 +48,20 @@ type EventLogView struct {
 
 	Body BodyView
 
+	// Entrypoint names the entrypoint the event arrived at, or for a
+	// resubmitted copy, which did not arrive, the one its original
+	// arrived at: its description, "Entrypoint" when it has none, or
+	// "deleted entrypoint". Never its URL, which is the entrypoint's
+	// secret.
+	Entrypoint string
+
+	// Headers is the event's request headers, one "Name: value"
+	// per value, sorted by name. HeadersCut reports headers left
+	// out because they hold more than maxRenderedBodyBytes, stored
+	// or as lines; only the event log leaves them out.
+	Headers    []string
+	HeadersCut bool
+
 	// ResubmittedFromID names the event this one was copied
 	// from, empty for an event that arrived on the receiver.
 	ResubmittedFromID string
@@ -60,27 +82,35 @@ func (v EventLogView) ResubmittedFrom() bool {
 }
 
 // eventLogRow is one row of the event log projection, or of
-// eventColumns. In the event log its body column arrives
-// already cut to the cap by SQLite, with the true size beside
-// it.
+// eventColumns. In the event log its headers and body columns
+// arrive already cut to the cap by SQLite, each with its true
+// size beside it.
 type eventLogRow struct {
 	ID                string
 	CreatedAt         time.Time
 	Method            string
 	ContentType       string
 	ResubmittedFromID *string
+	EntrypointID      string
+	Headers           string
+	HeadersBytes      int64
 	Body              []byte
 	BodyBytes         int64
 }
 
 // view projects a loaded row of the webhook's events for
-// rendering.
-func (r *eventLogRow) view(webhookID string) EventLogView {
+// rendering. It shows the request headers when the row holds them
+// whole and their lines hold at most maxHeaderBytes.
+func (r *eventLogRow) view(
+	webhookID string, maxHeaderBytes int,
+) EventLogView {
 	var from string
 	if r.ResubmittedFromID != nil {
 		from = *r.ResubmittedFromID
 	}
 
+	headers, fit := requestHeaderLines(r.Headers, maxHeaderBytes)
+
 	return EventLogView{
 		ID:          r.ID,
 		Method:      r.Method,
@@ -90,10 +120,82 @@ func (r *eventLogRow) view(webhookID string) EventLogView {
 		Body: newBodyView(
 			"/hook/"+webhookID+"/events/"+r.ID, r.Body, r.BodyBytes,
 		),
+		Headers:           headers,
+		HeadersCut:        !fit || r.HeadersBytes > int64(len(r.Headers)),
 		ResubmittedFromID: from,
 	}
 }
 
+// requestHeaderLines turns an event's stored request headers, the
+// JSON the receiver writes, into one "Name: value" line per value,
+// sorted by name. Headers that do not parse, as when the event log
+// has cut them, show as none. It reports false, with no lines, when
+// the lines would hold more than maxBytes: a header sent many times
+// is stored with its name once but shown with it on every line.
+func requestHeaderLines(headersJSON string, maxBytes int) ([]string, bool) {
+	var headers http.Header
+
+	if json.Unmarshal([]byte(headersJSON), &headers) != nil {
+		return nil, true
+	}
+
+	names := make([]string, 0, len(headers))
+	for name := range headers {
+		names = append(names, name)
+	}
+
+	slices.Sort(names)
+
+	var lines []string
+
+	size := 0
+
+	for _, name := range names {
+		for _, value := range headers[name] {
+			line := name + ": " + value
+
+			size += len(line)
+			if size > maxBytes {
+				return nil, false
+			}
+
+			lines = append(lines, line)
+		}
+	}
+
+	return lines, true
+}
+
+// entrypointNames maps each of the webhook's entrypoints to the name
+// an event that arrived at it shows: its description, or "Entrypoint"
+// when it has none, as the webhook page names it. A deleted
+// entrypoint is left out.
+func (h *Handlers) entrypointNames(
+	webhookID string,
+) (map[string]string, error) {
+	var entrypoints []database.Entrypoint
+
+	err := h.db.DB().Where(
+		"webhook_id = ?", webhookID,
+	).Find(&entrypoints).Error
+	if err != nil {
+		return nil, err
+	}
+
+	names := make(map[string]string, len(entrypoints))
+
+	for i := range entrypoints {
+		name := entrypoints[i].Description
+		if name == "" {
+			name = "Entrypoint"
+		}
+
+		names[entrypoints[i].ID] = name
+	}
+
+	return names, nil
+}
+
 // trimPartialRune drops a trailing UTF-8 sequence that the
 // byte-wise cut left incomplete, so a multi-byte rune severed
 // at the cap does not surface as a mojibake tail.

