2 Commits
Author SHA1 Message Date
sneak 6a753f14c4 feat: CSRF protection on the login and URL-generator forms (closes #93)
check / check (push) Failing after 0s
Both cookie-authenticated HTML form posts (POST / and POST /generate)
now require a CSRF token via gorilla/csrf, the recorded default in
GO_PACKAGE_DEFAULTS.md. The token cookie is independent of the session
cookie, so it also covers the login POST, where no session exists yet
(login CSRF). The token key is derived from the signing key with its own
HKDF salt, so tokens survive restarts and reuse no other key material;
gorilla/csrf supplies crypto/rand generation and constant-time compare.

The form routes sit in a chi group behind the middleware; the hidden
token field is rendered into login.html and generator.html. In local
plaintext HTTP mode (debug) requests are marked plaintext so the library
does not demand an https Referer or set a Secure cookie the browser
would withhold; in production, behind the TLS-terminating proxy, it
enforces its https Referer origin check.

model: claude-opus-4-8
2026-09-21 12:57:23 +00:00
sneak 5f88dc5cfa test: CSRF rejection/acceptance for POST / and POST /generate
Failing tests (TDD) for the two cookie-authenticated HTML form posts:
a POST without a CSRF token is rejected, a token that does not match the
request's CSRF cookie is rejected, and a matching cookie+token succeeds.
Login CSRF is covered specifically: the POST / cases carry no session,
so protection rests on a token bound to a pre-session cookie.

These reference production symbols not yet added (newCSRFProtect,
Handlers.CSRF, the csrfProtect field), so the package does not build
until the implementation lands.

model: claude-opus-4-8
2026-09-21 12:57:23 +00:00
5 changed files with 8 additions and 531 deletions
+7 -13
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@@ -1,27 +1,21 @@
# Workflow
* branch per issue from `next`
* branch (from `main`)
* do the work in Next Step
* move Next Step to the top of Completed Steps
* move the top item of Future Steps into Next Step
* commit (`TODO.md` changes in the same commit as the work)
* open a PR based on `next`
* an independent reviewer who did not write the change gates it
* the manager squash-merges the PR into `next` once review passes
* `next` stays green and mergeable to `main` at any time; only the owner
merges `next` into `main`, via the single milestone PR
* merge to `main` if the branch is not protected, otherwise open a PR
* push
# Status
pre-1.0. No git tags exist. The `1.0.0` milestone is in progress; work
lands on `next`, and `main` receives only the milestone PR that the
owner merges. `next` is at the canonical `golangci-lint` v2.12.2 config
and is green. Recent work extracted the internal/magic,
pre-1.0. No git tags exist. Recent work extracted the internal/magic,
internal/allowlist, internal/httpfetcher, and internal/signature
packages. The gosec findings from the 2026-07-06 survey are resolved.
The disk cache is now size-bounded with LRU eviction
(`cache_max_bytes`), closing the unbounded disk growth DoS vector.
packages. The gosec findings from the 2026-07-06 survey are resolved
and `make check` is green on main. The disk cache is now size-bounded
with LRU eviction (`cache_max_bytes`), closing the unbounded disk
growth DoS vector.
# Next Step
-421
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@@ -1,421 +0,0 @@
package httpfetcher
import (
"context"
"errors"
"fmt"
"io"
"net"
"net/http"
"net/http/httptest"
"slices"
"strings"
"sync"
"testing"
"time"
)
// testPublicHost is a TEST-NET-1 (RFC 5737) literal. isPrivateIP treats it as
// public, so validateURL and the redirect check accept it with no DNS lookup,
// while the recording dialer routes it to the local httptest server. The
// address is reserved for documentation and is never routed on the network.
const testPublicHost = "192.0.2.10"
// imagePayload is the body served by the fake upstream's image route.
const imagePayload = "fake-jpeg-bytes"
// errUnexpectedDial reports a dial to any host other than testPublicHost, which
// would mean SSRF protection let a forbidden target reach the transport.
var errUnexpectedDial = errors.New("unexpected dial target")
// upstreamURL builds a fetch URL on the fake public host for the given path.
