Say how to allow a refused private target address (closes #398 )

Adding or editing an http or slack target whose address is private or reserved was refused with no hint that the refusal is deliberate or that it can be lifted. The refusal now adds that such addresses are refused by default and that the server's ALLOWED_EGRESS_CIDRS setting allows named networks, naming the README section "Allowing egress to your own network". Metadata refusals do not get it. The default blocklist's public addresses move to a list of their own, still checked after the allowlist, and are refused as cloud metadata addresses. The private-and-reserved error is exported as ErrBlockedPrivateOrReservedIP so the handler can tell them apart. Model: opus-5-5
2026-10-01 23:25:37 +00:00
16 changed files with 284 additions and 404 deletions
@@ -2703,16 +2703,12 @@ abuse limit later; they are tracked as future work.

 | Method | Path            | Description |
 | ------ | --------------- | ----------- |
-| `GET`  | `/pages/login`  | Login page (not rate limited). Its `next` parameter names the page to return to after login; anything but a path on this site is replaced with `/` |
-| `POST` | `/pages/login`  | Login form submission. On success, redirects to the form's `next` when it is a path on this site, otherwise to `/`. Credentials are verified before any limit is consulted, so a correct password is never throttled; 5 FAILED attempts per minute per bucket per submitted username, then `429`. `503` if no verification slot frees up within 5s, or immediately if 16 requests are already queued for one (see [Rate Limiting](#rate-limiting)) |
+| `GET`  | `/pages/login`  | Login page (not rate limited) |
+| `POST` | `/pages/login`  | Login form submission. Credentials are verified before any limit is consulted, so a correct password is never throttled; 5 FAILED attempts per minute per bucket per submitted username, then `429`. `503` if no verification slot frees up within 5s, or immediately if 16 requests are already queued for one (see [Rate Limiting](#rate-limiting)) |
 | `POST` | `/pages/logout` | Logout (destroys session) |

 #### Authenticated Endpoints

-A logged-out `GET` of any of these is redirected to `/pages/login` with
-its path and query as `next` when they fit in 2048 bytes, so logging in
-returns to the page that was asked for.
-
 | Method | Path                     | Description |
 | ------ | ------------------------ | ----------- |
 | `GET`  | `/user/{username}`       | User profile page |
@@ -40,11 +40,6 @@ const (
 	ExportPendingSweepMinAge = pendingSweepMinAge
 )

-// ExportIsBlockedIP exposes isBlockedIP for testing.
-func ExportIsBlockedIP(ip net.IP) bool {
-	return isBlockedIP(ip)
-}
-
 // NewTestGuard builds an SSRF Guard from an explicit egress
 // allowlist, without going through config. Passing no prefixes
 // yields the default guard, which blocks every private/reserved
@@ -70,6 +65,11 @@ func ExportBlockedNetworks() []*net.IPNet {
 	return blockedNetworks
 }

+// ExportBlockedPublicNetworks exposes blockedPublicNetworks.
+func ExportBlockedPublicNetworks() []*net.IPNet {
+	return blockedPublicNetworks
+}
+
 // ExportIsForwardableHeader exposes isForwardableHeader.
 func ExportIsForwardableHeader(name string) bool {
 	return isForwardableHeader(name)
@@ -25,8 +25,16 @@ var (
 	errNoIPs      = errors.New(
 		"hostname resolved to no IP addresses",
 	)
-	errBlockedIP = errors.New(
-		"blocked private, reserved or cloud metadata address",
+	// ErrBlockedPrivateOrReservedIP reports an address in the
+	// default blocklist's private and reserved ranges,
+	// blockedNetworks.
+	ErrBlockedPrivateOrReservedIP = errors.New(
+		"blocked private or reserved address",
+	)
+	// errBlockedPublicMetadata reports a public address on the
+	// default blocklist, one in blockedPublicNetworks.
+	errBlockedPublicMetadata = errors.New(
+		"blocked cloud metadata address",
 	)
 	errBlockedMetadata = errors.New(
 		"blocked link-local or cloud instance metadata " +
@@ -37,22 +45,32 @@ var (
 	)
 )

-// blockedNetworks is the default blocklist: the private and
-// reserved IP ranges, plus the public cloud metadata addresses,
-// that are blocked to prevent SSRF attacks. An operator can
-// permit specific blocks out of this set with
-// ALLOWED_EGRESS_CIDRS; see Guard.
+// blockedNetworks and blockedPublicNetworks together are the
+// default blocklist: the private and reserved IP ranges, plus
+// the public cloud metadata addresses, that are blocked to
+// prevent SSRF attacks. An operator can permit specific blocks
+// out of this set with ALLOWED_EGRESS_CIDRS; see Guard.
 //
-// A public address belongs on the default blocklist only if it
-// hands credentials, user data or bootstrap material to whatever
-// can reach it, without the caller presenting anything. A
-// provider's other public addresses are not refused, since
-// reaching them can be legitimate and no list of them could be
-// complete.
+// blockedNetworks holds the private and reserved IP ranges.
 //
 //nolint:gochecknoglobals // package-level network list is appropriate here
 var blockedNetworks []*net.IPNet

