Experimental Physics and
Industrial Control System

Hi,

I've had instances of both an IOC and a CAS being unable to create a channel access port. The servers attempt to bind to the usual channel access server port number, but rather than EADDRINUSE being returned on failure they are seeing EACCES. Looking at https://msdn.microsoft.com/en-us/library/windows/desktop/ms740668(v=vs.85).aspx suggests another application/service might have bound to the port already with SO_EXCLUSIVEADDRUSE and this appears to be the situation (the National Instruments network variables server process in this case). If I change things to request a dynamic port allocation after any bind() failure (rather than only on EADDRINUSE) as per the attached patch then everything works fine

Regards,

Freddie

diff --git a/src/cas/io/bsdSocket/casIntfIO.cc b/src/cas/io/bsdSocket/casIntfIO.cc
index 16cd908..7580173 100644
--- a/src/cas/io/bsdSocket/casIntfIO.cc
+++ b/src/cas/io/bsdSocket/casIntfIO.cc
@@ -61,18 +61,16 @@ casIntfIO::casIntfIO ( const caNetAddr & addrIn ) :
                       reinterpret_cast <sockaddr *> (&this->addr),
                       sizeof(this->addr) );
 	if (status<0) {
-		if (SOCKERRNO == SOCK_EADDRINUSE) {
 			//
 			// enable assignment of a default port
 			// (so the getsockname() call below will
 			// work correctly)
 			//
-			this->addr.sin_port = ntohs (0);
+			this->addr.sin_port = htons (0);
 			status = bind(
                     this->sock,
                     reinterpret_cast <sockaddr *> (&this->addr),
                     sizeof(this->addr) );
-		}
 		if (status<0) {
             char sockErrBuf[64];
             epicsSocketConvertErrnoToString ( sockErrBuf, sizeof ( sockErrBuf ) );
diff --git a/src/rsrv/caservertask.c b/src/rsrv/caservertask.c
index 51b7e99..b4cbe1b 100644
--- a/src/rsrv/caservertask.c
+++ b/src/rsrv/caservertask.c
@@ -106,16 +106,14 @@ static void req_server (void *pParm)
     /* get server's Internet address */
     status = bind ( IOC_sock, (struct sockaddr *) &serverAddr, sizeof ( serverAddr ) );
 	if ( status < 0 ) {
-		if ( SOCKERRNO == SOCK_EADDRINUSE ) {
 			/*
 			 * enable assignment of a default port
 			 * (so the getsockname() call below will
 			 * work correctly)
 			 */
-			serverAddr.sin_port = ntohs (0);
+			serverAddr.sin_port = htons (0);
 			status = bind ( IOC_sock, 
                 (struct sockaddr *) &serverAddr, sizeof ( serverAddr ) );
-		}
 		if ( status < 0 ) {
             char sockErrBuf[64];
             epicsSocketConvertErrnoToString ( 

Replies:

Re: CA server bind failure on Windows Ben Franksen

Re: CA server bind failure on Windows Andrew Johnson

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