Merge origin/main (license, compose, #65 leak guard) into cans work

internal/api/admin.go

@@ -172,6 +172,11 @@ func (a *apiServer) adminKeyOK(r *http.Request, key string) bool {
 
 func (a *apiServer) adminAuth(next http.HandlerFunc, key string) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
+		if !rateLimitAdmin(r) {
+			log.Printf("admin auth RATE LIMITED: %s %s from %s", r.Method, r.URL.Path, r.RemoteAddr)
+			writeRateLimited(w, 60)
+			return
+		}
 		if !a.adminKeyOK(r, key) {
 			log.Printf("admin auth FAILURE: %s %s from %s", r.Method, r.URL.Path, r.RemoteAddr)
 			writeErr(w, 401, "unauthorized")

internal/api/adminratelimit_test.go

@@ -0,0 +1,80 @@
+package api
+
+// #66: admin key attempts must be rate limited per IP (5/min), constant-time
+// compared, and failures logged. Hammering bad keys must yield 429s.
+
+import (
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// TestAdminKeyRateLimited: burst of 5 bad-key attempts allowed (401), the 6th
+// gets 429, and even the correct key is blocked from that IP until refill.
+func TestAdminKeyRateLimited(t *testing.T) {
+	srv := newTestServer(t)
+	h := srv.routes()
+	reqIP := "10.7.7.1:1234"
+
+	var got429, retryAfter bool
+	var lastCode int
+	for i := 0; i < 10; i++ {
+		req := httptest.NewRequest("POST", "/admin/api/settings", nil)
+		req.RemoteAddr = reqIP
+		req.Header.Set("X-Admin-Key", "wrong-key")
+		rec := httptest.NewRecorder()
+		h.ServeHTTP(rec, req)
+		lastCode = rec.Code
+		if rec.Code == 429 {
+			got429 = true
+			retryAfter = rec.Header().Get("Retry-After") != ""
+			break
+		}
+	}
+	if !got429 {
+		t.Fatalf("expected 429 after hammering bad keys, last status %d", lastCode)
+	}
+	if !retryAfter {
+		t.Error("429 missing Retry-After header")
+	}
+
+	// Correct key from the same IP is also locked out.
+	req := httptest.NewRequest("POST", "/admin/api/settings", nil)
+	req.RemoteAddr = reqIP
+	req.Header.Set("X-Admin-Key", srv.adminKey)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	if rec.Code != 429 {
+		t.Errorf("correct key after lockout: got %d, want 429", rec.Code)
+	}
+
+	// A different IP is unaffected.
+	req2 := httptest.NewRequest("POST", "/admin/api/settings", strings.NewReader(`{"rate_limit_burst":5,"rate_limit_per_minute":60,"max_content_bytes":1048576,"custom_slug_reservation_days":30,"burn_viewer_window_minutes":15}`))
+	req2.RemoteAddr = "203.0.113.9:1234"
+	req2.Header.Set("X-Admin-Key", srv.adminKey)
+	rec2 := httptest.NewRecorder()
+	h.ServeHTTP(rec2, req2)
+	if rec2.Code != 200 {
+		t.Errorf("correct key from another IP: got %d, want 200", rec2.Code)
+	}
+}
+
+// TestAdminKeyConstantTimeCompare: sanity check that the comparison is
+// constant-time (uses subtle.ConstantTimeCompare, not ==).
+func TestAdminKeyConstantTimeCompare(t *testing.T) {
+	srv := newTestServer(t)
+	r := httptest.NewRequest("GET", "/", nil)
+	r.Header.Set("X-Admin-Key", "test-admin-key")
+	if !srv.adminKeyOK(r, srv.adminKey) {
+		t.Fatal("correct key rejected")
+	}
+	r.Header.Set("X-Admin-Key", "wrong")
+	if srv.adminKeyOK(r, srv.adminKey) {
+		t.Fatal("wrong key accepted")
+	}
+	// differ in length: must not panic/mismatch unexpectedly
+	r.Header.Set("X-Admin-Key", "test-admin-key-longer")
+	if srv.adminKeyOK(r, srv.adminKey) {
+		t.Fatal("longer wrong key accepted")
+	}
+}

internal/api/cans_expiry_test.go

@@ -0,0 +1,45 @@
+package api
+
+import (
+	"net/http/httptest"
+	"testing"
+)
+
+// #60: the cans API must clamp expires_in at the boundary exactly like the
+// pastes API — reject zero/negative durations and anything over the 1-year
+// UI cap, accept the exact boundaries.
+func TestCreateCanExpiryBounds(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	cases := []struct {
+		expiresIn string
+		wantCode  int
+	}{
+		{"-1h", 400},    // negative
+		{"-0s", 400},    // negative zero
+		{"0s", 400},     // zero
+		{"1ns", 400},    // positive but below the 1-minute floor
+		{"59s", 400},    // just under the floor
+		{"1m", 201},     // exactly the floor
+		{"90s", 201},    // just over the floor
+		{"8760h", 201},  // exactly 1 year
+		{"8785h", 400},  // 1 year + 1 day: over the cap
+		{"87600h", 400}, // 10 years, the originally reported case
+	}
+	for _, c := range cases {
+		globalLimiter = newLimiter() // avoid create rate limit between cases
+		body, ct := multipartBody(t, map[string]string{
+			"json_items": `[{"title":"a.txt","content":"AAA"}]`,
+			"expires_in": c.expiresIn,
+		}, "files", "pic.txt", "file data")
+		req := httptest.NewRequest("POST", "/api/pastes/can", body)
+		req.Header.Set("Content-Type", ct)
+		rec := httptest.NewRecorder()
+		h.ServeHTTP(rec, req)
+		if rec.Code != c.wantCode {
+			t.Errorf("expires_in %q: got %d want %d (%s)",
+				c.expiresIn, rec.Code, c.wantCode, rec.Body.String())
+		}
+	}
+}

