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FairEmail/app/src/main/java/eu/faircode/email/HtmlHelper.java

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package eu.faircode.email;
/*
This file is part of FairEmail.
FairEmail is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
FairEmail is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FairEmail. If not, see <http://www.gnu.org/licenses/>.
Copyright 2018-2019 by Marcel Bokhorst (M66B)
*/
import android.content.Context;
import android.content.SharedPreferences;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LevelListDrawable;
import android.os.Handler;
import android.text.Html;
import android.text.Spanned;
import android.text.TextUtils;
import android.util.Base64;
import android.util.DisplayMetrics;
import android.view.View;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.text.HtmlCompat;
import androidx.core.util.PatternsCompat;
import androidx.preference.PreferenceManager;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Attribute;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.nodes.Node;
import org.jsoup.nodes.TextNode;
import org.jsoup.safety.Cleaner;
import org.jsoup.safety.Whitelist;
import org.jsoup.select.NodeTraversor;
import org.jsoup.select.NodeVisitor;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import static androidx.core.text.HtmlCompat.FROM_HTML_SEPARATOR_LINE_BREAK_LIST_ITEM;
import static androidx.core.text.HtmlCompat.TO_HTML_PARAGRAPH_LINES_CONSECUTIVE;
public class HtmlHelper {
static final int PREVIEW_SIZE = 250;
private static final int TRACKING_PIXEL_SURFACE = 25;
private static final List<String> heads = Collections.unmodifiableList(Arrays.asList(
"h1", "h2", "h3", "h4", "h5", "h6", "p", "ol", "ul", "table", "br", "hr"));
private static final List<String> tails = Collections.unmodifiableList(Arrays.asList(
"h1", "h2", "h3", "h4", "h5", "h6", "p", "ol", "ul", "li"));
private static final ExecutorService executor =
Executors.newSingleThreadExecutor(Helper.backgroundThreadFactory);
static String sanitize(Context context, String html, boolean show_images) {
Document parsed = Jsoup.parse(html);
// <html xmlns:v="urn:schemas-microsoft-com:vml"
// xmlns:o="urn:schemas-microsoft-com:office:office"
// xmlns:w="urn:schemas-microsoft-com:office:word"
// xmlns:m="http://schemas.microsoft.com/office/2004/12/omml"
// xmlns="http://www.w3.org/TR/REC-html40">
// <o:p>&nbsp;</o:p></span>
// Default XHTML namespace: http://www.w3.org/1999/xhtml
String ns = null;
for (Element h : parsed.select("html"))
for (Attribute a : h.attributes()) {
String key = a.getKey();
String value = a.getValue();
if (value != null &&
key.startsWith("xmlns:") &&
value.startsWith("http://www.w3.org/")) {
ns = key.split(":")[1];
break;
}
}
for (Element e : parsed.select("*")) {
String tag = e.tagName();
if (tag.contains(":")) {
if (ns != null && tag.startsWith(ns)) {
e.tagName(tag.split(":")[1]);
Log.i("Updated tag=" + tag + " to=" + e.tagName());
} else {
e.remove();
Log.i("Removed tag=" + tag);
}
}
}
Whitelist whitelist = Whitelist.relaxed()
.addTags("hr", "abbr")
.removeTags("col", "colgroup", "thead", "tbody")
.removeAttributes("table", "width")
.removeAttributes("td", "colspan", "rowspan", "width")
.removeAttributes("th", "colspan", "rowspan", "width")
.addProtocols("img", "src", "cid")
.addProtocols("img", "src", "data");
final Document document = new Cleaner(whitelist).clean(parsed);
// Short quotes
for (Element q : document.select("q")) {
q.prependText("\"");
q.appendText("\"");
q.tagName("em");
}
// Pre formatted text
for (Element code : document.select("pre")) {
code.html(code.html().replaceAll("\\r?\\n", "<br />"));
code.tagName("div");
}
// Code
document.select("code").tagName("div");
// Lines
for (Element hr : document.select("hr")) {
hr.tagName("div");
hr.text("----------------------------------------");
}
// Descriptions
document.select("dl").tagName("div");
for (Element dt : document.select("dt")) {
dt.tagName("strong");
dt.appendElement("br");
}
for (Element dd : document.select("dd")) {
dd.tagName("em");
dd.appendElement("br").appendElement("br");
}
