Question

我试图编写一个连接到OpenSSL服务器的c ++应用程序。我可以发送未损坏的数据到服务器，但读取操作只读取1个字节。

代码：

char*           dest_url = "147.87.116.74";
X509                *cert = NULL;
X509_name_st    *certname = NULL;
const SSL_METHOD *method;
SSL_CTX *ctx;
SSL *ssl;
int server = 0;
int ret, i;

/* ---------------------------------------------------------- *
* These function calls initialize openssl for correct work.  *
* ---------------------------------------------------------- */
OpenSSL_add_all_algorithms();
ERR_load_BIO_strings();
ERR_load_crypto_strings();
SSL_load_error_strings();

/* ---------------------------------------------------------- *
* initialize SSL library and register algorithms             *
* ---------------------------------------------------------- */
SSL_library_init();

/* ---------------------------------------------------------- *
* Set SSLv2 client hello, also announce SSLv3 and TLSv1      *
* ---------------------------------------------------------- */
method = TLSv1_2_client_method();

/* ---------------------------------------------------------- *
* Try to create a new SSL context                            *
* ---------------------------------------------------------- */
ctx = SSL_CTX_new(method);

/* ---------------------------------------------------------- *
* SSL certificate checking      AND MY STUFF    
* thanks guys http://h71000.www7.hp.com/doc/83final/ba554_90007/ch05s03.html
* ---------------------------------------------------------- */
SSL_CTX_load_verify_locations(ctx, "ca.crt", nullptr);
SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
SSL_CTX_set_verify_depth(ctx, 1);

/* ---------------------------------------------------------- *
* Create new SSL connection state object                     *
* ---------------------------------------------------------- */
ssl = SSL_new(ctx);

/* ---------------------------------------------------------- *
* Make the underlying TCP socket connection                  *
* ---------------------------------------------------------- */
server = create_socket(dest_url);

/* ---------------------------------------------------------- *
* Attach the SSL session to the socket descriptor            *
* ---------------------------------------------------------- */
SSL_set_fd(ssl, server);

/* ---------------------------------------------------------- *
* Try to SSL-connect here, returns 1 for success             *
* ---------------------------------------------------------- */
SSL_connect(ssl);

/* ---------------------------------------------------------- *
* send some text                                              *
* -----------------------------------------------------------*/
char* tSend = "testdata";
int sendSize = strlen(tSend);
int net_tSend = htonl(sendSize);

SSL_write(ssl, &net_tSend, 4);
SSL_write(ssl, tSend, sendSize);

long size = 0L;
int bytesread = SSL_read(ssl, &size, 4);

我的问题：是否必须使用BIO对象？为什么read（）函数只读取1个字节？我如何检索/读取错误？

Answer 1

读取的字节数是任意的。如果您确切知道应该接收多少字节，则可以使用准确读取该数字的函数。

此函数是SSL_read的替代品，除非出现错误，否则始终精确读取指定的字节数。它在出错时返回＆lt; 0（call SSL_get_error）。如果连接关闭，它返回0。成功时，它返回读取的字节数，它将始终与请求的数字相同。

int SSL_read_all(SSL *ssl, void* buf, int num)
{
    char* ptr = reinterpret_cast<char*>(buf);
    int read_bytes = 0;
    while (read_bytes < num)
    {
         int r = SSL_read(ssl, ptr + read_bytes, num - read_bytes);
         if (r <= 0)
             return r;
         read_bytes += r;
    }
    return read_bytes;
}

如果OpenSSL直接与套接字通话，则无需明确使用BIO。

Answer 2

您可以像这样读取所有SSL流：

char buf[1024];
int c=1024;
while(c==1024)
     {
     c=SSL_read(ssl,buf,1024);
     buf[c]='\0';
     printf("%s",buf);
     }

OpenSSL SSL_read故障

2 个答案: