Add db-connect, a SQL over HTTPS server

vendor/github.com/kshvakov/clickhouse/tls_config.go

@@ -0,0 +1,45 @@
+package clickhouse
+
+import (
+	"crypto/tls"
+	"sync"
+)
+
+// Based on the original implementation in the project go-sql-driver/mysql:
+// https://github.com/go-sql-driver/mysql/blob/master/utils.go
+
+var (
+	tlsConfigLock     sync.RWMutex
+	tlsConfigRegistry map[string]*tls.Config
+)
+
+// RegisterTLSConfig registers a custom tls.Config to be used with sql.Open.
+func RegisterTLSConfig(key string, config *tls.Config) error {
+	tlsConfigLock.Lock()
+	if tlsConfigRegistry == nil {
+		tlsConfigRegistry = make(map[string]*tls.Config)
+	}
+
+	tlsConfigRegistry[key] = config
+	tlsConfigLock.Unlock()
+	return nil
+}
+
+// DeregisterTLSConfig removes the tls.Config associated with key.
+func DeregisterTLSConfig(key string) {
+	tlsConfigLock.Lock()
+	if tlsConfigRegistry != nil {
+		delete(tlsConfigRegistry, key)
+	}
+	tlsConfigLock.Unlock()
+}
+
+func getTLSConfigClone(key string) (config *tls.Config) {
+	tlsConfigLock.RLock()
+	if v, ok := tlsConfigRegistry[key]; ok {
+		config = v.Clone()
+	}
+	tlsConfigLock.RUnlock()
+	return
+}
+