In a XPages application I want to make use of the Dropbox Java SDK (2.1.2) for API v2 to get information about my Dropbox account. The following code is used to retrieve the corresponding account object:
String atoken = "****";
DbxRequestConfig rc = new DbxRequestConfig("****");
DbxClientV2 client = new DbxClientV2(rc,atoken);
DbxUserUsersRequests users = client.users();
FullAccount acc = users.getCurrentAccount(); // Exception raised here
The last line raises the following exception:
com.dropbox.core.NetworkIOException: No appropriate protocol
at com.dropbox.core.DbxRequestUtil.startPostRaw(DbxRequestUtil.java:240)
...
Caused by: javax.net.ssl.SSLHandshakeException: No appropriate protocol
at com.ibm.jsse2.kb.c(kb.java:347)
...
From the stacktrace I concluded that IBMJSSE2 is the security provider used to handle the SSL handshake. So I ran the code from above in a non-Domino JVM (JRE7) which uses the SunJSSE security provider and it worked without any problems. Hence the problem must be related to IBM's Domino JVM but I can't figure out how to fix it.
Can anybody help me with this or provide a hint to a solution?
Additional information:
Version of Domino server: 9.0.1 FP4 HF70
Java runtime version: pwa6460sr16fp4-20150414_01 (SR16 FP4) [22B8:0002-1E88]
JVM version: JRE 1.6.0 IBM J9 2.4 Windows 7 amd64-64 jvmwa6460sr16fp4-20150406_242976 (JIT enabled, AOT enabled) J9VM - 20150406_242976 JIT - r9_20150402_88984 GC - GA24_Java6_SR16_20150406_1410_B242976
Unrestricted JCE policy files have been installed in the Domino JVM.
Properties of the IBMJSSE2 security provider:
Alg.Alias.TrustManagerFactory.IbmPKIX = PKIX
Alg.Alias.TrustManagerFactory.X.509 = PKIX
Alg.Alias.TrustManagerFactory.X509 = PKIX
KeyManagerFactory.IbmX509 = com.ibm.jsse2.rc$a_
KeyManagerFactory.NewIbmX509 = com.ibm.jsse2.rc$b_
Provider.id className = com.ibm.jsse2.IBMJSSEProvider2
Provider.id info = IBM JSSE provider2 (implements IbmX509 key/trust factories, SSLv3, TLSv1)
Provider.id name = IBMJSSE2
Provider.id version = 1.6
SSLContext.Default = com.ibm.jsse2.tc
SSLContext.SSL = com.ibm.jsse2.uc
SSLContext.SSL_TLS = com.ibm.jsse2.vc
SSLContext.SSL_TLSv2 = com.ibm.jsse2.wc
SSLContext.TLS = com.ibm.jsse2.yc
SSLContext.TLSv1 = com.ibm.jsse2.zc
SSLContext.TLSv1.1 = com.ibm.jsse2.ad
SSLContext.TLSv1.2 = com.ibm.jsse2.bd
TrustManagerFactory.IbmX509 = com.ibm.jsse2.ed$b_
TrustManagerFactory.PKIX = com.ibm.jsse2.ed$a_
Full stacktrace of exception:
com.dropbox.core.NetworkIOException: No appropriate protocol
at com.dropbox.core.DbxRequestUtil.startPostRaw(DbxRequestUtil.java:240)
at com.dropbox.core.v2.DbxRawClientV2$1.execute(DbxRawClientV2.java:100)
at com.dropbox.core.v2.DbxRawClientV2.executeRetriable(DbxRawClientV2.java:256)
at com.dropbox.core.v2.DbxRawClientV2.rpcStyle(DbxRawClientV2.java:97)
at com.dropbox.core.v2.users.DbxUserUsersRequests.getCurrentAccount(DbxUserUsersRequests.java:120)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:60)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
at java.lang.reflect.Method.invoke(Method.java:611)
at com.ibm.jscript.types.JavaAccessObject.call(JavaAccessObject.java:321)
at com.ibm.jscript.types.FBSObject.call(FBSObject.java:161)
at com.ibm.jscript.ASTTree.ASTCall.interpret(ASTCall.java:197)
at com.ibm.jscript.ASTTree.ASTAssign.interpret(ASTAssign.java:91)
at com.ibm.jscript.ASTTree.ASTBlock.interpret(ASTBlock.java:100)
at com.ibm.jscript.ASTTree.ASTTry.interpret(ASTTry.java:109)
at com.ibm.jscript.ASTTree.ASTBlock.interpret(ASTBlock.java:100)
at com.ibm.jscript.ASTTree.ASTTry.interpret(ASTTry.java:109)
at com.ibm.jscript.std.FunctionObject._executeFunction(FunctionObject.java:261)
at com.ibm.jscript.std.FunctionObject.executeFunction(FunctionObject.java:185)
at com.ibm.jscript.std.FunctionObject.call(FunctionObject.java:171)
at com.ibm.jscript.types.FBSObject.call(FBSObject.java:161)
at com.ibm.jscript.ASTTree.ASTCall.interpret(ASTCall.java:197)
at com.ibm.jscript.ASTTree.ASTAssign.interpret(ASTAssign.java:91)
at com.ibm.jscript.ASTTree.ASTBlock.interpret(ASTBlock.java:100)
at com.ibm.jscript.ASTTree.ASTIf.interpret(ASTIf.java:85)
at com.ibm.jscript.ASTTree.ASTProgram.interpret(ASTProgram.java:119)
at com.ibm.jscript.types.FBSGlobalObject$GlobalMethod.call(FBSGlobalObject.java:280)
at com.ibm.jscript.types.FBSObject.call(FBSObject.java:161)
at com.ibm.jscript.types.FBSGlobalObject$GlobalMethod.call(FBSGlobalObject.java:219)
at com.ibm.jscript.ASTTree.ASTCall.interpret(ASTCall.java:197)
at com.ibm.jscript.ASTTree.ASTBlock.interpret(ASTBlock.java:100)
at com.ibm.jscript.ASTTree.ASTIf.interpret(ASTIf.java:85)
at com.ibm.jscript.ASTTree.ASTBlock.interpret(ASTBlock.java:100)
at com.ibm.jscript.ASTTree.ASTTry.interpret(ASTTry.java:109)
at com.ibm.jscript.std.FunctionObject._executeFunction(FunctionObject.java:261)
at com.ibm.jscript.std.FunctionObject.executeFunction(FunctionObject.java:185)
at com.ibm.jscript.std.FunctionObject.call(FunctionObject.java:171)
at com.ibm.jscript.std.FunctionPrototype$FunctionMethod.call(FunctionPrototype.java:169)
at com.ibm.jscript.types.FBSObject.call(FBSObject.java:161)
at com.ibm.jscript.ASTTree.ASTCall.interpret(ASTCall.java:197)
at com.ibm.jscript.ASTTree.ASTAssign.interpret(ASTAssign.java:91)
at com.ibm.jscript.ASTTree.ASTBlock.interpret(ASTBlock.java:100)
at com.ibm.jscript.ASTTree.ASTIf.interpret(ASTIf.java:85)
at com.ibm.jscript.ASTTree.ASTBlock.interpret(ASTBlock.java:100)
at com.ibm.jscript.ASTTree.ASTTry.interpret(ASTTry.java:109)
at com.ibm.jscript.ASTTree.ASTProgram.interpret(ASTProgram.java:119)
at com.ibm.jscript.ASTTree.ASTProgram.interpretEx(ASTProgram.java:139)
at com.ibm.jscript.JSExpression._interpretExpression(JSExpression.java:435)
at com.ibm.jscript.JSExpression.access$1(JSExpression.java:424)
at com.ibm.jscript.JSExpression$2.run(JSExpression.java:414)
at java.security.AccessController.doPrivileged(AccessController.java:448)
at com.ibm.jscript.JSExpression.interpretExpression(JSExpression.java:410)
at com.ibm.jscript.JSExpression.evaluateValue(JSExpression.java:251)
at com.ibm.jscript.JSExpression.evaluateValue(JSExpression.java:234)
at com.ibm.xsp.javascript.JavaScriptInterpreter.interpret(JavaScriptInterpreter.java:222)
at com.ibm.xsp.binding.javascript.JavaScriptMethodBinding.invoke(JavaScriptMethodBinding.java:111)
