add check for internal error
[openssl.git] / ssl / s3_pkt.c
index 238508034790f2c7ef8d7ffbc16cc0868e70fcbc..93d1461a32678c9511cc70f85b6a9c60288ee3e2 100644 (file)
  * copied and put under another distribution licence
  * [including the GNU Public Licence.]
  */
+/* ====================================================================
+ * Copyright (c) 1998-1999 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).
+ *
+ */
 
 #include <stdio.h>
 #include <errno.h>
 #define USE_SOCKETS
-#include "evp.h"
-#include "buffer.h"
+#include <openssl/evp.h>
+#include <openssl/buffer.h>
 #include "ssl_locl.h"
 
-/* SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_PEER_ERROR_NO_CIPHER);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_PEER_ERROR_NO_CERTIFICATE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_PEER_ERROR_CERTIFICATE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_PEER_ERROR_UNSUPPORTED_CERTIFICATE_TYPE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_UNKNOWN_REMOTE_ERROR_TYPE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_UNEXPECTED_MESSAGE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_BAD_RECORD_MAC);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_DECOMPRESSION_FAILURE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_HANDSHAKE_FAILURE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_NO_CERTIFICATE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_BAD_CERTIFICATE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_UNSUPPORTED_CERTIFICATE);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_CERTIFICATE_REVOKED);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_CERTIFICATE_EXPIRED);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_CERTIFICATE_UNKNOWN);
- * SSLerr(SSL_F_GET_SERVER_HELLO,SSL_R_SSLV3_ALERT_ILLEGAL_PARAMETER);
- */
-
-#ifndef NOPROTO
-static int do_ssl3_write(SSL *s, int type, char *buf, unsigned int len);
-static int ssl3_write_pending(SSL *s, int type, char *buf, unsigned int len);
+static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
+                        unsigned int len);
+static int ssl3_write_pending(SSL *s, int type, const unsigned char *buf,
+                             unsigned int len);
 static int ssl3_get_record(SSL *s);
 static int do_compress(SSL *ssl);
 static int do_uncompress(SSL *ssl);
 static int do_change_cipher_spec(SSL *ssl);
-#else
-static int do_ssl3_write();
-static int ssl3_write_pending();
-static int ssl3_get_record();
-static int do_compress();
-static int do_uncompress();
-static int do_change_cipher_spec();
-#endif
 
-static int ssl3_read_n(s,n,max,extend)
-SSL *s;
-int n;
-int max;
-int extend;
+static int ssl3_read_n(SSL *s, int n, int max, int extend)
        {
+       /* If extend == 0, obtain new n-byte packet; if extend == 1, increase
+        * packet by another n bytes.
+        * The packet will be in the sub-array of s->s3->rbuf.buf specified
+        * by s->packet and s->packet_length.
+        * (If s->read_ahead is set, 'max' bytes may be stored in rbuf
+        * [plus s->packet_length bytes if extend == 1].)
+        */
        int i,off,newb;
 
-       /* if there is stuff still in the buffer from a previous read,
-        * and there is more than we want, take some. */
+       if (!extend)
+               {
+               /* start with empty packet ... */
+               if (s->s3->rbuf.left == 0)
+                       s->s3->rbuf.offset = 0;
+               s->packet = s->s3->rbuf.buf + s->s3->rbuf.offset;
+               s->packet_length = 0;
+               /* ... now we can act as if 'extend' was set */
+               }
+
+       /* if there is enough in the buffer from a previous read, take some */
        if (s->s3->rbuf.left >= (int)n)
                {
-               if (extend)
-                       s->packet_length+=n;
-               else
-                       {
-                       s->packet= &(s->s3->rbuf.buf[s->s3->rbuf.offset]);
-                       s->packet_length=n;
-                       }
+               s->packet_length+=n;
                s->s3->rbuf.left-=n;
                s->s3->rbuf.offset+=n;
                return(n);
                }
 
