Adding SocketChannel toString to connection exception messages (original) (raw)

Steven Schlansker stevenschlansker at gmail.com
Fri Dec 22 00:29:18 UTC 2017

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On Dec 21, 2017, at 11:11 AM, Steven Schlansker <stevenschlansker at gmail.com> wrote:

What if ConnectException included the attempted hostname / IP / port SocketAddress? java.net.ConnectException: Connection to 'foo.mycorp.com[10.x.x.x]:12345' refused Much more useful! This could also be extended to various other socket exceptions.

I started hacking around with this, first with PlainSocketImpl only. I apologize in advance for what is likely to be terrible JNI style, as I don't have much experience with it and I omitted any error handling for the POC - but I think it proves that this isn't too big of a project, as I would want to cover SocketChannelImpl and maybe UnixAsynchronousSocketChannelImpl and call it good enough for my uses.

Behold!

[me at myhost]% java pkg.SocketFail java.net.ConnectException: Connection refused (Connection refused)

[me at myhost]% ~/code/jdk10/build/macosx-x86_64-normal-server-release/jdk/bin/java pkg.SocketFail java.net.ConnectException: Connection refused (Connection refused: localhost/127.0.0.1:12345)

Am I correct that the best path towards acceptance for this kind of change is to target jdk10 and then beg for a backport to jdk9u? Thanks again for considering this improvement! WIP patch below inline.

diff --git a/src/java.base/unix/native/libnet/PlainSocketImpl.c b/src/java.base/unix/native/libnet/PlainSocketImpl.c --- a/src/java.base/unix/native/libnet/PlainSocketImpl.c +++ b/src/java.base/unix/native/libnet/PlainSocketImpl.c @@ -217,6 +217,9 @@ (*env)->SetIntField(env, fdObj, IO_fd_fdID, fd); }

+// private helper for socketConnect to describe errors +static void sockErrDescribe(JNIEnv env, char errbuf, char* msg, jobject ia, jint port); + /*

• inetAddress is the address object passed to the socket connect
• call. @@ -230,6 +233,7 @@ jobject iaObj, jint port, jint timeout)

{

• char errmsg[256]; jint localport = (env)->GetIntField(env, this, psi_localportID); int len = 0; / fdObj is the FileDescriptor field on this */ @@ -249,7 +253,8 @@ int connect_rv = -1;

  if (IS_NULL(fdObj)) {

•    JNU_ThrowByName(env, JNU_JAVANETPKG "SocketException", "Socket closed");

•    sockErrDescribe(env, errmsg, "Socket closed", iaObj, port);

•    JNU_ThrowByName(env, JNU_JAVANETPKG "SocketException", errmsg);
     return;

  } else { fd = (*env)->GetIntField(env, fdObj, IO_fd_fdID);

@@ -329,8 +334,8 @@ jlong prevNanoTime = JVM_NanoTime(env, 0);

         if (errno != EINPROGRESS) {

•            NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ConnectException",

•                         "connect failed");

•            sockErrDescribe(env, errmsg, "connect failed", iaObj, port);

•            NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ConnectException", errmsg);
             SET_BLOCKING(fd);
             return;
         }

@@ -372,8 +377,8 @@ } /* while */

         if (connect_rv == 0) {

•            JNU_ThrowByName(env, JNU_JAVANETPKG "SocketTimeoutException",

•                        "connect timed out");

•            sockErrDescribe(env, errmsg, "connect timed out", iaObj, port);

•            JNU_ThrowByName(env, JNU_JAVANETPKG "SocketTimeoutException", errmsg);
  
             /*
              * Timeout out but connection may still be established.

@@ -419,36 +424,37 @@ * a more descriptive exception text is used. */ if (connect_rv == -1 && errno == EINVAL) {

•        JNU_ThrowByName(env, JNU_JAVANETPKG "SocketException",

•            "Invalid argument or cannot assign requested address");

•        sockErrDescribe(errmsg, "Invalid argument or cannot assign requested address", iaObj, port)

•        JNU_ThrowByName(env, JNU_JAVANETPKG "SocketException", errmsg);
         return;
     }

#endif #if defined(EPROTO) if (errno == EPROTO) {

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ProtocolException",

•                       "Protocol error");

•        sockErrDescribe(env, errmsg, "Protocol error", iaObj, port);

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ProtocolException", errmsg);
         return;
     }

#endif if (errno == ECONNREFUSED) {

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ConnectException",

•                       "Connection refused");

•        sockErrDescribe(env, errmsg, "Connection refused", iaObj, port);

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ConnectException", errmsg);
     } else if (errno == ETIMEDOUT) {

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ConnectException",

•                       "Connection timed out");

•        sockErrDescribe(env, errmsg, "Connection timed out", iaObj, port);

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "ConnectException", errmsg);
     } else if (errno == EHOSTUNREACH) {

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "NoRouteToHostException",

•                       "Host unreachable");

•        sockErrDescribe(env, errmsg, "Host unreachable", iaObj, port);

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "NoRouteToHostException", errmsg);
     } else if (errno == EADDRNOTAVAIL) {

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "NoRouteToHostException",

•                         "Address not available");

•        sockErrDescribe(env, errmsg, "Address not available", iaObj, port);

•        NET_ThrowByNameWithLastError(env, JNU_JAVANETPKG "NoRouteToHostException", errmsg);
     } else if ((errno == EISCONN) || (errno == EBADF)) {

•        JNU_ThrowByName(env, JNU_JAVANETPKG "SocketException",

•                        "Socket closed");

•        sockErrDescribe(env, errmsg, "Socket closed", iaObj, port);

•        JNU_ThrowByName(env, JNU_JAVANETPKG "SocketException", errmsg);
     } else {

•        sockErrDescribe(env, errmsg, "connect failed", iaObj, port);
         JNU_ThrowByNameWithMessageAndLastError

•            (env, JNU_JAVANETPKG "SocketException", "connect failed");

•            (env, JNU_JAVANETPKG "SocketException", errmsg);
     }
     return;

  } @@ -479,6 +485,15 @@ } }

+static void sockErrDescribe(JNIEnv env, char errbuf, char* msg, jobject ia, jint port) {

• jclass obj = (*env)->FindClass(env, "java/lang/Object");
• jmethodID toStr = (*env)->GetMethodID(env, obj, "toString", "()Ljava/lang/String;");
• jstring iaJstr = (*env)->CallObjectMethod(env, ia, toStr);
• const char *iaStr = (*env)->GetStringUTFChars(env, iaJstr, 0);
• jio_snprintf(errbuf, 128, "%s: %s:%d", msg, iaStr, port);
• (*env)->ReleaseStringUTFChars(env, iaJstr, iaStr);

+} + /*

• Class: java_net_PlainSocketImpl
• Method: socketBind

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