demos/state_machine/state_machine.c - third_party/openssl - Git at Google

 /* ====================================================================
  * Copyright (c) 2000 The OpenSSL Project.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * 3. All advertising materials mentioning features or use of this
  *    software must display the following acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  *
  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  *    endorse or promote products derived from this software without
  *    prior written permission. For written permission, please contact
  *    openssl-core@openssl.org.
  *
  * 5. Products derived from this software may not be called "OpenSSL"
  *    nor may "OpenSSL" appear in their names without prior written
  *    permission of the OpenSSL Project.
  *
  * 6. Redistributions of any form whatsoever must retain the following
  *    acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  *
  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  * ====================================================================
  *
  * This product includes cryptographic software written by Eric Young
  * (eay@cryptsoft.com).  This product includes software written by Tim
  * Hudson (tjh@cryptsoft.com).
  *
  */

 /*
  * Nuron, a leader in hardware encryption technology, generously
  * sponsored the development of this demo by Ben Laurie.
  *
  * See http://www.nuron.com/.
  */

 /*
  * the aim of this demo is to provide a fully working state-machine
  * style SSL implementation, i.e. one where the main loop acquires
  * some data, then converts it from or to SSL by feeding it into the
  * SSL state machine. It then does any I/O required by the state machine
  * and loops.
  *
  * In order to keep things as simple as possible, this implementation
  * listens on a TCP socket, which it expects to get an SSL connection
  * on (for example, from s_client) and from then on writes decrypted
  * data to stdout and encrypts anything arriving on stdin. Verbose
  * commentary is written to stderr.
  *
  * This implementation acts as a server, but it can also be done for a client.  */

 #include <openssl/ssl.h>
 #include <assert.h>
 #include <unistd.h>
 #include <string.h>
 #include <openssl/err.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>

 /* die_unless is intended to work like assert, except that it happens
    always, even if NDEBUG is defined. Use assert as a stopgap. */

 #define die_unless(x)	assert(x)

 typedef struct
     {
     SSL_CTX *pCtx;
     BIO *pbioRead;
     BIO *pbioWrite;
     SSL *pSSL;
     } SSLStateMachine;

 void SSLStateMachine_print_error(SSLStateMachine *pMachine,const char *szErr)
     {
     unsigned long l;

     fprintf(stderr,"%s\n",szErr);
     while((l=ERR_get_error()))
 	{
 	char buf[1024];

 	ERR_error_string_n(l,buf,sizeof buf);
 	fprintf(stderr,"Error %lx: %s\n",l,buf);
 	}
     }

 SSLStateMachine *SSLStateMachine_new(const char *szCertificateFile,
 				     const char *szKeyFile)
     {
     SSLStateMachine *pMachine=malloc(sizeof *pMachine);
     int n;

     die_unless(pMachine);

     pMachine->pCtx=SSL_CTX_new(SSLv23_server_method());
     die_unless(pMachine->pCtx);

     n=SSL_CTX_use_certificate_file(pMachine->pCtx,szCertificateFile,
 				   SSL_FILETYPE_PEM);
     die_unless(n > 0);

     n=SSL_CTX_use_PrivateKey_file(pMachine->pCtx,szKeyFile,SSL_FILETYPE_PEM);
     die_unless(n > 0);

     pMachine->pSSL=SSL_new(pMachine->pCtx);
     die_unless(pMachine->pSSL);

     pMachine->pbioRead=BIO_new(BIO_s_mem());

     pMachine->pbioWrite=BIO_new(BIO_s_mem());

     SSL_set_bio(pMachine->pSSL,pMachine->pbioRead,pMachine->pbioWrite);

     SSL_set_accept_state(pMachine->pSSL);

     return pMachine;
     }

 void SSLStateMachine_read_inject(SSLStateMachine *pMachine,
 				 const unsigned char *aucBuf,int nBuf)
     {
     int n=BIO_write(pMachine->pbioRead,aucBuf,nBuf);
     /* If it turns out this assert fails, then buffer the data here
      * and just feed it in in churn instead. Seems to me that it
      * should be guaranteed to succeed, though.
      */
     assert(n == nBuf);
     fprintf(stderr,"%d bytes of encrypted data fed to state machine\n",n);
     }

 int SSLStateMachine_read_extract(SSLStateMachine *pMachine,
 				 unsigned char *aucBuf,int nBuf)
     {
     int n;

     if(!SSL_is_init_finished(pMachine->pSSL))
 	{
 	fprintf(stderr,"Doing SSL_accept\n");
 	n=SSL_accept(pMachine->pSSL);
 	if(n == 0)
 	    fprintf(stderr,"SSL_accept returned zero\n");
 	if(n < 0)
 	    {
 	    int err;

 	    if((err=SSL_get_error(pMachine->pSSL,n)) == SSL_ERROR_WANT_READ)
 		{
 		fprintf(stderr,"SSL_accept wants more data\n");
 		return 0;
 		}

 	    SSLStateMachine_print_error(pMachine,"SSL_accept error");
 	    exit(7);
 	    }
 	return 0;
 	}

     n=SSL_read(pMachine->pSSL,aucBuf,nBuf);
     if(n < 0)
 	{
 	int err=SSL_get_error(pMachine->pSSL,n);

 	if(err == SSL_ERROR_WANT_READ)
 	    {
 	    fprintf(stderr,"SSL_read wants more data\n");
 	    return 0;
 	    }

 	SSLStateMachine_print_error(pMachine,"SSL_read error");
 	exit(8);
 	}

     fprintf(stderr,"%d bytes of decrypted data read from state machine\n",n);
     return n;
     }

 int SSLStateMachine_write_can_extract(SSLStateMachine *pMachine)
     {
     int n=BIO_pending(pMachine->pbioWrite);
     if(n)
 	fprintf(stderr,"There is encrypted data available to write\n");
     else
 	fprintf(stderr,"There is no encrypted data available to write\n");

     return n;
     }

 int SSLStateMachine_write_extract(SSLStateMachine *pMachine,
 				  unsigned char *aucBuf,int nBuf)
     {
     int n;

     n=BIO_read(pMachine->pbioWrite,aucBuf,nBuf);
     fprintf(stderr,"%d bytes of encrypted data read from state machine\n",n);
     return n;
     }

 void SSLStateMachine_write_inject(SSLStateMachine *pMachine,
 				  const unsigned char *aucBuf,int nBuf)
     {
     int n=SSL_write(pMachine->pSSL,aucBuf,nBuf);
     /* If it turns out this assert fails, then buffer the data here
      * and just feed it in in churn instead. Seems to me that it
      * should be guaranteed to succeed, though.
      */
     assert(n == nBuf);
     fprintf(stderr,"%d bytes of unencrypted data fed to state machine\n",n);
     }

 int OpenSocket(int nPort)
     {
     int nSocket;
     struct sockaddr_in saServer;
     struct sockaddr_in saClient;
     int one=1;
     int nSize;
     int nFD;
     int nLen;

     nSocket=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
     if(nSocket < 0)
 	{
 	perror("socket");
 	exit(1);
 	}

     if(setsockopt(nSocket,SOL_SOCKET,SO_REUSEADDR,(char *)&one,sizeof one) < 0)
 	{
 	perror("setsockopt");
         exit(2);
 	}

     memset(&saServer,0,sizeof saServer);
     saServer.sin_family=AF_INET;
     saServer.sin_port=htons(nPort);
     nSize=sizeof saServer;
     if(bind(nSocket,(struct sockaddr *)&saServer,nSize) < 0)
 	{
 	perror("bind");
 	exit(3);
 	}