        /* else we need to read more data */
-       if (!s->read_ahead) max=n;
-       if (max > SSL3_RT_MAX_PACKET_SIZE)
-               max=SSL3_RT_MAX_PACKET_SIZE;
-
-       /* First check if there is some left or we want to extend */
-       off=0;
-       if (    (s->s3->rbuf.left != 0) ||
-               ((s->packet_length != 0) && extend))
-               {
-               newb=s->s3->rbuf.left;
-               if (extend)
-                       {
-                       /* Copy bytes back to the front of the buffer 
-                        * Take the bytes already pointed to by 'packet'
-                        * and take the extra ones on the end. */
-                       off=s->packet_length;
-                       if (s->packet != s->s3->rbuf.buf)
-                               memcpy(s->s3->rbuf.buf,s->packet,newb+off);
-                       }
-               else if (s->s3->rbuf.offset != 0)
-                       { /* so the data is not at the start of the buffer */
-                       memcpy(s->s3->rbuf.buf,
-                               &(s->s3->rbuf.buf[s->s3->rbuf.offset]),newb);
-                       s->s3->rbuf.offset=0;
-                       }
+       if (!s->read_ahead)
+               max=n;
 
-               s->s3->rbuf.left=0;
+       {
+               /* avoid buffer overflow */
+               int max_max = SSL3_RT_MAX_PACKET_SIZE - s->packet_length;
+               if (s->options & SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER)
+                       max_max += SSL3_RT_MAX_EXTRA;
+               if (max > max_max)
+                       max = max_max;
+       }
+       if (n > max) /* does not happen */
+               {
+               SSLerr(SSL_F_SSL3_READ_N,SSL_R_INTERNAL_ERROR);
+               return -1;
                }
-       else
-               newb=0;
-
-       /* So we now have 'newb' bytes at the front of 
-        * s->s3->rbuf.buf and need to read some more in on the end
-        * We start reading into the buffer at 's->s3->rbuf.offset'
-        */
-       s->packet=s->s3->rbuf.buf;
 
+       off = s->packet_length;
+       newb = s->s3->rbuf.left;
+       /* Move any available bytes to front of buffer:
+        * 'off' bytes already pointed to by 'packet',
+        * 'newb' extra ones at the end */
+       if (s->packet != s->s3->rbuf.buf)
+               {
+               /*  off > 0 */
+               memmove(s->s3->rbuf.buf, s->packet, off+newb);
+               s->packet = s->s3->rbuf.buf;
+               }
+       
        while (newb < n)
                {
+               /* Now we have off+newb bytes at the front of s->s3->rbuf.buf and need
+                * to read in more until we have off+n (up to off+max if possible) */
+
                clear_sys_error();
                if (s->rbio != NULL)
                        {
                        s->rwstate=SSL_READING;
-                       i=BIO_read(s->rbio,
-                               (char *)&(s->s3->rbuf.buf[off+newb]),
-                               max-newb);
+                       i=BIO_read(s->rbio,     &(s->s3->rbuf.buf[off+newb]), max-newb);
                        }
                else
                        {
                        SSLerr(SSL_F_SSL3_READ_N,SSL_R_READ_BIO_NOT_SET);
-                       i= -1;
+                       i = -1;
                        }
 
                if (i <= 0)
                        {
-                       s->s3->rbuf.left+=newb;
+                       s->s3->rbuf.left = newb;
                        return(i);
                        }
                newb+=i;
                }
 
-       /* record used data read */
-       if (newb > n)
-               {
-               s->s3->rbuf.offset=n+off;
-               s->s3->rbuf.left=newb-n;
-               }
-       else
-               {
-               s->s3->rbuf.offset=0;
-               s->s3->rbuf.left=0;
-               }
-
-       if (extend)
-               s->packet_length+=n;
-       else
-               s->packet_length+=n;
+       /* done reading, now the book-keeping */
+       s->s3->rbuf.offset = off + n;
+       s->s3->rbuf.left = newb - n;
+       s->packet_length += n;
        return(n);
        }
 
@@ -206,14 +221,12 @@ int extend;
  * It will return <= 0 if more data is needed, normally due to an error
  * or non-blocking IO.
  * When it finishes, one packet has been decoded and can be found in
- * ssl->s3->rrec.type  - is the type of record
- * ssl->s3->rrec.data,         - data
+ * ssl->s3->rrec.type    - is the type of record
+ * ssl->s3->rrec.data,          - data
  * ssl->s3->rrec.length, - number of bytes
  */
-static int ssl3_get_record(s)
-SSL *s;
+static int ssl3_get_record(SSL *s)
        {
-       char tmp_buf[512];
        int ssl_major,ssl_minor,al;
        int n,i,ret= -1;
        SSL3_BUFFER *rb;
@@ -285,7 +298,7 @@ again:
                        goto f_err;
                        }
 