at com.ibm.xsp.component.UIViewRootEx.invokePhaseMethodBinding(UIViewRootEx.java:1735)
at com.ibm.xsp.controller.FacesControllerImpl.invokePhaseMethodBinding(FacesControllerImpl.java:450)
at com.ibm.xsp.controller.FacesControllerImpl.access$0(FacesControllerImpl.java:444)
at com.ibm.xsp.controller.FacesControllerImpl$ViewPhaseListener.afterPhase(FacesControllerImpl.java:512)
at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:218)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:120)
at com.ibm.xsp.controller.FacesControllerImpl.render(FacesControllerImpl.java:270)
at com.ibm.xsp.webapp.FacesServlet.serviceView(FacesServlet.java:261)
at com.ibm.xsp.webapp.FacesServletEx.serviceView(FacesServletEx.java:157)
at com.ibm.xsp.webapp.FacesServlet.service(FacesServlet.java:160)
at com.ibm.xsp.webapp.FacesServletEx.service(FacesServletEx.java:138)
at com.ibm.xsp.webapp.DesignerFacesServlet.service(DesignerFacesServlet.java:103)
at com.ibm.designer.runtime.domino.adapter.ComponentModule.invokeServlet(ComponentModule.java:576)
at com.ibm.domino.xsp.module.nsf.NSFComponentModule.invokeServlet(NSFComponentModule.java:1335)
at com.ibm.designer.runtime.domino.adapter.ComponentModule$AdapterInvoker.invokeServlet(ComponentModule.java:853)
at com.ibm.designer.runtime.domino.adapter.ComponentModule$ServletInvoker.doService(ComponentModule.java:796)
at com.ibm.designer.runtime.domino.adapter.ComponentModule.doService(ComponentModule.java:565)
at com.ibm.domino.xsp.module.nsf.NSFComponentModule.doService(NSFComponentModule.java:1319)
at com.ibm.domino.xsp.module.nsf.NSFService.doServiceInternal(NSFService.java:662)
at com.ibm.domino.xsp.module.nsf.NSFService.doService(NSFService.java:482)
at com.ibm.designer.runtime.domino.adapter.LCDEnvironment.doService(LCDEnvironment.java:357)
at com.ibm.designer.runtime.domino.adapter.LCDEnvironment.service(LCDEnvironment.java:313)
at com.ibm.domino.xsp.bridge.http.engine.XspCmdManager.service(XspCmdManager.java:272)
Caused by: javax.net.ssl.SSLHandshakeException: No appropriate protocol
at com.ibm.jsse2.kb.c(kb.java:347)
at com.ibm.jsse2.SSLSocketImpl.i(SSLSocketImpl.java:363)
at com.ibm.jsse2.SSLSocketImpl.h(SSLSocketImpl.java:650)
at com.ibm.jsse2.SSLSocketImpl.a(SSLSocketImpl.java:669)
at com.ibm.jsse2.SSLSocketImpl.startHandshake(SSLSocketImpl.java:95)
at com.ibm.net.ssl.www2.protocol.https.c.afterConnect(c.java:162)
at com.ibm.net.ssl.www2.protocol.https.d.connect(d.java:36)
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1044)
at com.ibm.net.ssl.www2.protocol.https.b.getOutputStream(b.java:53)
at com.dropbox.core.http.StandardHttpRequestor.getOutputStream(StandardHttpRequestor.java:123)
at com.dropbox.core.http.StandardHttpRequestor.access$000(StandardHttpRequestor.java:28)
at com.dropbox.core.http.StandardHttpRequestor$Uploader.(StandardHttpRequestor.java:133)
at com.dropbox.core.http.StandardHttpRequestor.startPost(StandardHttpRequestor.java:72)
at com.dropbox.core.http.StandardHttpRequestor.startPost(StandardHttpRequestor.java:28)
at com.dropbox.core.DbxRequestUtil.startPostRaw(DbxRequestUtil.java:232)
...
