Support using a seeds host for bootstrapping connections.

core/core.js

@@ -64,6 +64,11 @@ const k_global_settings = {
 				: undefined,
 		description: 'Blobs older than this will be automatically deleted.',
 	},
+	seeds_host: {
+		type: 'string',
+		default_value: '',
+		description: 'Hostname for seed connections.',
+	},
 };
 
 let gGlobalSettings = {

src/ssb.c

@@ -8,6 +8,7 @@
 #include "trace.h"
 #include "util.js.h"
 
+#include "ares.h"
 #include "quickjs.h"
 #include "sodium/crypto_auth.h"
 #include "sodium/crypto_box.h"
@@ -20,6 +21,10 @@
 #include "sqlite3.h"
 #include "uv.h"
 
+#if !defined(_WIN32)
+#include <arpa/nameser.h>
+#endif
+
 #include <assert.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -256,6 +261,7 @@ typedef struct _tf_ssb_t
 	uv_thread_t thread_self;
 	bool is_room;
 	char* room_name;
+	char seeds_host[256];
 
 	tf_ssb_timer_t** timers;
 	int timers_count;
@@ -351,6 +357,7 @@ static JSClassID _connection_class_id;
 static int s_connection_index;
 static int s_tunnel_index;
 
+static void _tf_ssb_add_broadcast(tf_ssb_t* ssb, const tf_ssb_broadcast_t* broadcast);
 static void _tf_ssb_connection_client_send_hello(tf_ssb_connection_t* connection);
 static void _tf_ssb_connection_close(tf_ssb_connection_t* connection, const char* reason);
 static void _tf_ssb_connection_destroy(tf_ssb_connection_t* connection, const char* reason);
@@ -358,6 +365,7 @@ static void _tf_ssb_connection_finalizer(JSRuntime* runtime, JSValue value);
 static void _tf_ssb_connection_on_close(uv_handle_t* handle);
 static void _tf_ssb_nonce_inc(uint8_t* nonce);
 static void _tf_ssb_notify_connections_changed(tf_ssb_t* ssb, tf_ssb_change_t change, tf_ssb_connection_t* connection);
+static bool _tf_ssb_parse_broadcast(const char* in_broadcast, tf_ssb_broadcast_t* out_broadcast);
 static void _tf_ssb_start_update_settings(tf_ssb_t* ssb);
 static void _tf_ssb_update_settings(tf_ssb_t* ssb);
 static void _tf_ssb_write(tf_ssb_connection_t* connection, void* data, size_t size);
@@ -2892,6 +2900,59 @@ static void _tf_ssb_send_broadcast(tf_ssb_t* ssb, struct sockaddr_in* address, s
 	}
 }
 
+typedef struct _seeds_t
+{
+	char** seeds;
+	int seeds_count;
+} seeds_t;
+
+static void _tf_ssb_update_seed_callback(void* arg, ares_status_t status, size_t timeouts, const ares_dns_record_t* record)
+{
+	seeds_t* seeds = arg;
+	for (int i = 0; i < (int)ares_dns_record_rr_cnt(record, ARES_SECTION_ANSWER); i++)
+	{
+		const ares_dns_rr_t* rr = ares_dns_record_rr_get_const(record, ARES_SECTION_ANSWER, i);
+		size_t len = 0;
+		const unsigned char* str = ares_dns_rr_get_bin(rr, ARES_RR_TXT_DATA, &len);
+		seeds->seeds = tf_resize_vec(seeds->seeds, sizeof(char*) * (seeds->seeds_count + 1));
+		seeds->seeds[seeds->seeds_count++] = tf_strdup((const char*)str);
+	}
+}
+
+static void _tf_ssb_update_seeds_work(tf_ssb_t* ssb, void* user_data)
+{
+	if (ares_library_init(0) == ARES_SUCCESS)
+	{
+		ares_channel channel;
+		struct ares_options options = { .evsys = ARES_EVSYS_DEFAULT };
+		if (ares_init_options(&channel, &options, ARES_OPT_EVENT_THREAD) == ARES_SUCCESS)
+		{
+			if (ares_query_dnsrec(channel, ssb->seeds_host, ARES_CLASS_IN, ARES_REC_TYPE_TXT, _tf_ssb_update_seed_callback, user_data, NULL) == ARES_SUCCESS)
+			{
+				ares_queue_wait_empty(channel, -1);
+			}
+			ares_destroy(channel);
+		}
+		ares_library_cleanup();
+	}
+}
+
+static void _tf_ssb_update_seeds_after_work(tf_ssb_t* ssb, int status, void* user_data)
+{
+	seeds_t* seeds = user_data;
+	for (int i = 0; i < seeds->seeds_count; i++)
+	{
+		tf_ssb_broadcast_t broadcast = { 0 };
+		if (_tf_ssb_parse_broadcast(seeds->seeds[i], &broadcast))
+		{
+			_tf_ssb_add_broadcast(ssb, &broadcast);
+		}
+		tf_free(seeds->seeds[i]);
+	}
+	tf_free(seeds->seeds);
+	tf_free(seeds);
+}
+
 static void _tf_ssb_broadcast_timer(uv_timer_t* timer)
 {
 	tf_ssb_t* ssb = timer->data;
@@ -2908,6 +2969,14 @@ static void _tf_ssb_broadcast_timer(uv_timer_t* timer)
 		}
 		uv_free_interface_addresses(info, count);
 	}
+
+	seeds_t* seeds = tf_malloc(sizeof(seeds_t));
+	*seeds = (seeds_t) { 0 };
+
+	if (*ssb->seeds_host)
+	{
+		tf_ssb_run_work(ssb, _tf_ssb_update_seeds_work, _tf_ssb_update_seeds_after_work, seeds);
+	}
 }
 
 int tf_ssb_server_open(tf_ssb_t* ssb, int port)
@@ -3924,6 +3993,7 @@ void tf_ssb_set_room_name(tf_ssb_t* ssb, const char* room_name)
 typedef struct _update_settings_t
 {
 	bool is_room;
+	char seeds_host[256];
 	char room_name[1024];
 } update_settings_t;
 
@@ -3981,6 +4051,7 @@ static void _tf_ssb_update_settings_work(tf_ssb_t* ssb, void* user_data)
 	update_settings_t* update = user_data;
 	update->is_room = _get_global_setting_bool(ssb, "room", true);
 	_get_global_setting_string(ssb, "room_name", update->room_name, sizeof(update->room_name));
+	_get_global_setting_string(ssb, "seeds_host", update->seeds_host, sizeof(update->seeds_host));
 }
 
 static void _tf_ssb_update_settings_after_work(tf_ssb_t* ssb, int result, void* user_data)
@@ -3988,6 +4059,7 @@ static void _tf_ssb_update_settings_after_work(tf_ssb_t* ssb, int result, void*
 	update_settings_t* update = user_data;
 	tf_ssb_set_is_room(ssb, update->is_room);
 	tf_ssb_set_room_name(ssb, update->room_name);
+	snprintf(ssb->seeds_host, sizeof(ssb->seeds_host), "%s", update->seeds_host);
 	_tf_ssb_start_update_settings(ssb);
 	tf_free(update);
 }