如何通过代码解决MariaDB Connector/C 3.4.8 Win64的SSL连接错误

问题背景 #

安装mariadb-connector-c-3.4.8-win64.msi SDK后，连接Fedora 40系统上的MariaDB服务器时，出现如下报错：

TLS/SSL error: SSL is required, but the server does not support it

服务器版本信息 #

> dnf list installed|grep -i maria
mariadb.x86_64                                       3:10.11.11-1.fc40                   @updates
mariadb-backup.x86_64                                3:10.11.11-1.fc40                   @updates
mariadb-client-utils.x86_64                          3:10.11.11-1.fc40                   @updates
mariadb-common.noarch                                3:10.11.11-1.fc40                   @updates
mariadb-connector-c.x86_64                           3.3.8-3.fc40                        @fedora
mariadb-connector-c-config.noarch                    3.3.8-3.fc40                        @fedora
mariadb-cracklib-password-check.x86_64               3:10.11.11-1.fc40                   @updates
mariadb-errmsg.noarch                                3:10.11.11-1.fc40                   @updates
mariadb-gssapi-server.x86_64                         3:10.11.11-1.fc40                   @updates
mariadb-server.x86_64                                3:10.11.11-1.fc40                   @updates
mariadb-server-utils.x86_64                          3:10.11.11-1.fc40                   @updates
perl-DBD-MariaDB.x86_64                              1.23-4.fc40                         @fedora

报错的连接代码 #

// Connect to MariaDB.
MYSQL* pconn = mysql_init( nullptr );
if ( !mysql_real_connect( pconn, "192.168.11.1", "foo", "bar", "database",
     0, nullptr, 0 ) ) {
    fprintf( stderr, "mysql_real_connect(): %s\n", mysql_error( pconn ) );
    return 1;
}
printf( "mysql_real_connect(): SUCCESS\n" );

// Your code here.

mysql_close( pconn );
printf( "mysql_close(): SUCCESS\n" );

代码修复方法 #

问题根源是MariaDB Connector/C 3.4.x版本默认强制启用SSL连接要求，但你的服务器未配置SSL支持。以下两种代码方式可直接解决：

方法1：设置SSL模式为禁用（推荐） #

在mysql_real_connect调用前，通过mysql_options明确设置SSL模式为SSL_MODE_DISABLED，跳过SSL检查：

// Connect to MariaDB.
MYSQL* pconn = mysql_init( nullptr );
// 添加禁用SSL的配置
mysql_options(pconn, MYSQL_OPT_SSL_MODE, SSL_MODE_DISABLED);
if ( !mysql_real_connect( pconn, "192.168.11.1", "foo", "bar", "database",
     0, nullptr, 0 ) ) {
    fprintf( stderr, "mysql_real_connect(): %s\n", mysql_error( pconn ) );
    return 1;
}
printf( "mysql_real_connect(): SUCCESS\n" );

// Your code here.

mysql_close( pconn );
printf( "mysql_close(): SUCCESS\n" );

方法2：通过mysql_ssl_set禁用SSL #

调用mysql_ssl_set并传递所有空参数，明确告知客户端不使用SSL加密：

// Connect to MariaDB.
MYSQL* pconn = mysql_init( nullptr );
// 传递空参数禁用SSL
mysql_ssl_set(pconn, NULL, NULL, NULL, NULL, NULL);
if ( !mysql_real_connect( pconn, "192.168.11.1", "foo", "bar", "database",
     0, nullptr, 0 ) ) {
    fprintf( stderr, "mysql_real_connect(): %s\n", mysql_error( pconn ) );
    return 1;
}
printf( "mysql_real_connect(): SUCCESS\n" );

// Your code here.

mysql_close( pconn );
printf( "mysql_close(): SUCCESS\n" );

说明 #

• 方法1是Connector/C 3.2+引入的标准配置方式，语义更清晰，优先推荐。
• 如果后续服务器配置了SSL支持，只需移除该配置即可恢复SSL连接。

内容的提问来源于stack exchange，提问作者Swiss Frank