     if(listen(nSocket,512) < 0)
 	{
 	perror("listen");
 	exit(4);
 	}

     nLen=sizeof saClient;
     nFD=accept(nSocket,(struct sockaddr *)&saClient,&nLen);
     if(nFD < 0)
 	{
 	perror("accept");
 	exit(5);
 	}

     fprintf(stderr,"Incoming accepted on port %d\n",nPort);

     return nFD;
     }

 int main(int argc,char **argv)
     {
     SSLStateMachine *pMachine;
     int nPort;
     int nFD;
     const char *szCertificateFile;
     const char *szKeyFile;
     char rbuf[1];
     int nrbuf=0;

     if(argc != 4)
 	{
 	fprintf(stderr,"%s <port> <certificate file> <key file>\n",argv[0]);
 	exit(6);
 	}

     nPort=atoi(argv[1]);
     szCertificateFile=argv[2];
     szKeyFile=argv[3];

     SSL_library_init();
     OpenSSL_add_ssl_algorithms();
     SSL_load_error_strings();
     ERR_load_crypto_strings();

     nFD=OpenSocket(nPort);

     pMachine=SSLStateMachine_new(szCertificateFile,szKeyFile);

     for( ; ; )
 	{
 	fd_set rfds,wfds;
 	unsigned char buf[1024];
 	int n;

 	FD_ZERO(&rfds);
 	FD_ZERO(&wfds);

 	/* Select socket for input */
 	FD_SET(nFD,&rfds);

 	/* check whether there's decrypted data */
 	if(!nrbuf)
 	    nrbuf=SSLStateMachine_read_extract(pMachine,rbuf,1);

 	/* if there's decrypted data, check whether we can write it */
 	if(nrbuf)
 	    FD_SET(1,&wfds);

 	/* Select socket for output */
 	if(SSLStateMachine_write_can_extract(pMachine))
 	    FD_SET(nFD,&wfds);

 	/* Select stdin for input */
 	FD_SET(0,&rfds);

 	/* Wait for something to do something */
 	n=select(nFD+1,&rfds,&wfds,NULL,NULL);
 	assert(n > 0);

 	/* Socket is ready for input */
 	if(FD_ISSET(nFD,&rfds))
 	    {
 	    n=read(nFD,buf,sizeof buf);
 	    if(n == 0)
 		{
 		fprintf(stderr,"Got EOF on socket\n");
 		exit(0);
 		}
 	    assert(n > 0);

 	    SSLStateMachine_read_inject(pMachine,buf,n);
 	    }

 	/* stdout is ready for output (and hence we have some to send it) */
 	if(FD_ISSET(1,&wfds))
 	    {
 	    assert(nrbuf == 1);
 	    buf[0]=rbuf[0];
 	    nrbuf=0;

 	    n=SSLStateMachine_read_extract(pMachine,buf+1,sizeof buf-1);
 	    if(n < 0)
 		{
 		SSLStateMachine_print_error(pMachine,"read extract failed");
 		break;
 		}
 	    assert(n >= 0);
 	    ++n;
 	    if(n > 0) /* FIXME: has to be true now */
 		{
 		int w;

 		w=write(1,buf,n);
 		/* FIXME: we should push back any unwritten data */
 		assert(w == n);
 		}
 	    }

 	/* Socket is ready for output (and therefore we have output to send) */
 	if(FD_ISSET(nFD,&wfds))
 	    {
 	    int w;

 	    n=SSLStateMachine_write_extract(pMachine,buf,sizeof buf);
 	    assert(n > 0);

 	    w=write(nFD,buf,n);
 	    /* FIXME: we should push back any unwritten data */
 	    assert(w == n);
 	    }

 	/* Stdin is ready for input */
 	if(FD_ISSET(0,&rfds))
 	    {
 	    n=read(0,buf,sizeof buf);
 	    if(n == 0)
 		{
 		fprintf(stderr,"Got EOF on stdin\n");
 		exit(0);
 		}
 	    assert(n > 0);

