/*
 *   stunnel       Universal SSL tunnel
 *   Copyright (c) 1998-2000 Michal Trojnara <Michal.Trojnara@mirt.net>
 *                 All Rights Reserved
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/* For US citizens having problems with patents, undefined by default */
/* Uncomment the next line to disable RSA support */
/* #define NO_RSA */

/* Experimental DH support is disabled by default */
/* Comment out the next line if you need it */
#define NO_DH

/* Non-blocking sockets are disabled by default */
/* It works on most systems so feel free to uncomment the next line */
/* #define USE_NBIO */

#ifndef NO_RSA

/* Cache temporary keys up to 2048 bits */
#define KEY_CACHE_LENGTH 2049

/* Cache temporary keys up to 1 hour */
#define KEY_CACHE_TIME 3600

#endif /* NO_RSA */

/* Undefine if you have problems with make_sockets() */
#define INET_SOCKET_PAIR

/* Max number of children */
#define MAX_CLIENTS    100

/* I/O buffer size */
#define BUFFSIZE       8192

#include "common.h"

#include <stdio.h>

#ifdef HAVE_OPENSSL
#include <openssl/lhash.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#else
#include <lhash.h>
#include <ssl.h>
#include <err.h>
#endif

#ifdef USE_WIN32

#define Win32_Winsock
#include <windows.h>
#include <io.h>
#include <stdlib.h>
#include <process.h>
#include <malloc.h>
#include <string.h>
#include <sys/stat.h>
#define ECONNRESET WSAECONNRESET
#define ENOTSOCK WSAENOTSOCK

#else /* defined USE_WIN32 */

/* Must be included before sys/stat.h for Ultrix */
#include <sys/types.h>   /* u_short, u_long */

/* General headers */
#include <errno.h>       /* errno */
#include <sys/stat.h>    /* stat */
#include <signal.h>      /* signal */
#include <sys/wait.h>    /* wait */
#include <string.h>      /* strerror */
#include <ctype.h>
#include <stdlib.h>
#include <netdb.h>
#ifdef HAVE_GETOPT_H
#include <getopt.h>      /* getopt */
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>      /* getpid, fork, execv, exit */
#endif

/* Networking headers */
#include <netinet/in.h>  /* struct sockaddr_in */
#include <sys/socket.h>  /* getpeername */
#include <arpa/inet.h>   /* inet_ntoa */
#include <sys/time.h>    /* select */
#include <sys/ioctl.h>   /* ioctl */
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>  /* for aix */
#endif

    /* TCP wrapper */
#ifdef USE_LIBWRAP
#include <tcpd.h>
int allow_severity=LOG_NOTICE;
int deny_severity=LOG_WARNING;
#endif

#endif /* defined USE_WIN32 */

extern server_options options;

int auth_user(struct sockaddr_in *);

    /* SSL functions */
void context_init();
void context_free();
void client(int);
int  prng_seeded(int);
int  add_rand_file(char *);
void initialize_prng();
static int transfer(SSL *, int);
#ifndef NO_RSA
static RSA *tmp_rsa_cb(SSL *, int, int);
#endif /* NO_RSA */
static int verify_callback (int, X509_STORE_CTX *);
static void info_callback(SSL *, int, int);
static void print_stats();
static void print_cipher(SSL *);
static void sslerror(char *);

SSL_CTX *ctx;           /* global SSL context */
#if SSLEAY_VERSION_NUMBER >= 0x0922
static unsigned char *sid_ctx=(unsigned char *)"stunnel SID";
    /* const allowed here */
#endif


/* shortcut to determine if sufficient entropy for PRNG is present */
int prng_seeded( int bytes ) {

#if SSLEAY_VERSION_NUMBER >= 0x0090581fL
    if ( RAND_status() ) {
    	log(LOG_DEBUG, "RAND_status claims sufficient entropy for the PRNG");
	return(1);
    }
#else
    if ( bytes >= options.random_bytes ) {
    	log(LOG_INFO, "Sufficient entropy in PRNG assumed (>= %d)", options.random_bytes);
	return(1);
    }
#endif

    return(0);	/* assume we don't have enough */
}

int add_rand_file( char *filename ) {
    int readbytes;
    int writebytes;
    struct stat sb;

    if ( stat(filename, &sb) !=0 ) { return(0); }
    
    if ( (readbytes = RAND_load_file(filename, options.random_bytes )) ) {
	log(LOG_DEBUG, "Snagged %d random bytes from %s", readbytes, filename);
    } else {
	log(LOG_INFO, "Unable to retrieve any random data from %s", filename);
    }

    /* Write new random data for future seeding if it's a regular file */
    if ( options.rand_write && (sb.st_mode & S_IFREG) ) {
	writebytes = RAND_write_file(filename);
    	if ( -1 == writebytes ) {
		log(LOG_WARNING, "Failed to write strong random data to %s.  May "
			"be a permissions or seeding problem", filename); 
	} else {
		log(LOG_DEBUG, "Wrote %d new random bytes to %s", writebytes, filename);
	}
    }
    return(readbytes);
}



void initialize_prng( void ) {
    int totbytes=0;
    char filename[STRLEN];
    int bytes;
    bytes=0; /* avoid warning if #ifdef'd out for windows */

    filename[0]='\0';

    /* If they specify a rand file on the command line we
       assume that they really do want it, so try it first */
    if ( options.rand_file ) {
    	totbytes += add_rand_file(options.rand_file);
	if ( prng_seeded(totbytes) ) { goto SEEDED; }
    }
    /* Yes.  goto.  Deal with it. */

    /* try the $RANDFILE or $HOME/.rnd files */
    RAND_file_name(filename, STRLEN);
    if ( filename[0] ) {
        filename[STRLEN-1]='\0';	/* just in case */
    	totbytes += add_rand_file(filename);
	if ( prng_seeded(totbytes) ) { goto SEEDED; }
    }

#ifdef RANDOM_FILE
    totbytes += add_rand_file( RANDOM_FILE );
    if ( prng_seeded(totbytes) ) { goto SEEDED; }
#endif

#ifdef USE_WIN32
    RAND_screen();
    if ( prng_seeded(totbytes) ) {
        log(LOG_DEBUG, "Seeded PRNG with RAND_screen");
	goto SEEDED;
    } else {
        log(LOG_DEBUG, "RAND_screen failed to sufficiently seed PRNG");
    }
#else

#if SSLEAY_VERSION_NUMBER >= 0x0090581fL
    if ( options.egd_sock ) {
        if ( (bytes=RAND_egd(options.egd_sock)) == -1 ) {
            log(LOG_WARNING, "EGD Socket %s failed", options.egd_sock);
	    bytes=0;
        } else {
	    totbytes += bytes;
            log(LOG_DEBUG, "Snagged %d random bytes from EGD Socket %s",
                bytes, options.egd_sock);
	    goto SEEDED;  /* openssl always gets what it needs or fails,
	    		     so no need to check if seeded sufficiently */
        }
    }
#ifdef EGD_SOCKET
    if ( (bytes=RAND_egd( EGD_SOCKET )) == -1 ) {
        log(LOG_WARNING, "EGD Socket %s failed", EGD_SOCKET);
    } else {
	totbytes += bytes;
        log(LOG_DEBUG, "Snagged %d random bytes from EGD Socket %s",
                bytes, EGD_SOCKET);
	goto SEEDED; /* ditto */
    }
#endif /* EGD_SOCKET */

#endif /* OpenSSL-0.9.5a */
#endif /* USE_WIN32 */


    /* Try the good-old default /dev/urandom, if available  */
    totbytes += add_rand_file( "/dev/urandom" );
    if ( prng_seeded(totbytes) ) { goto SEEDED; }

    /* Random file specified during configure */

    log(LOG_INFO, "PRNG seeded with %d bytes total", totbytes);
    log(LOG_WARNING, "PRNG may not have been seeded with enough random bytes");
    return;

SEEDED:
    log(LOG_INFO, "PRNG seeded successfully");
    return;
    