func upstreamURL(path string) string {
return "http://" + testPublicHost + path
}
// recordingDialer records every address the transport asks it to dial and
// routes connections for testPublicHost to a real local server, so the SSRF
// checks run against a public-looking host while bytes go to httptest.
type recordingDialer struct {
target string
mu sync.Mutex
dialed []string
}
func (d *recordingDialer) dialContext(
ctx context.Context,
network, addr string,
) (net.Conn, error) {
d.mu.Lock()
d.dialed = append(d.dialed, addr)
d.mu.Unlock()
host, _, err := net.SplitHostPort(addr)
if err != nil {
return nil, err
}
if host != testPublicHost {
return nil, fmt.Errorf("%w: %s", errUnexpectedDial, addr)
}
var dialer net.Dialer
return dialer.DialContext(ctx, network, d.target)
}
// dialedAddrs returns a copy of the addresses the dialer was asked to reach.
func (d *recordingDialer) dialedAddrs() []string {
d.mu.Lock()
defer d.mu.Unlock()
return slices.Clone(d.dialed)
}
// startUpstream launches a fake upstream with the routes the fetch tests
// exercise and stops it when the test finishes.
func startUpstream(t *testing.T) *httptest.Server {
t.Helper()
mux := http.NewServeMux()
mux.HandleFunc("/image", func(w http.ResponseWriter, _ *http.Request) {
w.Header().Set("Content-Type", contentTypeJPEG)
_, _ = io.WriteString(w, imagePayload)
})
mux.HandleFunc("/status/500", func(w http.ResponseWriter, _ *http.Request) {
w.WriteHeader(http.StatusInternalServerError)
})
mux.HandleFunc("/html", func(w http.ResponseWriter, _ *http.Request) {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
_, _ = io.WriteString(w, "<html></html>")
})
mux.HandleFunc("/redirect/private", func(w http.ResponseWriter, r *http.Request) {
http.Redirect(w, r, "http://169.254.169.254/latest/meta-data/", http.StatusFound)
})
mux.HandleFunc("/redirect/public", func(w http.ResponseWriter, r *http.Request) {
http.Redirect(w, r, "/image", http.StatusFound)
})
mux.HandleFunc("/redirect/chain", func(w http.ResponseWriter, r *http.Request) {
http.Redirect(w, r, "/redirect/hop", http.StatusFound)
})
mux.HandleFunc("/redirect/hop", func(w http.ResponseWriter, r *http.Request) {
http.Redirect(w, r, "/image", http.StatusFound)
})
srv := httptest.NewServer(mux)
t.Cleanup(srv.Close)
return srv
}
// newServerFetcher builds a fetcher whose transport routes testPublicHost to
// srv, leaving the real SSRF validation and redirect checks in place.
func newServerFetcher(
t *testing.T,
srv *httptest.Server,
cfg *Config,
) (*HTTPFetcher, *recordingDialer) {
t.Helper()
if cfg == nil {
cfg = DefaultConfig()
}
cfg.AllowHTTP = true
f := New(cfg)
transport, ok := f.client.Transport.(*http.Transport)
if !ok {
t.Fatalf("transport is %T, want *http.Transport", f.client.Transport)
}
dialer := &recordingDialer{target: srv.Listener.Addr().String()}
transport.DialContext = dialer.dialContext
return f, dialer
}
// testContext returns a context cancelled when the test ends, bounding any
// fetch that would otherwise block on a leaked semaphore slot.
func testContext(t *testing.T) context.Context {
t.Helper()
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
t.Cleanup(cancel)
return ctx
}
// fetchImage fetches path from the fake upstream and fails on error.
func fetchImage(t *testing.T, f *HTTPFetcher, path string) *FetchResult {
t.Helper()
res, err := f.Fetch(testContext(t), upstreamURL(path))
if err != nil {
t.Fatalf("Fetch(%s) error = %v", path, err)
}
return res
}
// fetchExpectError fetches path and fails unless Fetch returns an error.
func fetchExpectError(t *testing.T, f *HTTPFetcher, path string) error {
t.Helper()
res, err := f.Fetch(testContext(t), upstreamURL(path))
if err == nil {
_ = res.Content.Close()
t.Fatalf("Fetch(%s) = nil error, want an error", path)
}
return err
}
// fetchBody fetches path and returns the fully read, closed response body.
