refactor: remove raw pointers from dns code

include/dpp/dns.h

@@ -32,6 +32,7 @@
 #include <string>
 #include <unordered_map>
 #include <cstring>
+#include <memory>
 #include <dpp/socket.h>
 
 namespace dpp {
@@ -83,7 +84,7 @@ namespace dpp {
 	/**
 	 * @brief Cache container type
 	 */
-	using dns_cache_t = std::unordered_map<std::string, dns_cache_entry*>;
+	using dns_cache_t = std::unordered_map<std::string, std::unique_ptr<dns_cache_entry>>;
 
 	/**
 	 * @brief Resolve a hostname to an addrinfo

src/dpp/dns.cpp

@@ -70,7 +70,7 @@ const dns_cache_entry *resolve_hostname(const std::string &hostname, const std::
 			exists = true;
 			if (now < iter->second->expire_timestamp) {
 				/* there is a cached entry that is still valid, return it */
-				return iter->second;
+				return iter->second.get();
 			}
 		}
 	}
@@ -82,7 +82,6 @@ const dns_cache_entry *resolve_hostname(const std::string &hostname, const std::
 		std::unique_lock dns_cache_lock(dns_cache_mutex);
 		iter = dns_cache.find(hostname);
 		if (iter != dns_cache.end()) { /* re-validate iter */
-			delete iter->second;
 			dns_cache.erase(iter);
 		}
 	}
@@ -108,7 +107,7 @@ const dns_cache_entry *resolve_hostname(const std::string &hostname, const std::
 	{
 		/* Update cache, requires unique lock */
 		std::unique_lock dns_cache_lock(dns_cache_mutex);
-		dns_cache_entry* cache_entry = new dns_cache_entry();
+		auto cache_entry = std::make_unique<dns_cache_entry>();
 
 		for (struct addrinfo* rp = addrs; rp != nullptr; rp = rp->ai_next) {
 			/* Discord only support ipv4, so iterate over any ipv6 results */
@@ -127,11 +126,13 @@ const dns_cache_entry *resolve_hostname(const std::string &hostname, const std::
 		}
 
 		cache_entry->expire_timestamp = now + one_hour;
-		dns_cache[hostname] = cache_entry;
+		auto r = dns_cache.emplace(hostname, std::move(cache_entry));
 
 		/* Now we're done with this horrible struct, free it and return */
 		freeaddrinfo(addrs);
-		return cache_entry;
+
+		/* Return either the existing entry, or the newly inserted entry */
+		return r.first->second.get();
 	}
 }