LibCore+LookupServer: Implement and use UDPServer::send

Author: https://github.com/sin-ack
Commit: https://github.com/SerenityOS/serenity/commit/0cca6cef958
Pull-request: https://github.com/SerenityOS/serenity/pull/9977
Reviewed-by: https://github.com/Dexesttp
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibCore/UDPServer.cpp

@@ -102,4 +102,18 @@ Optional<u16> UDPServer::local_port() const
     return ntohs(address.sin_port);
 }
 
+ErrorOr<size_t> UDPServer::send(ReadonlyBytes buffer, sockaddr_in const& to)
+{
+    if (m_fd < 0) {
+        return Error::from_errno(EBADF);
+    }
+
+    auto result = ::sendto(m_fd, buffer.data(), buffer.size(), 0, (sockaddr const*)&to, sizeof(to));
+    if (result < 0) {
+        return Error::from_errno(errno);
+    }
+
+    return result;
+}
+
 }

Userland/Libraries/LibCore/UDPServer.h

@@ -30,6 +30,8 @@ public:
         return receive(size, saddr);
     };
 
+    ErrorOr<size_t> send(ReadonlyBytes, sockaddr_in const& to);
+
     Optional<IPv4Address> local_address() const;
     Optional<u16> local_port() const;
 

Userland/Services/LookupServer/DNSServer.cpp

@@ -58,7 +58,9 @@ void DNSServer::handle_client()
         response.set_code(DNSPacket::Code::NOERROR);
 
     buffer = response.to_byte_buffer();
-    sendto(fd(), buffer.data(), buffer.size(), 0, (const sockaddr*)&client_address, sizeof(client_address));
+
+    // FIXME: We should be handling errors here.
+    [[maybe_unused]] auto result = send(buffer, client_address);
 }
 
 }

Userland/Services/LookupServer/MulticastDNS.cpp

@@ -100,16 +100,17 @@ void MulticastDNS::announce()
         response.add_answer(answer);
     }
 
-    if (emit_packet(response) < 0)
+    if (emit_packet(response).is_error())
         perror("Failed to emit response packet");
 }
 
-ssize_t MulticastDNS::emit_packet(const DNSPacket& packet, const sockaddr_in* destination)
+ErrorOr<size_t> MulticastDNS::emit_packet(const DNSPacket& packet, const sockaddr_in* destination)
 {
     auto buffer = packet.to_byte_buffer();
     if (!destination)
         destination = &mdns_addr;
-    return sendto(fd(), buffer.data(), buffer.size(), 0, (const sockaddr*)destination, sizeof(*destination));
+
+    return send(buffer, *destination);
 }
 
 Vector<IPv4Address> MulticastDNS::local_addresses() const
@@ -148,7 +149,7 @@ Vector<DNSAnswer> MulticastDNS::lookup(const DNSName& name, DNSRecordType record
     request.set_recursion_desired(false);
     request.add_question({ name, record_type, DNSRecordClass::IN, false });
 
-    if (emit_packet(request) < 0) {
+    if (emit_packet(request).is_error()) {
         perror("failed to emit request packet");
         return {};
     }

Userland/Services/LookupServer/MulticastDNS.h

@@ -24,7 +24,7 @@ private:
     explicit MulticastDNS(Object* parent = nullptr);
 
     void announce();
-    ssize_t emit_packet(const DNSPacket&, const sockaddr_in* destination = nullptr);
+    ErrorOr<size_t> emit_packet(const DNSPacket&, const sockaddr_in* destination = nullptr);
 
     void handle_packet();
     void handle_query(const DNSPacket&);