Fix bug where EzRpcClient would segfault if the target host resolved to multiple…

Fix bug where EzRpcClient would segfault if the target host resolved to multiple addresses and the connection to the first of those failed.

c++/src/capnp/ez-rpc.c++

@@ -72,6 +72,10 @@ private:
 
 // =======================================================================================
 
+kj::Promise<kj::Own<kj::AsyncIoStream>> connectAttach(kj::Own<kj::NetworkAddress>&& addr) {
+  return addr->connect().attach(kj::mv(addr));
+}
+
 struct EzRpcClient::Impl {
   kj::Own<EzRpcContext> context;
 
@@ -123,7 +127,7 @@ struct EzRpcClient::Impl {
         setupPromise(context->getIoProvider().getNetwork()
             .parseAddress(serverAddress, defaultPort)
             .then([readerOpts](kj::Own<kj::NetworkAddress>&& addr) {
-              return addr->connect();
+              return connectAttach(kj::mv(addr));
             }).then([this, readerOpts](kj::Own<kj::AsyncIoStream>&& stream) {
               clientContext = kj::heap<ClientContext>(kj::mv(stream),
                                                       readerOpts);
@@ -132,8 +136,9 @@ struct EzRpcClient::Impl {
   Impl(const struct sockaddr* serverAddress, uint addrSize,
        ReaderOptions readerOpts)
       : context(EzRpcContext::getThreadLocal()),
-        setupPromise(context->getIoProvider().getNetwork()
-            .getSockaddr(serverAddress, addrSize)->connect()
+        setupPromise(
+            connectAttach(context->getIoProvider().getNetwork()
+                .getSockaddr(serverAddress, addrSize))
             .then([this, readerOpts](kj::Own<kj::AsyncIoStream>&& stream) {
               clientContext = kj::heap<ClientContext>(kj::mv(stream),
                                                       readerOpts);