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Refactoring

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M66B
2023-03-17 08:01:54 +01:00
parent 3d6876d51f
commit cb9102b9ed
1 changed files with 188 additions and 181 deletions
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369
app/src/main/java/eu/faircode/email/MessageHelper.java
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@@ -2013,187 +2013,9 @@ public class MessageHelper {
return signers;
for (String header : headers) {
Map<String, String> kv = getKeyValues(MimeUtility.unfold(header));
String a = kv.get("a");
String halgo;
String salgo;
if ("rsa-sha1".equals(a)) {
halgo = "SHA-1";
salgo = "SHA1withRSA";
} else if ("rsa-sha256".equals(a)) {
halgo = "SHA-256";
salgo = "SHA256withRSA";
} else {
// TODO: Ed25519
Log.i("DKIM a=" + a);
continue;
}
try {
String signer = kv.get("d");
String dns = kv.get("s") + "._domainkey." + signer;
Log.i("DKIM lookup " + dns);
DnsHelper.DnsRecord[] records = DnsHelper.lookup(context, dns, "txt");
if (records.length == 0)
continue;
Log.i("DKIM got " + records[0].name);
Map<String, String> dk = getKeyValues(records[0].name);
String canonic = kv.get("c");
Log.i("DKIM canonicalization=" + canonic);
if (canonic == null)
canonic = "simple/simple";
String[] c = canonic.split("/");
StringBuilder head = new StringBuilder();
String hs = kv.get("h");
Log.i("DKIM headers=" + hs);
boolean from = false;
List<String> keys = new ArrayList<>();
if (hs != null)
for (String key : hs.split(":")) {
keys.add(key.trim());
from = (from || "from".equalsIgnoreCase(key.trim()));
}
if (!from)
throw new IllegalArgumentException("from missing: " + hs);
keys.add(DKIM_SIGNATURE);
Map<String, Integer> index = new Hashtable<>();
for (String key : keys) {
// https://datatracker.ietf.org/doc/html/rfc6376/#section-5.4.2
String _key = key.toLowerCase(Locale.ROOT);
Integer idx = index.get(_key);
idx = (idx == null ? 1 : idx + 1);
index.put(_key, idx);
String[] values = (DKIM_SIGNATURE.equals(key)
? new String[]{header}
: amessage.getHeader(key));
if (values == null || idx > values.length) {
// https://datatracker.ietf.org/doc/html/rfc6376/#section-5.4
Log.i("DKIM missing header=" +
key + "[" + idx + "/" + (values == null ? null : values.length) + "]");
continue;
}
String value = values[values.length - idx];
if (DKIM_SIGNATURE.equals(key)) {
int b = value.lastIndexOf("b=");
int s = value.indexOf(";", b + 2);
value = value.substring(0, b + 2) + (s < 0 ? "" : value.substring(s));
} else
Log.i("DKIM " + key + "=" + value.replaceAll("\\r?\\n", "|"));
if ("simple".equals(c[0])) {
if (DKIM_SIGNATURE.equals(key))
head.append(key).append(": ").append(value);
else {
// Find original header/name (case sensitive)
int _idx = values.length - idx;
Enumeration<Header> oheaders = amessage.getAllHeaders();
while (oheaders.hasMoreElements()) {
Header oheader = oheaders.nextElement();
if (key.equalsIgnoreCase(oheader.getName())) {
if (_idx-- == 0) {
head.append(oheader.getName()).append(": ")
.append(oheader.getValue());
break;
}
}
}
}
} else if ("relaxed".equals(c[0])) {
value = MimeUtility.unfold(value);
head.append(_key).append(':')
.append(value.replaceAll("\\s+", " ").trim());
} else
throw new IllegalArgumentException(c[0]);
if (!DKIM_SIGNATURE.equals(key))
head.append("\r\n");
}
Log.i("DKIM head=" + head.toString().replace("\r\n", "|"));
ByteArrayOutputStream bos = new ByteArrayOutputStream();
Helper.copy(amessage.getRawInputStream(), bos);
String body = bos.toString(); // TODO: charset?
