Fully abstract connection type

Abstract common interface of connection type, so Redis can hide the
implementation and uplayer only calls connection API without macro.

               uplayer
                  |
           connection layer
             /          \
          socket        TLS

Currently, for both socket and TLS, all the methods of connection type
are declared as static functions.

It's possible to build TLS(even socket) as a shared library, and Redis
loads it dynamically in the next step.

Also add helper function connTypeOfCluster() and
connTypeOfReplication() to simplify the code:
link->conn = server.tls_cluster ? connCreateTLS() : connCreateSocket();
-> link->conn = connCreate(connTypeOfCluster());

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

1 files changed, 8 insertions, 1 deletions

diff --git a/src/replication.c b/src/replication.c
index 3ae130252..8de14c9f2 100644
--- a/src/replication.c
+++ b/src/replication.c
@@ -55,6 +55,13 @@ int cancelReplicationHandshake(int reconnect);
 int RDBGeneratedByReplication = 0;
 
 /* --------------------------- Utility functions ---------------------------- */
+static int connTypeOfReplication() {
+    if (server.tls_replication) {
+        return CONN_TYPE_TLS;
+    }
+
+    return CONN_TYPE_SOCKET;
+}
 
 /* Return the pointer to a string representing the slave ip:listening_port
  * pair. Mostly useful for logging, since we want to log a slave using its
@@ -2864,7 +2871,7 @@ write_error: /* Handle sendCommand() errors. */
 }
 
 int connectWithMaster(void) {
-    server.repl_transfer_s = server.tls_replication ? connCreateTLS() : connCreateSocket();
+    server.repl_transfer_s = connCreate(connTypeOfReplication());
     if (connConnect(server.repl_transfer_s, server.masterhost, server.masterport,
                 server.bind_source_addr, syncWithMaster) == C_ERR) {
         serverLog(LL_WARNING,"Unable to connect to MASTER: %s",