}

void verify_info() {
	/*
	STACK_OF(X509_NAME) *stack;
	X509_STORE *store;

	stack= SSL_CTX_get_client_CA_list(ctx);
	log(LOG_DEBUG, "there are %d CA_list things", sk_X509_NAME_num(stack));

	store=SSL_CTX_get_cert_store(ctx);
	log(LOG_DEBUG, "it's a %p", store);
	*/
}

void context_init() /* init SSL */
{
#ifndef NO_DH
    static DH *dh=NULL;
    BIO *bio=NULL;
#endif /* NO_DH */

    initialize_prng();

    SSLeay_add_ssl_algorithms();
    SSL_load_error_strings();
    if(options.option&OPT_CLIENT) {
        ctx=SSL_CTX_new(SSLv3_client_method());
    } else { /* Server mode */
        ctx=SSL_CTX_new(SSLv23_server_method());
#ifndef NO_RSA
        SSL_CTX_set_tmp_rsa_callback(ctx, tmp_rsa_cb);
#endif /* NO_RSA */
#ifndef NO_DH
        if(!(bio=BIO_new_file(options.pem, "r"))) {
            log(LOG_ERR, "DH: Could not read %s: %s", options.pem,
                strerror(errno));
            goto dh_failed;
        }
        if(!(dh=PEM_read_bio_DHparams(bio, NULL, NULL
#if SSLEAY_VERSION_NUMBER >= 0x00904000L
                , NULL
#endif
                ))) {
            log(LOG_ERR, "Could not load DH parameters from %s",
                options.pem);
            goto dh_failed;
        }
        SSL_CTX_set_tmp_dh(ctx, dh);
        log(LOG_DEBUG, "Diffie-Hellman initialized with %d bit key",
            8*DH_size(dh));
        goto dh_done;
dh_failed:
        log(LOG_WARNING, "Diffie-Hellman initialization failed");
dh_done:
        if(bio)
            BIO_free(bio);
        if(dh)
            DH_free(dh);
#endif /* NO_DH */
    }

    SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_BOTH);
    SSL_CTX_set_timeout(ctx, options.session_timeout);
    if(options.option&OPT_CERT) {
        if(!SSL_CTX_use_certificate_file(ctx, options.pem,
                SSL_FILETYPE_PEM)) {
            log(LOG_ERR, "Error reading certificate file: %s", options.pem);
            sslerror("SSL_CTX_use_certificate_file");
            exit(1);
        }
        log(LOG_DEBUG, "Certificate: %s", options.pem);
#ifdef NO_RSA
        if(!SSL_CTX_use_PrivateKey_file(ctx, options.pem,
                SSL_FILETYPE_PEM)) {
            sslerror("SSL_CTX_use_PrivateKey_file");
            exit(1);
        }
#else /* NO_RSA */
        if(!SSL_CTX_use_RSAPrivateKey_file(ctx, options.pem,
                SSL_FILETYPE_PEM)) {
            sslerror("SSL_CTX_use_RSAPrivateKey_file");
            exit(1);
        }
#endif /* NO_RSA */
	if(!SSL_CTX_check_private_key(ctx)) {
	    sslerror("Private key does not match the certificate");
	    exit(1);
	}
    }
    if(options.verify_level!=SSL_VERIFY_NONE) {

	log(LOG_DEBUG, "cert_defaults is %d", options.cert_defaults);
	log(LOG_DEBUG, "cert_dir is %s", options.cert_dir);
	log(LOG_DEBUG, "cert_file is %s", options.cert_file);
	if ( options.cert_defaults & SSL_CERT_DEFAULTS ) {
		log(LOG_DEBUG, "Initializing SSL library verify paths.");
		if ((!SSL_CTX_set_default_verify_paths(ctx))) { 
		    sslerror("X509_set_default_verify_paths");
		    exit(1);
		}
	}

