win32/resolv: get_dns_server_list

* ext/win32/resolv/resolv.c (get_dns_server_list): [Win32] get DNS
  servers only for connected network devices by GetNetworkParams
  API.  [Bug #12604]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55781 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 73 insertions, 0 deletions

diff --git a/ext/win32/resolv/extconf.rb b/ext/win32/resolv/extconf.rb
new file mode 100644
index 0000000000..2ae4bb29f7
--- /dev/null
+++ b/ext/win32/resolv/extconf.rb
@@ -0,0 +1 @@
+create_makefile('win32/resolv')
diff --git a/ext/win32/resolv/resolv.c b/ext/win32/resolv/resolv.c
new file mode 100644
index 0000000000..03252f5ffc
--- /dev/null
+++ b/ext/win32/resolv/resolv.c
@@ -0,0 +1,72 @@
+#include <ruby.h>
+#include <ruby/encoding.h>
+#include <iphlpapi.h>
+
+static VALUE
+w32error_init(VALUE self, VALUE code)
+{
+    VALUE str = rb_str_new_cstr(rb_w32_strerror(NUM2INT(code)));
+    rb_ivar_set(self, rb_intern("@code"), code);
+    return rb_call_super(1, &str);
+}
+
+static VALUE
+w32error_make_error(DWORD e)
+{
+    VALUE code = ULONG2NUM(e);
+    return rb_class_new_instance(1, &code, rb_path2class("Win32::Error"));
+}
+
+static void
+w32error_raise(DWORD e)
+{
+    rb_exc_raise(w32error_make_error(e));
+}
+
+static VALUE
+get_dns_server_list(VALUE self)
+{
+    FIXED_INFO *fixedinfo = NULL;
+    ULONG buflen = 0;
+    DWORD ret;
+    VALUE buf, nameservers = Qnil;
+
+    ret = GetNetworkParams(NULL, &buflen);
+    if (ret != NO_ERROR && ret != ERROR_BUFFER_OVERFLOW) {
+	w32error_raise(ret);
+    }
+    fixedinfo = ALLOCV(buf, buflen);
+    ret = GetNetworkParams(fixedinfo, &buflen);
+    if (ret == NO_ERROR) {
+	const IP_ADDR_STRING *ipaddr = &fixedinfo->DnsServerList;
+	nameservers = rb_ary_new();
+	do {
+	    const char *s = ipaddr->IpAddress.String;
+	    if (!*s) continue;
+	    if (strcmp(s, "0.0.0.0") == 0) continue;
+	    rb_ary_push(nameservers, rb_str_new_cstr(s));
+	} while ((ipaddr = ipaddr->Next) != NULL);
+    }
+    ALLOCV_END(buf);
+    if (ret != NO_ERROR) w32error_raise(ret);
+
+    return nameservers;
+}
+
+void
+InitVM_resolv(void)
+{
+    VALUE mWin32 = rb_define_module("Win32");
+    VALUE resolv = rb_define_module_under(mWin32, "Resolv");
+    VALUE singl = rb_singleton_class(resolv);
+    VALUE eclass = rb_define_class_under(mWin32, "Error", rb_eStandardError);
+    rb_define_method(eclass, "initialize", w32error_init, 1);
+    rb_define_private_method(singl, "get_dns_server_list", get_dns_server_list, 0);
+}
+
+void
+Init_resolv(void)
+{
+    message_free = (rb_w32_osver() >= 10) ? heap_free : local_free;
+    InitVM(resolv);
+}