Timezone settings

client/common/cmdline.c

@@ -4609,6 +4609,22 @@ static int freerdp_client_settings_parse_command_line_arguments_int(
 			if (!freerdp_settings_set_uint32(settings, FreeRDP_TcpAckTimeout, (UINT32)val))
 				return COMMAND_LINE_ERROR_UNEXPECTED_VALUE;
 		}
+		CommandLineSwitchCase(arg, "timezone")
+		{
+			TIME_ZONE_INFORMATION* ctz = winpr_GetWindowsTimezoneFromIANA(arg->Value);
+			if (!ctz)
+				return COMMAND_LINE_ERROR_UNEXPECTED_VALUE;
+
+			TIME_ZONE_INFORMATION* tz =
+			    freerdp_settings_get_pointer_writable(settings, FreeRDP_ClientTimeZone);
+			if (!tz)
+			{
+				free(ctz);
+				return COMMAND_LINE_ERROR_MEMORY;
+			}
+			*tz = *ctz;
+			free(ctz);
+		}
 		CommandLineSwitchCase(arg, "aero")
 		{
 			if (!freerdp_settings_set_bool(settings, FreeRDP_AllowDesktopComposition, enable))

client/common/cmdline.h

@@ -451,6 +451,8 @@ static const COMMAND_LINE_ARGUMENT_A global_cmd_args[] = {
 	{ "timeout", COMMAND_LINE_VALUE_REQUIRED, "<time in ms>", "9000", NULL, -1, "timeout",
 	  "Advanced setting for high latency links: Adjust connection timeout, use if you encounter "
 	  "timeout failures with your connection" },
+	{ "timezone", COMMAND_LINE_VALUE_REQUIRED, "<IANA timezone>", NULL, NULL, -1, NULL,
+	  "Use supplied IANA timezone for connection (requires server support)" },
 	{ "tls", COMMAND_LINE_VALUE_REQUIRED, "[ciphers|seclevel|secrets-file|enforce]", NULL, NULL, -1,
 	  NULL,
 	  "TLS configuration options:"

winpr/include/winpr/timezone.h

@@ -74,6 +74,8 @@ extern "C"
 
 #endif
 
+	WINPR_API TIME_ZONE_INFORMATION* winpr_GetWindowsTimezoneFromIANA(const char* tzid);
+
 /*
  * GetDynamicTimeZoneInformation is provided by the SDK if _WIN32_WINNT >= 0x0600 in SDKs above 7.1A
  * and incorrectly if _WIN32_WINNT >= 0x0501 in older SDKs

winpr/libwinpr/timezone/timezone.c

@@ -685,3 +685,14 @@ DWORD GetDynamicTimeZoneInformationEffectiveYears(
 }
 
 #endif
+
+TIME_ZONE_INFORMATION* winpr_GetWindowsTimezoneFromIANA(const char* tzid)
+{
+	WCHAR* wzid = tz_map_iana_to_windows(tzid);
+	if (!wzid)
+		return NULL;
+
+	TIME_ZONE_INFORMATION* entry = winpr_get_from_id(tzid, wzid);
+	free(wzid);
+	return entry;
+}