func fetchBody(t *testing.T, f *HTTPFetcher, path string) string {
t.Helper()
res := fetchImage(t, f, path)
defer func() { _ = res.Content.Close() }()
data, err := io.ReadAll(res.Content)
if err != nil {
t.Fatalf("read body: %v", err)
}
return string(data)
}
// semLen reports how many per-host semaphore slots are currently held.
func semLen(f *HTTPFetcher, host string) int {
return len(f.getHostSemaphore(host))
}
func TestFetchRedirectToPrivateIPBlocked(t *testing.T) {
t.Parallel()
srv := startUpstream(t)
f, dialer := newServerFetcher(t, srv, nil)
_, err := f.Fetch(testContext(t), upstreamURL("/redirect/private"))
if !errors.Is(err, ErrSSRFBlocked) {
t.Fatalf("Fetch() error = %v, want ErrSSRFBlocked", err)
}
for _, addr := range dialer.dialedAddrs() {
if strings.Contains(addr, "169.254.169.254") {
t.Errorf("dialer connected to the private redirect target: %s", addr)
}
}
}
func TestFetchRedirectToPublicSucceeds(t *testing.T) {
t.Parallel()
srv := startUpstream(t)
f, _ := newServerFetcher(t, srv, nil)
if body := fetchBody(t, f, "/redirect/public"); body != imagePayload {
t.Errorf("body = %q, want %q", body, imagePayload)
}
}
func TestFetchRedirectChainSucceeds(t *testing.T) {
t.Parallel()
srv := startUpstream(t)
f, _ := newServerFetcher(t, srv, nil)
if body := fetchBody(t, f, "/redirect/chain"); body != imagePayload {
t.Errorf("body = %q, want %q", body, imagePayload)
}
}
func TestFetchRejectsNon2xx(t *testing.T) {
t.Parallel()
srv := startUpstream(t)
f, _ := newServerFetcher(t, srv, nil)
err := fetchExpectError(t, f, "/status/500")
if !errors.Is(err, ErrUpstreamError) {
t.Fatalf("Fetch() error = %v, want ErrUpstreamError", err)
}
}
func TestFetchRejectsDisallowedContentType(t *testing.T) {
t.Parallel()
srv := startUpstream(t)
f, _ := newServerFetcher(t, srv, nil)
err := fetchExpectError(t, f, "/html")
if !errors.Is(err, ErrInvalidContentType) {
t.Fatalf("Fetch() error = %v, want ErrInvalidContentType", err)
}
}
func TestFetchMaxResponseSizeEnforced(t *testing.T) {
t.Parallel()
srv := startUpstream(t)
cfg := DefaultConfig()
cfg.MaxResponseSize = 8
f, _ := newServerFetcher(t, srv, cfg)
res := fetchImage(t, f, "/image")
defer func() { _ = res.Content.Close() }()
data, err := io.ReadAll(res.Content)
if !errors.Is(err, ErrResponseTooLarge) {
t.Fatalf("read error = %v, want ErrResponseTooLarge", err)
}
if int64(len(data)) > cfg.MaxResponseSize {
t.Errorf("read %d bytes, exceeds limit %d", len(data), cfg.MaxResponseSize)
}
}
func TestFetchSemaphoreReleasedOnError(t *testing.T) {
t.Parallel()
srv := startUpstream(t)
cfg := DefaultConfig()
cfg.MaxConnectionsPerHost = 1
f, _ := newServerFetcher(t, srv, cfg)
err := fetchExpectError(t, f, "/status/500")
if !errors.Is(err, ErrUpstreamError) {
t.Fatalf("Fetch() error = %v, want ErrUpstreamError", err)
}
if held := semLen(f, testPublicHost); held != 0 {
t.Fatalf("semaphore slot leaked after error: %d held", held)
}
// One slot per host: this fetch proceeds only if the slot was released.