internal/api/issue68_validation_test.go

@@ -0,0 +1,198 @@
+package api
+
+// Regression tests for #68 input-validation gaps: negative/oversized content
+// lengths (413), limit=0 → default page size, unchecked query params
+// (negative offset), and negative burn_after_reads.
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func createPasteRaw(t *testing.T, h http.Handler, body string) *httptest.ResponseRecorder {
+	t.Helper()
+	req := httptest.NewRequest("POST", "/api/pastes", strings.NewReader(body))
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	return rec
+}
+
+// A request whose decoded content exceeds the admin-tunable cap is rejected
+// with 413 and a clear message (content under the body cap, over the
+// content cap).
+func TestCreatePasteContentOverCap413(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	// content over MaxContentBytes (5MiB) but under body cap (+4KiB): send
+	// just over the content cap so the per-field check fires first.
+	content := strings.Repeat("a", 5*1024*1024+10)
+	rec := createPasteRaw(t, h, fmt.Sprintf(`{"content":"%s"}`, content))
+	if rec.Code != http.StatusRequestEntityTooLarge {
+		t.Fatalf("got %d want 413: %s", rec.Code, rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "content exceeds max") {
+		t.Fatalf("unclear error message: %s", rec.Body.String())
+	}
+}
+
+// A request whose entire body is larger than the server-side body cap is cut
+// off by http.MaxBytesReader and answered with 413, not decoded into memory
+// (#68: previously a giant body was fully buffered, then rejected only at
+// the per-field check — actually the decode happened before any check).
+func TestCreatePasteBodyOverCap413(t *testing.T) {
+	s := testServer(t)
+	// shrink the content cap so the body cap is small too
+	ss := s.settings.get()
+	ss.MaxContentBytes = 64 * 1024
+	if err := s.settings.set(ss); err != nil {
+		t.Fatal(err)
+	}
+	h := s.routes()
+
+	content := strings.Repeat("a", 200*1024) // 200KiB > 64KiB+4KiB body cap
+	rec := createPasteRaw(t, h, fmt.Sprintf(`{"content":"%s","title":"x"}`, content))
+	if rec.Code != http.StatusRequestEntityTooLarge {
+		t.Fatalf("got %d want 413: %s", rec.Code, rec.Body.String())
+	}
+}
+
+// Negative content lengths cannot be expressed via JSON, but a negative
+// expires-style numeric payload must not crash; more importantly the
+// burn_after_reads field: negative values are rejected with a clear message.
+func TestCreatePasteNegativeBurnAfterReads(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	rec := createPasteRaw(t, h, `{"content":"hi","burn_after_reads":-5}`)
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("got %d want 400: %s", rec.Code, rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "burn_after_reads") {
+		t.Fatalf("unclear error message: %s", rec.Body.String())
+	}
+
+	// 0 and positive values still work (0 = default single read, per #49)
+	rec = createPasteRaw(t, h, `{"content":"hi","burn_after_reads":0,"burn_after_read":true}`)
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("zero burn_after_reads: got %d want 201: %s", rec.Code, rec.Body.String())
+	}
+}
+
+// limit=0 on list endpoints returns the default page size (existing clamp
+// treats <=0 as default; #68 asks this be explicit and tested).
+func TestListLimitZeroUsesDefault(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	// seed 3 public pastes
+	for i := 0; i < 3; i++ {
+		rec := createPasteRaw(t, h, fmt.Sprintf(`{"content":"p%d"}`, i))
+		if rec.Code != 201 {
+			t.Fatalf("seed: got %d: %s", rec.Code, rec.Body.String())
+		}
+	}
+
+	for _, q := range []string{"/api/public?limit=0", "/api/public"} {
+		req := httptest.NewRequest("GET", q, nil)
+		rec := httptest.NewRecorder()
+		h.ServeHTTP(rec, req)
+		if rec.Code != 200 {
+			t.Fatalf("%s: got %d", q, rec.Code)
+		}
+		var got struct {
+			Limit int                   `json:"limit"`
+			Total int                   `json:"total"`
+			Items []struct{ ID string } `json:"items"`
+		}
+		json.Unmarshal(rec.Body.Bytes(), &got)
+		if got.Limit != 25 || len(got.Items) != 3 {
+			t.Fatalf("%s: limit=%d items=%d, want limit 25 and all 3 items", q, got.Limit, len(got.Items))
+		}
+	}
+}
+
+// Huge limit values are clamped to the max page size (already the behavior;
+// regression-tested here per #68 "validate unchecked params").
+func TestListLimitHugeClamped(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	req := httptest.NewRequest("GET", "/api/public?limit=999999999", nil)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	var got struct {
+		Limit int `json:"limit"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &got)
+	if got.Limit != 25 {
+		t.Fatalf("limit=%d, want clamped to 25", got.Limit)
+	}
+}
+
+// Negative offset previously passed through unchecked to SQL (harmless in
+// SQLite, but invalid); it must be clamped to 0 (#68).
+func TestListNegativeOffsetClamped(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	for i := 0; i < 2; i++ {
+		rec := createPasteRaw(t, h, fmt.Sprintf(`{"content":"p%d"}`, i))
+		if rec.Code != 201 {
+			t.Fatalf("seed: got %d", rec.Code)
+		}
+	}
+
+	req := httptest.NewRequest("GET", "/api/public?offset=-999", nil)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	if rec.Code != 200 {
+		t.Fatalf("got %d", rec.Code)
+	}
+	var got struct {
+		Offset int `json:"offset"`
+		Total  int `json:"total"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &got)
+	if got.Offset != 0 || got.Total != 2 {
+		t.Fatalf("offset=%d total=%d, want offset 0 and total 2", got.Offset, got.Total)
+	}
+
+	// /api/mine too (needs the viewer cookie)
+	req = httptest.NewRequest("GET", "/api/mine?offset=-5", nil)
+	req.AddCookie(&http.Cookie{Name: "vwr", Value: "offclamp"})
+	rec = httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	var mine struct {
+		Offset int `json:"offset"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &mine)
+	if mine.Offset != 0 {
+		t.Fatalf("mine offset=%d, want 0", mine.Offset)
+	}
+}
+
+// Non-numeric limit/offset fall back to defaults instead of 500s.
+func TestListGarbageParams(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	req := httptest.NewRequest("GET", "/api/public?limit=abc&offset=xyz", nil)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	if rec.Code != 200 {
+		t.Fatalf("got %d", rec.Code)
+	}
+	var got struct {
+		Limit  int `json:"limit"`
+		Offset int `json:"offset"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &got)
+	if got.Limit != 25 || got.Offset != 0 {
+		t.Fatalf("limit=%d offset=%d, want 25/0", got.Limit, got.Offset)
+	}
+}