 	    SSLStateMachine_write_inject(pMachine,buf,n);
 	    }
 	}
     /* not reached */
     return 0;
     }
	/* ====================================================================
	* Copyright (c) 2000 The OpenSSL Project. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in
	* the documentation and/or other materials provided with the
	* distribution.
	*
	* 3. All advertising materials mentioning features or use of this
	* software must display the following acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
	*
	* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
	* endorse or promote products derived from this software without
	* prior written permission. For written permission, please contact
	* openssl-core@openssl.org.
	*
	* 5. Products derived from this software may not be called "OpenSSL"
	* nor may "OpenSSL" appear in their names without prior written
	* permission of the OpenSSL Project.
	*
	* 6. Redistributions of any form whatsoever must retain the following
	* acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
	*
	* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
	* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
	* OF THE POSSIBILITY OF SUCH DAMAGE.
	* ====================================================================
	*
	* This product includes cryptographic software written by Eric Young
	* (eay@cryptsoft.com). This product includes software written by Tim
	* Hudson (tjh@cryptsoft.com).
	*
	*/

	/*
	* Nuron, a leader in hardware encryption technology, generously
	* sponsored the development of this demo by Ben Laurie.
	*
	* See http://www.nuron.com/.
	*/

	/*
	* the aim of this demo is to provide a fully working state-machine
	* style SSL implementation, i.e. one where the main loop acquires
	* some data, then converts it from or to SSL by feeding it into the
	* SSL state machine. It then does any I/O required by the state machine
	* and loops.
	*
	* In order to keep things as simple as possible, this implementation
	* listens on a TCP socket, which it expects to get an SSL connection
	* on (for example, from s_client) and from then on writes decrypted
	* data to stdout and encrypts anything arriving on stdin. Verbose
	* commentary is written to stderr.
	*
	* This implementation acts as a server, but it can also be done for a client. */

	#include <openssl/ssl.h>
	#include <assert.h>
	#include <unistd.h>
	#include <string.h>
	#include <openssl/err.h>
	#include <sys/types.h>
	#include <sys/socket.h>
	#include <netinet/in.h>

	/* die_unless is intended to work like assert, except that it happens
	always, even if NDEBUG is defined. Use assert as a stopgap. */

	#define die_unless(x) assert(x)

	typedef struct
	{
	SSL_CTX *pCtx;
	BIO *pbioRead;
	BIO *pbioWrite;
	SSL *pSSL;
	} SSLStateMachine;

	void SSLStateMachine_print_error(SSLStateMachine pMachine,const char szErr)
	{
	unsigned long l;

	fprintf(stderr,"%s\n",szErr);
	while((l=ERR_get_error()))
	{
	char buf[1024];

	ERR_error_string_n(l,buf,sizeof buf);
	fprintf(stderr,"Error %lx: %s\n",l,buf);
	}
	}

	SSLStateMachine SSLStateMachine_new(const char szCertificateFile,
	const char *szKeyFile)
	{
	SSLStateMachine pMachine=malloc(sizeof pMachine);
	int n;

	die_unless(pMachine);

	pMachine->pCtx=SSL_CTX_new(SSLv23_server_method());
	die_unless(pMachine->pCtx);

	n=SSL_CTX_use_certificate_file(pMachine->pCtx,szCertificateFile,
	SSL_FILETYPE_PEM);
	die_unless(n > 0);

	n=SSL_CTX_use_PrivateKey_file(pMachine->pCtx,szKeyFile,SSL_FILETYPE_PEM);
	die_unless(n > 0);

	pMachine->pSSL=SSL_new(pMachine->pCtx);
	die_unless(pMachine->pSSL);

	pMachine->pbioRead=BIO_new(BIO_s_mem());

	pMachine->pbioWrite=BIO_new(BIO_s_mem());

