LibDNS: Implement Traits for DNSAnswer class

This enables DNSAnswer instances being used e.g. in a HashTable for
caching purposes.

Userland/Libraries/LibDNS/DNSAnswer.cpp

@@ -26,6 +26,34 @@ bool DNSAnswer::has_expired() const
     return time(nullptr) >= m_received_time + m_ttl;
 }
 
+unsigned DNSAnswer::hash() const
+{
+    auto hash = pair_int_hash(CaseInsensitiveStringTraits::hash(name().as_string()), (u32)type());
+    hash = pair_int_hash(hash, pair_int_hash((u32)class_code(), ttl()));
+    hash = pair_int_hash(hash, record_data().hash());
+    hash = pair_int_hash(hash, (u32)mdns_cache_flush());
+    return hash;
+}
+
+bool DNSAnswer::operator==(DNSAnswer const& other) const
+{
+    if (&other == this)
+        return true;
+    if (!DNSName::Traits::equals(name(), other.name()))
+        return false;
+    if (type() != other.type())
+        return false;
+    if (class_code() != other.class_code())
+        return false;
+    if (ttl() != other.ttl())
+        return false;
+    if (record_data() != other.record_data())
+        return false;
+    if (mdns_cache_flush() != other.mdns_cache_flush())
+        return false;
+    return true;
+}
+
 }
 
 ErrorOr<void> AK::Formatter<DNS::DNSRecordType>::format(AK::FormatBuilder& builder, DNS::DNSRecordType value)

Userland/Libraries/LibDNS/DNSAnswer.h

@@ -9,6 +9,7 @@
 #include "DNSName.h"
 #include <AK/Format.h>
 #include <AK/String.h>
+#include <AK/Traits.h>
 #include <AK/Types.h>
 
 namespace DNS {
@@ -33,6 +34,7 @@ enum class DNSRecordClass : u16 {
 
 class DNSAnswer {
 public:
+    DNSAnswer() = default;
     DNSAnswer(DNSName const& name, DNSRecordType type, DNSRecordClass class_code, u32 ttl, String const& record_data, bool mdns_cache_flush);
 
     DNSName const& name() const { return m_name; }
@@ -46,6 +48,9 @@ public:
 
     bool has_expired() const;
 
+    unsigned hash() const;
+    bool operator==(DNSAnswer const&) const;
+
 private:
     DNSName m_name;
     DNSRecordType m_type { 0 };
@@ -57,6 +62,13 @@ private:
 };
 
 }
+
+template<>
+struct AK::Traits<DNS::DNSAnswer> : public GenericTraits<DNS::DNSAnswer> {
+    static constexpr bool is_trivial() { return false; }
+    static unsigned hash(DNS::DNSAnswer a) { return a.hash(); }
+};
+
 template<>
 struct AK::Formatter<DNS::DNSRecordType> : StandardFormatter {
     Formatter() = default;

Userland/Libraries/LibDNS/DNSName.cpp

@@ -23,12 +23,12 @@ DNSName::DNSName(String const& name)
 DNSName DNSName::parse(u8 const* data, size_t& offset, size_t max_offset, size_t recursion_level)
 {
     if (recursion_level > 4)
-        return DNSName({});
+        return {};
 
     StringBuilder builder;
     while (true) {
         if (offset >= max_offset)
-            return DNSName({});
+            return {};
         u8 b = data[offset++];
         if (b == '\0') {
             // This terminates the name.
@@ -36,7 +36,7 @@ DNSName DNSName::parse(u8 const* data, size_t& offset, size_t max_offset, size_t
         } else if ((b & 0xc0) == 0xc0) {
             // The two bytes tell us the offset when to continue from.
             if (offset >= max_offset)
-                return DNSName({});
+                return {};
             size_t dummy = (b & 0x3f) << 8 | data[offset++];
             auto rest_of_name = parse(data, dummy, max_offset, recursion_level + 1);
             builder.append(rest_of_name.as_string());
@@ -44,7 +44,7 @@ DNSName DNSName::parse(u8 const* data, size_t& offset, size_t max_offset, size_t
         } else {
             // This is the length of a part.
             if (offset + b >= max_offset)
-                return DNSName({});
+                return {};
             builder.append((char const*)&data[offset], (size_t)b);
             builder.append('.');
             offset += b;

Userland/Libraries/LibDNS/DNSName.h

@@ -14,6 +14,7 @@ namespace DNS {
 
 class DNSName {
 public:
+    DNSName() = default;
     DNSName(String const&);
 
     static DNSName parse(u8 const* data, size_t& offset, size_t max_offset, size_t recursion_level = 0);