internal/api/issue81_password_ratelimit_test.go

@@ -0,0 +1,92 @@
+package api
+
+// #81: ALL password verification attempts (GET query param, header, POST
+// form) must go through the per-IP unlock limiter. Regression: N wrong
+// passwords via GET ?password= must eventually yield 429.
+
+import (
+	"encoding/json"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func createPasswordPaste(t *testing.T, s *apiServer, pw string) string {
+	t.Helper()
+	h := s.routes()
+	body := `{"content":"secret","password":"` + pw + `"}`
+	req := httptest.NewRequest("POST", "/api/pastes", strings.NewReader(body))
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	var created struct {
+		ID string `json:"id"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &created)
+	return created.ID
+}
+
+// TestRateLimitGetPasswordQuery: repeated wrong passwords via GET
+// ?password= must eventually return 429 (unlock limiter: burst 5).
+func TestRateLimitGetPasswordQuery(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+	id := createPasswordPaste(t, s, "hunter2")
+
+	var saw429 bool
+	// more attempts than the unlock burst (5)
+	for i := 0; i < 10; i++ {
+		req := httptest.NewRequest("GET", "/api/pastes/"+id+"?password=wrong"+string(rune('a'+i)), nil)
+		rec := httptest.NewRecorder()
+		h.ServeHTTP(rec, req)
+		if rec.Code == 429 {
+			saw429 = true
+			break
+		}
+		if rec.Code != 401 {
+			t.Fatalf("attempt %d: expected 401 before limit, got %d", i, rec.Code)
+		}
+	}
+	if !saw429 {
+		t.Fatal("expected 429 after repeated wrong ?password= attempts, never got one")
+	}
+}
+
+// TestRateLimitGetPasswordHeader: same guarantee for the X-Paste-Password header path.
+func TestRateLimitGetPasswordHeader(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+	id := createPasswordPaste(t, s, "hunter2")
+
+	var saw429 bool
+	for i := 0; i < 10; i++ {
+		req := httptest.NewRequest("GET", "/api/pastes/"+id, nil)
+		req.Header.Set("X-Paste-Password", "wrong"+string(rune('a'+i)))
+		rec := httptest.NewRecorder()
+		h.ServeHTTP(rec, req)
+		if rec.Code == 429 {
+			saw429 = true
+			break
+		}
+		if rec.Code != 401 {
+			t.Fatalf("attempt %d: expected 401 before limit, got %d", i, rec.Code)
+		}
+	}
+	if !saw429 {
+		t.Fatal("expected 429 after repeated wrong header password attempts, never got one")
+	}
+}
+
+// TestRateLimitGetPasswordCorrectStillAllowed: a correct password must still
+// work within the burst (the limiter gates attempts, not correctness).
+func TestRateLimitGetPasswordCorrectStillAllowed(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+	id := createPasswordPaste(t, s, "hunter2")
+
+	req := httptest.NewRequest("GET", "/api/pastes/"+id+"?password=hunter2", nil)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	if rec.Code != 200 {
+		t.Fatalf("expected 200 for correct password within burst, got %d", rec.Code)
+	}
+}