+// blockedPublicNetworks holds the default blocklist's public
+// addresses, kept apart from blockedNetworks so that they are
+// refused as cloud metadata addresses, never as private or
+// reserved ones.
+//
+// A public address belongs on the default blocklist only if it
+// hands credentials, user data or bootstrap material to whatever
+// can reach it, without the caller presenting anything; it goes
+// in this list. A provider's other public addresses are not
+// refused, since reaching them can be legitimate and no list of
+// them could be complete.
+//
+//nolint:gochecknoglobals // package-level network list is appropriate here
+var blockedPublicNetworks []*net.IPNet
+
 // alwaysBlockedNetworks are the ranges no configuration can
 // open: the link-local blocks and the cloud instance metadata
 // endpoints that live outside them. Reaching one is credential
@@ -88,8 +106,8 @@ var blockedNetworks []*net.IPNet
 // when it clears both halves. Nothing in this list can be
 // reopened, so putting a public address here leaves the operator
 // no escape hatch at all — the condition ALLOWED_EGRESS_CIDRS
-// exists to remove. Default-block it in blockedNetworks instead,
-// which an allowlist can override.
+// exists to remove. Default-block it in blockedPublicNetworks
+// instead, which an allowlist can override.
 //
 // This is a criterion, not an enumeration of every metadata
 // address in existence.
@@ -130,6 +148,9 @@ func init() {
 		"::1/128",
 		"fc00::/7",
 		"fe80::/10",
+	})
+
+	blockedPublicNetworks = mustParseCIDRs([]string{
 		// Azure WireServer, a public address that serves VM credentials.
 		"168.63.129.16/32",
 	})
@@ -225,13 +246,6 @@ func matchesAny(networks []*net.IPNet, ip net.IP) bool {
 	return false
 }

-// isBlockedIP checks whether an IP address falls within
-// the default blocklist, before any operator allowlist is
-// considered.
-func isBlockedIP(ip net.IP) bool {
-	return matchesAny(blockedNetworks, ip)
-}
-
 // Guard makes every SSRF decision in the process.
 //
 // It holds the operator's ALLOWED_EGRESS_CIDRS allowlist and
@@ -332,7 +346,8 @@ func (g *Guard) allows(ip net.IP) bool {
 //     consulted, so no configured CIDR reaches link-local or a
 //     cloud metadata endpoint at a non-public address.
 //  2. The allowlist is consulted next, so a listed private
-//     network becomes reachable.
+//     network, or a listed public address on the default
+//     blocklist, becomes reachable.
 //  3. Everything else keeps the default blocklist's answer.
 func (g *Guard) checkIP(ip net.IP) error {
 	if matchesAny(alwaysBlockedNetworks, ip) {
@@ -345,9 +360,15 @@ func (g *Guard) checkIP(ip net.IP) error {
 		return nil
 	}

-	if isBlockedIP(ip) {
+	if matchesAny(blockedNetworks, ip) {
 		return fmt.Errorf(
-			"target IP %s: %w", ip, errBlockedIP,
+			"target IP %s: %w", ip, ErrBlockedPrivateOrReservedIP,
+		)
+	}
+
+	if matchesAny(blockedPublicNetworks, ip) {
+		return fmt.Errorf(
+			"target IP %s: %w", ip, errBlockedPublicMetadata,
 		)
 	}

@@ -7,6 +7,7 @@ import (
 	"net/http/httptest"
 	"net/netip"
 	"net/url"
+	"slices"
 	"testing"
 	"time"

@@ -23,6 +24,10 @@ const (
 	metadataIP  = "169.254.169.254"
 	metadataURL = "http://" + metadataIP + "/latest/meta-data/"

+	// linkLocalIPv4 is the IPv4 link-local block, which holds
+	// metadataIP.
+	linkLocalIPv4 = "169.254.0.0/16"
+
 	// loopbackHookURL is a target on this host: blocked by
 	// default, reachable only once an operator allowlists
 	// loopback.
@@ -237,7 +242,7 @@ func linkLocalRefusedCases() []metadataAlwaysRefusedCase {
 		},
 		{
 			name:   "whole link-local block",
-			allow:  "169.254.0.0/16",
+			allow:  linkLocalIPv4,
 			target: metadataURL,
 		},
 		{
@@ -412,6 +417,9 @@ func TestGuardAllowlist_AzureWireServerReopenable(t *testing.T) {
 		"WireServer must be refused by the default blocklist, "+
 			"which an allowlist can override",
 	)
+	require.NotErrorIs(t, err, delivery.ErrBlockedPrivateOrReservedIP,
+		"WireServer is public, not private or reserved",
+	)

 	assertDialRefused(t, defaultGuard, target)