	/* put in defaults (if not set on cmd line) if -S says to */
	if ( options.cert_defaults & STUNNEL_CERT_DEFAULTS ) {
		log(LOG_DEBUG, "installing defaults where not set");
		if ( ! options.cert_file[0] ) 
			safecopy(options.cert_file, CERT_FILE);
		if ( ! options.cert_dir[0] ) 
			safecopy(options.cert_dir, CERT_DIR);
	}
	if ( options.cert_file[0] ) {
	    if (!SSL_CTX_load_verify_locations(ctx, options.cert_file,NULL)) {
		log(LOG_ERR, "Error loading verify certificates from %s",
		    options.cert_file);
		sslerror("SSL_CTX_load_verify_locations");
		exit(1);
	    }
            SSL_CTX_set_client_CA_list(ctx, 
		SSL_load_client_CA_file(options.cert_file));
	    log(LOG_DEBUG, "Loaded verify certificates from %s",
		options.cert_file);
	}
	if ( options.cert_dir[0] ) {
	    if (!SSL_CTX_load_verify_locations(ctx,NULL ,options.cert_dir)) {
		log(LOG_ERR, "Error setting verify directory to %s",
		    options.cert_dir);
		sslerror("SSL_CTX_load_verify_locations");
		exit(1);
	    }
	    log(LOG_DEBUG, "Set verify directory to %s", options.cert_dir);
	}

        /*
	if (!SSL_CTX_load_verify_locations(ctx, options.cert_file,
		options.cert_dir)) {
            sslerror("X509_load_verify_locations");
            exit(1);
        }
	*/

        SSL_CTX_set_verify(ctx, options.verify_level, verify_callback);


        if (options.verify_use_only_my)
            log(LOG_NOTICE, "Peer certificate location %s", options.cert_dir);


    }
    SSL_CTX_set_info_callback(ctx, info_callback);
    if(options.cipher_list) {
        if (!SSL_CTX_set_cipher_list(ctx, options.cipher_list)) {
            sslerror("SSL_CTX_set_cipher_list");
            exit(1);
        }
    }
}


void context_free() /* free SSL */
{
    SSL_CTX_free(ctx);
}

void client(int local)
{
    struct sockaddr_in addr;
    int addrlen;
    SSL *ssl;
    int remote;
    struct linger l;
    u_long ip;
#ifdef USE_LIBWRAP
    struct request_info request;
#endif

    log(LOG_DEBUG, "%s started", options.servname);
    l.l_onoff=1;
    l.l_linger=0;
    addrlen=sizeof(addr);
    if(getpeername(local, (struct sockaddr *)&addr, &addrlen)<0) {
        if(options.option&OPT_TRANSPARENT || errno!=ENOTSOCK) {
            sockerror("getpeerbyname");
            goto cleanup_local;
        }
        /* Ignore ENOTSOCK error so 'local' doesn't have to be a socket */
    } else {
#ifdef USE_LIBWRAP
        request_init(&request, RQ_DAEMON, options.servname, RQ_FILE, local, 0);
        fromhost(&request);
        if (!hosts_access(&request)) {
            log(LOG_WARNING, "Connection from %s:%d REFUSED by libwrap",
                inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
            log(LOG_DEBUG, "See hosts_access(5) for details");
            goto cleanup_local;
        }
#endif
        if(auth_user(&addr)<0) {
            log(LOG_WARNING, "Connection from %s:%d REFUSED by IDENT",
                inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
            goto cleanup_local;
        }
        log(LOG_NOTICE, "%s connected from %s:%d", options.servname,
            inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
    }

    /* create connection to host/service */
    ip=options.option&OPT_TRANSPARENT ? addr.sin_addr.s_addr : 0;
    if(options.option&OPT_REMOTE) { /* remote host */
        if((remote=connect_remote(ip))<0)
            goto cleanup_local; /* Failed to connect remote server */
        log(LOG_DEBUG, "Remote host connected");
    } else { /* local service */
        if((remote=connect_local(ip))<0)
            goto cleanup_local; /* Failed to spawn local service */
        log(LOG_DEBUG, "Local service connected");
    }

    /* negotiate protocol */
    if(negotiate(options.protocol, options.option&OPT_CLIENT,
            local, remote) <0) {
        log(LOG_ERR, "Protocol negotiations failed");
        goto cleanup_remote;
    }

