spp_pkt.c

        
        if (mac_size < 0)
            goto err;
    }

    /* 'create_empty_fragment' is true only when this function calls itself */
    /*if (!clear && !create_empty_fragment && !s->s3->empty_fragment_done) {
        /* countermeasure against known-IV weakness in CBC ciphersuites
         * (see http://www.openssl.org/~bodo/tls-cbc.txt) */

        /*if (s->s3->need_empty_fragments && type == SSL3_RT_APPLICATION_DATA) {
            /* recursive function call with 'create_empty_fragment' set;
             * this prepares and buffers the data for an empty fragment
             * (these 'prefix_len' bytes are sent out later
             * together with the actual payload) */
            /*prefix_len = do_spp_write(s, type, buf, 0, 1);
            if (prefix_len <= 0)
                    goto err;

            if (prefix_len > (SPP_RT_HEADER_LENGTH + 
                SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD)) {
                    /* insufficient space */
                    /*SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR);
                    goto err;
            }
        }

        s->s3->empty_fragment_done = 1;
    }*/

    if (create_empty_fragment) {
#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
        /* extra fragment would be couple of cipher blocks,
         * which would be multiple of SSL3_ALIGN_PAYLOAD, so
         * if we want to align the real payload, then we can
         * just pretent we simply have two headers. */
        align = (long)wb->buf + 2*SPP_RT_HEADER_LENGTH;
        align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
#endif
        p = wb->buf + align;
        wb->offset  = align;
    } else if (prefix_len) {
        p = wb->buf + wb->offset + prefix_len;
    } else {
#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
        align = (long)wb->buf + SPP_RT_HEADER_LENGTH;
        align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
#endif
        p = wb->buf + align;
        wb->offset  = align;
    }

    /* write the header */

    *(p++)=type&0xff;
    wr->type=type;

    *(p++)=(s->version>>8);
    *(p++)=s->version&0xff;            

    /* field where we are to write out packet length */
    plen=p; 
    p+=2;

    /* Write the slice ID as the 4th byte of the header. */
    wr->slice_id = slice == NULL ? 0 : slice->slice_id;
    *(p++)=wr->slice_id;
    
    /* Stats */
    if (type == SSL3_RT_APPLICATION_DATA)
        s->write_stats.app_bytes += len;
    else if (type == SSL3_RT_HANDSHAKE || type == SSL3_RT_CHANGE_CIPHER_SPEC)
        s->write_stats.handshake_bytes += len;
    else if (type == SSL3_RT_ALERT)
        s->write_stats.alert_bytes += len;
    
    if (type == SSL3_RT_HANDSHAKE || type == SSL3_RT_CHANGE_CIPHER_SPEC)
        s->write_stats.handshake_bytes += SPP_RT_HEADER_LENGTH;
    else
        s->write_stats.header_bytes += SPP_RT_HEADER_LENGTH;
#ifdef DEBUG
    fprintf(stderr, "Writing record header: ");
    spp_print_buffer(wb->buf + wb->offset, SPP_RT_HEADER_LENGTH);
#endif
    
    /* Explicit IV length, block ciphers and TLS version 1.1 or later */
    if (s->enc_write_ctx && s->version >= TLS1_1_VERSION) {
        int mode = EVP_CIPHER_CTX_mode(s->enc_write_ctx);
        if (mode == EVP_CIPH_CBC_MODE) {
            eivlen = EVP_CIPHER_CTX_iv_length(s->enc_write_ctx);
            if (eivlen <= 1)
                eivlen = 0;
        }
        /* Need explicit part of IV for GCM mode */
        else if (mode == EVP_CIPH_GCM_MODE)
            eivlen = EVP_GCM_TLS_EXPLICIT_IV_LEN;
        else
            eivlen = 0;
    } else {
        eivlen = 0;
    }

    /* lets setup the record stuff. */
    wr->data=p + eivlen;
    wr->length=(int)len;
    wr->input=(unsigned char *)buf;

    /* we now 'read' from wr->input, wr->length bytes into
     * wr->data */
    
/*#if DEBUG
    fprintf(stderr, "Decrypted packet:");
    spp_print_buffer(wr->input, wr->len);
#endif*/

    /* first we compress */
    if (s->compress != NULL) {
        if (!ssl3_do_compress(s)) {
            SSLerr(SSL_F_DO_SSL3_WRITE,SSL_R_COMPRESSION_FAILURE);
            goto err;
        }
    } else {
        memcpy(wr->data,wr->input,wr->length);
        wr->input=wr->data;
    }

    /* we should still have the output to wr->data and the input
     * from wr->input.  Length should be wr->length.
     * wr->data still points in the wb->buf */
    if (mac_size != 0 && slice != NULL) {
#ifdef DEBUG
        printf("Generating 3MAC\n");
#endif
        s->write_stats.mac_bytes += mac_size*3;
        /* Must have read access, so write the read MAC. */
        spp_copy_mac_state(s, slice->read_mac, 1);
        if (s->method->ssl3_enc->mac(s,&(p[wr->length + eivlen]),1) < 0)
                goto err;
        