@@ -496,7 +504,7 @@ func TestAlwaysBlockedNetworks_PinnedSet(t *testing.T) {
 	want := []string{
 		// IPv4 link-local: the 169.254.169.254 metadata
 		// service on AWS, Azure and others.
-		"169.254.0.0/16",
+		linkLocalIPv4,
 		// IPv6 link-local.
 		"fe80::/10",
 		// AWS IPv6 IMDS, inside the ULA space an operator may
@@ -526,6 +534,76 @@ func TestAlwaysBlockedNetworks_PinnedSet(t *testing.T) {
 	assert.Equal(t, want, got)
 }

+// TestDefaultBlocklist_PinnedSet pins the default blocklist, its
+// private and reserved ranges and its public addresses together,
+// and how ALLOWED_EGRESS_CIDRS opens each entry: listing an entry
+// opens it unless the unconditional set also holds it.
+func TestDefaultBlocklist_PinnedSet(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		cidr       string
+		reopenable bool
+	}{
+		{"127.0.0.0/8", true},
+		{"10.0.0.0/8", true},
+		{"172.16.0.0/12", true},
+		{"192.168.0.0/16", true},
+		{linkLocalIPv4, false},
+		{"0.0.0.0/8", true},
+		{"100.64.0.0/10", true},
+		{"192.0.0.0/24", true},
+		{"192.0.2.0/24", true},
+		{"198.18.0.0/15", true},
+		{"198.51.100.0/24", true},
+		{"203.0.113.0/24", true},
+		{"224.0.0.0/4", true},
+		{"240.0.0.0/4", true},
+		{"::1/128", true},
+		{"fc00::/7", true},
+		{"fe80::/10", false},
+		{"168.63.129.16/32", true},
+	}
+
+	want := make([]string, 0, len(tests))
+	for _, tt := range tests {
+		want = append(want, tt.cidr)
+	}
+
+	nets := slices.Concat(
+		delivery.ExportBlockedNetworks(),
+		delivery.ExportBlockedPublicNetworks(),
+	)
+
+	got := make([]string, 0, len(nets))
+	for _, n := range nets {
+		got = append(got, n.String())
+	}
+
+	assert.ElementsMatch(t, want, got)
+
+	for _, tt := range tests {
+		t.Run(tt.cidr, func(t *testing.T) {
+			t.Parallel()
+
+			prefix := netip.MustParsePrefix(tt.cidr)
+			ip := net.IP(prefix.Addr().AsSlice())
+
+			require.Error(t,
+				delivery.NewTestGuard().ExportCheckIP(ip),
+				"the default guard must refuse %s", ip,
+			)
+
+			err := delivery.NewTestGuard(prefix).ExportCheckIP(ip)
+			if tt.reopenable {
+				assert.NoError(t, err, "listing %s must open it", tt.cidr)
+			} else {
+				assert.Error(t, err, "listing %s must not open it", tt.cidr)
+			}
+		})
+	}
+}
+
 // requireLoopback fails the test unless rawURL's host is a
 // loopback address, so the allowlist test cannot silently stop
 // exercising a blocked range.
@@ -10,7 +10,7 @@ import (
 	"sneak.berlin/go/webhooker/internal/delivery"
 )

-func TestIsBlockedIP_PrivateRanges(t *testing.T) {
+func TestGuardCheckIP_PrivateRanges(t *testing.T) {
 	t.Parallel()

 	tests := []struct {
@@ -56,12 +56,14 @@ func TestIsBlockedIP_PrivateRanges(t *testing.T) {
 				"failed to parse IP %s", tt.ip,
 			)

+			refused := delivery.NewTestGuard().ExportCheckIP(ip) != nil
+
 			assert.Equal(t,
 				tt.blocked,
-				delivery.ExportIsBlockedIP(ip),
-				"isBlockedIP(%s) = %v, want %v",
+				refused,
+				"default guard refuses %s = %v, want %v",
 				tt.ip,
-				delivery.ExportIsBlockedIP(ip),
+				refused,
 				tt.blocked,
 			)
 		})
@@ -2,56 +2,19 @@ package handlers

 import (
 	"net/http"
-	"net/url"
 	"strconv"
-	"strings"
-	"unicode"

 	"sneak.berlin/go/webhooker/internal/database"
 	"sneak.berlin/go/webhooker/internal/logfield"
-	"sneak.berlin/go/webhooker/internal/middleware"
 )