    /* do the job */
    if(!(ssl=SSL_new(ctx))) {
        sslerror("SSL_new");
        goto cleanup_remote;
    }
#if SSLEAY_VERSION_NUMBER >= 0x0922
    SSL_set_session_id_context(ssl, sid_ctx, strlen(sid_ctx));
#endif
    if(options.option&OPT_CLIENT) {
	/* Attempt to use the most recent id in the session cache */
	if ( ctx->session_cache_head )
	    if ( ! SSL_set_session(ssl, ctx->session_cache_head) )
		log(LOG_WARNING, "Cannot set SSL session id to most recent used");
        SSL_set_fd(ssl, remote);
        SSL_set_connect_state(ssl);
        if(SSL_connect(ssl)<=0) {
            sslerror("SSL_connect");
            goto cleanup_ssl;
        }
        print_cipher(ssl);
        if(transfer(ssl, local)<0)
            goto cleanup_ssl;
    } else {
        SSL_set_fd(ssl, local);
        SSL_set_accept_state(ssl);
        if(SSL_accept(ssl)<=0) {
            sslerror("SSL_accept");
            goto cleanup_ssl;
        }
        print_cipher(ssl);
        if(transfer(ssl, remote)<0)
            goto cleanup_ssl;
    }
    /* No error - normal shutdown */
    SSL_set_shutdown(ssl, SSL_SENT_SHUTDOWN|SSL_RECEIVED_SHUTDOWN);
    SSL_free(ssl);
    ERR_remove_state(0);
    closesocket(remote);
    closesocket(local);
    goto done;
cleanup_ssl: /* close SSL and reset sockets */
    SSL_set_shutdown(ssl, SSL_SENT_SHUTDOWN|SSL_RECEIVED_SHUTDOWN);
    SSL_free(ssl);
    ERR_remove_state(0);
cleanup_remote: /* reset remote and local socket */
    if ((options.option & OPT_REMOTE) &&
        setsockopt(remote, SOL_SOCKET, SO_LINGER, (char *)&l, sizeof(l)) < 0 &&
        errno != ENOTSOCK)
        sockerror("linger (remote)");
    closesocket(remote);
cleanup_local: /* reset local socket */
    if (!((options.option & OPT_CLIENT) && (options.option & OPT_PROGRAM)) &&
        setsockopt(local, SOL_SOCKET, SO_LINGER, (char *)&l, sizeof(l)) < 0 &&
        errno != ENOTSOCK)
        sockerror("linger (local)");
    closesocket(local);
done:
#ifndef USE_FORK
    enter_critical_section(2); /* for multi-cpu machines */
    log(LOG_DEBUG, "%s finished (%d left)", options.servname,
        --options.clients);
    leave_critical_section(2);
#endif
    ; /* ANSI C compiler needs it */
}

static int transfer(SSL *ssl, int sock_fd) /* transfer data */
{
    fd_set rd_set, wr_set;
    int num, fdno, ssl_fd, ssl_bytes, sock_bytes, retval;
    char sock_buff[BUFFSIZE], ssl_buff[BUFFSIZE];
    int sock_ptr, ssl_ptr, sock_open, ssl_open;
#if defined FIONBIO && defined USE_NBIO
    unsigned long l;
#endif

    int check_SSL_pending;

    ssl_fd=SSL_get_fd(ssl);
    fdno=(ssl_fd>sock_fd ? ssl_fd : sock_fd)+1;
    sock_ptr=0;
    ssl_ptr=0;
    sock_open=1;
    ssl_open=1;
    sock_bytes=0;
    ssl_bytes=0;