// Abbreviations
document.select("abbr").tagName("u");
// Subscript/Superscript
for (Element subp : document.select("sub,sup")) {
Element small = document.createElement("small");
small.html(subp.html());
subp.html(small.outerHtml());
}
// Lists
for (Element li : document.select("li")) {
li.tagName("span");
li.prependText("* ");
li.appendElement("br"); // line break after list item
}
document.select("ol").tagName("div");
document.select("ul").tagName("div");
// Tables
for (Element col : document.select("th,td")) {
// separate columns by a space
if (col.nextElementSibling() == null) {
if (col.selectFirst("div,table,p") == null)
col.appendElement("br");
} else
col.append("&nbsp;");
if ("th".equals(col.tagName()))
col.tagName("strong");
else
col.tagName("span");
}
for (Element row : document.select("tr"))
row.tagName("span");
document.select("caption").tagName("p");
for (Element table : document.select("table"))
if (table.parent() != null && "a".equals(table.parent().tagName()))
table.tagName("span"); // Links cannot contain tables
else
table.tagName("div");
// Images
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
boolean disable_tracking = prefs.getBoolean("disable_tracking", true);
for (Element img : document.select("img")) {
// Remove link tracking pixels
if (disable_tracking && isTrackingPixel(img)) {
String src = img.attr("src");
img.removeAttr("src");
img.tagName("a");
img.attr("href", src);
img.appendText(context.getString(R.string.title_hint_tracking_image,
img.attr("width"), img.attr("height")));
}
if (!show_images) {
String alt = img.attr("alt");
if (!TextUtils.isEmpty(alt)) {
img.appendText(alt);
}
}
// Annotate source with width and height
if (img.hasAttr("src")) {
int width = 0;
int height = 0;
String awidth = img.attr("width");
for (int i = 0; i < awidth.length(); i++)
if (Character.isDigit(awidth.charAt(i)))
width = width * 10 + (byte) awidth.charAt(i) - (byte) '0';
else
break;
String aheight = img.attr("height");
for (int i = 0; i < aheight.length(); i++)
if (Character.isDigit(aheight.charAt(i)))
height = height * 10 + (byte) aheight.charAt(i) - (byte) '0';
else
break;
if (width != 0 || height != 0) {
String src = img.attr("src");
AnnotatedSource a = new AnnotatedSource(src, width, height);
img.attr("src", a.getAnnotated());
}
}
}
// Autolink
final Pattern pattern = Pattern.compile(
PatternsCompat.AUTOLINK_EMAIL_ADDRESS.pattern() + "|" +
PatternsCompat.AUTOLINK_WEB_URL.pattern());
NodeTraversor.traverse(new NodeVisitor() {
@Override
public void head(Node node, int depth) {
if (node instanceof TextNode) {
TextNode tnode = (TextNode) node;
String text = tnode.text();
Matcher matcher = pattern.matcher(text);
if (matcher.find()) {
Element span = document.createElement("span");
int pos = 0;
do {
boolean linked = false;
Node parent = tnode.parent();
while (parent != null) {
if ("a".equals(parent.nodeName())) {
linked = true;
break;
}
parent = parent.parent();
}
boolean email = matcher.group().contains("@") && !matcher.group().contains(":");
if (BuildConfig.DEBUG)
Log.i("Web url=" + matcher.group() +
" " + matcher.start() + "..." + matcher.end() + "/" + text.length() +
" linked=" + linked + " email=" + email);
if (linked)
span.appendText(text.substring(pos, matcher.end()));
else {
span.appendText(text.substring(pos, matcher.start()));
Element a = document.createElement("a");
a.attr("href", (email ? "mailto:" : "") + matcher.group());
a.text(matcher.group());
span.appendChild(a);
}
pos = matcher.end();
} while (matcher.find());
span.appendText(text.substring(pos));
tnode.before(span);
tnode.text("");
}
}
}
@Override
public void tail(Node node, int depth) {
}
}, document);
// Remove block elements displaying nothing
for (Element e : document.select("*"))
if (e.isBlock() &&
!e.hasText() &&
e.select("br").size() == 0 &&
e.select("img").size() == 0)
e.remove();
// Prevent too many line breaks
for (Element div : document.select("div")) {
div.tagName("span");
if (div.parent() != null)
div.after(document.createElement("br"));
}
Element body = document.body();
return (body == null ? "" : body.html());
}
