1package eu.siacs.conversations.crypto;
2
3import android.util.Log;
4import android.util.Pair;
5
6import com.google.common.collect.ImmutableList;
7
8import org.bouncycastle.asn1.ASN1Primitive;
9import org.bouncycastle.asn1.DERIA5String;
10import org.bouncycastle.asn1.DERTaggedObject;
11import org.bouncycastle.asn1.DERUTF8String;
12import org.bouncycastle.asn1.DLSequence;
13import org.bouncycastle.asn1.x500.RDN;
14import org.bouncycastle.asn1.x500.X500Name;
15import org.bouncycastle.asn1.x500.style.BCStyle;
16import org.bouncycastle.asn1.x500.style.IETFUtils;
17import org.bouncycastle.cert.jcajce.JcaX509CertificateHolder;
18
19import java.io.IOException;
20import java.net.IDN;
21import java.security.cert.Certificate;
22import java.security.cert.CertificateEncodingException;
23import java.security.cert.CertificateParsingException;
24import java.security.cert.X509Certificate;
25import java.util.ArrayList;
26import java.util.Collection;
27import java.util.List;
28import java.util.Locale;
29
30import javax.net.ssl.SSLPeerUnverifiedException;
31import javax.net.ssl.SSLSession;
32
33public class XmppDomainVerifier {
34
35 private static final String LOGTAG = "XmppDomainVerifier";
36
37 private static final String SRV_NAME = "1.3.6.1.5.5.7.8.7";
38 private static final String XMPP_ADDR = "1.3.6.1.5.5.7.8.5";
39
40 private static List<String> getCommonNames(X509Certificate certificate) {
41 List<String> domains = new ArrayList<>();
42 try {
43 X500Name x500name = new JcaX509CertificateHolder(certificate).getSubject();
44 RDN[] rdns = x500name.getRDNs(BCStyle.CN);
45 for (int i = 0; i < rdns.length; ++i) {
46 domains.add(IETFUtils.valueToString(x500name.getRDNs(BCStyle.CN)[i].getFirst().getValue()));
47 }
48 return domains;
49 } catch (CertificateEncodingException e) {
50 return domains;
51 }
52 }
53
54 private static Pair<String, String> parseOtherName(byte[] otherName) {
55 try {
56 ASN1Primitive asn1Primitive = ASN1Primitive.fromByteArray(otherName);
57 if (asn1Primitive instanceof DERTaggedObject) {
58 ASN1Primitive inner = ((DERTaggedObject) asn1Primitive).getObject();
59 if (inner instanceof DLSequence) {
60 DLSequence sequence = (DLSequence) inner;
61 if (sequence.size() >= 2 && sequence.getObjectAt(1) instanceof DERTaggedObject) {
62 String oid = sequence.getObjectAt(0).toString();
63 ASN1Primitive value = ((DERTaggedObject) sequence.getObjectAt(1)).getObject();
64 if (value instanceof DERUTF8String) {
65 return new Pair<>(oid, ((DERUTF8String) value).getString());
66 } else if (value instanceof DERIA5String) {
67 return new Pair<>(oid, ((DERIA5String) value).getString());
68 }
69 }
70 }
71 }
72 return null;
73 } catch (IOException e) {
74 return null;
75 }
76 }
77
78 public static boolean matchDomain(final String needle, final List<String> haystack) {
79 for (final String entry : haystack) {
80 if (entry.startsWith("*.")) {
81 int offset = 0;
82 while (offset < needle.length()) {
83 int i = needle.indexOf('.', offset);
84 if (i < 0) {
85 break;
86 }
87 if (needle.substring(i).equalsIgnoreCase(entry.substring(1))) {
88 return true;
89 }
90 offset = i + 1;
91 }
92 } else {
93 if (entry.equalsIgnoreCase(needle)) {
94 return true;
95 }
96 }
97 }
98 return false;
99 }
100
101 public boolean verify(final String unicodeDomain, final String unicodeHostname, SSLSession sslSession) throws SSLPeerUnverifiedException {
102 final String domain = IDN.toASCII(unicodeDomain);