	SSL_set_bio(pMachine->pSSL,pMachine->pbioRead,pMachine->pbioWrite);

	SSL_set_accept_state(pMachine->pSSL);

	return pMachine;
	}

	void SSLStateMachine_read_inject(SSLStateMachine *pMachine,
	const unsigned char *aucBuf,int nBuf)
	{
	int n=BIO_write(pMachine->pbioRead,aucBuf,nBuf);
	/* If it turns out this assert fails, then buffer the data here
	* and just feed it in in churn instead. Seems to me that it
	* should be guaranteed to succeed, though.
	*/
	assert(n == nBuf);
	fprintf(stderr,"%d bytes of encrypted data fed to state machine\n",n);
	}

	int SSLStateMachine_read_extract(SSLStateMachine *pMachine,
	unsigned char *aucBuf,int nBuf)
	{
	int n;

	if(!SSL_is_init_finished(pMachine->pSSL))
	{
	fprintf(stderr,"Doing SSL_accept\n");
	n=SSL_accept(pMachine->pSSL);
	if(n == 0)
	fprintf(stderr,"SSL_accept returned zero\n");
	if(n < 0)
	{
	int err;

	if((err=SSL_get_error(pMachine->pSSL,n)) == SSL_ERROR_WANT_READ)
	{
	fprintf(stderr,"SSL_accept wants more data\n");
	return 0;
	}

	SSLStateMachine_print_error(pMachine,"SSL_accept error");
	exit(7);
	}
	return 0;
	}

	n=SSL_read(pMachine->pSSL,aucBuf,nBuf);
	if(n < 0)
	{
	int err=SSL_get_error(pMachine->pSSL,n);

	if(err == SSL_ERROR_WANT_READ)
	{
	fprintf(stderr,"SSL_read wants more data\n");
	return 0;
	}

	SSLStateMachine_print_error(pMachine,"SSL_read error");
	exit(8);
	}

	fprintf(stderr,"%d bytes of decrypted data read from state machine\n",n);
	return n;
	}

	int SSLStateMachine_write_can_extract(SSLStateMachine *pMachine)
	{
	int n=BIO_pending(pMachine->pbioWrite);
	if(n)
	fprintf(stderr,"There is encrypted data available to write\n");
	else
	fprintf(stderr,"There is no encrypted data available to write\n");

	return n;
	}

	int SSLStateMachine_write_extract(SSLStateMachine *pMachine,
	unsigned char *aucBuf,int nBuf)
	{
	int n;

	n=BIO_read(pMachine->pbioWrite,aucBuf,nBuf);
	fprintf(stderr,"%d bytes of encrypted data read from state machine\n",n);
	return n;
	}

	void SSLStateMachine_write_inject(SSLStateMachine *pMachine,
	const unsigned char *aucBuf,int nBuf)
	{
	int n=SSL_write(pMachine->pSSL,aucBuf,nBuf);
	/* If it turns out this assert fails, then buffer the data here
	* and just feed it in in churn instead. Seems to me that it
	* should be guaranteed to succeed, though.
	*/
	assert(n == nBuf);
	fprintf(stderr,"%d bytes of unencrypted data fed to state machine\n",n);
	}

	int OpenSocket(int nPort)
	{
	int nSocket;
	struct sockaddr_in saServer;
	struct sockaddr_in saClient;
	int one=1;
	int nSize;
	int nFD;
	int nLen;

	nSocket=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
	if(nSocket < 0)
	{
	perror("socket");
	exit(1);
	}

	if(setsockopt(nSocket,SOL_SOCKET,SO_REUSEADDR,(char *)&one,sizeof one) < 0)
	{
	perror("setsockopt");
	exit(2);
	}

	memset(&saServer,0,sizeof saServer);
	saServer.sin_family=AF_INET;
	saServer.sin_port=htons(nPort);
	nSize=sizeof saServer;
	if(bind(nSocket,(struct sockaddr *)&saServer,nSize) < 0)
	{
	perror("bind");
	exit(3);
	}

