Re: a problem about openssl lib:SSL_connect()

["berg" <zealberg () 163 com>]

I resolved this problem, use something named BIO. But I still do not know why SSL_connect() causes buf overflow....

the code below, use nonblock socket.

int https_check(unsigned long dip, unsigned short dport, unsigned int timeout, char *url)
{
        int status = -1;
        SSL *ssl = NULL;
        SSL_CTX *ctx = NULL;
        BIO *sbio = NULL;
        unsigned long ndip = htonl(dip);
        int ret;
        struct timeval tv;

        gettimeofday(&tv, NULL);
        tv.tv_sec += timeout;

        ERR_load_crypto_strings();
        ERR_load_SSL_strings();
        OpenSSL_add_all_algorithms();

        ctx = SSL_CTX_new(SSLv23_client_method());

        if (ctx == NULL)
        {
                dbg_mon_err("SSL_CTX_new");
                goto RET;
        }

        sbio = BIO_new_ssl_connect(ctx);

        BIO_get_ssl(sbio, &ssl);

        if (ssl == NULL)
        {
                dbg_mon_err("SSL_new");
                goto RET;
        }

        SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
        BIO_set_conn_ip(sbio, &ndip);
        BIO_set_conn_int_port(sbio, &dport);
        BIO_set_nbio(sbio, 1);

        do
        {
                if (ck_timeout(&tv))  // own function, check if time out
                {
                        dbg_mon_err("timeout");  // own debug function
                        goto RET;
                }

                ret = BIO_do_connect(sbio);
                if (ret == 0)
                {
                        dbg_mon_err("connect_failed");
                        goto RET;
                }
                else if (ret < 0 && !BIO_should_retry(sbio))
                {
                        dbg_mon_err("BIO_do_connect_retry");
                        goto RET;
                }
                usleep(10);
        }while (ret < 0);


        do
        {
                if (ck_timeout(&tv))
                {
                        dbg_mon_err("timeout");
                        goto RET;
                }

                ret = BIO_do_handshake(sbio);
                if (ret == 0)
                {
                        dbg_mon_err("connect_failed");
                        goto RET;
                }
                else if (ret < 0 && !BIO_should_retry(sbio))
                {
                        dbg_mon_err("BIO_do_connect_retry");
                        goto RET;
                }
                usleep(10);
        } while (ret < 0);

        // own function, send and recv https packets, use BIO_read() and BIO_write()
        if ( (status=send_https_request(sbio, dip, url)) > 0)
        {
                status = recv_https_response(sbio, &tv);
        }

RET:
        BIO_free_all(sbio);

        return status;
}


Best Regards
Berg
----- Original Message ----- 
From: "berg" <zealberg () 163 com>
To: <security-basics () securityfocus com>
Sent: Thursday, September 07, 2006 4:33 PM
Subject: a problem about openssl lib:SSL_connect()


> Hello, everyone
>
>    I met a problem while using the function SSL_connect(), it always returns -1, and output some chaotic characters 
> to the console(It seems that memory overflow). And I did not capture the ssl handshake packets. Does anyone knows the 
> reason, and how to use it?
>
>    Thanks for any advise.
>
>    My codes as follow:
> ............
>        int sd;
>        int ret;
>        SSL *ssl;
>        SSL_CTX *ctx;
>
>        // initial ssl library
>        SSL_library_init();
>        SSL_load_error_strings();
>
>        // create ssl context
>        ctx = SSL_CTX_new(SSLv23_client_method());
>
>        if (ctx == NULL)
>        {
>                return -1;
>        }
>
>        SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, NULL);
>
>        // create ssl
>        ssl = SSL_new(ctx);
>        if (ssl == NULL)
>        {
>                return -1;
>        }
>
>        // the function below returns a normal tcp connection socket description
>        sd = create_https_socket(dip, dport);  
>        if (sd <= 0)
>        {
>                return -1;
>        }
>
>        ret = SSL_set_fd(ssl, sd);
>        if (ret == 0)
>        {
>                close(sd);
>                return -1;
>        }
>
>        RAND_poll();
>        while (RAND_status() == 0)
>        {
>                unsigned short rand_ret = rand() % 65536;
>                RAND_seed(&rand_ret, sizeof(rand_ret));
>        }
>
>        // error occur
>        ret = SSL_connect(ssl);
>        printf("ret=%d\n", ret);    // the value of ret is -1
>        if( ret != 1 )
>        {
>                close(sd);
>                return -1;
>        }
>
>
> ...........
>
> Best Regards
> Berg