-               s->rstate=SSL_ST_READ_BODY;
+               /* now s->rstate == SSL_ST_READ_BODY; */
                }
 
        /* get and decode the data */
@@ -294,7 +307,6 @@ again:
                if (rr->length > (s->packet_length-SSL3_RT_HEADER_LENGTH))
                        {
                        i=rr->length;
-                       /*-(s->packet_length-SSL3_RT_HEADER_LENGTH); */
                        n=ssl3_read_n(s,i,i,1);
                        if (n <= 0) return(n); /* error or non-blocking io */
                        }
@@ -331,7 +343,6 @@ again:
 
        /* decrypt in place in 'rr->input' */
        rr->data=rr->input;
-       memcpy(tmp_buf,rr->input,(rr->length > 512)?512:rr->length);
 
        if (!s->method->ssl3_enc->enc(s,0))
                {
@@ -340,7 +351,7 @@ again:
                }
 #ifdef TLS_DEBUG
 printf("dec %d\n",rr->length);
-{ int z; for (z=0; z<rr->length; z++) printf("%02X%c",rr->data[z],((z+1)%16)?' ':'\n'); }
+{ unsigned int z; for (z=0; z<rr->length; z++) printf("%02X%c",rr->data[z],((z+1)%16)?' ':'\n'); }
 printf("\n");
 #endif
        /* r->length is now the compressed data plus mac */
@@ -378,7 +389,7 @@ printf("\n");
                }
 
        /* r->length is now just compressed */
-       if ((sess != NULL) && (sess->read_compression != NULL))
+       if (s->expand != NULL)
                {
                if (rr->length > 
                        (unsigned int)SSL3_RT_MAX_COMPRESSED_LENGTH+extra)
@@ -424,27 +435,47 @@ err:
        return(ret);
        }
 
-static int do_uncompress(ssl)
-SSL *ssl;
+static int do_uncompress(SSL *ssl)
        {
+       int i;
+       SSL3_RECORD *rr;
+
+       rr= &(ssl->s3->rrec);
+       i=COMP_expand_block(ssl->expand,rr->comp,
+               SSL3_RT_MAX_PLAIN_LENGTH,rr->data,(int)rr->length);
+       if (i < 0)
+               return(0);
+       else
+               rr->length=i;
+       rr->data=rr->comp;
+
        return(1);
        }
 
-static int do_compress(ssl)
-SSL *ssl;
+static int do_compress(SSL *ssl)
        {
+       int i;
+       SSL3_RECORD *wr;
+
+       wr= &(ssl->s3->wrec);
+       i=COMP_compress_block(ssl->compress,wr->data,
+               SSL3_RT_MAX_COMPRESSED_LENGTH,
+               wr->input,(int)wr->length);
+       if (i < 0)
+               return(0);
+       else
+               wr->length=i;
+
+       wr->input=wr->data;
        return(1);
        }
 
 /* Call this to write data
  * It will return <= 0 if not all data has been sent or non-blocking IO.
  */
-int ssl3_write_bytes(s,type,buf,len)
-SSL *s;
-int type;
-char *buf;
-int len;
+int ssl3_write_bytes(SSL *s, int type, const void *_buf, int len)
        {
+       const unsigned char *buf=_buf;
        unsigned int tot,n,nw;
        int i;
 
@@ -479,20 +510,22 @@ int len;
                        }
 
                if (type == SSL3_RT_HANDSHAKE)
-                       ssl3_finish_mac(s,(unsigned char *)&(buf[tot]),i);
+                       ssl3_finish_mac(s,&(buf[tot]),i);
 