if ("simple".equals(c[c.length > 1 ? 1 : 0])) {
if (TextUtils.isEmpty(body))
body = "\r\n";
else if (!body.endsWith("\r\n"))
body += "\r\n";
else {
while (body.endsWith("\r\n\r\n"))
body = body.substring(0, body.length() - 2);
}
} else if ("relaxed".equals(c[c.length > 1 ? 1 : 0])) {
if (TextUtils.isEmpty(body))
body = "";
else {
body = body.replaceAll("[ \\t]+\r\n", "\r\n");
body = body.replaceAll("[ \\t]+", " ");
while (body.endsWith("\r\n\r\n"))
body = body.substring(0, body.length() - 2);
if ("\r\n".equals(body))
body = "";
}
} else
throw new IllegalArgumentException(c[1]);
String length = kv.get("l");
if (!TextUtils.isEmpty(length) && TextUtils.isDigitsOnly(length)) {
int l = Integer.parseInt(length);
if (l < DKIM_MIN_TEXT)
throw new IllegalArgumentException("Body length " + l + " < " + DKIM_MIN_TEXT);
if (l < body.length())
body = body.substring(0, l);
}
Log.i("DKIM body=" + body.replace("\r\n", "|"));
byte[] bh = MessageDigest.getInstance(halgo).digest(body.getBytes()); // TODO: charset?
Log.i("DKIM bh=" + Base64.encodeToString(bh, Base64.NO_WRAP) + "/" + kv.get("bh"));
String pubkey = dk.get("p");
if (pubkey == null)
continue;
String p = pubkey.replaceAll("\\s+", "");
Log.i("DKIM pubkey=" + p);
X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(Base64.decode(p, Base64.DEFAULT));
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);
Signature sig = Signature.getInstance(salgo); // a=
String hash = kv.get("b");
if (hash == null)
continue;
String s = hash.replaceAll("\\s+", "");
Log.i("DKIM signature=" + s);
byte[] signature = Base64.decode(s, Base64.DEFAULT);
sig.initVerify(pubKey);
sig.update(head.toString().getBytes());
boolean verified = sig.verify(signature);
Log.i("DKIM valid=" + verified +
" dns=" + dns +
" from=" + formatAddresses(getFrom()));
if (verified &&
!signers.contains(signer))
signers.add(signer);
} catch (Throwable ex) {
Log.e("DKIM", ex);
}
String signer = verifySignatureHeader(context, header, DKIM_SIGNATURE, amessage);
if (signer != null && !signers.contains(signer))
signers.add(signer);
}
Log.i("DKIM signers=" + TextUtils.join(",", signers));
@@ -2204,6 +2026,191 @@ public class MessageHelper {
return signers;
}
private String verifySignatureHeader(Context context, String header, String name, MimeMessage amessage) {
Map<String, String> kv = getKeyValues(MimeUtility.unfold(header));
String a = kv.get("a");
String halgo;
String salgo;
if ("rsa-sha1".equals(a)) {
halgo = "SHA-1";
salgo = "SHA1withRSA";
} else if ("rsa-sha256".equals(a)) {
halgo = "SHA-256";
salgo = "SHA256withRSA";
} else {
// TODO: Ed25519
Log.i("DKIM a=" + a);
return null;
}
try {
String signer = kv.get("d");
String dns = kv.get("s") + "._domainkey." + signer;
Log.i("DKIM lookup " + dns);
DnsHelper.DnsRecord[] records = DnsHelper.lookup(context, dns, "txt");
if (records.length == 0)
return null;
Log.i("DKIM got " + records[0].name);
Map<String, String> dk = getKeyValues(records[0].name);
String canonic = kv.get("c");
Log.i("DKIM canonicalization=" + canonic);
if (canonic == null)
canonic = "simple/simple";
String[] c = canonic.split("/");
StringBuilder head = new StringBuilder();
String hs = kv.get("h");
Log.i("DKIM headers=" + hs);
boolean from = false;
List<String> keys = new ArrayList<>();
if (hs != null)
for (String key : hs.split(":")) {
keys.add(key.trim());
from = (from || "from".equalsIgnoreCase(key.trim()));
}
if (!from)
throw new IllegalArgumentException("from missing: " + hs);
keys.add(name);
Map<String, Integer> index = new Hashtable<>();
for (String key : keys) {
// https://datatracker.ietf.org/doc/html/rfc6376/#section-5.4.2