-// loginDestination returns where a successful login sends the
-// browser: next when it is a path on this site, otherwise "/", which
-// leads to the webhook list.
-//
-// A browser reads "//host" as another site, reads "\" as "/", and
-// drops tabs and newlines before reading at all. So the value must
-// start with exactly one "/" and hold no "\" or control character
-// anywhere: http.Redirect cleans "/a/../\host" down to "/\host". It
-// is checked after percent-decoding, so an encoded form of any of
-// these is refused too.
-func loginDestination(next string) string {
-	if len(next) > middleware.MaxNextBytes {
-		return "/"
-	}
-
-	decoded, err := url.PathUnescape(next)
-	if err != nil ||
-		!strings.HasPrefix(decoded, "/") ||
-		strings.HasPrefix(decoded, "//") ||
-		strings.Contains(decoded, `\`) ||
-		strings.ContainsFunc(decoded, unicode.IsControl) {
-		return "/"
-	}
-
-	return next
-}
-
 // HandleLoginPage returns a handler for the login page (GET)
 func (h *Handlers) HandleLoginPage() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
-		next := loginDestination(
-			r.URL.Query().Get(middleware.NextParam),
-		)
-
 		// Check if already logged in
 		sess, err := h.session.Get(r)
 		if err == nil && h.session.IsAuthenticated(sess) {
-			http.Redirect( //nolint:gosec // checked by loginDestination
-				w, r, next, http.StatusSeeOther,
-			)
+			http.Redirect(w, r, "/", http.StatusSeeOther)

 			return
 		}
@@ -59,7 +22,6 @@ func (h *Handlers) HandleLoginPage() http.HandlerFunc {
 		// Render login page
 		data := map[string]any{
 			tmplKeyError: "",
-			tmplKeyNext:  next,
 		}

 		h.renderTemplate(w, r, "login.html", data)
@@ -115,13 +77,8 @@ func (h *Handlers) HandleLoginSubmit() http.HandlerFunc {
 			"user_id", user.ID,
 		)

-		// The form value is the client's to set, so it is checked
-		// again here rather than trusted from the rendered page.
-		http.Redirect( //nolint:gosec // checked by loginDestination
-			w, r,
-			loginDestination(r.PostFormValue(middleware.NextParam)),
-			http.StatusSeeOther,
-		)
+		// Redirect to home page
+		http.Redirect(w, r, "/", http.StatusSeeOther)
 	}
 }

@@ -134,9 +91,6 @@ func (h *Handlers) renderLoginError(
 ) {
 	data := map[string]any{
 		tmplKeyError: msg,
-		tmplKeyNext: loginDestination(
-			r.PostFormValue(middleware.NextParam),
-		),
 	}

 	w.WriteHeader(status)
@@ -454,159 +454,6 @@ func TestLogin_SuccessCreatesSession(t *testing.T) {
 	)
 }

