Merge pull request #2118 from chenhw2/master

Multipe nameservers support

doc/shadowsocks-libev.asciidoc

@@ -121,7 +121,7 @@ Specify destination server address and port for local port forwarding.
 Only available in tunnel mode.
 
 -d <addr>::
-Setup name servers for internal DNS resolver (libudns).
+Setup name servers for internal DNS resolver (libc-ares).
 The default server is fetched from /etc/resolv.conf.
 +
 Only available in server and manager mode.

doc/ss-manager.asciidoc

@@ -90,7 +90,7 @@ Enable UDP relay and disable TCP relay.
 Enable onetime authentication.
 
 -d <addr>::
-Setup name servers for internal DNS resolver (libudns).
+Setup name servers for internal DNS resolver (libc-ares).
 The default server is fetched from `/etc/resolv.conf`.
 
 --fast-open::

doc/ss-server.asciidoc

@@ -100,7 +100,7 @@ Enable UDP relay and disable TCP relay.
 Resovle hostname to IPv6 address first.
 
 -d <addr>::
-Setup name servers for internal DNS resolver (libudns).
+Setup name servers for internal DNS resolver (libc-ares).
 The default server is fetched from '/etc/resolv.conf'.
 
 --fast-open::

docker/alpine/Dockerfile

@@ -10,8 +10,7 @@ ENV SERVER_PORT 8388
 ENV PASSWORD=
 ENV METHOD      aes-256-cfb
 ENV TIMEOUT     300
-ENV DNS_ADDR    8.8.8.8
-ENV DNS_ADDR_2  8.8.4.4
+ENV DNS_ADDRS    8.8.8.8,8.8.4.4
 ENV ARGS=
 
 COPY . /tmp/repo
@@ -51,7 +50,6 @@ CMD exec ss-server \
       -m $METHOD \
       -t $TIMEOUT \
       --fast-open \
-      -d $DNS_ADDR \
-      -d $DNS_ADDR_2 \
+      -d $DNS_ADDRS \
       -u \
       $ARGS

docker/alpine/README.md

@@ -33,7 +33,7 @@ $ docker run -p 8388:8388 -p 8388:8388/udp -d --restart always shadowsocks/shado
 ```
 This starts a container of the latest release with all the default settings, which is equivalent to
 ```bash
-$ ss-server -s 0.0.0.0 -p 8388 -k "$(hostname)" -m aes-256-cfb -t 300 --fast-open -d 8.8.8.8 -d 8.8.4.4 -u
+$ ss-server -s 0.0.0.0 -p 8388 -k "$(hostname)" -m aes-256-cfb -t 300 --fast-open -d "8.8.8.8,8.8.4.4" -u
 ```
 > **Note**: It's the hostname in the container that is used as the password, not that of the host.
 
@@ -61,7 +61,7 @@ Besides `PASSWORD`, the image also defines the following environment variables t
 * `SERVER_ADDR`: the IP/domain to bind to, defaults to `0.0.0.0`
 * `METHOD`: encryption method to use, defaults to `aes-256-cfb`
 * `TIMEOUT`: defaults to `300`
-* `DNS_ADDR`, `DNS_ADDR_2`: DNS servers to redirect NS lookup requests to, defaults to `8.8.8.8` and `8.8.4.4`
+* `DNS_ADDRS`: DNS servers to redirect NS lookup requests to, defaults to `8.8.8.8,8.8.4.4`
 
 Additional arguments supported by `ss-server` can be passed with the environment variable `ARGS`, for instance to start in verbose mode:
 ```bash

src/manager.c

@@ -208,9 +208,9 @@ construct_command_line(struct manager_ctx *manager, struct server *server)
         int len = strlen(cmd);
         snprintf(cmd + len, BUF_SIZE - len, " --plugin-opts \"%s\"", manager->plugin_opts);
     }
-    for (i = 0; i < manager->nameserver_num; i++) {
+    if (manager->nameservers) {
         int len = strlen(cmd);
-        snprintf(cmd + len, BUF_SIZE - len, " -d %s", manager->nameservers[i]);
+        snprintf(cmd + len, BUF_SIZE - len, " -d \"%s\"", manager->nameservers);
     }
     for (i = 0; i < manager->host_num; i++) {
         int len = strlen(cmd);
@@ -871,8 +871,7 @@ main(int argc, char **argv)
     int server_num = 0;
     char *server_host[MAX_REMOTE_NUM];
 
-    char *nameservers[MAX_DNS_NUM + 1];
-    int nameserver_num = 0;
+    char *nameservers = NULL;
 
     jconf_t *conf = NULL;
 
@@ -953,9 +952,7 @@ main(int argc, char **argv)
             iface = optarg;
             break;
         case 'd':
-            if (nameserver_num < MAX_DNS_NUM) {
-                nameservers[nameserver_num++] = optarg;
-            }
+            nameservers = optarg;
             break;
         case 'a':
             user = optarg;
@@ -1024,8 +1021,8 @@ main(int argc, char **argv)
         if (reuse_port == 0) {
             reuse_port = conf->reuse_port;
         }
-        if (conf->nameserver != NULL) {
-            nameservers[nameserver_num++] = conf->nameserver;
+        if (nameservers == NULL) {
+            nameservers = conf->nameserver;
         }
         if (mode == TCP_ONLY) {
             mode = conf->mode;
@@ -1118,7 +1115,6 @@ main(int argc, char **argv)
     manager.hosts           = server_host;
     manager.host_num        = server_num;
     manager.nameservers     = nameservers;
-    manager.nameserver_num  = nameserver_num;
     manager.mtu             = mtu;
     manager.plugin          = plugin;
     manager.plugin_opts     = plugin_opts;

src/manager.h

@@ -56,8 +56,7 @@ struct manager_ctx {
     char *manager_address;
     char **hosts;
     int host_num;
-    char **nameservers;
-    int nameserver_num;
+    char *nameservers;
     int mtu;
     int ipv6first;
 #ifdef HAVE_SETRLIMIT