| 1 | /**************************************************************** |
| 2 | * Licensed to the Apache Software Foundation (ASF) under one * |
| 3 | * or more contributor license agreements. See the NOTICE file * |
| 4 | * distributed with this work for additional information * |
| 5 | * regarding copyright ownership. The ASF licenses this file * |
| 6 | * to you under the Apache License, Version 2.0 (the * |
| 7 | * "License"); you may not use this file except in compliance * |
| 8 | * with the License. You may obtain a copy of the License at * |
| 9 | * * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 * |
| 11 | * * |
| 12 | * Unless required by applicable law or agreed to in writing, * |
| 13 | * software distributed under the License is distributed on an * |
| 14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * |
| 15 | * KIND, either express or implied. See the License for the * |
| 16 | * specific language governing permissions and limitations * |
| 17 | * under the License. * |
| 18 | ****************************************************************/ |
| 19 | |
| 20 | package org.apache.james.jdkim; |
| 21 | |
| 22 | import java.io.IOException; |
| 23 | import java.io.InputStream; |
| 24 | import java.io.OutputStream; |
| 25 | import java.security.InvalidKeyException; |
| 26 | import java.security.NoSuchAlgorithmException; |
| 27 | import java.security.Signature; |
| 28 | import java.security.SignatureException; |
| 29 | import java.util.Arrays; |
| 30 | import java.util.HashMap; |
| 31 | import java.util.Hashtable; |
| 32 | import java.util.Iterator; |
| 33 | import java.util.LinkedList; |
| 34 | import java.util.List; |
| 35 | import java.util.Map; |
| 36 | |
| 37 | import org.apache.james.jdkim.api.BodyHasher; |
| 38 | import org.apache.james.jdkim.api.Headers; |
| 39 | import org.apache.james.jdkim.api.PublicKeyRecord; |
| 40 | import org.apache.james.jdkim.api.PublicKeyRecordRetriever; |
| 41 | import org.apache.james.jdkim.api.SignatureRecord; |
| 42 | import org.apache.james.jdkim.canon.CompoundOutputStream; |
| 43 | import org.apache.james.jdkim.exceptions.FailException; |
| 44 | import org.apache.james.jdkim.exceptions.PermFailException; |
| 45 | import org.apache.james.jdkim.exceptions.TempFailException; |
| 46 | import org.apache.james.jdkim.impl.BodyHasherImpl; |
| 47 | import org.apache.james.jdkim.impl.DNSPublicKeyRecordRetriever; |
| 48 | import org.apache.james.jdkim.impl.Message; |
| 49 | import org.apache.james.jdkim.impl.MultiplexingPublicKeyRecordRetriever; |
| 50 | import org.apache.james.jdkim.tagvalue.PublicKeyRecordImpl; |
| 51 | import org.apache.james.jdkim.tagvalue.SignatureRecordImpl; |
| 52 | import org.apache.james.mime4j.MimeException; |
| 53 | |
| 54 | public class DKIMVerifier extends DKIMCommon { |
| 55 | |
| 56 | private PublicKeyRecordRetriever publicKeyRecordRetriever; |
| 57 | |
| 58 | public DKIMVerifier() { |
| 59 | this.publicKeyRecordRetriever = new MultiplexingPublicKeyRecordRetriever( |
| 60 | "dns", new DNSPublicKeyRecordRetriever()); |
| 61 | } |
| 62 | |
| 63 | public DKIMVerifier(PublicKeyRecordRetriever publicKeyRecordRetriever) { |
| 64 | this.publicKeyRecordRetriever = publicKeyRecordRetriever; |
| 65 | } |
| 66 | |
| 67 | protected PublicKeyRecord newPublicKeyRecord(String record) { |
| 68 | return new PublicKeyRecordImpl(record); |
| 69 | } |
| 70 | |
| 71 | public SignatureRecord newSignatureRecord(String record) { |
| 72 | return new SignatureRecordImpl(record); |
| 73 | } |
| 74 | |
| 75 | public BodyHasher newBodyHasher(SignatureRecord signRecord) |
| 76 | throws PermFailException { |
| 77 | return new BodyHasherImpl(signRecord); |
| 78 | } |
| 79 | |
| 80 | protected PublicKeyRecordRetriever getPublicKeyRecordRetriever() |
| 81 | throws PermFailException { |
| 82 | return publicKeyRecordRetriever; |
| 83 | } |
| 84 | |
| 85 | public PublicKeyRecord publicKeySelector(List records) |
| 86 | throws PermFailException { |