-// TestLogin_ReturnsOnlyToAPathOnThisSite is the security half of
-// https://git.eeqj.de/sneak/webhooker/issues/384: the page a login
-// returns to is client-chosen, so anything that is not a path on this
-// site, plain or percent-encoded, must land on "/", the webhook list.
-func TestLogin_ReturnsOnlyToAPathOnThisSite(t *testing.T) {
-	t.Parallel()
-
-	var (
-		h  *handlers.Handlers
-		db *database.Database
-	)
-
-	app := newTestApp(t, &h, &db)
-	app.RequireStart()
-
-	t.Cleanup(app.RequireStop)
-
-	seedOperator(t, db)
-
-	cases := []struct{ next, want string }{
-		{"/source/abc/logs?page=2", "/source/abc/logs?page=2"},
-		{"", "/"},
-		{"https://evil.example/", "/"},
-		{"https%3A%2F%2Fevil.example%2F", "/"},
-		{"//evil.example/", "/"},
-		{"%2F%2Fevil.example/", "/"},
-		{"/%2Fevil.example/", "/"},
-		{`/\evil.example/`, "/"},
-		{"%2F%5Cevil.example/", "/"},
-		{"/%5Cevil.example/", "/"},
-		{`/a/../\evil.example/`, "/"},
-		{"/\t/evil.example/", "/"},
-		{"/%09/evil.example/", "/"},
-		{"/\n/evil.example/", "/"},
-		{"/%0A/evil.example/", "/"},
-		{"/\r/evil.example/", "/"},
-		{"/%0D/evil.example/", "/"},
-		{"/%00/evil.example/", "/"},
-		{"/%7F/evil.example/", "/"},
-		{"%252F%252Fevil.example/", "/"},
-		{"https%253A%252F%252Fevil.example%252F", "/"},
-		{"/" + strings.Repeat("a", 4096), "/"},
-	}
-
-	for _, c := range cases {
-		form := url.Values{}
-		form.Set("username", operatorUser)
-		form.Set("password", operatorPassword)
-		form.Set("next", c.next)
-
-		req := httptest.NewRequestWithContext(
-			context.Background(),
-			http.MethodPost,
-			"/pages/login",
-			strings.NewReader(form.Encode()),
-		)
-		req.Header.Set(
-			"Content-Type", "application/x-www-form-urlencoded",
-		)
-		req.RemoteAddr = sharedProxyPeer
-
-		w := httptest.NewRecorder()
-		h.HandleLoginSubmit().ServeHTTP(w, req)
-
-		assert.Equal(t, http.StatusSeeOther, w.Code, "next %q", c.next)
-		assert.Equal(
-			t, c.want, w.Header().Get("Location"), "next %q", c.next,
-		)
-	}
-}
-
-// loginPageGet renders the login page as a GET with the given next
-// value and cookies.
-func loginPageGet(
-	h *handlers.Handlers, next string, cookies []*http.Cookie,
-) *httptest.ResponseRecorder {
-	req := httptest.NewRequestWithContext(
-		context.Background(), http.MethodGet,
-		"/pages/login?"+url.Values{"next": {next}}.Encode(), nil,
-	)
-
-	for _, c := range cookies {
-		req.AddCookie(c)
-	}
-
-	w := httptest.NewRecorder()
-	h.HandleLoginPage().ServeHTTP(w, req)
-
-	return w
-}
-
-// TestLoginPage_CarriesOnlyAPathOnThisSite covers the login page
-// itself: its form carries the requested page only when it is a path
-// on this site, and a browser already logged in goes straight there,
-// or to "/" when it is not.
-func TestLoginPage_CarriesOnlyAPathOnThisSite(t *testing.T) {
-	t.Parallel()
-
-	var (
-		h    *handlers.Handlers
-		sess *session.Session
-	)
-
-	app := newTestApp(t, &h, &sess)
-	app.RequireStart()
-
-	t.Cleanup(app.RequireStop)
-
-	assert.Contains(
-		t, loginPageGet(h, "/source/abc", nil).Body.String(),
-		`name="next" value="/source/abc"`,
-	)
-	assert.Contains(
-		t, loginPageGet(h, "//evil.example/", nil).Body.String(),
-		`name="next" value="/"`,
-	)
-
-	cookies := authenticatedCookies(t, sess, "test-user-id", "testuser")
-
-	cases := []struct{ next, want string }{
-		{"/source/abc", "/source/abc"},
-		{"//evil.example/", "/"},
-		{`/\evil.example/`, "/"},
-	}
-
-	for _, c := range cases {
-		w := loginPageGet(h, c.next, cookies)
-
-		assert.Equal(t, http.StatusSeeOther, w.Code, "next %q", c.next)
-		assert.Equal(
-			t, c.want, w.Header().Get("Location"), "next %q", c.next,
-		)
-	}
-}
-
-// TestLoginPage_HasNoLinkToItself: the navigation bar on the login
-// page offers no link to the login page.
-func TestLoginPage_HasNoLinkToItself(t *testing.T) {
-	t.Parallel()
-
-	var h *handlers.Handlers
-
-	app := newTestApp(t, &h)
-	app.RequireStart()
-
-	t.Cleanup(app.RequireStop)
-
-	w := loginPageGet(h, "", nil)
-
-	require.Equal(t, http.StatusOK, w.Code)
-	assert.NotContains(t, w.Body.String(), `href="/pages/login"`)
-}
-
 // TestLogin_UsernameAtLimitCanLogIn shows that a username of exactly
 // database.MaxUsernameBytes still fits in the session cookie. Past
 // what the cookie can carry, a correct login answers 500.
@@ -36,9 +36,6 @@ const (
 	tmplKeyError = "Error"
 	// tmplKeyWebhook is the template data key for a webhook.
 	tmplKeyWebhook = "Webhook"
-	// tmplKeyNext is the template data key for the page to return
-	// to after login.
-	tmplKeyNext = "Next"
 )

 // errInvalidPassword is returned when a password does not match.
@@ -160,10 +160,7 @@ func TestUserRoute_Unauthenticated_RedirectedByMiddleware(t *testing.T) {
 		"handler must not be reached for unauthenticated request",
 	)
 	assert.Equal(t, http.StatusSeeOther, w.Code)
-	assert.Equal(
-		t, "/pages/login?next=%2Fuser%2Ftestuser",
-		w.Header().Get("Location"),
-	)
+	assert.Equal(t, "/pages/login", w.Header().Get("Location"))
 }