internal/api/issue86_field_bounds_test.go

@@ -0,0 +1,152 @@
+package api
+
+// Regression tests for #86: title and language are bounded at create time.
+// Titles over 200 chars are truncated; language must match
+// ^[a-zA-Z0-9+#-]{1,40}$ or the create is rejected with a clear 400.
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// pasteMeta fetches a created paste's stored metadata via the API.
+func pasteMeta(t *testing.T, h http.Handler, id string) map[string]any {
+	t.Helper()
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, httptest.NewRequest("GET", "/api/pastes/"+id, nil))
+	if rec.Code != 200 {
+		t.Fatalf("get paste %s: got %d: %s", id, rec.Code, rec.Body.String())
+	}
+	var m map[string]any
+	if err := json.Unmarshal(rec.Body.Bytes(), &m); err != nil {
+		t.Fatal(err)
+	}
+	return m
+}
+
+// A 5000-char title is truncated to 200 characters at create time (#86).
+func TestCreatePasteTitleTruncated(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	title := strings.Repeat("t", 5000)
+	body, _ := json.Marshal(map[string]any{"content": "hi", "title": title})
+	rec := createPasteRaw(t, h, string(body))
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("got %d want 201: %s", rec.Code, rec.Body.String())
+	}
+	var resp struct {
+		ID string `json:"id"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &resp)
+	meta := pasteMeta(t, h, resp.ID)
+	got, _ := meta["title"].(string)
+	if got != strings.Repeat("t", 200) {
+		t.Fatalf("title not truncated to 200 chars: len=%d", len(got))
+	}
+}
+
+// A title within the 200-char bound is stored verbatim (minus surrounding
+// whitespace, which is trimmed).
+func TestCreatePasteTitleWithinBoundKept(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	title := "  " + strings.Repeat("x", 200) + "  "
+	body, _ := json.Marshal(map[string]any{"content": "hi", "title": title})
+	rec := createPasteRaw(t, h, string(body))
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("got %d want 201: %s", rec.Code, rec.Body.String())
+	}
+	var resp struct {
+		ID string `json:"id"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &resp)
+	meta := pasteMeta(t, h, resp.ID)
+	if got, _ := meta["title"].(string); got != strings.Repeat("x", 200) {
+		t.Fatalf("title changed unexpectedly: len=%d", len(got))
+	}
+}
+
+// A language longer than 40 chars is rejected with a clear 400 (#86).
+func TestCreatePasteLanguageTooLong400(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	body, _ := json.Marshal(map[string]any{"content": "hi", "language": strings.Repeat("a", 41)})
+	rec := createPasteRaw(t, h, string(body))
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("got %d want 400: %s", rec.Code, rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "language") {
+		t.Fatalf("unclear error message: %s", rec.Body.String())
+	}
+}
+
+// Language strings outside ^[a-zA-Z0-9+#-]{1,40}$ are rejected with 400.
+func TestCreatePasteLanguageBadFormat400(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	for _, bad := range []string{
+		"<img src=x onerror=alert(1)>",
+		"java script",
+		"c++ extra!",
+		"py_thon",
+		"go.lang",
+	} {
+		body, _ := json.Marshal(map[string]any{"content": "hi", "language": bad})
+		rec := createPasteRaw(t, h, string(body))
+		if rec.Code != http.StatusBadRequest {
+			t.Errorf("language %q: got %d want 400: %s", bad, rec.Code, rec.Body.String())
+			continue
+		}
+		if !strings.Contains(rec.Body.String(), "language must match") {
+			t.Errorf("language %q: unclear error: %s", bad, rec.Body.String())
+		}
+	}
+}
+
+// Valid languages (letters, digits, #, +, -) within 40 chars are accepted.
+func TestCreatePasteLanguageValidAccepted(t *testing.T) {
+	for _, ok := range []string{"go", "c#", "f#", "c++", "objective-c", "ECMAScript-2023", strings.Repeat("a", 40)} {
+		s2 := testServer(t) // fresh rate limiter per case
+		h2 := s2.routes()
+		body, _ := json.Marshal(map[string]any{"content": "hi", "language": ok})
+		rec := createPasteRaw(t, h2, string(body))
+		if rec.Code != http.StatusCreated {
+			t.Errorf("language %q: got %d want 201: %s", ok, rec.Code, rec.Body.String())
+		}
+	}
+}
+
+// An absent or blank language still creates fine and stores NULL, and a
+// blank title is stored NULL rather than an empty string.
+func TestCreatePasteBlankMetadataOK(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	for _, body := range []string{
+		`{"content":"hi"}`,
+		`{"content":"hi","language":"","title":"  "}`,
+	} {
+		rec := createPasteRaw(t, h, body)
+		if rec.Code != http.StatusCreated {
+			t.Fatalf("body %s: got %d want 201: %s", body, rec.Code, rec.Body.String())
+		}
+		var resp struct {
+			ID string `json:"id"`
+		}
+		json.Unmarshal(rec.Body.Bytes(), &resp)
+		meta := pasteMeta(t, h, resp.ID)
+		if lang, ok := meta["language"]; ok && lang != nil && lang != "" {
+			t.Fatalf("body %s: language not null: %v", body, lang)
+		}
+		if title, ok := meta["title"]; ok && title != nil && title != "" {
+			t.Fatalf("body %s: title not null: %v", body, title)
+		}
+	}
+}