103 final String hostname = unicodeHostname == null ? null : IDN.toASCII(unicodeHostname);
104 final Certificate[] chain = sslSession.getPeerCertificates();
105 if (chain.length == 0 || !(chain[0] instanceof X509Certificate)) {
106 return false;
107 }
108 final X509Certificate certificate = (X509Certificate) chain[0];
109 final List<String> commonNames = getCommonNames(certificate);
110 if (isSelfSigned(certificate)) {
111 if (commonNames.size() == 1 && matchDomain(domain, commonNames)) {
112 Log.d(LOGTAG, "accepted CN in self signed cert as work around for " + domain);
113 return true;
114 }
115 }
116 try {
117 final ValidDomains validDomains = parseValidDomains(certificate);
118 Log.d(LOGTAG, "searching for " + domain + " in srvNames: " + validDomains.srvNames + " xmppAddrs: " + validDomains.xmppAddrs + " domains:" + validDomains.domains);
119 if (hostname != null) {
120 Log.d(LOGTAG, "also trying to verify hostname " + hostname);
121 }
122 return validDomains.xmppAddrs.contains(domain)
123 || validDomains.srvNames.contains("_xmpp-client." + domain)
124 || matchDomain(domain, validDomains.domains)
125 || (hostname != null && matchDomain(hostname, validDomains.domains));
126 } catch (final Exception e) {
127 return false;
128 }
129 }
130
131 public static ValidDomains parseValidDomains(final X509Certificate certificate) throws CertificateParsingException {
132 final List<String> commonNames = getCommonNames(certificate);
133 final Collection<List<?>> alternativeNames = certificate.getSubjectAlternativeNames();
134 final List<String> xmppAddrs = new ArrayList<>();
135 final List<String> srvNames = new ArrayList<>();
136 final List<String> domains = new ArrayList<>();
137 if (alternativeNames != null) {
138 for (List<?> san : alternativeNames) {
139 final Integer type = (Integer) san.get(0);
140 if (type == 0) {
141 final Pair<String, String> otherName = parseOtherName((byte[]) san.get(1));
142 if (otherName != null && otherName.first != null && otherName.second != null) {
143 switch (otherName.first) {
144 case SRV_NAME:
145 srvNames.add(otherName.second.toLowerCase(Locale.US));
146 break;
147 case XMPP_ADDR:
148 xmppAddrs.add(otherName.second.toLowerCase(Locale.US));
149 break;
150 default:
151 Log.d(LOGTAG, "oid: " + otherName.first + " value: " + otherName.second);
152 }
153 }
154 } else if (type == 2) {
155 final Object value = san.get(1);
156 if (value instanceof String) {
157 domains.add(((String) value).toLowerCase(Locale.US));
158 }
159 }
160 }
161 }
162 if (srvNames.size() == 0 && xmppAddrs.size() == 0 && domains.size() == 0) {
163 domains.addAll(commonNames);
164 }
165 return new ValidDomains(xmppAddrs, srvNames, domains);
166 }
167
168 public static final class ValidDomains {
169 final List<String> xmppAddrs;
170 final List<String> srvNames;
171 final List<String> domains;
172
173 private ValidDomains(List<String> xmppAddrs, List<String> srvNames, List<String> domains) {
174 this.xmppAddrs = xmppAddrs;
175 this.srvNames = srvNames;
176 this.domains = domains;
177 }
178
179 public List<String> all() {
180 ImmutableList.Builder<String> all = new ImmutableList.Builder<>();
181 all.addAll(xmppAddrs);
182 all.addAll(srvNames);
183 all.addAll(domains);
184 return all.build();
185 }
186 }
187
188 private boolean isSelfSigned(X509Certificate certificate) {
189 try {
190 certificate.verify(certificate.getPublicKey());
191 return true;
192 } catch (Exception e) {
193 return false;
194 }
195 }
196}