internal/handlers/event_request_test.go

@@ -0,0 +1,276 @@
+package handlers_test
+
+import (
+	"encoding/json"
+	"net/http"
+	"slices"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gorm.io/gorm/clause"
+	"sneak.berlin/go/webhooker/internal/database"
+)
+
+// arrivedAt is how a page names the entrypoint an event arrived at.
+func arrivedAt(name string) string {
+	return `Arrived at <span class="text-gray-900">` + name + `</span>`
+}
+
+// originalArrivedAt is how a page names the entrypoint a resubmitted
+// copy's original arrived at.
+func originalArrivedAt(name string) string {
+	return `Its original arrived at <span class="text-gray-900">` +
+		name + `</span>`
+}
+
+// headerLine is how a page shows one request header line.
+func headerLine(line string) string {
+	return `<div class="whitespace-pre-wrap">` + line + `</div>`
+}
+
+// showHeadersLink is the event log's link to an event's own page for
+// request headers it leaves out.
+func showHeadersLink(webhookID, eventID string) string {
+	return `<a href="/hook/` + webhookID + `/events/` + eventID +
+		`" class="btn-small">Show the request headers</a>`
+}
+
+// entrypoint records one of the fixture webhook's entrypoints.
+func (f *recentEventsFixture) entrypoint(
+	t *testing.T, description string,
+) *database.Entrypoint {
+	t.Helper()
+
+	ep := &database.Entrypoint{
+		WebhookID:   f.webhook.ID,
+		Path:        uuid.NewString(),
+		Description: description,
+		Active:      true,
+	}
+
+	require.NoError(t, f.db.DB().Omit(clause.Associations).Create(ep).Error)
+
+	return ep
+}
+
+// eventAt records an event that arrived at the entrypoint with the
+// given request headers, stored as JSON as the receiver stores them.
+func (f *recentEventsFixture) eventAt(
+	t *testing.T,
+	ep *database.Entrypoint,
+	headersJSON string,
+	receivedAt time.Time,
+) *database.Event {
+	t.Helper()
+
+	event := &database.Event{
+		WebhookID:    f.webhook.ID,
+		EntrypointID: ep.ID,
+		Method:       http.MethodPost,
+		Headers:      headersJSON,
+		Body:         "{}",
+		BodyBytes:    2,
+		ContentType:  contentTypeJSON,
+	}
+	event.CreatedAt = receivedAt
+
+	require.NoError(t, f.webhookDB.Omit(
+		clause.Associations,
+	).Create(event).Error)
+
+	return event
+}
+
+// TestEventRequest_EachEventShowsItsOwnEntrypointAndHeaders proves two
+// events that arrived at two entrypoints each show their own
+// entrypoint and request headers, in the event log and on their own
+// pages, with the headers sorted by name, escaped and keeping their
+// whitespace, and never the entrypoint's URL.
+func TestEventRequest_EachEventShowsItsOwnEntrypointAndHeaders(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	f := newRecentEventsFixture(t)
+	billing := f.entrypoint(t, "Billing sender")
+	unnamed := f.entrypoint(t, "")
+
+	// Stored in reverse name order.
+	older := f.eventAt(t, billing,
+		`{"X-Shop-Event":["order.created"],`+
+			`"User-Agent":["shop/1  build\t7"],"Accept":["*/*"]}`,
+		time.Now().Add(-time.Minute))
+	newer := f.eventAt(t, unnamed,
+		`{"X-Shop-Event":["order.paid"],"X-Note":["<b>hi</b>"]}`,
+		time.Now())
+
+	olderShows := func(t *testing.T, page string) {
+		t.Helper()
+
+		const (
+			accept    = "Accept: */*"
+			userAgent = "User-Agent: shop/1  build\t7"
+			shopEvent = "X-Shop-Event: order.created"
+		)
+
+		assert.Contains(t, page, arrivedAt("Billing sender"))
+		assert.Contains(t, page, headerLine(accept))
+		assert.Contains(t, page, headerLine(userAgent))
+		assert.Contains(t, page, headerLine(shopEvent))
+		assert.Less(t,
+			strings.Index(page, accept), strings.Index(page, userAgent),
+			"headers are sorted by name",
+		)
+		assert.Less(t,
+			strings.Index(page, userAgent), strings.Index(page, shopEvent),
+			"headers are sorted by name",
+		)
+		assert.NotContains(t, page, "order.paid")
+		assert.NotContains(t, page, billing.Path)
+	}
+
+	newerShows := func(t *testing.T, page string) {
+		t.Helper()
+
+		assert.Contains(t, page, arrivedAt("Entrypoint"))
+		assert.Contains(t, page, headerLine("X-Shop-Event: order.paid"))
+		assert.Contains(t, page, headerLine("X-Note: &lt;b&gt;hi&lt;/b&gt;"))
+		assert.NotContains(t, page, "<b>hi</b>")
+		assert.NotContains(t, page, "order.created")
+		assert.NotContains(t, page, unnamed.Path)
+	}
+
+	// The log lists the newer event first, so everything between
+	// the two events' first mentions belongs to the newer one.
+	_, rest, found := strings.Cut(renderSourceLogsPage(
