feat(local): local-dns client_cache_size set default when creating server instance

Author: zonyitoo

README.md

@@ -596,7 +596,9 @@ Example configuration:
             // Remote DNS address, DNS queries will be sent through ssserver to this address
             "remote_dns_address": "8.8.8.8",
             // OPTIONAL. Remote DNS's port, 53 by default
-            "remote_dns_port": 53
+            "remote_dns_port": 53,
+            // OPTIONAL. DNS Client Cache (TCP & UDP sockets)
+            "client_cache_size": 5
         },
         {
             // Tun local server (feature = "local-tun")

crates/shadowsocks-service/src/config.rs

@@ -925,7 +925,7 @@ impl LocalConfig {
             #[cfg(feature = "local-dns")]
             remote_dns_addr: None,
             #[cfg(feature = "local-dns")]
-            client_cache_size: Some(5),
+            client_cache_size: None,
 
             #[cfg(feature = "local-tun")]
             tun_interface_name: None,
@@ -1553,6 +1553,11 @@ impl Config {
                             });
                         }
 
+                        #[cfg(feature = "local-dns")]
+                        {
+                            local_config.client_cache_size = local.client_cache_size;
+                        }
+
                         #[cfg(feature = "local-tun")]
                         if let Some(tun_interface_address) = local.tun_interface_address {
                             match tun_interface_address.parse::<IpNet>() {
@@ -2464,6 +2469,8 @@ impl fmt::Display for Config {
                                 Address::DomainNameAddress(.., port) => Some(*port),
                             },
                         },
+                        #[cfg(feature = "local-dns")]
+                        client_cache_size: local.client_cache_size.clone(),
                         #[cfg(feature = "local-tun")]
                         tun_interface_name: local.tun_interface_name.clone(),
                         #[cfg(feature = "local-tun")]

crates/shadowsocks-service/src/local/mod.rs

@@ -353,7 +353,7 @@ impl Server {
                     let mut server_builder = {
                         let local_addr = local_config.local_dns_addr.expect("missing local_dns_addr");
                         let remote_addr = local_config.remote_dns_addr.expect("missing remote_dns_addr");
-                        let client_cache_size = local_config.client_cache_size.unwrap();
+                        let client_cache_size = local_config.client_cache_size.unwrap_or_else(5);
 
                         DnsBuilder::with_context(
                             context.clone(),