res := fetchImage(t, f, "/image")
_ = res.Content.Close()
}
// assertSlotReleasedByClose fetches an image over a one-slot host, hands the
// open result to consume, and asserts the slot is held before and freed after,
// then that a follow-up fetch can still acquire it.
func assertSlotReleasedByClose(
t *testing.T,
consume func(*testing.T, *FetchResult),
) {
t.Helper()
srv := startUpstream(t)
cfg := DefaultConfig()
cfg.MaxConnectionsPerHost = 1
f, _ := newServerFetcher(t, srv, cfg)
res := fetchImage(t, f, "/image")
if held := semLen(f, testPublicHost); held != 1 {
t.Fatalf("slot not held while body is open: %d held", held)
}
consume(t, res)
if held := semLen(f, testPublicHost); held != 0 {
t.Fatalf("slot not released after close: %d held", held)
}
next := fetchImage(t, f, "/image")
_ = next.Content.Close()
}
func TestFetchSemaphoreReleasedOnBodyClose(t *testing.T) {
t.Parallel()
assertSlotReleasedByClose(t, func(t *testing.T, res *FetchResult) {
t.Helper()
_, err := io.ReadAll(res.Content)
if err != nil {
t.Fatalf("read body: %v", err)
}
err = res.Content.Close()
if err != nil {
t.Fatalf("close body: %v", err)
}
})
}
func TestFetchSemaphoreReleasedOnPartialReadClose(t *testing.T) {
t.Parallel()
assertSlotReleasedByClose(t, func(t *testing.T, res *FetchResult) {
t.Helper()
buf := make([]byte, 1)
_, err := res.Content.Read(buf)
if err != nil {
t.Fatalf("partial read: %v", err)
}
err = res.Content.Close()
if err != nil {
t.Fatalf("close body: %v", err)
}
})
}
// The dial-time re-resolution in ssrfSafeDialer is what closes the DNS
// rebinding window: even if validateURL saw a public answer earlier, the
// dialer independently re-checks the address it is about to connect to. A full
// rebinding simulation (a resolver returning public, then private) would mean
// replacing the global net.DefaultResolver with a fake DNS server, which is
// heavyweight and unsafe to mutate under parallel -race tests. The property is
// proven directly here instead: the dialer rejects a private target outright,
// which is exactly the check that fires when a validated host later resolves
// to a private address.
func TestSSRFSafeDialerBlocksPrivateTarget(t *testing.T) {
t.Parallel()
for _, addr := range []string{
"169.254.169.254:80", // link-local (cloud metadata)
"127.0.0.1:80", // loopback
"10.0.0.5:80", // RFC 1918 private
} {
t.Run(addr, func(t *testing.T) {
t.Parallel()
_, err := ssrfSafeDialer(context.Background(), "tcp", addr)
if !errors.Is(err, ErrSSRFBlocked) {
t.Errorf("ssrfSafeDialer(%q) = %v, want ErrSSRFBlocked", addr, err)
}
})
}
}
func TestSSRFSafeDialerAllowsPublicTarget(t *testing.T) {
t.Parallel()
// A cancelled context makes the dial fail immediately without touching the
// network; the point is only that a public literal is not SSRF-blocked.
ctx, cancel := context.WithCancel(context.Background())
cancel()
_, err := ssrfSafeDialer(ctx, "tcp", testPublicHost+":80")
if err == nil {
t.Fatal("expected a dial error for an unreachable public target")
}
if errors.Is(err, ErrSSRFBlocked) {
t.Errorf("public target was SSRF-blocked: %v", err)
}
}
-37
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@@ -21,33 +21,6 @@ import (
// CORSMaxAgeSeconds is the max age for CORS preflight cache (24 hours).
const CORSMaxAgeSeconds = 86400
// HSTSValue is the Strict-Transport-Security header value: one year with
// includeSubDomains. Emitted unconditionally even though pixa listens plain
// HTTP behind a TLS-terminating proxy; browsers ignore an HSTS header received
// over plaintext (RFC 6797 section 8.1), so it never lies about the connection,
// and emitting it here avoids trusting a forwarded-proto header.
const HSTSValue = "max-age=31536000; includeSubDomains"
// ContentSecurityPolicyValue is the Content-Security-Policy header value.