| 87 | String lastError = null; |
| 88 | if (records == null || records.size() == 0) { |
| 89 | lastError = "no key for signature"; |
| 90 | } else { |
| 91 | for (Iterator i = records.iterator(); i.hasNext();) { |
| 92 | String record = (String) i.next(); |
| 93 | try { |
| 94 | PublicKeyRecord pk = newPublicKeyRecord(record); |
| 95 | pk.validate(); |
| 96 | // we expect a single valid record, otherwise the result |
| 97 | // is unpredictable. |
| 98 | // in case of multiple valid records we use the first one. |
| 99 | return pk; |
| 100 | } catch (IllegalStateException e) { |
| 101 | // do this at last. |
| 102 | lastError = "invalid key for signature: " + e.getMessage(); |
| 103 | } |
| 104 | } |
| 105 | } |
| 106 | // return PERMFAIL ($error). |
| 107 | throw new PermFailException(lastError); |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * asserts applicability of a signature record the a public key record. |
| 112 | * throws an |
| 113 | * |
| 114 | * @param pkr public key record |
| 115 | * @param sign signature record |
| 116 | * @throws PermFailException when the keys are not applicable |
| 117 | */ |
| 118 | public static void apply(PublicKeyRecord pkr, SignatureRecord sign) throws PermFailException { |
| 119 | if (!pkr.getGranularityPattern().matcher(sign.getIdentityLocalPart()) |
| 120 | .matches()) { |
| 121 | throw new PermFailException("inapplicable key identity local=" |
| 122 | + sign.getIdentityLocalPart() + " Pattern: " |
| 123 | + pkr.getGranularityPattern().pattern()); |
| 124 | } |
| 125 | |
| 126 | if (!pkr.isHashMethodSupported(sign.getHashMethod())) { |
| 127 | throw new PermFailException("inappropriate hash for a=" |
| 128 | + sign.getHashKeyType() + "/" + sign.getHashMethod()); |
| 129 | } |
| 130 | if (!pkr.isKeyTypeSupported(sign.getHashKeyType())) { |
| 131 | throw new PermFailException("inappropriate key type for a=" |
| 132 | + sign.getHashKeyType() + "/" + sign.getHashMethod()); |
| 133 | } |
| 134 | |
| 135 | if (pkr.isDenySubdomains()) { |
| 136 | if (!sign.getIdentity().toString().toLowerCase().endsWith( |
| 137 | ("@" + sign.getDToken()).toLowerCase())) { |
| 138 | throw new PermFailException( |
| 139 | "AUID in subdomain of SDID is not allowed by the public key record."); |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | } |
| 144 | |
| 145 | /** |
| 146 | * Iterates through signature's declared lookup method |
| 147 | * |
| 148 | * @param sign |
| 149 | * the signature record |
| 150 | * @return an "applicable" PublicKeyRecord |
| 151 | * @throws TempFailException |
| 152 | * @throws PermFailException |
| 153 | */ |
| 154 | public PublicKeyRecord publicRecordLookup(SignatureRecord sign) |
| 155 | throws TempFailException, PermFailException { |
| 156 | // System.out.println(sign); |
| 157 | PublicKeyRecord key = null; |
| 158 | TempFailException lastTempFailure = null; |
| 159 | PermFailException lastPermFailure = null; |
| 160 | for (Iterator rlm = sign.getRecordLookupMethods().iterator(); key == null |
| 161 | && rlm.hasNext();) { |
| 162 | String method = (String) rlm.next(); |
| 163 | try { |
| 164 | PublicKeyRecordRetriever pkrr = getPublicKeyRecordRetriever(); |
| 165 | List records = pkrr.getRecords(method, sign.getSelector() |
| 166 | .toString(), sign.getDToken().toString()); |
| 167 | PublicKeyRecord tempKey = publicKeySelector(records); |
| 168 | // checks wether the key is applicable to the signature |
| 169 | // TODO check with the IETF group to understand if this is the |
| 170 | // right thing to do. |
| 171 | // TODO loggin |
| 172 | apply(tempKey, sign); |
| 173 | key = tempKey; |
| 174 | } catch (TempFailException tf) { |
| 175 | lastTempFailure = tf; |
| 176 | } catch (PermFailException pf) { |
| 177 | lastPermFailure = pf; |
| 178 | } |
| 179 | } |
| 180 | if (key == null) { |
| 181 | if (lastTempFailure != null) |
| 182 | throw lastTempFailure; |
| 183 | else if (lastPermFailure != null) |
| 184 | throw lastPermFailure; |