#if defined FIONBIO && defined USE_NBIO
    l=1; /* ON */
    if(ioctlsocket(sock_fd, FIONBIO, &l)<0)
        sockerror("ioctlsocket (sock)"); /* non-critical */
    if(ioctlsocket(ssl_fd, FIONBIO, &l)<0)
        sockerror("ioctlsocket (ssl)"); /* non-critical */
    log(LOG_DEBUG, "Sockets set to non-blocking mode");
#endif

    while((sock_open||sock_ptr) && (ssl_open||ssl_ptr)) {

        FD_ZERO(&rd_set);

        if(sock_open && sock_ptr<BUFFSIZE) /* can read from socket */
            FD_SET(sock_fd, &rd_set);

        if (   ssl_open
            && (    (ssl_ptr<BUFFSIZE) /* I want to read from SSL */
                || (sock_ptr && SSL_want_read(ssl) )
                  /* I want to SSL_write but read from the underlying
                   * socket needed for the SSL protocol. */
               )
           ) {
          FD_SET(ssl_fd, &rd_set);
        }

        FD_ZERO(&wr_set);

        if(sock_open && ssl_ptr) /* can write to socket */
            FD_SET(sock_fd, &wr_set);

        if (   ssl_open
            && (   (sock_ptr) /* can write to SSL */
                || ( (ssl_ptr<BUFFSIZE) && SSL_want_write( ssl ) )
                   /* I want to SSL_read but write to the underlying
                    * socket needed for the SSL protocol. */
               )
           ) {
          FD_SET(ssl_fd, &wr_set);
        }

        if(select(fdno, &rd_set, &wr_set, NULL, NULL)<0) {
            sockerror("select");
            goto error;
        }

        /* Set flag to try and read any buffered SSL data if we made
         * room in the buffer by writing to the socket. */

        check_SSL_pending = 0;

        if(sock_open && FD_ISSET(sock_fd, &wr_set)) {
            num=writesocket(sock_fd, ssl_buff, ssl_ptr);
            if(num<0) {
                sockerror("write");
                goto error;
            }
            if(num) {
                memcpy(ssl_buff, ssl_buff+num, ssl_ptr-num);

                if (ssl_ptr ==BUFFSIZE) check_SSL_pending = 1;

                ssl_ptr-=num;
                sock_bytes+=num;
            } else { /* close */
                log(LOG_DEBUG, "Socket closed on write");
                sock_open=0;
            }
        }


        if (   ssl_open
            && sock_ptr
            && (   FD_ISSET(ssl_fd, &wr_set)
                  /* See if application data can be written. */

                || ( SSL_want_read(ssl) && FD_ISSET(ssl_fd, &rd_set) )
                   /* I want to SSL_write but read from the underlying
                    * socket needed for the SSL protocol. */
               )
           ) {

            num=SSL_write(ssl, sock_buff, sock_ptr);

            switch(SSL_get_error(ssl, num)) {
            case SSL_ERROR_NONE:
                memcpy(sock_buff, sock_buff+num, sock_ptr-num);
                sock_ptr-=num;
                ssl_bytes+=num;
                break;
            case SSL_ERROR_WANT_WRITE:
            case SSL_ERROR_WANT_READ:
            case SSL_ERROR_WANT_X509_LOOKUP:
                log(LOG_DEBUG, "SSL_write returned WANT_ - retry");
                break;
            case SSL_ERROR_SYSCALL:
                if(num) { /* not EOF */
                    sockerror("SSL_write (socket)");
                    goto error;
                }
            case SSL_ERROR_ZERO_RETURN:
                log(LOG_DEBUG, "SSL closed on write");
                ssl_open=0;
                break;
            case SSL_ERROR_SSL:
                sslerror("SSL_write");
                goto error;
            }
        }

        if(sock_open && FD_ISSET(sock_fd, &rd_set)) {
            num=readsocket(sock_fd, sock_buff+sock_ptr, BUFFSIZE-sock_ptr);

            if(num<0 && errno==ECONNRESET) {
                log(LOG_NOTICE, "IPC reset (child died)");
                break; /* close connection */
            }
            if (num < 0 && errno != EIO) {
                sockerror("read");
                goto error;
            } else if (num > 0) {
                sock_ptr += num;
            } else { /* close */
                log(LOG_DEBUG, "Socket closed on read");
                sock_open = 0;
            }
        }

        if(   ssl_open

           && (ssl_ptr<BUFFSIZE)

