LookupServer: Propagate the errors from MulticastDNS::lookup()

This patch slightly change the signature of lookup() method
and propagates all the errors to the caller with help of ErrorOr.

3 files changed, 13 insertions, 18 deletions

diff --git a/Userland/Services/LookupServer/LookupServer.cpp b/Userland/Services/LookupServer/LookupServer.cpp
index 9f946c4fc7..5b77ca408a 100644
--- a/Userland/Services/LookupServer/LookupServer.cpp
+++ b/Userland/Services/LookupServer/LookupServer.cpp
@@ -183,7 +183,7 @@ ErrorOr<Vector<Answer>> LookupServer::lookup(Name const& name, RecordType record
 
     // Fourth, look up .local names using mDNS instead of DNS nameservers.
     if (name.as_string().ends_with(".local"sv)) {
-        answers = m_mdns->lookup(name, record_type);
+        answers = TRY(m_mdns->lookup(name, record_type));
         for (auto& answer : answers)
             put_in_cache(answer);
         return answers;
diff --git a/Userland/Services/LookupServer/MulticastDNS.cpp b/Userland/Services/LookupServer/MulticastDNS.cpp
index f806c6a6c4..75f26c54f0 100644
--- a/Userland/Services/LookupServer/MulticastDNS.cpp
+++ b/Userland/Services/LookupServer/MulticastDNS.cpp
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Sergey Bugaev <bugaevc@serenityos.org>
+ * Copyright (c) 2022, Alexander Narsudinov <a.narsudinov@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -11,6 +12,7 @@
 #include <AK/JsonObject.h>
 #include <AK/JsonValue.h>
 #include <LibCore/File.h>
+#include <LibCore/System.h>
 #include <limits.h>
 #include <poll.h>
 #include <sys/socket.h>
@@ -142,36 +144,28 @@ Vector<IPv4Address> MulticastDNS::local_addresses() const
     return addresses;
 }
 
-Vector<Answer> MulticastDNS::lookup(Name const& name, RecordType record_type)
+ErrorOr<Vector<Answer>> MulticastDNS::lookup(Name const& name, RecordType record_type)
 {
     Packet request;
     request.set_is_query();
     request.set_recursion_desired(false);
     request.add_question({ name, record_type, RecordClass::IN, false });
 
-    if (emit_packet(request).is_error()) {
-        perror("failed to emit request packet");
-        return {};
-    }
-
+    TRY(emit_packet(request));
     Vector<Answer> answers;
 
     // FIXME: It would be better not to block
     // the main loop while we wait for a response.
     while (true) {
-        pollfd pfd { fd(), POLLIN, 0 };
-        auto rc = poll(&pfd, 1, 1000);
-        if (rc < 0) {
-            perror("poll");
-        } else if (rc == 0) {
+        auto pfd = pollfd { fd(), POLLIN, 0 };
+        auto rc = TRY(Core::System::poll({ &pfd, 1 }, 1000));
+        if (rc == 0) {
             // Timed out.
-            return {};
+            return Vector<Answer> {};
         }
-
-        // TODO: propagate the error somehow
-        auto buffer = MUST(receive(1024));
+        auto buffer = TRY(receive(1024));
         if (buffer.is_empty())
-            return {};
+            return Vector<Answer> {};
         auto optional_packet = Packet::from_raw_packet(buffer.data(), buffer.size());
         if (!optional_packet.has_value()) {
             dbgln("Got an invalid mDNS packet");
diff --git a/Userland/Services/LookupServer/MulticastDNS.h b/Userland/Services/LookupServer/MulticastDNS.h
index ff3ecfd2f3..4ccba4865d 100644
--- a/Userland/Services/LookupServer/MulticastDNS.h
+++ b/Userland/Services/LookupServer/MulticastDNS.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Sergey Bugaev <bugaevc@serenityos.org>
+ * Copyright (c) 2022, Alexander Narsudinov <a.narsudinov@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -20,7 +21,7 @@ using namespace DNS;
 class MulticastDNS : public Core::UDPServer {
     C_OBJECT(MulticastDNS)
 public:
-    Vector<Answer> lookup(Name const&, RecordType record_type);
+    ErrorOr<Vector<Answer>> lookup(Name const&, RecordType record_type);
 
 private:
     explicit MulticastDNS(Object* parent = nullptr);