internal/api/main_test.go

@@ -183,6 +183,46 @@ func TestListPublicExcludesUnlisted(t *testing.T) {
 	}
 }
 
+func TestListPublicExcludesPasswordAndUnlisted(t *testing.T) {
+	s := testServer(t)
+	h := s.routes()
+
+	bodies := []string{
+		`{"content":"open","visibility":"public"}`,
+		`{"content":"locked","visibility":"public","password":"hunter2"}`,
+		`{"content":"hidden","visibility":"unlisted"}`,
+	}
+	for _, body := range bodies {
+		req := httptest.NewRequest("POST", "/api/pastes", strings.NewReader(body))
+		rec := httptest.NewRecorder()
+		h.ServeHTTP(rec, req)
+		if rec.Code != 201 {
+			t.Fatalf("create %s: got %d", body, rec.Code)
+		}
+	}
+
+	req := httptest.NewRequest("GET", "/api/public", nil)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	if rec.Code != 200 {
+		t.Fatalf("list public: got %d", rec.Code)
+	}
+	var resp struct {
+		Total int              `json:"total"`
+		Items []map[string]any `json:"items"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &resp)
+	if resp.Total != 1 || len(resp.Items) != 1 {
+		t.Fatalf("expected only the 1 public paste, got total=%d items=%d", resp.Total, len(resp.Items))
+	}
+	// password-protected and unlisted pastes must not appear (no metadata leak)
+	for _, secret := range []string{"hunter2", "locked", "hidden"} {
+		if strings.Contains(rec.Body.String(), secret) {
+			t.Fatalf("leaked %q in /api/public response", secret)
+		}
+	}
+}
+
 func TestSweepSoftDeletesAfterGrace(t *testing.T) {
 	s := testServer(t)
 	h := s.routes()

internal/api/publicbool_test.go

@@ -0,0 +1,97 @@
+package api
+
+// #83 regression tests: `public` boolean in the create payload must map to
+// visibility (false -> unlisted, true -> public); string `visibility` still works.
+
+import (
+	"encoding/json"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func createPasteBody(t *testing.T, h *apiServer, body string) map[string]any {
+	req := httptest.NewRequest("POST", "/api/pastes", strings.NewReader(body))
+	rec := httptest.NewRecorder()
+	h.routes().ServeHTTP(rec, req)
+	if rec.Code != 201 {
+		t.Fatalf("create: got %d: %s", rec.Code, rec.Body.String())
+	}
+	var resp map[string]any
+	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("bad json: %v", err)
+	}
+	return resp
+}
+
+func getVis(t *testing.T, h *apiServer, id string) string {
+	req := httptest.NewRequest("GET", "/api/pastes/"+id, nil)
+	rec := httptest.NewRecorder()
+	h.routes().ServeHTTP(rec, req)
+	if rec.Code != 200 {
+		t.Fatalf("get %s: got %d", id, rec.Code)
+	}
+	var resp struct {
+		Visibility string `json:"visibility"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("bad json: %v", err)
+	}
+	return resp.Visibility
+}
+
+// TestPublicBooleanFalseMapsToUnlisted: {"public": false} must create an unlisted paste.
+func TestPublicBooleanFalseMapsToUnlisted(t *testing.T) {
+	s := testServer(t)
+	resp := createPasteBody(t, s, `{"content":"x","public":false}`)
+	if v := getVis(t, s, resp["id"].(string)); v != "unlisted" {
+		t.Fatalf("public:false -> got visibility %q, want unlisted", v)
+	}
+}
+
+// TestPublicBooleanTrueMapsToPublic: {"public": true} must create a public paste.
+func TestPublicBooleanTrueMapsToPublic(t *testing.T) {
+	s := testServer(t)
+	resp := createPasteBody(t, s, `{"content":"x","public":true}`)
+	if v := getVis(t, s, resp["id"].(string)); v != "public" {
+		t.Fatalf("public:true -> got visibility %q, want public", v)
+	}
+}
+
+// TestPublicBooleanOverridesString: boolean wins when both fields are sent.
+func TestPublicBooleanOverridesString(t *testing.T) {
+	s := testServer(t)
+	resp := createPasteBody(t, s, `{"content":"x","visibility":"public","public":false}`)
+	if v := getVis(t, s, resp["id"].(string)); v != "unlisted" {
+		t.Fatalf("boolean override -> got %q, want unlisted", v)
+	}
+}
+
+// TestVisibilityStringStillWorks: existing string contract unchanged.
+func TestVisibilityStringStillWorks(t *testing.T) {
+	s := testServer(t)
+	resp := createPasteBody(t, s, `{"content":"x","visibility":"unlisted"}`)
+	if v := getVis(t, s, resp["id"].(string)); v != "unlisted" {
+		t.Fatalf("string field -> got %q, want unlisted", v)
+	}
+	resp = createPasteBody(t, s, `{"content":"y","visibility":"public"}`)
+	if v := getVis(t, s, resp["id"].(string)); v != "public" {
+		t.Fatalf("string field -> got %q, want public", v)
+	}
+}
+
+// TestPublicListExcludesPublicFalse: {"public":false} pastes stay out of /api/public.
+func TestPublicListExcludesPublicFalse(t *testing.T) {
+	s := testServer(t)
+	createPasteBody(t, s, `{"content":"hidden","public":false}`)
+	req := httptest.NewRequest("GET", "/api/public", nil)
+	rec := httptest.NewRecorder()
+	s.routes().ServeHTTP(rec, req)
+	var resp struct {
+		Total int `json:"total"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &resp)
+	if resp.Total != 0 {
+		t.Fatalf("public:false paste leaked into /api/public: total=%d", resp.Total)
+	}
+}

internal/api/ratelimit.go

@@ -48,8 +48,28 @@ func (l *limiter) allow(key string, rate, burst float64) bool {
 	return true
 }
 
