Introduce connection layer framework

Use connTypeRegister() to register a connection type into redis, and
query connection by connectionByType() via type.

With this change, we can hide TLS specified methods into connection
type:
- void tlsInit(void);
- void tlsCleanup(void);
- int tlsConfigure(redisTLSContextConfig *ctx_config);
- int isTlsConfigured(void);

Merge isTlsConfigured & tlsConfigure, use an argument *reconfigure*
to distinguish:
   tlsConfigure(&server.tls_ctx_config)
-> onnTypeConfigure(CONN_TYPE_TLS, &server.tls_ctx_config, 1)

   isTlsConfigured() && tlsConfigure(&server.tls_ctx_config)
-> connTypeConfigure(CONN_TYPE_TLS, &server.tls_ctx_config, 0)

Finally, we can remove USE_OPENSSL from config.c. If redis is built
without TLS, and still run redis with TLS, then redis reports:
 # Missing implement of connection type 1
 # Failed to configure TLS. Check logs for more info.

The log can be optimised, let's leave it in the future. Maybe we can
use connection type as a string.

Although uninitialized fields of a static struct are zero, we still
set them as NULL explicitly in socket.c, let them clear to read & maintain:
    .init = NULL,
    .cleanup = NULL,
    .configure = NULL,

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/socket.c b/src/socket.c
index 2ef29e1d4..d93882cce 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -352,6 +352,11 @@ ConnectionType CT_Socket = {
     /* connection type */
     .get_type = connSocketGetType,
 
+    /* connection type initialize & finalize & configure */
+    .init = NULL,
+    .cleanup = NULL,
+    .configure = NULL,
+
     /* ae & accept & listen & error & address handler */
     .ae_handler = connSocketEventHandler,
     .addr = connSocketAddr,
@@ -409,3 +414,7 @@ int connRecvTimeout(connection *conn, long long ms) {
     return anetRecvTimeout(NULL, conn->fd, ms);
 }
 
+int RedisRegisterConnectionTypeSocket()
+{
+    return connTypeRegister(&CT_Socket);
+}