Update: After setting javax.net.debug=ssl:handshake:data (as suggested by Jigar Joshi) the error log and trace log provide the following additional information:
Certificate with subject EMAILADDRESS=****, CN=****, O=****, L=****, ST=****, C=****, issued by CN=****, OU=****, O=****, C=****, is not trusted. Validation failed with error 3659.
CommonBaseEventLogRecord:sourceClassName = com.ibm.domino.napi.ssl.DominoX509TrustManager
CommonBaseEventLogRecord:sourceMethodName = checkServerTrusted
<sourcecomponentid component="Expeditor 6.2" componentidtype="ProductName" instanceid="" location="****" locationtype="Hostname" subcomponent="com.ibm.domino.napi.ssl" threadid="5" componenttype="http://www.w3.org/2001/XMLSchema-instance">
The certificate that is not trusted is my own, even though all certificates and the private key were imported into my keystore. The fact that the keystore works in the non-Domino JVM allows me to conclude that the keystore file should be valid. Yet, the certificate is still not trusted when running the code in the Domino JVM.
Update: The core part of the debug output (javax.net.debug=ssl:handshake) is
SSLContextImpl: Using X509ExtendedKeyManager com.ibm.jsse2.hd
SSLContextImpl: Using X509TrustManager com.ibm.jsse2.pc
IBMJSSE2 will ignore com.ibm.jsse2.overrideDefaultProtocol since was set to a non recognized value TLSv1
Installed Providers = IBMJSSE2, IBMJCE, IBMJGSSProvider, IBMCertPath, IBMSASL, IBMXMLCRYPTO, IBMXMLEnc, Policy, IBMSPNEGO
JsseJCE: Using SecureRandom IBMSecureRandom from provider IBMJCE version 1.2
trigger seeding of SecureRandom
done seeding SecureRandom
IBMJSSE2 will enable CBC protection
IBMJSSE2 to send SCSV Cipher Suite on initial ClientHello
JsseJCE: Using SecureRandom IBMSecureRandom from provider IBMJCE version 1.2
IBMJSSE2 will allow RFC 5746 renegotiation per com.ibm.jsse2.renegotiate set to none or default
IBMJSSE2 will not require renegotiation indicator during initial handshake per com.ibm.jsse2.renegotiation.indicator set to OPTIONAL or default taken
IBMJSSE2 will not perform identity checking against the peer cert check during renegotiation per com.ibm.jsse2.renegotiation.peer.cert.check set to OFF or default
IBMJSSE2 will not allow unsafe server certificate change during renegotiation per jdk.tls.allowUnsafeServerCertChange set to FALSE or default
Is initial handshake: true
JsseJCE: Using KeyAgreement ECDH from provider IBMJCE version 1.2
JsseJCE: Using signature SHA1withECDSA from provider TBD via init
JsseJCE: Using signature NONEwithECDSA from provider TBD via init
JsseJCE: Using KeyFactory EC from provider IBMJCE version 1.2
JsseJCE: Using KeyPairGenerator EC from provider TBD via init
JsseJce: EC is available
Ignoring disabled cipher suite: SSL_RENEGO_PROTECTION_REQUEST for TLSv1
No available cipher suite for TLSv1
Thread-8, handling exception: javax.net.ssl.SSLHandshakeException: No appropriate protocol
Thread-8, SEND TLSv1 ALERT: fatal,
description = handshake_failure
"No available cipher suite for TLSv1" seems to be the root of my problem.
