hostNameCache.cpp

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/*************************************************************************\
* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
*     National Laboratory.
* Copyright (c) 2002 The Regents of the University of California, as
*     Operator of Los Alamos National Laboratory.
* EPICS BASE is distributed subject to a Software License Agreement found
* in file LICENSE that is included with this distribution.
\*************************************************************************/

/*
 *
 *
 *                    L O S  A L A M O S
 *              Los Alamos National Laboratory
 *               Los Alamos, New Mexico 87545
 *
 *  Copyright, 1986, The Regents of the University of California.
 *
 *
 *  Author Jeffrey O. Hill
 *  johill@lanl.gov
 */

#include <algorithm>
#include <cstring>

#define epicsAssertAuthor "Jeff Hill johill@lanl.gov"
#include "hostNameCache.h"
#include "epicsGuard.h"

hostNameCache::hostNameCache (
    const osiSockAddr & addr, ipAddrToAsciiEngine & engine ) :
    dnsTransaction ( engine.createTransaction() ), nameLength ( 0 )
{
    sockAddrToDottedIP ( &addr.sa, hostNameBuf, sizeof ( hostNameBuf ) );
    hostNameBuf[ sizeof ( hostNameBuf ) - 1 ] = '\0';
    nameLength = strlen ( hostNameBuf );
    this->dnsTransaction.ipAddrToAscii ( addr, *this );
}

void hostNameCache::destroy ()
{
    delete this;
}

hostNameCache::~hostNameCache ()
{
    this->dnsTransaction.release ();
}

void hostNameCache::transactionComplete ( const char * pHostNameIn )
{
    epicsGuard < epicsMutex > guard ( this->mutex );
    // a few legacy clients have a direct pointer to this buffer so we
    // set the entrire string to nill terminators before we start copying
    // in the name (this reduces the chance that another thread will see
    // garbage characters).
    size_t newNameLen = strlen ( pHostNameIn );
    if ( newNameLen > sizeof ( this->hostNameBuf ) - 1u ) {
        newNameLen = sizeof ( this->hostNameBuf ) - 1u;
    }
    strncpy ( this->hostNameBuf, "", sizeof ( this->hostNameBuf ) );
    strncpy ( this->hostNameBuf, pHostNameIn, sizeof ( this->hostNameBuf ) - 1 );
    this->nameLength = newNameLen;
}

unsigned hostNameCache::getName (
    char * pBuf, unsigned bufSize ) const
{
    if ( bufSize == 0u ) {
        return 0u;
    }
    epicsGuard < epicsMutex > guard ( this->mutex );
    if ( this->nameLength > 0u ) {
        if ( this->nameLength < bufSize ) {
            strcpy ( pBuf, this->hostNameBuf );
            return this->nameLength;
        }
        else {
            unsigned reducedSize = bufSize - 1u;
            strncpy ( pBuf, this->hostNameBuf, reducedSize );
            pBuf [ reducedSize ] = '\0';
            return reducedSize;
        }
    }
    else {
        osiSockAddr tmpAddr = this->dnsTransaction.address ();
        return sockAddrToDottedIP ( &tmpAddr.sa, pBuf, bufSize );
    }
}