           && (   FD_ISSET(ssl_fd, &rd_set)
                  /* See if there's any application data coming in. */

               || ( SSL_want_write( ssl ) && FD_ISSET(ssl_fd, &wr_set) )
                  /* I want to SSL_read but write to the underlying
                   * socket needed for the SSL protocol. */

               || ( check_SSL_pending && SSL_pending(ssl) )
                  /* Write made space from full buffer. */
              )
          ) {

            num=SSL_read(ssl, ssl_buff+ssl_ptr, BUFFSIZE-ssl_ptr);

            switch(SSL_get_error(ssl, num)) {
            case SSL_ERROR_NONE:
                ssl_ptr+=num;
                break;
            case SSL_ERROR_WANT_WRITE:
            case SSL_ERROR_WANT_READ:
            case SSL_ERROR_WANT_X509_LOOKUP:
                log(LOG_DEBUG, "SSL_read returned WANT_ - retry");
                break;
            case SSL_ERROR_SYSCALL:
                if(num) { /* not EOF */
                    sockerror("SSL_read (socket)");
                    goto error;
                }
            case SSL_ERROR_ZERO_RETURN:
                log(LOG_DEBUG, "SSL closed on read");
                ssl_open=0;
                break;
            case SSL_ERROR_SSL:
                sslerror("SSL_read");
                goto error;
            }
        }
    }
    retval=0;
    goto done;
error:
    retval=-1;
done:

#if defined FIONBIO && defined USE_NBIO
    l=0; /* OFF */
    if(ioctlsocket(sock_fd, FIONBIO, &l)<0)
        sockerror("ioctlsocket (sock)"); /* non-critical */
    if(ioctlsocket(ssl_fd, FIONBIO, &l)<0)
        sockerror("ioctlsocket (ssl)"); /* non-critical */
#endif

    log(LOG_NOTICE,
        "Connection %s: %d bytes sent to SSL, %d bytes sent to socket",
        retval<0 ? "reset" : "closed", ssl_bytes, sock_bytes);
    return retval;
}

#ifndef NO_RSA

static RSA *make_temp_key(int keylen) {
    RSA *result;

    log(LOG_DEBUG, "Generating %d bit temporary RSA key...", keylen);
#if SSLEAY_VERSION_NUMBER >= 0x0900
    result=RSA_generate_key(keylen, RSA_F4, NULL, NULL);
# else
    result=RSA_generate_key(keylen, RSA_F4, NULL);
# endif
    log(LOG_DEBUG, "Temporary RSA key created");
    return result;
}

static RSA *tmp_rsa_cb(SSL *s, int export, int keylen) {
    static int initialized=0;
    static struct keytabstruct {
        RSA *key;
        time_t timeout;
    } keytable[KEY_CACHE_LENGTH];
    static RSA *longkey;
    static int longlen;
    static time_t longtime;
    RSA *oldkey;
    time_t now;
    int i;

    if(!initialized) {
        for(i=0; i<KEY_CACHE_LENGTH; i++) {
            keytable[i].key=NULL;
            keytable[i].timeout=0;
        }
        longkey=NULL;
        longlen=0;
        longtime=0;
        initialized=1;
    }

    /* TODO: make it fully mt-safe */
    time(&now);
    if(keylen<KEY_CACHE_LENGTH) {
        enter_critical_section(0);
        if(keytable[keylen].timeout<now) {
            oldkey=keytable[keylen].key;
            keytable[keylen].key=make_temp_key(keylen);
            keytable[keylen].timeout=now+KEY_CACHE_TIME;
            if(oldkey)
                RSA_free(oldkey);
        }
        leave_critical_section(0);
        return keytable[keylen].key;
    } else { /* Temp key > 2048 bits.  Is it possible? */
        enter_critical_section(1);
        if(longtime<now || longlen!=keylen) {
            oldkey=longkey;
            longkey=make_temp_key(keylen);
            longtime=now+KEY_CACHE_TIME;
            longlen=keylen;
            if(oldkey)
                RSA_free(oldkey);
        }
        leave_critical_section(1);
        return longkey;
    }
}
#endif /* NO_RSA */

static int verify_callback(int state, X509_STORE_CTX *ctx)
{ /* our verify callback function */
    char txt[256];
    X509_OBJECT ret;

