android HTTPURLConnection解决不能访问HTTPs请求
转载自： http://www.trinea.cn/android/android-java-https-ssl-exception-2/
详细分析Android及Java中访问https请求exception(SSLHandshakeException, SSLPeerUnverifiedException)的原因及解决方法。
1、现象
用Android(或Java)测试程序访问下面两个链接。
https链接一：web服务器为jetty，后台语言为java。
https链接二：web服务器为nginx，后台语言为php。
链接一能正常访问，访问链接二报异常，且用HttpURLConnection和apache的HttpClient两种不同的api访问异常信息不同，具体如下：
(1) 用HttpURLConnection访问，测试代码如下：
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 | public static String httpGet ( String httpUrl ) { BufferedReader input = null ; StringBuilder sb = null ; URL url = null ; HttpURLConnection con = null ; try { url = new URL ( httpUrl ) ; try { con = ( HttpURLConnection ) url . openConnection ( ) ; input = new BufferedReader ( new InputStreamReader ( con . getInputStream ( ) ) ) ; sb = new StringBuilder ( ) ; String s ; while ( ( s = input . readLine ( ) ) != null ) { sb . append ( s ) . append ( "\n" ) ; } } catch ( IOException e ) { e . printStackTrace ( ) ; } } catch ( MalformedURLException e1 ) { e1 . printStackTrace ( ) ; } finally { // close buffered if ( input != null ) { try { input . close ( ) ; } catch ( IOException e ) { e . printStackTrace ( ) ; } } // disconnecting releases the resources held by a connection so they may be closed or reused if ( con != null ) { con . disconnect ( ) ; } } return sb == null ? null : sb . toString ( ) ; } |
异常信息为：
| 1 | javax . net . ssl . SSLPeerUnverifiedException : No peer certificate |
(2) 用apache的HttpClient访问，测试代码如下：
HttpClient访问https Java| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | public static String httpGet ( String httpUrl ) { HttpClient httpClient = new HttpClient ( ) ; GetMethod httpGet = new GetMethod ( httpUrl ) ; try { if ( httpClient . executeMethod ( httpGet ) != HttpStatus . SC_OK ) { // System.err.println("HttpGet Method failed: " + httpGet.getStatusLine()); return null ; } return httpGet . getResponseBodyAsString ( ) ; } catch ( Exception e ) { e . printStackTrace ( ) ; } finally { httpGet . releaseConnection ( ) ; httpClient = null ; } return null ; } |
异常信息为：
| 1 | javax . net . ssl . SSLHandshakeException : sun . security . validator . ValidatorException : PKIX path building failed : sun . security . provider . certpath . SunCertPathBuilderException : unable to find valid certification path to requested target |
2、原因分析
需要快速寻求答案的可直接看第3部分 解决方式，这部分详细分析原因。
google发现stackoverflow上不少人反应，twitter和新浪微博的api也会报这个异常，不少人反映客户端需要导入证书，其实大可不必，如果要导证书的话，用户不得哭了。。
从上面的情况可以看出，用jetty做为容器是能正常访问的，只是当容器为nginx时才会异常。
配合后台开发调试了很久，开始以为是cipher suite的问题，为此特地把
ssl_ciphers EDH-RSA-DES-CBC3-SHA;
加入了nginx的配置中，后来发现依然无效。stackoverflow发现，如下代码是能正常访问上面异常的https url
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 | public static String httpGet ( String httpUrl ) { BufferedReader input = null ; StringBuilder sb = null ; URL url = null ; HttpURLConnection con = null ; try { url = new URL ( httpUrl ) ; try { // trust all hosts trustAllHosts ( ) ; HttpsURLConnection https = ( HttpsURLConnection ) url . openConnection ( ) ; if ( url . getProtocol ( ) . toLowerCase ( ) . equals ( "https" ) ) { https . setHostnameVerifier ( DO_NOT_VERIFY ) ; con = https ; } else { con = ( HttpURLConnection ) url . openConnection ( ) ; } input = new BufferedReader ( new InputStreamReader ( con . getInputStream ( ) ) ) ; sb = new StringBuilder ( ) ; String s ; while ( ( s = input . readLine ( ) ) != null ) { sb . append ( s ) . append ( "\n" ) ; } } catch ( IOException e ) { e . printStackTrace ( ) ; } } catch ( MalformedURLException e1 ) { e1 . printStackTrace ( ) ; } finally { // close buffered if ( input != null ) { try { input . close ( ) ; } catch ( IOException e ) { e . printStackTrace ( ) ; } } // disconnecting releases the resources held by a connection so they may be closed or reused if ( con != null ) { con . disconnect ( ) ; } } return sb == null ? null : sb . toString ( ) ; } final static HostnameVerifier DO_NOT_VERIFY = new HostnameVerifier ( ) { public boolean verify ( String hostname , SSLSession session ) { return true ; } } ; /** * Trust every server - dont check for any certificate */ private static void trustAllHosts ( ) { final String TAG = "trustAllHosts" ; // Create a trust manager that does not validate certificate chains TrustManager [ ] trustAllCerts = new TrustManager [ ] { new X509TrustManager ( ) { public java . security . cert . X509Certificate [ ] getAcceptedIssuers ( ) { return new java . security . cert . X509Certificate [ ] { } ; } public void checkClientTrusted ( X509Certificate [ ] chain , String authType ) throws CertificateException { Log . i ( TAG , "checkClientTrusted" ) ; } public void checkServerTrusted ( X509Certificate [ ] chain , String authType ) throws CertificateException { Log . i ( TAG , "checkServerTrusted" ) ; } } } ; // Install the all-trusting trust manager try { SSLContext sc = SSLContext . getInstance ( "TLS" ) ; sc . init ( null , trustAllCerts , new java . security . SecureRandom ( ) ) ; HttpsURLConnection . setDefaultSSLSocketFactory ( sc . getSocketFactory ( ) ) ; } catch ( Exception e ) { e . printStackTrace ( ) ; } } |
可以看出其中与之前的HttpsURLConnection测试代码主要的不同就是加入了
| 1 | trustAllHosts ( ) ; |
和
| 1 | https . setHostnameVerifier ( DO_NOT_VERIFY ) ; |
表示相信所有证书，并且所有host name验证返回true，这样就能定位到之前的异常是证书验证不通过的问题了。
在上面checkServerTrusted函数中添加断点，查看X509Certificate[] chain的值，即证书信息，发现访问两个不同链接X509Certificate[] chain值有所区别，nginx传过来证书信息缺少了startssl 的ca证书，证书如下：
至此原因大白：
android的证书库里已经带了startssl ca证书，而nginx默认不带startssl ca证书，这样android端访问nginx为容器的https url校验就会失败，jetty默认带startssl ca证书，所以正常。
PS：后来对windows和mac下java访问https也做了测试，发现mac上的jdk缺省不带startssl ca证书所以能访问通过，而加上startssl ca证书后同android一样访问不通过。而windows上的jdk缺省带startssl ca证书同android一样访问失败。
3、解决方式
上面的分析中已经介绍了一种解决方法即客户端相信所有证书，不过这种方式只是规避了问题，同时也给客户端带来了风险，比较合适的解决方式是为nginx添加startssl ca证书，添加方法如下：
First, use the StartSSL™ Control Panel to create a private key and certificate and transfer them to your server. Then execute the following steps (if you use a class 2 certificate replace class1 by class2 in the instructions below):
- Decrypt the private key by using the password you entered when you created your key:
openssl rsa -in ssl.key -out /etc/nginx/conf/ssl.key
Alternatively you can also use the Tool Box decryption tool of your StartSSL™ account.
- Protect your key from prying eyes:
chmod 600 /etc/nginx/conf/ssl.key
- Fetch the Root CA and Class 1 Intermediate Server CA certificates:
wget http://www.startssl.com/certs/ca.pem
wget http://www.startssl.com/certs/sub.class1.server.ca.pem
- Create a unified certificate from your certificate and the CA certificates:
cat ssl.crt sub.class1.server.ca.pem ca.pem > /etc/nginx/conf/ssl-unified.crt
- Configure your nginx server to use the new key and certificate (in the global settings or a server section):
ssl on;
ssl_certificate /etc/nginx/conf/ssl-unified.crt;
ssl_certificate_key /etc/nginx/conf/ssl.key;
- Tell nginx to reload its configuration:
killall -HUP nginx
也可以直接访问install startssl on nginx.
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