+		t, f.h, f.sess, f.webhook.ID,
+	), newer.ID)
+	require.True(t, found)
+
+	newerPart, olderPart, found := strings.Cut(rest, older.ID)
+	require.True(t, found)
+
+	newerShows(t, newerPart)
+	olderShows(t, olderPart)
+
+	w := serveEventPage(t, f.h, f.sess, f.webhook.ID, newer.ID)
+	require.Equal(t, http.StatusOK, w.Code)
+	newerShows(t, w.Body.String())
+
+	w = serveEventPage(t, f.h, f.sess, f.webhook.ID, older.ID)
+	require.Equal(t, http.StatusOK, w.Code)
+	olderShows(t, w.Body.String())
+}
+
+// TestEventRequest_DeletedEntrypoint proves an event whose entrypoint
+// has since been deleted says so in the event log and on its own page.
+func TestEventRequest_DeletedEntrypoint(t *testing.T) {
+	t.Parallel()
+
+	f := newRecentEventsFixture(t)
+	ep := f.entrypoint(t, "Retired sender")
+	event := f.eventAt(t, ep, `{}`, time.Now())
+
+	require.NoError(t, f.db.DB().Delete(ep).Error)
+
+	page := renderSourceLogsPage(t, f.h, f.sess, f.webhook.ID)
+	assert.Contains(t, page, arrivedAt("deleted entrypoint"))
+	assert.NotContains(t, page, "Retired sender")
+
+	w := serveEventPage(t, f.h, f.sess, f.webhook.ID, event.ID)
+	require.Equal(t, http.StatusOK, w.Code)
+	assert.Contains(t, w.Body.String(), arrivedAt("deleted entrypoint"))
+	assert.NotContains(t, w.Body.String(), "Retired sender")
+}
+
+// TestEventRequest_ResubmittedCopy proves a resubmitted copy says its
+// original arrived at the entrypoint, in the event log and on its own
+// page, and never that the copy did.
+func TestEventRequest_ResubmittedCopy(t *testing.T) {
+	t.Parallel()
+
+	f := newRecentEventsFixture(t)
+	ep := f.entrypoint(t, "Billing sender")
+	original := f.eventAt(t, ep, `{}`, time.Now().Add(-time.Minute))
+	copied := f.eventAt(t, ep, `{}`, time.Now())
+
+	require.NoError(t, f.webhookDB.Model(copied).Update(
+		"resubmitted_from_id", original.ID,
+	).Error)
+
+	// The log lists the copy first, and the original's Resubmit form
+	// comes after all of the copy and before the original's
+	// entrypoint.
+	copyPart, originalPart, found := strings.Cut(
+		renderSourceLogsPage(t, f.h, f.sess, f.webhook.ID),
+		"/events/"+original.ID+"/resubmit",
+	)
+	require.True(t, found)
+
+	assert.Contains(t, copyPart, originalArrivedAt("Billing sender"))
+	assert.NotContains(t, copyPart, arrivedAt("Billing sender"))
+	assert.Contains(t, originalPart, arrivedAt("Billing sender"))
+	assert.NotContains(t, originalPart, originalArrivedAt("Billing sender"))
+
+	w := serveEventPage(t, f.h, f.sess, f.webhook.ID, copied.ID)
+	require.Equal(t, http.StatusOK, w.Code)
+	assert.Contains(t, w.Body.String(), originalArrivedAt("Billing sender"))
+	assert.NotContains(t, w.Body.String(), arrivedAt("Billing sender"))
+}
+
+// TestEventRequest_HeadersOverTheLimit proves the event log leaves out
+// request headers that hold more than it shows of a body, whether
+// stored or as lines, and links to the event's own page, which shows
+// them all.
+func TestEventRequest_HeadersOverTheLimit(t *testing.T) {
+	t.Parallel()
+
+	// The receiver stores each "<" as six bytes of JSON, so this
+	// header is over the limit stored but not as a line.
+	const lessThans = bodyCap/6 + 1
+
+	// A header sent many times is stored with its name once, and
+	// shown with it on every line.
+	repeatedName := "X-Repeated-" + strings.Repeat("r", 1000)
+
+	tests := map[string]struct {
+		headers http.Header
+		line    string
+	}{
+		"stored": {
+			headers: http.Header{"X-Long": {strings.Repeat("<", lessThans)}},
+			line:    "X-Long: " + strings.Repeat("&lt;", lessThans),
+		},
+		"as lines": {
+			headers: http.Header{repeatedName: slices.Repeat([]string{""}, 41)},
+			line:    repeatedName + ": ",
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			headersJSON, err := json.Marshal(tc.headers)
+			require.NoError(t, err)
+
+			f := newRecentEventsFixture(t)
+			ep := f.entrypoint(t, "Billing sender")
+			event := f.eventAt(t, ep, string(headersJSON), time.Now())
+
+			page := renderSourceLogsPage(t, f.h, f.sess, f.webhook.ID)
+			assert.Contains(t, page, showHeadersLink(f.webhook.ID, event.ID))
+			assert.NotContains(t, page, tc.line)
+			assert.Less(t, len(page), 4*bodyCap)
+
+			w := serveEventPage(t, f.h, f.sess, f.webhook.ID, event.ID)
+			require.Equal(t, http.StatusOK, w.Code)
+			assert.Contains(t, w.Body.String(), headerLine(tc.line))
+			assert.NotContains(t, w.Body.String(), "Show the request headers")
+		})
+	}
+}

