Add new GRAVITY_RESTORED_MESSAGE message type

src/database/gravity-db.c

@@ -2720,6 +2720,49 @@ void check_inaccessible_adlists(void)
 	sqlite3_finalize(query_stmt);
 }
 
+/**
+ * @brief Check if gravity was restored from a local backup.
+ *
+ * This function checks the "gravity_restored" property in the "info" table of the gravity database.
+ * If the property value is "false", it means gravity was not restored and the function returns.
+ * Any other value indicates that gravity was restored, and a log entry is created.
+ *
+ * @note If the gravity database is not available or an SQL error occurs during query preparation,
+ *       an error message is logged and the function returns.
+ */
+void check_restored_gravity(void)
+{
+	// Do not proceed when database is not available
+	if(!gravityDB_opened && !gravityDB_open())
+	{
+		log_err("check_restored_gravity(): Gravity database not available");
+		return;
+	}
+
+	const char *querystr = "SELECT value FROM info WHERE property = 'gravity_restored'";
+	sqlite3_stmt *query_stmt = NULL;
+	int rc = sqlite3_prepare_v2(gravity_db, querystr, -1, &query_stmt, NULL);
+	if(rc != SQLITE_OK){
+		log_err("check_restored_gravity(): %s - SQL error prepare: %s", querystr, sqlite3_errstr(rc));
+		gravityDB_close();
+		return;
+	}
+
+	// Perform query
+	if((rc = sqlite3_step(query_stmt)) == SQLITE_ROW)
+	{
+		const char *restored = (const char*)sqlite3_column_text(query_stmt, 0);
+		if(strcmp(restored, "false") != 0)
+		{
+			// log to the message table
+			log_gravity_restored(restored);
+		}
+	}
+
+	// Finalize statement
+	sqlite3_finalize(query_stmt);
+}
+
 static sqlite3_int64 last_updated = -1;
 bool gravity_updated(void)
 {

src/database/gravity-db.h

@@ -50,6 +50,7 @@ char* get_client_names_from_ids(const char *group_ids) __attribute__ ((malloc));
 void gravityDB_finalizeTable(void);
 int gravityDB_count(const enum gravity_tables list);
 void check_inaccessible_adlists(void);
+void check_restored_gravity(void);
 bool gravity_updated(void);
 
 cJSON *gen_abp_patterns(const char *domain, const bool antigravity);

src/database/message-table.c

@@ -103,6 +103,8 @@ static const char *get_message_type_str(const enum message_type type)
 			return "NTP";
 		case VERIFY_MESSAGE:
 			return "VERIFY";
+		case GRAVITY_RESTORED_MESSAGE:
+			return "GRAVITY_RESTORED";
 		case MAX_MESSAGE:
 		default:
 			return "UNKNOWN";
@@ -141,6 +143,8 @@ static enum message_type get_message_type_from_string(const char *typestr)
 		return NTP_MESSAGE;
 	else if (strcmp(typestr, "VERIFY") == 0)
 		return VERIFY_MESSAGE;
+	else if (strcmp(typestr, "GRAVITY_RESTORED") == 0)
+		return GRAVITY_RESTORED_MESSAGE;
 	else
 		return MAX_MESSAGE;
 }
@@ -256,6 +260,14 @@ static unsigned char message_blob_types[MAX_MESSAGE][5] =
 			SQLITE_TEXT, // FTL commit hash
 			SQLITE_TEXT, // FTL architecture
 			SQLITE_NULL // not used
+		},
+		{
+			// GRAVITY_RESTORED_MESSAGE: The message column contains the status
+			SQLITE_NULL, // not used
+			SQLITE_NULL, // not used
+			SQLITE_NULL, // not used
+			SQLITE_NULL, // not used
+			SQLITE_NULL // not used
 		}
 	};
 // Create message table in the database
@@ -975,6 +987,37 @@ static void format_verify_message(char *plain, const int sizeof_plain, char *htm
 	free(escaped_arch);
 }
 