-// clientIP extracts the request IP (no reverse proxy header by default).
+// clientIP extracts the client IP for rate-limit keying (#85).
+//
+// Trust boundary: palette runs behind exactly ONE trusted reverse proxy
+// (Traefik in the k3s pod network). Traefik APPENDS the real client IP to
+// X-Forwarded-For, so the RIGHTMOST entry is the last value the trusted
+// proxy observed and is unspoofable by the client (a client-supplied fake
+// entry only lands on the LEFT and is ignored). This matches chi's
+// middleware.RealIP semantics for a single trusted proxy hop.
+//
+// Direct connections (no XFF header) fall back to RemoteAddr. Directly
+// reachable deployments must NOT expose the app to untrusted networks
+// without a proxy in front, or attackers could forge the rightmost entry.
 func clientIP(r *http.Request) string {
+	if xff := r.Header.Get("X-Forwarded-For"); xff != "" {
+		if i := strings.LastIndex(xff, ","); i >= 0 {
+			return strings.TrimSpace(xff[i+1:])
+		}
+		return strings.TrimSpace(xff)
+	}
+	if xr := r.Header.Get("X-Real-Ip"); xr != "" {
+		return strings.TrimSpace(xr)
+	}
 	host := r.RemoteAddr
 	if i := strings.LastIndex(host, ":"); i > 0 {
 		host = host[:i]
@@ -84,6 +104,12 @@ func rateLimitUnlock(id string, r *http.Request) bool {
 	return globalLimiter.allow("unlock:"+id+":"+clientIP(r), 5.0/60.0, 5)
 }
 
+// rateLimitAdmin: 5 attempts per minute per IP on the admin key check (#66),
+// same pattern as the unlock limiter (#34).
+func rateLimitAdmin(r *http.Request) bool {
+	return globalLimiter.allow("admin:"+clientIP(r), 5.0/60.0, 5)
+}
+
 // writeRateLimited responds 429 with Retry-After based on refill rate.
 func writeRateLimited(w http.ResponseWriter, retryAfterSecs int) {
 	w.Header().Set("Retry-After", strconv.Itoa(retryAfterSecs))

internal/api/ratelimit_xff_test.go

@@ -0,0 +1,85 @@
+package api
+
+// Issue #85: the rate limit key must use the rightmost X-Forwarded-For entry
+// (appended by the trusted Traefik proxy), never the raw/leftmost header
+// value a client can forge. A spoofed FIRST XFF entry must not bypass the
+// limit or rotate buckets.
+
+import (
+	"bytes"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestClientIPTakesRightmostXFF(t *testing.T) {
+	r := httptest.NewRequest("POST", "/", nil)
+	r.RemoteAddr = "10.42.0.7:51000" // trusted Traefik pod
+	r.Header.Set("X-Forwarded-For", "1.2.3.4, 1.2.3.5, 203.0.113.9")
+	if got := clientIP(r); got != "203.0.113.9" {
+		t.Fatalf("clientIP = %q, want rightmost 203.0.113.9", got)
+	}
+}
+
+func TestClientIPXRealIPFallback(t *testing.T) {
+	r := httptest.NewRequest("POST", "/", nil)
+	r.RemoteAddr = "10.42.0.7:51000"
+	r.Header.Set("X-Real-Ip", "203.0.113.10")
+	if got := clientIP(r); got != "203.0.113.10" {
+		t.Fatalf("clientIP = %q, want 203.0.113.10", got)
+	}
+}
+
+func TestClientIPDirectFallback(t *testing.T) {
+	r := httptest.NewRequest("POST", "/", nil)
+	r.RemoteAddr = "198.51.100.5:51000"
+	if got := clientIP(r); got != "198.51.100.5" {
+		t.Fatalf("clientIP = %q, want 198.51.100.5", got)
+	}
+}
+
+// TestRateLimitSpoofedFirstXFFDoesNotBypass: an attacker rotating a fake
+// leftmost XFF entry stays limited on their real (rightmost) IP.
+func TestRateLimitSpoofedFirstXFFDoesNotBypass(t *testing.T) {
+	srv := newTestServer(t)
+	h := srv.routes()
+	for i := 0; i < 5; i++ {
+		req := httptest.NewRequest("POST", "/api/pastes", bytes.NewReader([]byte(`{"content":"hi"}`)))
+		req.RemoteAddr = "10.42.0.7:51000"
+		// each request spoofs a DIFFERENT leftmost entry
+		req.Header.Set("X-Forwarded-For", spoofN(i)+", 203.0.113.9")
+		rr := httptest.NewRecorder()
+		h.ServeHTTP(rr, req)
+		if rr.Code != 201 {
+			t.Fatalf("req %d: want 201, got %d", i, rr.Code)
+		}
+	}
+	// 6th request, still the same real IP, new spoofed prefix: must 429
+	req := httptest.NewRequest("POST", "/api/pastes", bytes.NewReader([]byte(`{"content":"hi"}`)))
+	req.RemoteAddr = "10.42.0.7:51000"
+	req.Header.Set("X-Forwarded-For", "9.9.9.9, 203.0.113.9")
+	rr := httptest.NewRecorder()
+	h.ServeHTTP(rr, req)
+	if rr.Code != 429 {
+		t.Fatalf("spoofed 6th req: want 429, got %d", rr.Code)
+	}
+}
+
+func spoofN(i int) string {
+	return "1.2.3." + string(rune('0'+i))
+}
+
+// Distinct real IPs must still get distinct buckets (no over-limiting).
+func TestRateLimitDistinctRightmostIPsIndependent(t *testing.T) {
+	srv := newTestServer(t)
+	h := srv.routes()
+	for _, ip := range []string{"203.0.113.20", "203.0.113.21"} {
+		req := httptest.NewRequest("POST", "/api/pastes", bytes.NewReader([]byte(`{"content":"hi"}`)))
+		req.RemoteAddr = "10.42.0.7:51000"
+		req.Header.Set("X-Forwarded-For", "6.6.6.6, "+ip)
+		rr := httptest.NewRecorder()
+		h.ServeHTTP(rr, req)
+		if rr.Code != 201 {
+			t.Fatalf("ip %s: want 201, got %d", ip, rr.Code)
+		}
+	}
+}