static Drawable decodeImage(final Context context, final long id, String source, boolean show, final TextView view) {
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
boolean compact = prefs.getBoolean("compact", false);
int zoom = prefs.getInt("zoom", compact ? 0 : 1);
boolean inline = prefs.getBoolean("inline_images", false);
final int px = Helper.dp2pixels(context, (zoom + 1) * 24);
final Resources.Theme theme = context.getTheme();
final Resources res = context.getResources();
final AnnotatedSource a = new AnnotatedSource(source);
if (TextUtils.isEmpty(a.source)) {
Drawable d = res.getDrawable(R.drawable.baseline_broken_image_24, theme);
d.setBounds(0, 0, px, px);
return d;
}
boolean embedded = a.source.startsWith("cid:");
boolean data = a.source.startsWith("data:");
if (BuildConfig.DEBUG)
Log.i("Image show=" + show + " inline=" + inline +
" embedded=" + embedded + " data=" + data + " source=" + a.source);
// Embedded images
if (embedded && (show || inline)) {
DB db = DB.getInstance(context);
String cid = "<" + a.source.substring(4) + ">";
EntityAttachment attachment = db.attachment().getAttachment(id, cid);
if (attachment == null) {
Log.i("Image not found CID=" + cid);
Drawable d = res.getDrawable(R.drawable.baseline_broken_image_24, theme);
d.setBounds(0, 0, px, px);
return d;
} else if (!attachment.available) {
Log.i("Image not available CID=" + cid);
Drawable d = res.getDrawable(R.drawable.baseline_photo_library_24, theme);
d.setBounds(0, 0, px, px);
return d;
} else {
Bitmap bm = Helper.decodeImage(attachment.getFile(context),
res.getDisplayMetrics().widthPixels);
if (bm == null) {
Log.i("Image not decodable CID=" + cid);
Drawable d = res.getDrawable(R.drawable.baseline_broken_image_24, theme);
d.setBounds(0, 0, px, px);
return d;
} else {
Drawable d = new BitmapDrawable(res, bm);
DisplayMetrics dm = context.getResources().getDisplayMetrics();
d.setBounds(0, 0, Math.round(bm.getWidth() * dm.density), Math.round(bm.getHeight() * dm.density));
if (view != null)
fitDrawable(d, a, view);
return d;
}
}
}
// Data URI
if (data && (show || inline))
try {
Drawable d = getDataDrawable(context, a.source);
if (view != null)
fitDrawable(d, a, view);
return d;
} catch (IllegalArgumentException ex) {
Log.w(ex);
Drawable d = res.getDrawable(R.drawable.baseline_broken_image_24, theme);
d.setBounds(0, 0, px, px);
return d;
}
if (!show) {
// Show placeholder icon
int resid = (embedded || data ? R.drawable.baseline_photo_library_24 : R.drawable.baseline_image_24);
Drawable d = res.getDrawable(resid, theme);
d.setBounds(0, 0, px, px);
return d;
}
// Get cache file name
File dir = new File(context.getCacheDir(), "images");
if (!dir.exists())
dir.mkdir();
final File file = new File(dir, id + "_" + Math.abs(a.source.hashCode()) + ".png");
Drawable cached = getCachedImage(context, file);
if (cached != null || view == null) {
if (view == null)
if (cached == null) {
Drawable d = res.getDrawable(R.drawable.baseline_hourglass_empty_24, theme);
d.setBounds(0, 0, px, px);
return d;
} else
return cached;
else
fitDrawable(cached, a, view);
return cached;
}
final LevelListDrawable lld = new LevelListDrawable();
Drawable wait = res.getDrawable(R.drawable.baseline_hourglass_empty_24, theme);
lld.addLevel(1, 1, wait);
lld.setBounds(0, 0, px, px);
lld.setLevel(1);
executor.submit(new Runnable() {
@Override
public void run() {
try {
Drawable cached = getCachedImage(context, file);
if (cached != null) {
fitDrawable(cached, a, view);
post(cached, a.source);
return;
}
BitmapFactory.Options options = new BitmapFactory.Options();
Log.i("Probe " + a.source);
try (InputStream probe = new URL(a.source).openStream()) {
options.inJustDecodeBounds = true;
BitmapFactory.decodeStream(probe, null, options);
}
Log.i("Download " + a.source);
Bitmap bm;
try (InputStream is = new URL(a.source).openStream()) {
int scaleTo = res.getDisplayMetrics().widthPixels;
int factor = 1;
while (options.outWidth / factor > scaleTo)
factor *= 2;
if (factor > 1) {
Log.i("Download image factor=" + factor);
options.inJustDecodeBounds = false;
options.inSampleSize = factor;
bm = BitmapFactory.decodeStream(is, null, options);
} else
bm = BitmapFactory.decodeStream(is);