    X509_NAME_oneline(X509_get_subject_name(ctx->current_cert),
        txt, sizeof(txt));
    if(!state) {
        /* Remote site specified a certificate, but it's not correct */
        log(LOG_WARNING, "VERIFY ERROR: depth=%d error=%s: %s",
            ctx->error_depth,
            X509_verify_cert_error_string (ctx->error), txt);
        return 0; /* Reject connection */
    }
    if(options.verify_use_only_my && ctx->error_depth==0 &&
            X509_STORE_get_by_subject(ctx, X509_LU_X509,
                X509_get_subject_name(ctx->current_cert), &ret)!=1) {
        log (LOG_WARNING, "VERIFY ERROR ONLY MY: no cert for: %s", txt);
        return 0; /* Reject connection */
    }
    log(LOG_NOTICE, "VERIFY OK: depth=%d: %s", ctx->error_depth, txt);
    return 1; /* Accept connection */
}

static void info_callback(SSL *s, int where, int ret)
{
    log(LOG_DEBUG, "%s", SSL_state_string_long(s));
    if(where==SSL_CB_HANDSHAKE_DONE)
        print_stats();
}

static void print_stats() /* print statistics */
{
    log(LOG_DEBUG, "%4ld items in the session cache",
        SSL_CTX_sess_number(ctx));
    log(LOG_DEBUG, "%4d client connects (SSL_connect())",
        SSL_CTX_sess_connect(ctx));
    log(LOG_DEBUG, "%4d client connects that finished",
        SSL_CTX_sess_connect_good(ctx));
#if SSLEAY_VERSION_NUMBER >= 0x0922
    log(LOG_DEBUG, "%4d client renegotiatations requested",
        SSL_CTX_sess_connect_renegotiate(ctx));
#endif
    log(LOG_DEBUG, "%4d server connects (SSL_accept())",
        SSL_CTX_sess_accept(ctx));
    log(LOG_DEBUG, "%4d server connects that finished",
        SSL_CTX_sess_accept_good(ctx));
#if SSLEAY_VERSION_NUMBER >= 0x0922
    log(LOG_DEBUG, "%4d server renegotiatiations requested",
        SSL_CTX_sess_accept_renegotiate(ctx));
#endif
    log(LOG_DEBUG, "%4d session cache hits", SSL_CTX_sess_hits(ctx));
    log(LOG_DEBUG, "%4d session cache misses", SSL_CTX_sess_misses(ctx));
    log(LOG_DEBUG, "%4d session cache timeouts", SSL_CTX_sess_timeouts(ctx));
}

static void print_cipher(SSL *ssl) /* print negotiated cipher */
{
#if SSLEAY_VERSION_NUMBER > 0x0800
    SSL_CIPHER *c;
    char *ver;
    int bits;
#endif

#if SSLEAY_VERSION_NUMBER <= 0x0800
    log(LOG_INFO, "%s opened with SSLv%d, cipher %s",
        options.servname, ssl->session->ssl_version, SSL_get_cipher(ssl));
#else
    switch(ssl->session->ssl_version) {
    case SSL2_VERSION:
        ver="SSLv2"; break;
    case SSL3_VERSION:
        ver="SSLv3"; break;
    case TLS1_VERSION:
        ver="TLSv1"; break;
    default:
        ver="UNKNOWN";
    }
    c=SSL_get_current_cipher(ssl);
    SSL_CIPHER_get_bits(c, &bits);
    log(LOG_INFO, "%s opened with %s, cipher %s (%u bits)",
        options.servname, ver, SSL_CIPHER_get_name(c), bits);
#endif
}

static void sslerror(char *txt) /* SSL Error handler */
{
    char string[120];

    ERR_error_string(ERR_get_error(), string);
    log(LOG_ERR, "%s: %s", txt, string);
}

/* End of ssl.c */