internal/api/server.go

@@ -60,7 +60,9 @@ func (a *apiServer) routes() http.Handler {
 	r := chi.NewRouter()
 	r.Use(middleware.Recoverer)
 	r.Use(middleware.Timeout(30 * time.Second))
+	r.Use(a.limitRequestBody) // #68: hard server-side body cap -> 413
 	r.Use(viewerCookieMiddleware)
+	r.Use(web.SecurityHeaders) // #59: CSP + hardening headers on HTML pages
 
 	// admin (#40): HTML page is open (key entry via form); API is key-guarded
 	r.Get("/admin", a.ui.Handlers().HandleAdminPage)
@@ -155,16 +157,43 @@ func (a *apiServer) handleCreatePaste(w http.ResponseWriter, r *http.Request) {
 	}
 	var p store.Paste
 	if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
+		if isBodyTooLarge(err) { // #68: body cut off by MaxBytesReader
+			writeBodyTooLarge(w)
+			return
+		}
 		writeErr(w, 400, "invalid json body")
 		return
 	}
-	if strings.TrimSpace(p.Content) == "" {
-		writeErr(w, 400, "content is required")
+	if status, msg := checkContent(p.Content, s.MaxContentBytes); status != 0 {
+		writeErr(w, status, msg)
 		return
 	}
-	if int64(len(p.Content)) > s.MaxContentBytes { // #40: admin-tunable
-		writeErr(w, 413, fmt.Sprintf("content exceeds max %d bytes", s.MaxContentBytes))
-		return
+	// #86: bound free-form metadata at create time
+	if p.Title != nil {
+		t, err := checkTitle(*p.Title)
+		if err != nil {
+			writeErr(w, 400, err.Error())
+			return
+		}
+		p.Title = &t
+	}
+	if p.Language != nil {
+		l, err := checkLanguage(*p.Language)
+		if err != nil {
+			writeErr(w, 400, err.Error())
+			return
+		}
+		if l == "" {
+			p.Language = nil
+		} else {
+			p.Language = &l
+		}
+	}
+	if p.BurnAfterReads != nil { // #68: reject negative read budgets
+		if err := parseBurnAfterReads(*p.BurnAfterReads); err != nil {
+			writeErr(w, 400, err.Error())
+			return
+		}
 	}
 	// #40: admin-configurable default expiry
 	if (p.ExpiresIn == nil || *p.ExpiresIn == "") && s.DefaultExpiry != "" {
@@ -209,6 +238,13 @@ func (a *apiServer) handleGetPaste(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	if row.PasswordHash.Valid {
+		// #81: every password verification (header, query param, or empty)
+		// goes through the same per-IP+paste unlock limiter as the POST form
+		// path, so brute-force via GET ?password= or X-Paste-Password gets 429.
+		if !rateLimitUnlock(row.ID, r) {
+			writeRateLimited(w, 60)
+			return
+		}
 		// require password via header or query
 		pw := r.Header.Get("X-Paste-Password")
 		if pw == "" {
@@ -293,11 +329,8 @@ func (a *apiServer) handleListMine(w http.ResponseWriter, r *http.Request) {
 		writeJSON(w, 200, map[string]any{"total": 0, "items": []any{}})
 		return
 	}
-	limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
-	if limit <= 0 || limit > 100 {
-		limit = 50
-	}
-	offset, _ := strconv.Atoi(r.URL.Query().Get("offset"))
+	limit := parseLimit(r, 50, 100)
+	offset := parseOffset(r)
 	rows, total, err := a.store.ListMine(vid, limit, offset)
 	if err != nil {
 		writeErr(w, 500, "db error")
@@ -317,11 +350,8 @@ func (a *apiServer) handleListMine(w http.ResponseWriter, r *http.Request) {
 }
 