Update: Getting the default SSL server socket factory (SSLServerSocketFactory.getDefault()) and the corresponding default and supported cipher suites (getDefaultCipherSuites() / getSupportedCipherSuites()) revealed that only SSL cipher suites are available:
SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA [supported]
SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA [default]
SSL_DHE_DSS_WITH_AES_128_CBC_SHA [default]
SSL_DHE_DSS_WITH_AES_128_CBC_SHA256 [supported]
SSL_DHE_DSS_WITH_AES_128_GCM_SHA256 [supported]
SSL_DHE_DSS_WITH_AES_256_CBC_SHA [default]
SSL_DHE_DSS_WITH_AES_256_CBC_SHA256 [supported]
SSL_DHE_DSS_WITH_AES_256_GCM_SHA384 [supported]
SSL_DHE_DSS_WITH_DES_CBC_SHA [default]
SSL_DHE_DSS_WITH_RC4_128_SHA [supported]
SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA [supported]
SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA [default]
SSL_DHE_RSA_WITH_AES_128_CBC_SHA [default]
SSL_DHE_RSA_WITH_AES_128_CBC_SHA256 [supported]
SSL_DHE_RSA_WITH_AES_128_GCM_SHA256 [supported]
SSL_DHE_RSA_WITH_AES_256_CBC_SHA [default]
SSL_DHE_RSA_WITH_AES_256_CBC_SHA256 [supported]
SSL_DHE_RSA_WITH_AES_256_GCM_SHA384 [supported]
SSL_DHE_RSA_WITH_DES_CBC_SHA [default]
SSL_DH_anon_EXPORT_WITH_DES40_CBC_SHA [supported]
SSL_DH_anon_EXPORT_WITH_RC4_40_MD5 [supported]
SSL_DH_anon_WITH_3DES_EDE_CBC_SHA [supported]
SSL_DH_anon_WITH_AES_128_CBC_SHA [supported]
SSL_DH_anon_WITH_AES_128_CBC_SHA256 [supported]
SSL_DH_anon_WITH_AES_128_GCM_SHA256 [supported]
SSL_DH_anon_WITH_AES_256_CBC_SHA [supported]
SSL_DH_anon_WITH_AES_256_CBC_SHA256 [supported]
SSL_DH_anon_WITH_AES_256_GCM_SHA384 [supported]
SSL_DH_anon_WITH_DES_CBC_SHA [supported]
SSL_DH_anon_WITH_RC4_128_MD5 [supported]
SSL_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA [supported]
SSL_ECDHE_ECDSA_WITH_AES_128_CBC_SHA [supported]
SSL_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 [supported]
SSL_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 [supported]
SSL_ECDHE_ECDSA_WITH_AES_256_CBC_SHA [supported]
SSL_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 [supported]
SSL_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 [supported]
SSL_ECDHE_ECDSA_WITH_NULL_SHA [supported]
SSL_ECDHE_ECDSA_WITH_RC4_128_SHA [supported]
SSL_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA [supported]
SSL_ECDHE_RSA_WITH_AES_128_CBC_SHA [supported]
SSL_ECDHE_RSA_WITH_AES_128_CBC_SHA256 [supported]
SSL_ECDHE_RSA_WITH_AES_128_GCM_SHA256 [supported]
SSL_ECDHE_RSA_WITH_AES_256_CBC_SHA [supported]
SSL_ECDHE_RSA_WITH_AES_256_CBC_SHA384 [supported]
SSL_ECDHE_RSA_WITH_AES_256_GCM_SHA384 [supported]
SSL_ECDHE_RSA_WITH_NULL_SHA [supported]
SSL_ECDHE_RSA_WITH_RC4_128_SHA [supported]
SSL_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA [supported]
SSL_ECDH_ECDSA_WITH_AES_128_CBC_SHA [supported]
SSL_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 [supported]
SSL_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 [supported]
SSL_ECDH_ECDSA_WITH_AES_256_CBC_SHA [supported]
SSL_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 [supported]
SSL_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 [supported]