}
if (bm == null)
throw new FileNotFoundException("Download image failed source=" + a.source);
Log.i("Downloaded image source=" + a.source);
try (OutputStream os = new FileOutputStream(file)) {
bm.compress(Bitmap.CompressFormat.PNG, 90, os);
}
// Create drawable from bitmap
Drawable d = new BitmapDrawable(res, bm);
DisplayMetrics dm = context.getResources().getDisplayMetrics();
d.setBounds(0, 0, Math.round(bm.getWidth() * dm.density), Math.round(bm.getHeight() * dm.density));
fitDrawable(d, a, view);
post(d, a.source);
} catch (Throwable ex) {
// Show broken icon
Log.w(ex);
int resid = (ex instanceof IOException && !(ex instanceof FileNotFoundException)
? R.drawable.baseline_cloud_off_24
: R.drawable.baseline_broken_image_24);
Drawable d = res.getDrawable(resid, theme);
d.setBounds(0, 0, px, px);
post(d, a.source);
}
}
private void post(final Drawable d, String source) {
Log.i("Posting image=" + source);
new Handler(context.getMainLooper()).post(new Runnable() {
@Override
public void run() {
Rect bounds = d.getBounds();
lld.addLevel(0, 0, d);
lld.setBounds(0, 0, bounds.width(), bounds.height());
lld.setLevel(0);
view.setText(view.getText());
}
});
}
});
return lld;
}
private static void fitDrawable(Drawable d, AnnotatedSource a, View view) {
Rect bounds = d.getBounds();
int w = bounds.width();
int h = bounds.height();
if (a.width == 0 && a.height != 0)
a.width = Math.round(a.height * w / (float) h);
if (a.height == 0 && a.width != 0)
a.height = Math.round(a.width * h / (float) w);
if (a.width != 0 && a.height != 0) {
w = Helper.dp2pixels(view.getContext(), a.width);
h = Helper.dp2pixels(view.getContext(), a.height);
d.setBounds(0, 0, w, h);
}
float width = view.getWidth();
if (w > width) {
float scale = width / w;
w = Math.round(w * scale);
h = Math.round(h * scale);
d.setBounds(0, 0, w, h);
}
}
private static Drawable getDataDrawable(Context context, String source) {
// "<img src=\"data:image/png;base64,iVBORw0KGgoAAA" +
// "ANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4" +
// "//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU" +
// "5ErkJggg==\" alt=\"Red dot\" />";
String base64 = source.substring(source.indexOf(',') + 1);
byte[] bytes = Base64.decode(base64.getBytes(), 0);
Bitmap bm = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
if (bm == null)
throw new IllegalArgumentException("decode byte array failed");
Drawable d = new BitmapDrawable(context.getResources(), bm);
DisplayMetrics dm = context.getResources().getDisplayMetrics();
d.setBounds(0, 0, Math.round(bm.getWidth() * dm.density), Math.round(bm.getHeight() * dm.density));
return d;
}
static private Drawable getCachedImage(Context context, File file) {
if (file.exists()) {
Log.i("Using cached " + file);
Bitmap bm = BitmapFactory.decodeFile(file.getAbsolutePath());
if (bm != null) {
Drawable d = new BitmapDrawable(context.getResources(), bm);
DisplayMetrics dm = context.getResources().getDisplayMetrics();
d.setBounds(0, 0, Math.round(bm.getWidth() * dm.density), Math.round(bm.getHeight() * dm.density));
return d;
}
}
return null;
}
static String getPreview(String body) {
String text = (body == null ? null : Jsoup.parse(body).text());
return (text == null ? null : text.substring(0, Math.min(text.length(), PREVIEW_SIZE)));
}
static String getText(String html) {
final StringBuilder sb = new StringBuilder();
NodeTraversor.traverse(new NodeVisitor() {
private int qlevel = 0;
private int tlevel = 0;
public void head(Node node, int depth) {
if (node instanceof TextNode) {
append(((TextNode) node).text());
append(" ");
} else {
String name = node.nodeName();
if ("li".equals(name))
append("* ");
else if ("blockquote".equals(name))
qlevel++;
if (heads.contains(name))
newline();
}
}
public void tail(Node node, int depth) {
String name = node.nodeName();
if ("a".equals(name)) {
append("[");
append(node.absUrl("href"));
append("] ");
} else if ("img".equals(name)) {
append("[");
append(node.absUrl("src"));
append("] ");
} else if ("th".equals(name) || "td".equals(name)) {
Node next = node.nextSibling();
if (next == null || !("th".equals(next.nodeName()) || "td".equals(next.nodeName())))