String _key = key.toLowerCase(Locale.ROOT);
Integer idx = index.get(_key);
idx = (idx == null ? 1 : idx + 1);
index.put(_key, idx);
String[] values = (name.equals(key)
? new String[]{header}
: amessage.getHeader(key));
if (values == null || idx > values.length) {
// https://datatracker.ietf.org/doc/html/rfc6376/#section-5.4
Log.i("DKIM missing header=" +
key + "[" + idx + "/" + (values == null ? null : values.length) + "]");
continue;
}
String value = values[values.length - idx];
if (name.equals(key)) {
int b = value.lastIndexOf("b=");
int s = value.indexOf(";", b + 2);
value = value.substring(0, b + 2) + (s < 0 ? "" : value.substring(s));
} else
Log.i("DKIM " + key + "=" + value.replaceAll("\\r?\\n", "|"));
if ("simple".equals(c[0])) {
if (name.equals(key))
head.append(key).append(": ").append(value);
else {
// Find original header/name (case sensitive)
int _idx = values.length - idx;
Enumeration<Header> oheaders = amessage.getAllHeaders();
while (oheaders.hasMoreElements()) {
Header oheader = oheaders.nextElement();
if (key.equalsIgnoreCase(oheader.getName())) {
if (_idx-- == 0) {
head.append(oheader.getName()).append(": ")
.append(oheader.getValue());
break;
}
}
}
}
} else if ("relaxed".equals(c[0])) {
value = MimeUtility.unfold(value);
head.append(_key).append(':')
.append(value.replaceAll("\\s+", " ").trim());
} else
throw new IllegalArgumentException(c[0]);
if (!name.equals(key))
head.append("\r\n");
}
Log.i("DKIM head=" + head.toString().replace("\r\n", "|"));
ByteArrayOutputStream bos = new ByteArrayOutputStream();
Helper.copy(amessage.getRawInputStream(), bos);
String body = bos.toString(); // TODO: charset?
if ("simple".equals(c[c.length > 1 ? 1 : 0])) {
if (TextUtils.isEmpty(body))
body = "\r\n";
else if (!body.endsWith("\r\n"))
body += "\r\n";
else {
while (body.endsWith("\r\n\r\n"))
body = body.substring(0, body.length() - 2);
}
} else if ("relaxed".equals(c[c.length > 1 ? 1 : 0])) {
if (TextUtils.isEmpty(body))
body = "";
else {
body = body.replaceAll("[ \\t]+\r\n", "\r\n");
body = body.replaceAll("[ \\t]+", " ");
while (body.endsWith("\r\n\r\n"))
body = body.substring(0, body.length() - 2);
if ("\r\n".equals(body))
body = "";
}
} else
throw new IllegalArgumentException(c[1]);
String length = kv.get("l");
if (!TextUtils.isEmpty(length) && TextUtils.isDigitsOnly(length)) {
int l = Integer.parseInt(length);
if (l < DKIM_MIN_TEXT)
throw new IllegalArgumentException("Body length " + l + " < " + DKIM_MIN_TEXT);
if (l < body.length())
body = body.substring(0, l);
}
Log.i("DKIM body=" + body.replace("\r\n", "|"));
byte[] bh = MessageDigest.getInstance(halgo).digest(body.getBytes()); // TODO: charset?
Log.i("DKIM bh=" + Base64.encodeToString(bh, Base64.NO_WRAP) + "/" + kv.get("bh"));
String pubkey = dk.get("p");
if (pubkey == null)
return null;
String p = pubkey.replaceAll("\\s+", "");
Log.i("DKIM pubkey=" + p);
X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(Base64.decode(p, Base64.DEFAULT));
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);
Signature sig = Signature.getInstance(salgo); // a=
String hash = kv.get("b");
if (hash == null)
return null;
String s = hash.replaceAll("\\s+", "");
Log.i("DKIM signature=" + s);
byte[] signature = Base64.decode(s, Base64.DEFAULT);
sig.initVerify(pubKey);
sig.update(head.toString().getBytes());
boolean verified = sig.verify(signature);
Log.i("DKIM valid=" + verified +
" dns=" + dns +
" from=" + formatAddresses(getFrom()));
if (verified)
return signer;
} catch (Throwable ex) {
Log.e("DKIM", ex);
}
return null;
}
Address[] getMailFrom(String[] headers) {
if (headers == null)
return null;