| 185 | // this is unexpected because the publicKeySelector always returns |
| 186 | // null or exception |
| 187 | else |
| 188 | throw new PermFailException( |
| 189 | "no key for signature [unexpected condition]"); |
| 190 | } |
| 191 | return key; |
| 192 | } |
| 193 | |
| 194 | /** |
| 195 | * Verifies all of the DKIM-Signature records declared in the supplied input |
| 196 | * stream |
| 197 | * |
| 198 | * @param is |
| 199 | * inputStream |
| 200 | * @return a list of verified signature records. |
| 201 | * @throws IOException |
| 202 | * @throws FailException |
| 203 | * if no signature can be verified |
| 204 | */ |
| 205 | public List/* SignatureRecord */verify(InputStream is) throws IOException, |
| 206 | FailException { |
| 207 | Message message; |
| 208 | try { |
| 209 | message = new Message(is); |
| 210 | return verify(message, message.getBodyInputStream()); |
| 211 | } catch (MimeException e1) { |
| 212 | throw new PermFailException("Mime parsing exception: " |
| 213 | + e1.getMessage(), e1); |
| 214 | } finally { |
| 215 | is.close(); |
| 216 | } |
| 217 | } |
| 218 | |
| 219 | /** |
| 220 | * Verifies all of the DKIM-Signature records declared in the Headers |
| 221 | * object. |
| 222 | * |
| 223 | * @param messageHeaders |
| 224 | * parsed headers |
| 225 | * @param bodyInputStream |
| 226 | * input stream for the body. |
| 227 | * @return a list of verified signature records |
| 228 | * @throws IOException |
| 229 | * @throws FailException |
| 230 | * if no signature can be verified |
| 231 | */ |
| 232 | public List/* SignatureRecord */verify(Headers messageHeaders, |
| 233 | InputStream bodyInputStream) throws IOException, FailException { |
| 234 | // System.out.println(message.getFields("DKIM-Signature")); |
| 235 | List fields = messageHeaders.getFields("DKIM-Signature"); |
| 236 | // if (fields.size() > 1) throw new RuntimeException("here we are!"); |
| 237 | if (fields.size() == 0) { |
| 238 | throw new PermFailException("DKIM-Signature field not found"); |
| 239 | } |
| 240 | |
| 241 | // For each DKIM-signature we prepare an hashjob. |
| 242 | // We calculate all hashes concurrently so to read |
| 243 | // the inputstream only once. |
| 244 | Map/* String, BodyHashJob */bodyHashJobs = new HashMap(); |
| 245 | List/* OutputStream */outputStreams = new LinkedList(); |
| 246 | Map/* String, Exception */signatureExceptions = new Hashtable(); |
| 247 | for (Iterator i = fields.iterator(); i.hasNext();) { |
| 248 | String signatureField = (String) i.next(); |
| 249 | try { |
| 250 | int pos = signatureField.indexOf(':'); |
| 251 | if (pos > 0) { |
| 252 | String v = signatureField.substring(pos + 1, signatureField |
| 253 | .length()); |
| 254 | SignatureRecord signatureRecord; |
| 255 | try { |
| 256 | signatureRecord = newSignatureRecord(v); |
| 257 | // validate |
| 258 | signatureRecord.validate(); |
| 259 | } catch (IllegalStateException e) { |
| 260 | throw new PermFailException(e.getMessage()); |
| 261 | } |
| 262 | |
| 263 | // TODO here we could check more parameters for |
| 264 | // validation before running a network operation like the |
| 265 | // dns lookup. |
| 266 | // e.g: the canonicalization method could be checked now. |
| 267 | PublicKeyRecord publicKeyRecord = publicRecordLookup(signatureRecord); |
| 268 | |
| 269 | List signedHeadersList = signatureRecord.getHeaders(); |
| 270 | |
| 271 | byte[] decoded = signatureRecord.getSignature(); |
| 272 | signatureVerify(messageHeaders, signatureRecord, decoded, |
| 273 | publicKeyRecord, signedHeadersList); |
| 274 | |
| 275 | // we track all canonicalizations+limit+bodyHash we |
| 276 | // see so to be able to check all of them in a single |
| 277 | // stream run. |
| 278 | BodyHasher bhj = newBodyHasher(signatureRecord); |
| 279 | |
| 280 | bodyHashJobs.put(signatureField, bhj); |
| 281 | outputStreams.add(bhj.getOutputStream()); |
| 282 | |
| 283 | } else { |
| 284 | throw new PermFailException( |
| 285 | "unexpected bad signature field"); |
