feat: https://discord.com/developers/docs/change-log#sessionspecific-gateway-resume-urls - discord/discord-api-docs#5282

Author: braindigitalis

include/dpp/discordclient.h

@@ -257,6 +257,12 @@ class DPP_EXPORT discord_client : public websocket_client
 	 */
 	void end_zlib();
 
+	/**
+	 * @brief Update the websocket hostname with the resume url
+	 * from the last READY event
+	 */
+	void set_resume_hostname();
+
 public:
 	/**
 	 * @brief Owning cluster
@@ -350,6 +356,11 @@ class DPP_EXPORT discord_client : public websocket_client
 	 */
 	std::unordered_map<snowflake, voiceconn*> connecting_voice_channels;
 
+	/**
+	 * @brief The gateway address we reconnect to when we resume a session
+	 */
+	std::string resume_gateway_url;
+
 	/**
 	 * @brief Log a message to whatever log the user is using.
 	 * The logged message is passed up the chain to the on_log event in user code which can then do whatever

src/dpp/discordclient.cpp

@@ -93,7 +93,8 @@ discord_client::discord_client(dpp::cluster* _cluster, uint32_t _shard_id, uint3
 	websocket_ping(0.0),
 	ready(false),
 	last_heartbeat_ack(time(nullptr)),
-	protocol(ws_proto)
+	protocol(ws_proto),
+	resume_gateway_url(DEFAULT_GATEWAY)
 {
 	zlib = new zlibcontext();
 	etf = new etf_parser();
@@ -141,6 +142,11 @@ void discord_client::end_zlib()
 	}
 }
 
+void discord_client::set_resume_hostname()
+{
+	hostname = resume_gateway_url;
+}
+
 void discord_client::thread_run()
 {
 	utility::set_thread_name(std::string("shard/") + std::to_string(shard_id));
@@ -155,9 +161,10 @@ void discord_client::thread_run()
 			end_zlib();
 			setup_zlib();
 			do {
-				this->log(ll_debug, "Attempting reconnection of shard " + std::to_string(this->shard_id));
+				this->log(ll_debug, "Attempting reconnection of shard " + std::to_string(this->shard_id) + " to wss://" + resume_gateway_url);
 				error = false;
 				try {
+					set_resume_hostname();
 					ssl_client::connect();
 					websocket_client::connect();
 				}

src/dpp/events/ready.cpp

@@ -21,6 +21,7 @@
 #include <dpp/discordevents.h>
 #include <dpp/cluster.h>
 #include <dpp/stringops.h>
+#include <dpp/dns.h>
 #include <dpp/nlohmann/json.hpp>
 
 using json = nlohmann::json;
@@ -43,6 +44,21 @@ std::mutex protect_the_loot;
 void ready::handle(discord_client* client, json &j, const std::string &raw) {
 	client->log(dpp::ll_info, "Shard id " + std::to_string(client->shard_id) + " (" + std::to_string(client->shard_id + 1) + "/" + std::to_string(client->max_shards) + ") ready!");
 	client->sessionid = j["d"]["session_id"];
+	/* Session-specific gateway resume url
+	 * https://discord.com/developers/docs/change-log#sessionspecific-gateway-resume-urls
+	 *
+	 * Discord give us the hostname wrapped in wss://crap/ like we're going to pass it to
+	 * some top-heavy lib. Let's strip all this out if given to us so we just have a
+	 * hostname.
+	 */
+	std::string ugly(j["d"]["resume_gateway_url"]);
+	if (ugly.substr(0, 6) == "wss://") {
+		client->resume_gateway_url = ugly.substr(6, ugly.length() - 7);
+	} else {
+		client->resume_gateway_url = ugly;
+	}
+	/* Pre-resolve it into our cache so that we aren't waiting on this when we need it later */
+	static_cast<void>(resolve_hostname(client->resume_gateway_url, "443"));
 
 	client->ready = true;
 

src/unittest.cpp

@@ -76,15 +76,15 @@ std::map<std::string, test_t> tests = {
 	{"COMPARISON", {tt_offline, "dpp::manged object comparison", false, false}},
 	{"CHANNELCACHE", {tt_online, "dpp::find_channel()", false, false}},
 	{"CHANNELTYPES", {tt_online, "dpp::channel type flags", false, false}},
-	{"PERMISSION_CLASS", {tt_offline, "testing dpp::permission functionality", false, false}},
-	{"USER.GET_MENTION", {tt_offline, "testing dpp::user::get_mention functionality", false, false}},
-	{"USER.FORMAT_USERNAME", {tt_offline, "testing dpp::user::format_username functionality", false, false}},
-	{"USER.GET_CREATION_TIME", {tt_offline, "testing dpp::user::get_creation_time functionality", false, false}},
-	{"UTILITY.ICONHASH", {tt_offline, "testing dpp::utility::iconhash functionality", false, false}},
-	{"UTILITY.MAKE_URL_PARAMETERS", {tt_offline, "testing dpp::utility::make_url_parameters functionality", false, false}},
-	{"UTILITY.MARKDOWN_ESCAPE", {tt_offline, "testing dpp::utility::markdown_escape functionality", false, false}},
-	{"UTILITY.TOKENIZE", {tt_offline, "testing dpp::utility::tokenize functionality", false, false}},
-	{"UTILITY.URL_ENCODE", {tt_offline, "testing dpp::utility::url_encode functionality", false, false}},
+	{"PERMISSION_CLASS", {tt_offline, "dpp::permission", false, false}},
+	{"USER.GET_MENTION", {tt_offline, "dpp::user::get_mention", false, false}},
+	{"USER.FORMAT_USERNAME", {tt_offline, "dpp::user::format_username", false, false}},
+	{"USER.GET_CREATION_TIME", {tt_offline, "dpp::user::get_creation_time", false, false}},
+	{"UTILITY.ICONHASH", {tt_offline, "dpp::utility::iconhash", false, false}},
+	{"UTILITY.MAKE_URL_PARAMETERS", {tt_offline, "dpp::utility::make_url_parameters", false, false}},
+	{"UTILITY.MARKDOWN_ESCAPE", {tt_offline, "dpp::utility::markdown_escape", false, false}},
+	{"UTILITY.TOKENIZE", {tt_offline, "dpp::utility::tokenize", false, false}},
+	{"UTILITY.URL_ENCODE", {tt_offline, "dpp::utility::url_encode", false, false}},
 };
 
 double start = dpp::utility::time_f();