newline();
} else if ("blockquote".equals(name))
qlevel--;
if (tails.contains(name))
newline();
}
private void append(String text) {
if (tlevel != qlevel) {
newline();
tlevel = qlevel;
}
sb.append(text);
}
private void newline() {
trimEnd(sb);
sb.append("\n");
for (int i = 0; i < qlevel; i++)
sb.append('>');
if (qlevel > 0)
sb.append(' ');
}
}, Jsoup.parse(html));
trimEnd(sb);
sb.append("\n");
return sb.toString();
}
static String getHtmlEmbedded(Context context, long id, String html) throws IOException {
DB db = DB.getInstance(context);
Document doc = Jsoup.parse(html);
for (Element img : doc.select("img")) {
String src = img.attr("src");
if (src.startsWith("cid:")) {
String cid = '<' + src.substring(4) + '>';
EntityAttachment attachment = db.attachment().getAttachment(id, cid);
if (attachment != null && attachment.available) {
File file = attachment.getFile(context);
try (InputStream is = new FileInputStream(file)) {
byte[] bytes = new byte[(int) file.length()];
if (is.read(bytes) != bytes.length)
throw new IOException("length");
StringBuilder sb = new StringBuilder();
sb.append("data:");
sb.append(attachment.type);
sb.append(";base64,");
sb.append(Base64.encodeToString(bytes, Base64.DEFAULT));
img.attr("src", sb.toString());
}
}
}
}
return doc.html();
}
private static boolean isTrackingPixel(Element img) {
String src = img.attr("src");
String width = img.attr("width").trim();
String height = img.attr("height").trim();
if (TextUtils.isEmpty(src))
return false;
if (TextUtils.isEmpty(width) || TextUtils.isEmpty(height))
return false;
try {
return (Integer.parseInt(width) * Integer.parseInt(height) <= TRACKING_PIXEL_SURFACE);
} catch (NumberFormatException ignored) {
return false;
}
}
private static void trimEnd(StringBuilder sb) {
int length = sb.length();
while (length > 0 && sb.charAt(length - 1) == ' ')
length--;
sb.setLength(length);
}
static Spanned fromHtml(@NonNull String html) {
return fromHtml(html, null, null);
}
static Spanned fromHtml(@NonNull String html, @Nullable Html.ImageGetter imageGetter, @Nullable Html.TagHandler tagHandler) {
Spanned spanned = HtmlCompat.fromHtml(html, FROM_HTML_SEPARATOR_LINE_BREAK_LIST_ITEM, imageGetter, tagHandler);
int i = spanned.length();
while (i > 1 && spanned.charAt(i - 2) == '\n' && spanned.charAt(i - 1) == '\n')
i--;
if (i != spanned.length())
spanned = (Spanned) spanned.subSequence(0, i);
return spanned;
}
static String toHtml(Spanned spanned) {
String html = HtmlCompat.toHtml(spanned, TO_HTML_PARAGRAPH_LINES_CONSECUTIVE);
// @Google: why convert size to and from in a different way?
Document doc = Jsoup.parse(html);
for (Element element : doc.select("span")) {
String style = element.attr("style");
if (style.startsWith("font-size:")) {
int colon = style.indexOf(':');
int semi = style.indexOf("em;", colon);
if (semi > colon)
try {
String hsize = style.substring(colon + 1, semi).replace(',', '.');
float size = Float.parseFloat(hsize);
element.tagName(size < 1.0f ? "small" : "big");
element.attributes().remove("style");
} catch (NumberFormatException ex) {
Log.e(ex);
}
}
}
return doc.outerHtml();
}
public static class AnnotatedSource {
private String source;
private int width = 0;
private int height = 0;
// Encapsulate some ugliness
AnnotatedSource(String source) {
this.source = source;
if (source != null && source.endsWith("###")) {
int pos = source.substring(0, source.length() - 3).lastIndexOf("###");
if (pos > 0) {
int x = source.indexOf("x", pos + 3);
if (x > 0)
try {
this.width = Integer.parseInt(source.substring(pos + 3, x));
this.height = Integer.parseInt(source.substring(x + 1, source.length() - 3));
this.source = source.substring(0, pos);
} catch (NumberFormatException ex) {
Log.e(ex);
this.width = 0;
this.height = 0;
}
}
}
}
private AnnotatedSource(String source, int width, int height) {
this.source = source;
this.width = width;
this.height = height;
}
public String getSource() {
return this.source;
}
private String getAnnotated() {
return (width == 0 && height == 0
? source
: source + "###" + width + "x" + height + "###");
}
}
}
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