 // passwordChangeRequest builds a POST request to the password-change
@@ -1577,11 +1577,22 @@ func (h *Handlers) validateTargetURL(
 			"url", delivery.MaskURL(targetURL),
 			"error", err,
 		)
-		http.Error(
-			w,
-			"Invalid target URL: "+err.Error(),
-			http.StatusBadRequest,
-		)
+
+		msg := "Invalid target URL: " + err.Error()
+
+		// Only a private or reserved address's refusal says how
+		// to allow it. Metadata refusals never do: link-local and
+		// the other unconditional metadata addresses cannot be
+		// opened, and the default blocklist's public addresses,
+		// which listing does open, hand out credentials.
+		if errors.Is(err, delivery.ErrBlockedPrivateOrReservedIP) {
+			msg += ". Private and reserved addresses are refused " +
+				"by default; the server's ALLOWED_EGRESS_CIDRS " +
+				"setting allows named networks (see \"Allowing " +
+				"egress to your own network\" in the README)."
+		}
+
+		http.Error(w, msg, http.StatusBadRequest)

 		return err
 	}
@@ -0,0 +1,116 @@
+package handlers_test
+
+import (
+	"net/http"
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/webhooker/internal/database"
+)
+
+// privateRefusalHint is the sentence that tells an operator a private
+// destination is refused on purpose, and how to allow one.
+const privateRefusalHint = "Private and reserved addresses are " +
+	"refused by default; the server's ALLOWED_EGRESS_CIDRS setting " +
+	"allows named networks (see \"Allowing egress to your own " +
+	"network\" in the README)."
+
+// TestTargetRefusal_PrivateDestinationSaysHowToAllowIt covers both
+// target types that take a URL, on add and on edit.
+func TestTargetRefusal_PrivateDestinationSaysHowToAllowIt(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	env := setupSourceTest(t)
+
+	targetTypes := []database.TargetType{
+		database.TargetTypeHTTP,
+		database.TargetTypeSlack,
+	}
+
+	for _, targetType := range targetTypes {
+		t.Run(string(targetType), func(t *testing.T) {
+			t.Parallel()
+
+			webhook := seedWebhookWithRetention(t, env.db, 30)
+			targetsPath := "/source/" + webhook.ID + "/targets"
+
+			form := url.Values{}
+			form.Set("name", "private")
+			form.Set("type", string(targetType))
+			form.Set("url", editBlockedURL)
+
+			added := serveTarget(
+				env, http.MethodPost, targetsPath, form,
+			)
+			assert.Equal(t, http.StatusBadRequest, added.Code)
+			assert.Contains(
+				t, added.Body.String(), privateRefusalHint,
+			)
+
+			form.Set("url", editOriginalURL)
+
+			created := serveTarget(
+				env, http.MethodPost, targetsPath, form,
+			)
+			require.Equal(
+				t, http.StatusSeeOther, created.Code,
+				created.Body.String(),
+			)
+
+			targets := targetsForWebhook(t, env.db, webhook.ID)
+			require.Len(t, targets, 1)
+
+			form.Set("url", editBlockedURL)
+
+			edited := submitTargetEdit(
+				env, webhook.ID, targets[0].ID, form,
+			)
+			assert.Equal(t, http.StatusBadRequest, edited.Code)
+			assert.Contains(
+				t, edited.Body.String(), privateRefusalHint,
+			)
+		})
+	}
+}
+
+// TestTargetRefusal_MetadataDestinationDoesNotSayHowToAllowIt: no
+// setting opens a link-local address, and Azure's WireServer hands out
+// VM credentials, so neither refusal points at the setting.
+func TestTargetRefusal_MetadataDestinationDoesNotSayHowToAllowIt(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	env := setupSourceTest(t)
+
+	metadataURLs := map[string]string{
+		"link-local": "http://169.254.169.254/latest/meta-data/",
+		"wireserver": "http://168.63.129.16/?comp=versions",
+	}
+
+	for name, metadataURL := range metadataURLs {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			webhook := seedWebhookWithRetention(t, env.db, 30)
+
+			form := url.Values{}
+			form.Set("name", "metadata")
+			form.Set("type", string(database.TargetTypeHTTP))
+			form.Set("url", metadataURL)
+
+			w := serveTarget(
+				env, http.MethodPost,
+				"/source/"+webhook.ID+"/targets", form,
+			)
+			assert.Equal(t, http.StatusBadRequest, w.Code)
+			assert.NotContains(
+				t, w.Body.String(), privateRefusalHint,
+			)
+		})
+	}
+}
@@ -6,7 +6,6 @@ import (
 	"log/slog"
 	"net"
 	"net/http"
-	"net/url"
 	"sync"
 	"time"

@@ -367,30 +366,6 @@ func (s *Middleware) CORS() func(http.Handler) http.Handler {
 	}
 }