SSL_ECDH_ECDSA_WITH_NULL_SHA [supported]
SSL_ECDH_ECDSA_WITH_RC4_128_SHA [supported]
SSL_ECDH_RSA_WITH_3DES_EDE_CBC_SHA [supported]
SSL_ECDH_RSA_WITH_AES_128_CBC_SHA [supported]
SSL_ECDH_RSA_WITH_AES_128_CBC_SHA256 [supported]
SSL_ECDH_RSA_WITH_AES_128_GCM_SHA256 [supported]
SSL_ECDH_RSA_WITH_AES_256_CBC_SHA [supported]
SSL_ECDH_RSA_WITH_AES_256_CBC_SHA384 [supported]
SSL_ECDH_RSA_WITH_AES_256_GCM_SHA384 [supported]
SSL_ECDH_RSA_WITH_NULL_SHA [supported]
SSL_ECDH_RSA_WITH_RC4_128_SHA [supported]
SSL_ECDH_anon_WITH_3DES_EDE_CBC_SHA [supported]
SSL_ECDH_anon_WITH_AES_128_CBC_SHA [supported]
SSL_ECDH_anon_WITH_AES_256_CBC_SHA [supported]
SSL_ECDH_anon_WITH_NULL_SHA [supported]
SSL_ECDH_anon_WITH_RC4_128_SHA [supported]
SSL_KRB5_EXPORT_WITH_DES_CBC_40_MD5 [supported]
SSL_KRB5_EXPORT_WITH_DES_CBC_40_SHA [supported]
SSL_KRB5_EXPORT_WITH_RC4_40_MD5 [supported]
SSL_KRB5_EXPORT_WITH_RC4_40_SHA [supported]
SSL_KRB5_WITH_3DES_EDE_CBC_MD5 [supported]
SSL_KRB5_WITH_3DES_EDE_CBC_SHA [supported]
SSL_KRB5_WITH_DES_CBC_MD5 [supported]
SSL_KRB5_WITH_DES_CBC_SHA [supported]
SSL_KRB5_WITH_RC4_128_MD5 [supported]
SSL_KRB5_WITH_RC4_128_SHA [supported]
SSL_RSA_EXPORT_WITH_DES40_CBC_SHA [supported]
SSL_RSA_EXPORT_WITH_RC4_40_MD5 [supported]
SSL_RSA_FIPS_WITH_3DES_EDE_CBC_SHA [default]
SSL_RSA_FIPS_WITH_DES_CBC_SHA [default]
SSL_RSA_WITH_3DES_EDE_CBC_SHA [default]
SSL_RSA_WITH_AES_128_CBC_SHA [default]
SSL_RSA_WITH_AES_128_CBC_SHA256 [supported]
SSL_RSA_WITH_AES_128_GCM_SHA256 [supported]
SSL_RSA_WITH_AES_256_CBC_SHA [default]
SSL_RSA_WITH_AES_256_CBC_SHA256 [supported]
SSL_RSA_WITH_AES_256_GCM_SHA384 [supported]
SSL_RSA_WITH_DES_CBC_SHA [default]
SSL_RSA_WITH_NULL_MD5 [supported]
SSL_RSA_WITH_NULL_SHA [supported]
SSL_RSA_WITH_NULL_SHA256 [supported]
SSL_RSA_WITH_RC4_128_MD5 [supported]
SSL_RSA_WITH_RC4_128_SHA [supported]
Can anybody tell me how to make TLS cipher suites available in the server socket factory?
Re
com.dropbox.core.NetworkIOException: No appropriate protocol
My best guess is that this line is a strong hint of your problem:
Provider.id info = IBM JSSE provider2 (implements IbmX509 key/trust factories, SSLv3, TLSv1)
"No appropriate protocol" sounds like it's probably telling you that the endpoint doesn't support SSLv3 or TLSv1.
I don't know about Dropbox, but many service providers are deprecating those older protocols due to known security problems.
You may find some useful info in these two IBM technotes.
The problem seems to be that the Dropbox Java SDK limits the enabled cipher suites in the SSL sockets based on a hard-coded list. All relevant cipher suite names in that list start with "TLS_". However, in the Domino JVM cipher suite names always start with "SSL_" even when the SSL context they are related to has protocol TLSv1 or higher.
I have now stopped working with the Dropbox Java SDK and started using the Dropbox API by making HTTP posts using HttpsUrlConnection. This is not as convenient as the Java SDK, but at least the SSL handshake with TLSv1 works as expected.
来源：https://stackoverflow.com/questions/40770758/getting-sslhandshakeexception-when-using-dropbox-java-sdk-for-api-v2