internal/handlers/handlers.go

@@ -167,12 +167,12 @@ func New(
 		),
 		"source_edit.html": parsePageTemplate("source_edit.html"),
 		"source_logs.html": parsePageTemplate(
-			"source_logs.html", "event_body.html", "delivery_row.html",
-			"delivery_attempts.html",
+			"source_logs.html", "event_request.html", "event_body.html",
+			"delivery_row.html", "delivery_attempts.html",
 		),
 		"event_detail.html": parsePageTemplate(
-			"event_detail.html", "event_body.html", "delivery_row.html",
-			"delivery_attempts.html",
+			"event_detail.html", "event_request.html", "event_body.html",
+			"delivery_row.html", "delivery_attempts.html",
 		),
 		"target_edit.html": parsePageTemplate("target_edit.html"),
 		"error.html":       parsePageTemplate("error.html"),

internal/handlers/source_management.go

@@ -1231,13 +1231,16 @@ func (h *Handlers) loadEventsWithDeliveries(
 
 	result, ok := h.eventLogViews(
 		w, r, webhookDB, webhook.ID, rows, targetMap,
+		maxRenderedBodyBytes,
 	)
 
 	return result, totalEvents, ok
 }
 
 // eventLogViews projects loaded events for rendering, each with
-// its deliveries and how many times it has been resubmitted. Like
+// its deliveries, how many times it has been resubmitted and the
+// entrypoint it arrived at, and with its request headers only when
+// their lines hold at most maxHeaderBytes. Like
 // loadEventsWithDeliveries, it reports false once it has answered
 // the request with an error.
 func (h *Handlers) eventLogViews(
@@ -1247,6 +1250,7 @@ func (h *Handlers) eventLogViews(
 	webhookID string,
 	rows []eventLogRow,
 	targetMap map[string]eventLogTarget,
+	maxHeaderBytes int,
 ) ([]EventLogView, bool) {
 	result := make([]EventLogView, len(rows))
 	eventDeliveries := make([][]database.Delivery, len(rows))
@@ -1256,7 +1260,7 @@ func (h *Handlers) eventLogViews(
 	eventIDs := make([]string, len(rows))
 
 	for i := range rows {
-		result[i] = rows[i].view(webhookID)
+		result[i] = rows[i].view(webhookID, maxHeaderBytes)
 		eventIDs[i] = rows[i].ID
 
 		webhookDB.Where(
@@ -1290,11 +1294,25 @@ func (h *Handlers) eventLogViews(
 		return nil, false
 	}
 
+	entrypoints, err := h.entrypointNames(webhookID)
+	if err != nil {
+		h.serverError(w, r, "failed to load entrypoints", err)
+
+		return nil, false
+	}
+
 	for i := range rows {
 		result[i].Deliveries = h.newDeliveryViews(
 			eventDeliveries[i], targetMap, attempts,
 		)
 		result[i].ResubmitCount = resubmits[rows[i].ID]
+
+		name, ok := entrypoints[rows[i].EntrypointID]
+		if !ok {
+			name = "deleted entrypoint"
+		}
+
+		result[i].Entrypoint = name
 	}
 
 	return result, true
@@ -1315,7 +1333,7 @@ func loadEventLogRows(
 	var rows []eventLogRow
 
 	webhookDB.Model(&database.Event{}).Select(
-		eventLogColumns, maxRenderedBodyBytes,
+		eventLogColumns, maxRenderedBodyBytes, maxRenderedBodyBytes,
 	).Where(
 		"webhook_id = ?", webhookID,
 	).Order("created_at DESC").Limit(recentEventLimit).Find(&rows)