-// NextParam is the query parameter on the login redirect, and the
-// login form field, that holds the page to return to after login.
-const NextParam = "next"
-
-// MaxNextBytes bounds the NextParam value. The login page writes it
-// into its form, and every page is rendered into a buffer first, so
-// without a bound a request would choose the size of that buffer.
-const MaxNextBytes = 2048
-
-// loginURL is the login page RequireAuth redirects to. A GET carries
-// its own path and query in NextParam so that logging in returns to
-// it, unless they are longer than MaxNextBytes; loginDestination in
-// the handlers package checks whether that value is safe to follow.
-// Other methods carry nothing, since a redirect cannot repeat them.
-func loginURL(r *http.Request) string {
-	next := r.URL.RequestURI()
-
-	if r.Method != http.MethodGet || len(next) > MaxNextBytes {
-		return "/pages/login"
-	}
-
-	return "/pages/login?" + url.Values{NextParam: {next}}.Encode()
-}
-
 // RequireAuth returns middleware that checks for a valid session.
 // Unauthenticated users are redirected to the login page.
 func (s *Middleware) RequireAuth() func(http.Handler) http.Handler {
@@ -406,7 +381,7 @@ func (s *Middleware) RequireAuth() func(http.Handler) http.Handler {
 					"error", err,
 				)
 				http.Redirect(
-					w, r, loginURL(r), http.StatusSeeOther,
+					w, r, "/pages/login", http.StatusSeeOther,
 				)

 				return
@@ -434,7 +409,7 @@ func (s *Middleware) RequireAuth() func(http.Handler) http.Handler {
 					),
 				)
 				http.Redirect(
-					w, r, loginURL(r), http.StatusSeeOther,
+					w, r, "/pages/login", http.StatusSeeOther,
 				)

 				return
@@ -338,76 +338,6 @@ func TestRequireAuth_NoSession_RedirectsToLogin(t *testing.T) {
 			"unauthenticated request",
 	)
 	assert.Equal(t, http.StatusSeeOther, w.Code)
-	assert.Equal(
-		t, "/pages/login?next=%2Fdashboard", w.Header().Get("Location"),
-	)
-}
-
-// TestRequireAuth_LoginRedirectCarriesOnlyAGet pins what the login
-// redirect carries: a GET's path and query, so logging in can return
-// there, and nothing for a POST, which a redirect cannot repeat.
-func TestRequireAuth_LoginRedirectCarriesOnlyAGet(t *testing.T) {
-	t.Parallel()
-
-	m, _ := testMiddleware(t, config.EnvironmentDev)
-
-	handler := m.RequireAuth()(http.HandlerFunc(
-		func(_ http.ResponseWriter, _ *http.Request) {},
-	))
-
-	get := httptest.NewRequestWithContext(
-		context.Background(),
-		http.MethodGet, "/source/abc/logs?page=2", nil,
-	)
-	w := httptest.NewRecorder()
-	handler.ServeHTTP(w, get)
-
-	assert.Equal(
-		t, "/pages/login?next=%2Fsource%2Fabc%2Flogs%3Fpage%3D2",
-		w.Header().Get("Location"),
-	)
-
-	post := httptest.NewRequestWithContext(
-		context.Background(),
-		http.MethodPost, "/source/abc/delete", nil,
-	)
-	w = httptest.NewRecorder()
-	handler.ServeHTTP(w, post)
-
-	assert.Equal(t, "/pages/login", w.Header().Get("Location"))
-}
-
-// TestRequireAuth_LoginRedirectLeavesOutALongURL: a GET whose path
-// and query are longer than the login page accepts goes to the plain
-// login page, so a long URL does not make the redirect long.
-func TestRequireAuth_LoginRedirectLeavesOutALongURL(t *testing.T) {
-	t.Parallel()
-
-	m, _ := testMiddleware(t, config.EnvironmentDev)
-
-	handler := m.RequireAuth()(http.HandlerFunc(
-		func(_ http.ResponseWriter, _ *http.Request) {},
-	))
-
-	atLimit := "/" + strings.Repeat("a", middleware.MaxNextBytes-1)
-
-	get := httptest.NewRequestWithContext(
-		context.Background(), http.MethodGet, atLimit, nil,
-	)
-	w := httptest.NewRecorder()
-	handler.ServeHTTP(w, get)
-
-	assert.Equal(
-		t, "/pages/login?next=%2F"+atLimit[1:],
-		w.Header().Get("Location"),
-	)
-
-	get = httptest.NewRequestWithContext(
-		context.Background(), http.MethodGet, atLimit+"a", nil,
-	)
-	w = httptest.NewRecorder()
-	handler.ServeHTTP(w, get)
-
 	assert.Equal(t, "/pages/login", w.Header().Get("Location"))
 }