+static void format_gravity_restored_message(char *plain, const int sizeof_plain, char *html, const int sizeof_html,
+                                            const char *status)
+{
+	const bool failed = strcmp(status, "failed") == 0;
+
+	if(snprintf(plain, sizeof_plain, "Gravity database restore %s", failed ? "failed" : "successful") > sizeof_plain)
+		log_warn("format_gravity_restored_message(): Buffer too small to hold plain message, warning truncated");
+
+	// Return early if HTML text is not required
+	if(sizeof_html < 1 || html == NULL)
+		return;
+
+	if(failed)
+	{
+		if(snprintf(html, sizeof_html, "Gravity database damaged, restore attempt <strong>failed</strong><br><br>Please check your filesystem for corruption, and your disk space for availability.") > sizeof_html)
+			log_warn("format_gravity_restored_message(): Buffer too small to hold HTML message, warning truncated");
+	}
+	else
+	{
+		char *escaped_status = escape_html(status);
+
+		// Return early if memory allocation failed
+		if(escaped_status == NULL)
+			return;
+
+		if(snprintf(html, sizeof_html, "Gravity database damaged, restore attempt <strong>successful</strong><br>The gravity database was restored using the backup file <code>%s</code><br><br>Please check your filesystem for corruption, and your disk space for availability.", escaped_status) > sizeof_html)
+
+		free(escaped_status);
+	}
+}
+
 int count_messages(const bool filter_dnsmasq_warnings)
 {
 	int count = 0;
@@ -1248,6 +1291,16 @@ bool format_messages(cJSON *array)
 				break;
 			}
 
+			case GRAVITY_RESTORED_MESSAGE:
+			{
+				const char *status = (const char*)sqlite3_column_text(stmt, 3);
+
+				format_gravity_restored_message(plain, sizeof(plain), html, sizeof(html),
+				                                status);
+
+				break;
+			}
+
 			case MAX_MESSAGE: // Fall through
 			default:
 				log_warn("format_messages() - Unknown message type: %s", mtypestr);
@@ -1533,3 +1586,17 @@ void log_verify_message(const char *expected, const char *actual)
 	add_message(VERIFY_MESSAGE, buf, expected, actual, GIT_HASH, FTL_ARCH);
 
 }
+
+void log_gravity_restored(const char *status)
+{
+	// Create message
+	char buf[2048];
+	format_gravity_restored_message(buf, sizeof(buf), NULL, 0, status);
+
+	// Log to FTL.log
+	log_warn("%s", buf);
+
+	// Log to database
+	add_message_no_args(GRAVITY_RESTORED_MESSAGE, status);
+
+}

src/database/message-table.h

@@ -32,5 +32,6 @@ void log_certificate_domain_mismatch(const char *certfile, const char *domain);
 void log_connection_error(const char *server, const char *reason, const char *error);
 void log_ntp_message(const bool error, const bool server, const char *message);
 void log_verify_message(const char *expected, const char *actual);
+void log_gravity_restored(const char *status);
 
 #endif //MESSAGETABLE_H

src/datastructure.c

@@ -679,6 +679,9 @@ void FTL_reload_all_domainlists(void)
 	// Check for inaccessible adlist URLs
 	check_inaccessible_adlists();
 
+	// Check for restored gravity database
+	check_restored_gravity();
+
 	// Reset FTL's internal DNS cache storing whether a specific domain
 	// has already been validated for a specific user
 	FTL_reset_per_client_domain_data();

src/enums.h

@@ -269,6 +269,7 @@ enum message_type {
 	CONNECTION_ERROR_MESSAGE,
 	NTP_MESSAGE,
 	VERIFY_MESSAGE,
+	GRAVITY_RESTORED_MESSAGE,
 	MAX_MESSAGE,
 } __attribute__ ((packed));