Harden inert snapshots and honor redirect URLs

CHANGELOG.md

@@ -6,6 +6,12 @@ All notable changes to kage are recorded here. The format follows
 
 ## [Unreleased]
 
+### Fixed
+
+- Saved pages no longer re-root relative URLs against the live origin via a leftover `<base href>`, and active content that escaped the script stripper is neutralized: `iframe` `srcdoc` and `data:text/html` sources, live remote frames, and HTML/SVG `object`/`embed` carriers.
+- Relative links on pages that redirected are resolved against the browser's final URL (and any document `<base href>`), while the page is still written under the discovered URL so existing offline links keep working.
+- Non-UTF-8 `<meta charset>` / Content-Type charset declarations are rewritten to `utf-8`, since kage always serialises pages as UTF-8 ([#16](https://github.com/tamnd/kage/issues/16)).
+
 ## [0.3.9] - 2026-07-08
 
 ### Fixed

README.md

@@ -259,7 +259,7 @@ cmd/kage/   thin main: pins the main thread, then hands off to cli.Execute
 cli/        the cobra command tree and flag wiring
 clone/      the crawl: frontier, render workers, asset workers, resume state
 browser/    headless Chrome control and DOM snapshotting
-sanitize/   strip scripts, handlers, and javascript: URLs from the DOM
+sanitize/   strip scripts, handlers, active frames, and javascript: URLs
 asset/      download and localise CSS, images, and fonts
 urlx/       the deterministic URL-to-path mapping
 zim/        a pure-Go ZIM reader and writer

clone/cloner.go

@@ -19,6 +19,7 @@ import (
 	"github.com/tamnd/kage/sanitize"
 	"github.com/tamnd/kage/urlx"
 	"golang.org/x/net/html"
+	"golang.org/x/net/html/atom"
 	"golang.org/x/time/rate"
 )
 
@@ -302,6 +303,13 @@ func (c *Cloner) processPage(ctx context.Context, j pageItem) {
 		return
 	}
 
+	// Resolve references against the post-redirect URL (and any <base href>),
+	// but keep writing the page under the discovered URL so existing offline
+	// links that pointed at /old still resolve. Cross-host redirects leave the
+	// resolve base as the final location for relative refs; scope checks still
+	// use that absolute URL.
+	resolveBase := pageResolveBase(j.u, res.FinalURL, root)
+
 	localFile := urlx.LocalPath(c.seedHost, j.u, urlx.Page, c.cfg.Reserved)
 	fileDir := urlx.Dir(localFile)
 
@@ -324,7 +332,7 @@ func (c *Cloner) processPage(ctx context.Context, j pageItem) {
 		}
 	}
 
-	asset.RewriteHTML(root, j.u, sink)
+	asset.RewriteHTML(root, resolveBase, sink)
 	sanitize.CleanTree(root, sanitize.Options{
 		KeepNoscript:   c.cfg.KeepNoscript,
 		MobileReadable: c.cfg.MobileReadable,
@@ -354,6 +362,55 @@ func (c *Cloner) waitForCrawlDelay(ctx context.Context) bool {
 	return c.crawlLimiter.Wait(ctx) == nil
 }
 
+// pageResolveBase picks the URL against which relative references on a rendered
+// page should resolve. Preference order:
+//  1. A document <base href> (the live page's own base);
+//  2. The browser's final URL after redirects;
+//  3. The URL that was enqueued.
+//
+// The page is still written under the enqueued URL so offline links discovered
+// as /old keep working when the server redirected /old → /new.
+func pageResolveBase(enqueued *url.URL, finalURL string, root *html.Node) *url.URL {
+	base := enqueued
+	if finalURL != "" {
+		if u, err := url.Parse(finalURL); err == nil && u.Scheme != "" && u.Host != "" {
+			// Drop fragment; keep query/path as the browser shows them.
+			u.Fragment = ""
+			base = u
+		}
+	}
+	if href := documentBaseHref(root); href != "" {
+		if u, err := urlx.Normalize(base, href); err == nil {
+			return u
+		}
+	}
+	return base
+}
+
+// documentBaseHref returns the first <base href> in document order, or "".
+func documentBaseHref(root *html.Node) string {
+	var found string
+	var walk func(*html.Node)
+	walk = func(n *html.Node) {
+		if found != "" || n == nil {
+			return
+		}
+		if n.Type == html.ElementNode && n.DataAtom == atom.Base {
+			for _, a := range n.Attr {
+				if strings.EqualFold(a.Key, "href") && strings.TrimSpace(a.Val) != "" {
+					found = strings.TrimSpace(a.Val)
+					return
+				}
+			}
+		}
+		for c := n.FirstChild; c != nil && found == ""; c = c.NextSibling {
+			walk(c)
+		}
+	}
+	walk(root)
+	return found
+}
+
 // processAsset downloads one asset, rewriting CSS references on the way, and
 // writes it to its deterministic local path.
 func (c *Cloner) processAsset(ctx context.Context, j assetItem) {

clone/resolve_test.go

@@ -0,0 +1,45 @@
+package clone
+
+import (
+	"net/url"
+	"strings"
+	"testing"
+
+	"golang.org/x/net/html"
+)
+
+func TestPageResolveBaseUsesFinalURL(t *testing.T) {
+	enqueued, _ := url.Parse("https://ex.com/old")
+	root, err := html.Parse(strings.NewReader(`<html><head></head><body><a href="next">n</a></body></html>`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	base := pageResolveBase(enqueued, "https://ex.com/new/", root)
+	if base.String() != "https://ex.com/new/" {
+		t.Fatalf("resolve base = %q, want final URL", base)
+	}
+}
+
+func TestPageResolveBasePrefersDocumentBase(t *testing.T) {
+	enqueued, _ := url.Parse("https://ex.com/page")
+	root, err := html.Parse(strings.NewReader(
+		`<html><head><base href="https://ex.com/dir/"></head><body></body></html>`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	base := pageResolveBase(enqueued, "https://ex.com/page", root)
+	if base.String() != "https://ex.com/dir/" {
+		t.Fatalf("resolve base = %q, want document <base>", base)
+	}
+}
+
+func TestDocumentBaseHref(t *testing.T) {
+	root, err := html.Parse(strings.NewReader(
+		`<html><head><base href="/subdir/"><base href="https://ignored.example/"></head></html>`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := documentBaseHref(root); got != "/subdir/" {
+		t.Fatalf("documentBaseHref = %q, want first base", got)
+	}
+}

docs/content/reference/release-notes.md

@@ -6,6 +6,11 @@ weight: 40
 
 The authoritative, commit-level history lives in [`CHANGELOG.md`](https://github.com/tamnd/kage/blob/main/CHANGELOG.md) and on the [releases page](https://github.com/tamnd/kage/releases). This page summarises each version.
 
+## Unreleased
+
+- **Inert-snapshot gaps closed.** `<base href>`, `iframe` `srcdoc` / `data:text/html`, live remote frames, and HTML/SVG `object`/`embed` no longer reintroduce live or executable content.
+- **Redirects resolve correctly.** Relative links use the post-redirect URL and any document `<base href>`, and non-UTF-8 charset metas are rewritten to UTF-8.
+
 ## v0.3.9
 
 A fix for the antivirus warning some Windows users hit when installing kage.