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