	if(listen(nSocket,512) < 0)
	{
	perror("listen");
	exit(4);
	}

	nLen=sizeof saClient;
	nFD=accept(nSocket,(struct sockaddr *)&saClient,&nLen);
	if(nFD < 0)
	{
	perror("accept");
	exit(5);
	}

	fprintf(stderr,"Incoming accepted on port %d\n",nPort);

	return nFD;
	}

	int main(int argc,char **argv)
	{
	SSLStateMachine *pMachine;
	int nPort;
	int nFD;
	const char *szCertificateFile;
	const char *szKeyFile;
	char rbuf[1];
	int nrbuf=0;

	if(argc != 4)
	{
	fprintf(stderr,"%s <port> <certificate file> <key file>\n",argv[0]);
	exit(6);
	}

	nPort=atoi(argv[1]);
	szCertificateFile=argv[2];
	szKeyFile=argv[3];

	SSL_library_init();
	OpenSSL_add_ssl_algorithms();
	SSL_load_error_strings();
	ERR_load_crypto_strings();

	nFD=OpenSocket(nPort);

	pMachine=SSLStateMachine_new(szCertificateFile,szKeyFile);

	for( ; ; )
	{
	fd_set rfds,wfds;
	unsigned char buf[1024];
	int n;

	FD_ZERO(&rfds);
	FD_ZERO(&wfds);

	/* Select socket for input */
	FD_SET(nFD,&rfds);

	/* check whether there's decrypted data */
	if(!nrbuf)
	nrbuf=SSLStateMachine_read_extract(pMachine,rbuf,1);

	/* if there's decrypted data, check whether we can write it */
	if(nrbuf)
	FD_SET(1,&wfds);

	/* Select socket for output */
	if(SSLStateMachine_write_can_extract(pMachine))
	FD_SET(nFD,&wfds);

	/* Select stdin for input */
	FD_SET(0,&rfds);

	/* Wait for something to do something */
	n=select(nFD+1,&rfds,&wfds,NULL,NULL);
	assert(n > 0);

	/* Socket is ready for input */
	if(FD_ISSET(nFD,&rfds))
	{
	n=read(nFD,buf,sizeof buf);
	if(n == 0)
	{
	fprintf(stderr,"Got EOF on socket\n");
	exit(0);
	}
	assert(n > 0);

	SSLStateMachine_read_inject(pMachine,buf,n);
	}

	/* stdout is ready for output (and hence we have some to send it) */
	if(FD_ISSET(1,&wfds))
	{
	assert(nrbuf == 1);
	buf[0]=rbuf[0];
	nrbuf=0;

	n=SSLStateMachine_read_extract(pMachine,buf+1,sizeof buf-1);
	if(n < 0)
	{
	SSLStateMachine_print_error(pMachine,"read extract failed");
	break;
	}
	assert(n >= 0);
	++n;
	if(n > 0) /* FIXME: has to be true now */
	{
	int w;

	w=write(1,buf,n);
	/* FIXME: we should push back any unwritten data */
	assert(w == n);
	}
	}

	/* Socket is ready for output (and therefore we have output to send) */
	if(FD_ISSET(nFD,&wfds))
	{
	int w;

	n=SSLStateMachine_write_extract(pMachine,buf,sizeof buf);
	assert(n > 0);

	w=write(nFD,buf,n);
	/* FIXME: we should push back any unwritten data */
	assert(w == n);
	}

	/* Stdin is ready for input */
	if(FD_ISSET(0,&rfds))
	{
	n=read(0,buf,sizeof buf);
	if(n == 0)
	{
	fprintf(stderr,"Got EOF on stdin\n");
	exit(0);
	}
	assert(n > 0);

	SSLStateMachine_write_inject(pMachine,buf,n);
	}
	}
	/* not reached */
	return 0;
	}