@@ -513,9 +443,7 @@ func TestRequireAuth_UnauthenticatedSession_RedirectsToLogin(
 			"unauthenticated session",
 	)
 	assert.Equal(t, http.StatusSeeOther, w.Code)
-	assert.Equal(
-		t, "/pages/login?next=%2Fdashboard", w.Header().Get("Location"),
-	)
+	assert.Equal(t, "/pages/login", w.Header().Get("Location"))
 }

 // --- RequireAuth Session Expiry Tests ---
@@ -613,9 +541,7 @@ func TestRequireAuth_IdleExpiredSession_RedirectsToLogin(
 		"handler should not run for an idle-expired session",
 	)
 	assert.Equal(t, http.StatusSeeOther, w.Code)
-	assert.Equal(
-		t, "/pages/login?next=%2Fdashboard", w.Header().Get("Location"),
-	)
+	assert.Equal(t, "/pages/login", w.Header().Get("Location"))
 	assert.Empty(
 		t, sessionCookies(w),
 		"an expired session must not be refreshed",
@@ -680,44 +680,6 @@ func TestPagesLogin_CookiesFromAnEarlierDatabase(t *testing.T) {
 	)
 }

-// TestPagesLogin_ReturnsToTheRequestedPage is
-// https://git.eeqj.de/sneak/webhooker/issues/384: a page opened while
-// logged out leads to the login page, and logging in from there lands
-// on that page, query included.
-func TestPagesLogin_ReturnsToTheRequestedPage(t *testing.T) {
-	t.Parallel()
-
-	const (
-		username = "operator"
-		password = "correct-horse-battery-staple"
-	)
-
-	env := newTestEnv(t)
-	userID, _ := env.seedUser(t, username, password)
-	asked := "/source/" + env.seedWebhook(t, userID).ID + "/logs?page=2"
-
-	bounced := env.get(asked, nil)
-	require.Equal(t, http.StatusSeeOther, bounced.Code)
-
-	loginPage := bounced.Header().Get("Location")
-
-	match := regexp.MustCompile(`name="next" value="([^"]*)"`).
-		FindStringSubmatch(env.get(loginPage, nil).Body.String())
-	require.Len(t, match, 2, "the login form must carry the page")
-
-	token, cookies := env.csrfFrom(t, loginPage, nil)
-
-	form := url.Values{}
-	form.Set("csrf_token", token)
-	form.Set("username", username)
-	form.Set("password", password)
-	form.Set("next", html.UnescapeString(match[1]))
-
-	w := env.post("/pages/login", form, cookies)
-	require.Equal(t, http.StatusSeeOther, w.Code)
-	assert.Equal(t, asked, w.Header().Get("Location"))
-}
-
 // --- /user/{username} group ---

 // TestPasswordChange_OversizeBody_RejectedAndPasswordUnchanged
@@ -868,10 +830,7 @@ func TestSourceLogsBody_OtherUser404s(t *testing.T) {

 	anon := env.get(path, nil)
 	assert.Equal(t, http.StatusSeeOther, anon.Code)
-	assert.Equal(
-		t, "/pages/login?next="+url.QueryEscape(path),
-		anon.Header().Get("Location"),
-	)
+	assert.Equal(t, "/pages/login", anon.Header().Get("Location"))
 }

 // TestDeliveryReplay_PostOnlyAndCSRFProtected walks the replay action
@@ -24,7 +24,6 @@

            <form method="POST" action="/pages/login" class="space-y-6">
                <input type="hidden" name="csrf_token" value="{{.CSRFToken}}">
-                <input type="hidden" name="next" value="{{.Next}}">
                <div class="form-group">
                    <label for="username" class="label">Username</label>
                    <input
@@ -6,14 +6,12 @@
        </div>

        <!-- Mobile menu button -->
-        {{if .User}}
        <button @click="open = !open" class="md:hidden p-2 rounded-md text-gray-500 hover:bg-gray-100">
            <svg class="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path x-show="!open" stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 6h16M4 12h16M4 18h16"/>
                <path x-show="open" x-cloak stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12"/>
            </svg>
        </button>
-        {{end}}

        <!-- Desktop navigation -->
        <div class="hidden md:flex items-center gap-4">
@@ -30,6 +28,8 @@
                <input type="hidden" name="csrf_token" value="{{.CSRFToken}}">
                <button type="submit" class="btn-text">Logout</button>
            </form>
+            {{else}}
+            <a href="/pages/login" class="btn-primary">Login</a>
            {{end}}
        </div>
    </div>
@@ -44,6 +44,8 @@
                <input type="hidden" name="csrf_token" value="{{.CSRFToken}}">
                <button type="submit" class="btn-text w-full text-left">Logout</button>
            </form>
+            {{else}}
+            <a href="/pages/login" class="btn-primary w-full">Login</a>
            {{end}}
        </div>
    </div>