-               if (i == (int)n) return(tot+i);
+               if ((i == (int)n) ||
+                       (type == SSL3_RT_APPLICATION_DATA &&
+                        (s->mode & SSL_MODE_ENABLE_PARTIAL_WRITE)))
+                       {
+                       return(tot+i);
+                       }
 
                n-=i;
                tot+=i;
                }
        }
 
-static int do_ssl3_write(s,type,buf,len)
-SSL *s;
-int type;
-char *buf;
-unsigned int len;
+static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
+                        unsigned int len)
        {
        unsigned char *p,*plen;
        int i,mac_size,clear=0;
@@ -552,7 +585,7 @@ unsigned int len;
         * wr->data */
 
        /* first we compress */
-       if ((sess != NULL) && (sess->write_compression != NULL))
+       if (s->compress != NULL)
                {
                if (!do_compress(s))
                        {
@@ -606,16 +639,15 @@ err:
        }
 
 /* if s->s3->wbuf.left != 0, we need to call this */
-static int ssl3_write_pending(s,type,buf,len)
-SSL *s;
-int type;
-char *buf;
-unsigned int len;
+static int ssl3_write_pending(SSL *s, int type, const unsigned char *buf,
+                             unsigned int len)
        {
        int i;
 
 /* XXXX */
-       if ((s->s3->wpend_tot > (int)len) || (s->s3->wpend_buf != buf)
+       if ((s->s3->wpend_tot > (int)len)
+               || ((s->s3->wpend_buf != buf) &&
+                       !(s->mode & SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER))
                || (s->s3->wpend_type != type))
                {
                SSLerr(SSL_F_SSL3_WRITE_PENDING,SSL_R_BAD_WRITE_RETRY);
@@ -650,18 +682,14 @@ unsigned int len;
                }
        }
 
-int ssl3_read_bytes(s,type,buf,len)
-SSL *s;
-int type;
-char *buf;
-int len;
+int ssl3_read_bytes(SSL *s, int type, unsigned char *buf, int len)
        {
        int al,i,j,n,ret;
        SSL3_RECORD *rr;
        void (*cb)()=NULL;
        BIO *bio;
 
-       if (s->s3->rbuf.buf == NULL) /* Not initalised yet */
+       if (s->s3->rbuf.buf == NULL) /* Not initialized yet */
                if (!ssl3_setup_buffers(s))
                        return(-1);
 
@@ -678,10 +706,10 @@ int len;
 start:
        s->rwstate=SSL_NOTHING;
 
-       /* s->s3->rrec.type     - is the type of record
-        * s->s3->rrec.data,    - data
-        * s->s3->rrec.off,     - ofset into 'data' for next read
-        * s->s3->rrec.length,  - number of bytes. */
+       /* s->s3->rrec.type         - is the type of record
+        * s->s3->rrec.data,    - data
+        * s->s3->rrec.off,     - offset into 'data' for next read
+        * s->s3->rrec.length,  - number of bytes. */
        rr= &(s->s3->rrec);
 
        /* get new packet */
@@ -708,16 +736,16 @@ start:
                return(0);
                }
 
-       /* Check for an incoming 'Client Request' message */
+       /* Check for an incoming 'Hello Request' message from client */
        if ((rr->type == SSL3_RT_HANDSHAKE) && (rr->length == 4) &&
-               (rr->data[0] == SSL3_MT_CLIENT_REQUEST) &&
+               (rr->data[0] == SSL3_MT_HELLO_REQUEST) &&
                (s->session != NULL) && (s->session->cipher != NULL))
                {
                if ((rr->data[1] != 0) || (rr->data[2] != 0) ||
                        (rr->data[3] != 0))
                        {
                        al=SSL_AD_DECODE_ERROR;
-                       SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_BAD_CLIENT_REQUEST);
+                       SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_BAD_HELLO_REQUEST);
                        goto err;
                        }
 
@@ -786,7 +814,8 @@ start:
 
