SS_SYSTEM_DNS_RESOLVER_FORCE_BUILTIN

- ref #773

Author: zonyitoo

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "shadowsocks-rust"
-version = "1.13.4"
+version = "1.13.5"
 authors = ["Shadowsocks Contributors"]
 description = "shadowsocks is a fast tunnel proxy that helps you bypass firewalls."
 repository = "https://github.com/shadowsocks/shadowsocks-rust"
@@ -164,7 +164,7 @@ jemallocator = { version = "0.3", optional = true }
 snmalloc-rs = { version = "0.2", optional = true }
 rpmalloc = { version = "0.2", optional = true }
 
-shadowsocks-service = { version = "1.13.4", path = "./crates/shadowsocks-service" }
+shadowsocks-service = { version = "1.13.5", path = "./crates/shadowsocks-service" }
 
 [target.'cfg(unix)'.dependencies]
 daemonize = "0.4"

Cargo.toml

@@ -662,6 +662,7 @@ Example configuration:
 ### Environment Variables
 
 - `SS_SERVER_PASSWORD`: A default password for servers that created from command line argument (`--server-addr`)
+- `SS_SYSTEM_DNS_RESOLVER_FORCE_BUILTIN`: `"system"` DNS resolver force use system's builtin (`getaddrinfo` in *NIX)
 
 ## Supported Ciphers
 

README.md

@@ -1,6 +1,6 @@
 [package]
 name = "shadowsocks-service"
-version = "1.13.4"
+version = "1.13.5"
 authors = ["Shadowsocks Contributors"]
 description = "shadowsocks is a fast tunnel proxy that helps you bypass firewalls."
 repository = "https://github.com/shadowsocks/shadowsocks-rust"

crates/shadowsocks-service/Cargo.toml

@@ -1,5 +1,6 @@
 //! DNS resolvers
 
+use log::trace;
 use shadowsocks::{dns_resolver::DnsResolver, net::ConnectOpts};
 
 use crate::config::DnsConfig;
@@ -11,19 +12,32 @@ pub async fn build_dns_resolver(dns: DnsConfig, ipv6_first: bool, connect_opts:
             #[cfg(feature = "trust-dns")]
             if crate::hint_support_default_system_resolver() {
                 use log::warn;
+                use std::env;
 
-                return match DnsResolver::trust_dns_system_resolver(ipv6_first).await {
-                    Ok(r) => Some(r),
-                    Err(err) => {
-                        warn!(
+                let force_system_builtin = match env::var("SS_SYSTEM_DNS_RESOLVER_FORCE_BUILTIN") {
+                    Ok(mut v) => {
+                        v.make_ascii_lowercase();
+                        v == "1" || v == "true"
+                    }
+                    Err(..) => false,
+                };
+
+                if !force_system_builtin {
+                    return match DnsResolver::trust_dns_system_resolver(ipv6_first).await {
+                        Ok(r) => Some(r),
+                        Err(err) => {
+                            warn!(
                             "initialize trust-dns DNS system resolver failed, fallback to default system resolver, error: {}",
                             err
                         );
-                        None
-                    }
-                };
+                            None
+                        }
+                    };
+                }
             }
 
+            trace!("initialized DNS system resolver builtin");
+
             None
         }
         #[cfg(feature = "trust-dns")]
@@ -42,7 +56,6 @@ pub async fn build_dns_resolver(dns: DnsConfig, ipv6_first: bool, connect_opts:
         #[cfg(feature = "local-dns")]
         DnsConfig::LocalDns(ns) => {
             use crate::local::dns::dns_resolver::DnsResolver as LocalDnsResolver;
-            use log::trace;
             use shadowsocks::config::Mode;
 
             trace!("initializing direct DNS resolver for {}", ns);

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

@@ -82,7 +82,7 @@ fn hint_support_default_system_resolver() -> bool {
     cfg!(all(
         unix,
         not(target_os = "android"),
-        /* not(target_os = "macos"),
-         * not(target_os = "ios") */
+        // not(target_os = "macos"),
+        // not(target_os = "ios")
     ))
 }

crates/shadowsocks-service/src/lib.rs

@@ -1,3 +1,9 @@
+shadowsocks-rust (1.13.5) unstable; urgency=medium
+
+  ## Features
+
+  - #773 Set environment variable `SS_SYSTEM_DNS_RESOLVER_FORCE_BUILTIN` to use system's builtin DNS resolver
+
 shadowsocks-rust (1.13.4) unstable; urgency=medium
 
   ## Features