| 286 | } |
| 287 | } catch (TempFailException e) { |
| 288 | signatureExceptions.put(signatureField, e); |
| 289 | } catch (PermFailException e) { |
| 290 | signatureExceptions.put(signatureField, e); |
| 291 | } catch (InvalidKeyException e) { |
| 292 | signatureExceptions.put(signatureField, new PermFailException(e |
| 293 | .getMessage(), e)); |
| 294 | } catch (NoSuchAlgorithmException e) { |
| 295 | signatureExceptions.put(signatureField, new PermFailException(e |
| 296 | .getMessage(), e)); |
| 297 | } catch (SignatureException e) { |
| 298 | signatureExceptions.put(signatureField, new PermFailException(e |
| 299 | .getMessage(), e)); |
| 300 | } |
| 301 | } |
| 302 | |
| 303 | OutputStream o; |
| 304 | if (bodyHashJobs.size() == 0) { |
| 305 | throw prepareException(signatureExceptions); |
| 306 | } else if (bodyHashJobs.size() == 1) { |
| 307 | o = ((BodyHasher) bodyHashJobs.values().iterator().next()) |
| 308 | .getOutputStream(); |
| 309 | } else { |
| 310 | o = new CompoundOutputStream(outputStreams); |
| 311 | } |
| 312 | |
| 313 | // simultaneous computation of all the hashes. |
| 314 | DKIMCommon.streamCopy(bodyInputStream, o); |
| 315 | |
| 316 | List/* SignatureRecord */verifiedSignatures = new LinkedList(); |
| 317 | for (Iterator i = bodyHashJobs.values().iterator(); i.hasNext();) { |
| 318 | BodyHasher bhj = (BodyHasher) i.next(); |
| 319 | |
| 320 | byte[] computedHash = bhj.getDigest(); |
| 321 | byte[] expectedBodyHash = bhj.getSignatureRecord().getBodyHash(); |
| 322 | |
| 323 | if (!Arrays.equals(expectedBodyHash, computedHash)) { |
| 324 | signatureExceptions |
| 325 | .put( |
| 326 | "DKIM-Signature:"+bhj.getSignatureRecord().toString(), |
| 327 | new PermFailException( |
| 328 | "Computed bodyhash is different from the expected one")); |
| 329 | } else { |
| 330 | verifiedSignatures.add(bhj.getSignatureRecord()); |
| 331 | } |
| 332 | } |
| 333 | |
| 334 | if (verifiedSignatures.size() == 0) { |
| 335 | throw prepareException(signatureExceptions); |
| 336 | } else { |
| 337 | // TODO list good and bad signatures. |
| 338 | // remove system out. |
| 339 | for (Iterator i = signatureExceptions.keySet().iterator(); i |
| 340 | .hasNext();) { |
| 341 | String f = (String) i.next(); |
| 342 | System.out.println("DKIM-Error: " |
| 343 | + ((FailException) signatureExceptions.get(f)) |
| 344 | .getMessage() + " FIELD: " + f); |
| 345 | } |
| 346 | for (Iterator i = verifiedSignatures.iterator(); i.hasNext();) { |
| 347 | SignatureRecord sr = (SignatureRecord) i.next(); |
| 348 | System.out.println("DKIM-Pass: " + sr); |
| 349 | } |
| 350 | return verifiedSignatures; |
| 351 | } |
| 352 | |
| 353 | } |
| 354 | |
| 355 | private FailException prepareException(Map signatureExceptions) { |
| 356 | if (signatureExceptions.size() == 1) { |
| 357 | return (FailException) signatureExceptions.values().iterator() |
| 358 | .next(); |
| 359 | } else { |
| 360 | // TODO loops signatureExceptions to give a more complete |
| 361 | // response, using nested exception or a compound exception. |
| 362 | // System.out.println(signatureExceptions); |
| 363 | return new PermFailException("found " + signatureExceptions.size() |
| 364 | + " invalid signatures"); |
| 365 | } |
| 366 | } |
| 367 | |
| 368 | private void signatureVerify(Headers h, SignatureRecord sign, |
| 369 | byte[] decoded, PublicKeyRecord key, List headers) |
| 370 | throws NoSuchAlgorithmException, InvalidKeyException, |
| 371 | SignatureException, PermFailException { |
| 372 | |
| 373 | Signature signature = Signature.getInstance(sign.getHashMethod() |
| 374 | .toString().toUpperCase() |
| 375 | + "with" + sign.getHashKeyType().toString().toUpperCase()); |
| 376 | signature.initVerify(key.getPublicKey()); |
| 377 | |
| 378 | signatureCheck(h, sign, headers, signature); |
| 379 | |
| 380 | if (!signature.verify(decoded)) |
| 381 | throw new PermFailException("Header signature does not verify"); |
| 382 | } |
| 383 | |
| 384 | } |