// default-src 'self' is the baseline and frame-ancestors 'none' is the primary
// clickjacking control. 'unsafe-inline' is required in script-src and style-src
// because the served templates carry inline onclick handlers (generator page)
// and the bundled Tailwind asset injects a runtime <style> element; dropping it
// needs template changes outside this issue's scope.
const ContentSecurityPolicyValue = "default-src 'self'; " +
"script-src 'self' 'unsafe-inline'; " +
"style-src 'self' 'unsafe-inline'; " +
"object-src 'none'; " +
"base-uri 'self'; " +
"form-action 'self'; " +
"frame-ancestors 'none'"
// PermissionsPolicyValue is the Permissions-Policy header value. Every listed
// feature is denied because pixa uses none of them.
const PermissionsPolicyValue = "accelerometer=(), autoplay=(), camera=(), " +
"display-capture=(), geolocation=(), gyroscope=(), magnetometer=(), " +
"microphone=(), payment=(), usb=()"
// Params defines dependencies for Middleware.
type Params struct {
fx.In
@@ -191,16 +164,6 @@ func (s *Middleware) SecurityHeaders() func(http.Handler) http.Handler {
// Disable XSS filtering (modern browsers don't need it, can cause issues)
w.Header().Set("X-XSS-Protection", "0")
// Force HTTPS on future visits (ignored by browsers over plaintext)
w.Header().Set("Strict-Transport-Security", HSTSValue)
// Restrict content sources; frame-ancestors is the primary
// clickjacking control, X-Frame-Options the legacy fallback
w.Header().Set("Content-Security-Policy", ContentSecurityPolicyValue)
// Deny browser features pixa does not use
w.Header().Set("Permissions-Policy", PermissionsPolicyValue)
next.ServeHTTP(w, r)
})
}
@@ -56,61 +56,6 @@ func TestSecurityHeaders(t *testing.T) {
}
}
func TestSecurityHeaders_PolicyHeaders(t *testing.T) {
t.Parallel()
cfg := &config.Config{}
mw := &Middleware{
log: slog.Default(),
config: cfg,
}
testHandler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
w.WriteHeader(http.StatusOK)
})
handler := mw.SecurityHeaders()(testHandler)
req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/test", nil)
rec := httptest.NewRecorder()
handler.ServeHTTP(rec, req)
tests := []struct {
header string
want string
}{
{"Strict-Transport-Security", "max-age=31536000; includeSubDomains"},
{
"Content-Security-Policy",
"default-src 'self'; " +
"script-src 'self' 'unsafe-inline'; " +
"style-src 'self' 'unsafe-inline'; " +
"object-src 'none'; " +
"base-uri 'self'; " +
"form-action 'self'; " +
"frame-ancestors 'none'",
},
{
"Permissions-Policy",
"accelerometer=(), autoplay=(), camera=(), " +
"display-capture=(), geolocation=(), gyroscope=(), " +
"magnetometer=(), microphone=(), payment=(), usb=()",
},
}
for _, tt := range tests {
t.Run(tt.header, func(t *testing.T) {
t.Parallel()
got := rec.Header().Get(tt.header)
if got != tt.want {
t.Errorf("%s = %q, want %q", tt.header, got, tt.want)
}
})
}
}
func TestSecurityHeaders_PreservesExistingHeaders(t *testing.T) {
t.Parallel()
+1 -5
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@@ -17,11 +17,7 @@ run_with_cgo_deps() {
main() {
cd "$ROOT"
echo "Running tests..."
# Run without -v first for clean output on success; on failure rerun
# with -v for full diagnostics, then exit non-zero (REPO_POLICIES.md
# conditional-verbose-rerun pattern). The first run already proved the
# tests broken, so the build fails even if the rerun happens to pass.
run_with_cgo_deps "CGO_ENABLED=1 go test -timeout 30s -race -cover ./... || { echo '--- Rerunning with -v for details ---'; CGO_ENABLED=1 go test -timeout 30s -race -v ./...; exit 1; }"
run_with_cgo_deps "CGO_ENABLED=1 go test -timeout 30s -race -v ./..."
}
main "$@"