        /* Compute the write hash. */
        if (slice->write_mac != NULL) {
#ifdef DEBUG
            printf("Generating write MAC\n");
#endif
            spp_copy_mac_state(s, slice->write_mac, 1);
            if (s->method->ssl3_enc->mac(s,&(p[wr->length + eivlen + mac_size]),1) < 0)
                goto err;
        } else {
            /* Copy from the previous record. */
            memcpy(&(p[wr->length + eivlen + mac_size]), spp_ctx->write_mac, mac_size);
        }
        /* Must be an end point, write the integrity hash. */
        if (s->def_ctx->read_access) {
#ifdef DEBUG
            printf("Generating integrity MAC\n");
#endif
            spp_copy_mac_state(s, s->def_ctx->read_mac, 1);
            if (s->method->ssl3_enc->mac(s,&(p[wr->length + eivlen + (mac_size*2)]),1) < 0)
                goto err;            
        } else {
            /* Copy from the previous record. */
            memcpy(&(p[wr->length + eivlen + (mac_size*2)]), spp_ctx->integrity_mac, mac_size);
        }        
        wr->length+=(mac_size*3);        
    } else if (mac_size != 0) {
        /* This will only happen when sending the finished message at the end of the handshake. 
         * Instead of using a slice, use the parameters computed via the standard TLS handshake to 
         * both encrypt and generate MAC. */
        s->write_stats.mac_bytes += mac_size;
        if (s->method->ssl3_enc->mac(s,&(p[wr->length + eivlen]),1) < 0)
            goto err;
	wr->length+=mac_size;
    }
    /* If we do not have read access, then the MACs were interpreted as part of the payload. */
    if (spp_ctx != NULL) {
        if (s->proxy) {
            OPENSSL_free(spp_ctx->read_mac);
        }
        OPENSSL_free(spp_ctx);
    }

    wr->input=p;
    wr->data=p;

    if (eivlen) {
/*	if (RAND_pseudo_bytes(p, eivlen) <= 0)
                goto err; */
        wr->length += eivlen;
    }
    
#ifdef DEBUG
    printf("Unencrypted packet: ");
    spp_print_buffer(wr->data, wr->length);
#endif

    /* ssl3_enc can only have an error on read */
    /* This is a call to spp_enc which will encrypt or not 
     * depending upon whether we have the encryption material. */
    s->method->ssl3_enc->enc(s,1);

#ifdef DEBUG
    printf("Encrypted packet: ");
    spp_print_buffer(wr->data, wr->length);
#endif
    
    s->write_stats.bytes += wr->length + SPP_RT_HEADER_LENGTH;
    
    /* record length after mac and block padding */
    s2n(wr->length,plen);

    /* we should now have
     * wr->data pointing to the encrypted data, which is
     * wr->length long */
    wr->type=type; /* not needed but helps for debugging */
    wr->length+=SPP_RT_HEADER_LENGTH;

    if (create_empty_fragment) {
        /* we are in a recursive call;
         * just return the length, don't write out anything here
         */
        return wr->length;
    }

    /* now let's set up wb */
    wb->left = prefix_len + wr->length;

    /* memorize arguments so that ssl3_write_pending can detect bad write retries later */
    s->s3->wpend_tot=len;
    s->s3->wpend_buf=buf;
    s->s3->wpend_type=type;
    s->s3->wpend_ret=len;

done:
    /* we now just need to write the buffer */
    return ssl3_write_pending(s,type,buf,len);
    /* Does not need changing since above function simply writes buffer to 
     * the wire. */
err:
    return -1;
}

/* This function is not actually changed from ssl3_write_bytes, 
 * but we need to change do_write, so we copy this here as well. */
int spp_write_bytes(SSL *s, int type, const void *buf_, int len) {
    const unsigned char *buf=buf_;
    unsigned int n,nw;
    int i,tot;

    s->rwstate=SSL_NOTHING;
    OPENSSL_assert(s->s3->wnum <= INT_MAX);
    tot=s->s3->wnum;
    s->s3->wnum=0;

    if (SSL_in_init(s) && !s->in_handshake) {
	i=s->handshake_func(s);
	if (i < 0) return(i);
	if (i == 0) {
            SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_SSL_HANDSHAKE_FAILURE);
            return -1;
	}
    }

    /* ensure that if we end up with a smaller value of data to write 
     * out than the the original len from a write which didn't complete 
     * for non-blocking I/O and also somehow ended up avoiding 
     * the check for this in ssl3_write_pending/SSL_R_BAD_WRITE_RETRY as
     * it must never be possible to end up with (len-tot) as a large
     * number that will then promptly send beyond the end of the users
     * buffer ... so we trap and report the error in a way the user
     * will notice
     */
    if (len < tot) {
        SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_BAD_LENGTH);
        return(-1);
    }    

    n=(len-tot);
    for (;;) {
	if (!s->proxy && n > s->max_send_fragment)
            nw=s->max_send_fragment;
        else
            nw=n;

        i=do_spp_write(s, type, &(buf[tot]), nw, 0);
	if (i <= 0) {
            s->s3->wnum=tot;
            return i;
	}

	if ((i == (int)n) ||
            (type == SSL3_RT_APPLICATION_DATA &&
            (s->mode & SSL_MODE_ENABLE_PARTIAL_WRITE))) {
		/* next chunk of data should get another prepended empty fragment
		 * in ciphersuites with known-IV weakness: */
		s->s3->empty_fragment_done = 0;
		return tot+i;
	}

	n-=i;
	tot+=i;
    }
}