                                s->rwstate=SSL_NOTHING;
                                s->s3->fatal_alert=n;
-                               SSLerr(SSL_F_SSL3_READ_BYTES,1000+n);
+                               SSLerr(SSL_F_SSL3_READ_BYTES,
+                                       SSL_AD_REASON_OFFSET+n);
                                sprintf(tmp,"%d",n);
                                ERR_add_error_data(2,"SSL alert number ",tmp);
                                s->shutdown|=SSL_RECEIVED_SHUTDOWN;
@@ -836,7 +865,9 @@ start:
                        if (((s->state&SSL_ST_MASK) == SSL_ST_OK) &&
                                !(s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS))
                                {
-                               s->state=SSL_ST_BEFORE;
+                               s->state=SSL_ST_BEFORE|(s->server)
+                                               ?SSL_ST_ACCEPT
+                                               :SSL_ST_CONNECT;
                                s->new_session=1;
                                }
                        n=s->handshake_func(s);
@@ -937,7 +968,7 @@ start:
                }
 
        if (type == SSL3_RT_HANDSHAKE)
-               ssl3_finish_mac(s,(unsigned char *)buf,n);
+               ssl3_finish_mac(s,buf,n);
        return(n);
 f_err:
        ssl3_send_alert(s,SSL3_AL_FATAL,al);
@@ -945,11 +976,10 @@ err:
        return(-1);
        }
 
-static int do_change_cipher_spec(s)
-SSL *s;
+static int do_change_cipher_spec(SSL *s)
        {
        int i;
-       unsigned char *sender;
+       const char *sender;
        int slen;
 
        if (s->state & SSL_ST_ACCEPT)
@@ -971,31 +1001,29 @@ SSL *s;
         * the finished message */
        if (s->state & SSL_ST_CONNECT)
                {
-               sender=s->method->ssl3_enc->server_finished;
-               slen=s->method->ssl3_enc->server_finished_len;
+               sender=s->method->ssl3_enc->server_finished_label;
+               slen=s->method->ssl3_enc->server_finished_label_len;
                }
        else
                {
-               sender=s->method->ssl3_enc->client_finished;
-               slen=s->method->ssl3_enc->client_finished_len;
+               sender=s->method->ssl3_enc->client_finished_label;
+               slen=s->method->ssl3_enc->client_finished_label_len;
                }
 
-       s->method->ssl3_enc->final_finish_mac(s,
+       s->s3->tmp.peer_finish_md_len = s->method->ssl3_enc->final_finish_mac(s,
                &(s->s3->finish_dgst1),
                &(s->s3->finish_dgst2),
-               sender,slen,&(s->s3->tmp.finish_md[0]));
+               sender,slen,s->s3->tmp.peer_finish_md);
 
        return(1);
        }
 
-int ssl3_do_write(s,type)
-SSL *s;
-int type;
+int ssl3_do_write(SSL *s, int type)
        {
        int ret;
 
-       ret=ssl3_write_bytes(s,type,(char *)
-               &(s->init_buf->data[s->init_off]),s->init_num);
+       ret=ssl3_write_bytes(s,type,&s->init_buf->data[s->init_off],
+                            s->init_num);
        if (ret == s->init_num)
                return(1);
        if (ret < 0) return(-1);
@@ -1004,10 +1032,7 @@ int type;
        return(0);
        }
 
-void ssl3_send_alert(s,level,desc)
-SSL *s;
-int level;
-int desc;
+void ssl3_send_alert(SSL *s, int level, int desc)
        {
        /* Map tls/ssl alert value to correct one */
        desc=s->method->ssl3_enc->alert_value(desc);
@@ -1025,14 +1050,13 @@ int desc;
         * some time in the future */
        }
 
-int ssl3_dispatch_alert(s)
-SSL *s;
+int ssl3_dispatch_alert(SSL *s)
        {
        int i,j;
        void (*cb)()=NULL;
 
        s->s3->alert_dispatch=0;
-       i=do_ssl3_write(s,SSL3_RT_ALERT,&(s->s3->send_alert[0]),2);
+       i=do_ssl3_write(s,SSL3_RT_ALERT,&s->s3->send_alert[0],2);
        if (i <= 0)
                {
                s->s3->alert_dispatch=1;
@@ -1043,7 +1067,7 @@ SSL *s;
                 * does not get sent due to non-blocking IO, we will
                 * not worry too much. */
                if (s->s3->send_alert[0] == SSL3_AL_FATAL)
-                       BIO_flush(s->wbio);
+                       (void)BIO_flush(s->wbio);
 
                if (s->info_callback != NULL)
                        cb=s->info_callback;
@@ -1058,4 +1082,3 @@ SSL *s;
                }
        return(i);
        }
-