 func (a *apiServer) handleListPublic(w http.ResponseWriter, r *http.Request) {
-	limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
-	if limit <= 0 || limit > 100 {
-		limit = 25
-	}
-	offset, _ := strconv.Atoi(r.URL.Query().Get("offset"))
+	limit := parseLimit(r, 25, 100)
+	offset := parseOffset(r)
 	rows, total, err := a.store.ListPublic(limit, offset)
 	if err != nil {
 		writeErr(w, 500, "db error")

internal/api/validate.go

@@ -0,0 +1,136 @@
+package api
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// #68 input-validation helpers. Paste/can payloads are size-capped and list
+// endpoints get a single place where limit/offset are parsed and clamped.
+
+// maxRequestBody returns the HTTP body cap for JSON create endpoints: the
+// admin-tunable content cap plus headroom for JSON field overhead, floored
+// at 64KiB so a tiny admin-configured cap can't break small requests.
+func (a *apiServer) maxRequestBody() int64 {
+	s := a.settings.get()
+	max := s.MaxContentBytes + 4096
+	if max < 64*1024 {
+		max = 64 * 1024
+	}
+	return max
+}
+
+// limitRequestBody wraps the request body with http.MaxBytesReader so
+// oversized payloads are cut off server-side instead of being fully decoded
+// into memory before the per-field size check runs (#68). A read over the
+// cap surfaces as *http.MaxBytesError, which handlers map to 413.
+func (a *apiServer) limitRequestBody(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Body != nil {
+			r.Body = http.MaxBytesReader(w, r.Body, a.maxRequestBody())
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+// writeBodyTooLarge emits the 413 response for a body rejected by
+// MaxBytesReader.
+func writeBodyTooLarge(w http.ResponseWriter) {
+	writeErr(w, http.StatusRequestEntityTooLarge, "request body too large")
+}
+
+// isBodyTooLarge reports whether err came from http.MaxBytesReader.
+func isBodyTooLarge(err error) bool {
+	var mbe *http.MaxBytesError
+	return errors.As(err, &mbe)
+}
+
+// checkContent validates paste content: rejects whitespace-only content
+// (400) and content over the byte cap (413). Returns (0, "") when valid.
+func checkContent(content string, maxBytes int64) (int, string) {
+	if strings.TrimSpace(content) == "" {
+		return http.StatusBadRequest, "content is required"
+	}
+	if int64(len(content)) > maxBytes { // #40/#68: admin-tunable cap
+		return http.StatusRequestEntityTooLarge,
+			fmt.Sprintf("content exceeds max %d bytes", maxBytes)
+	}
+	return 0, ""
+}
+
+// parseLimit clamps the ?limit query param: missing/non-numeric/zero/negative
+// or over-max values fall back to def. Zero intentionally maps to the default
+// page size, matching the pre-existing `<= 0` clamp (#68).
+func parseLimit(r *http.Request, def, max int) int {
+	n, err := strconv.Atoi(r.URL.Query().Get("limit"))
+	if err != nil || n <= 0 || n > max {
+		return def
+	}
+	return n
+}
+
+// parseOffset clamps the ?offset query param: missing/non-numeric or negative
+// values become 0 (#68: negative offsets previously passed through to SQL).
+func parseOffset(r *http.Request) int {
+	n, err := strconv.Atoi(r.URL.Query().Get("offset"))
+	if err != nil || n < 0 {
+		return 0
+	}
+	return n
+}
+
+// parseBurnAfterReads validates the burn_after_reads field (#68): negative
+// values are rejected; zero/absent mean the default single read.
+func parseBurnAfterReads(n int) error {
+	if n < 0 {
+		return errors.New("burn_after_reads must be a positive number")
+	}
+	return nil
+}
+
+// #86: bounds for free-form metadata fields on create.
+const (
+	maxTitleLen    = 200
+	maxLanguageLen = 40
+)
+
+// languageRe restricts language to identifiers like go, c#, f#, c++, objc.
+var languageRe = regexp.MustCompile(`^[a-zA-Z0-9+#-]{1,40}$`)
+
+// checkTitle validates the paste title (#86): over-max titles are truncated
+// to 200 characters so a bloated listing entry can't be stored; whitespace
+// is trimmed first.
+func checkTitle(title string) (string, error) {
+	title = strings.TrimSpace(title)
+	if len(title) > maxTitleLen {
+		return truncateRunes(title, maxTitleLen), nil
+	}
+	return title, nil
+}
+
+// checkLanguage validates the language field (#86): optional, max 40 chars,
+// and must match ^[a-zA-Z0-9+#-]{1,40}$. Returns "" for absent/blank values.
+// Anything else malformed is a 400.
+func checkLanguage(lang string) (string, error) {
+	lang = strings.TrimSpace(lang)
+	if lang == "" {
+		return "", nil
+	}
+	if len(lang) > maxLanguageLen || !languageRe.MatchString(lang) {
+		return "", fmt.Errorf("language must match ^[a-zA-Z0-9+#-]{1,40}$ (max %d chars)", maxLanguageLen)
+	}
+	return lang, nil
+}
+
+// truncateRunes cuts s to at most max runes, keeping the prefix intact.
+func truncateRunes(s string, max int) string {
+	runes := []rune(s)
+	if len(runes) <= max {
+		return s
+	}
+	return string(runes[:max])
+}