Before, handlers writing blockwise transfer assumed that the response
header length will match the request header length. This is true for
UDP, but not for TCP: The CoAP over TCP header contains a Len field,
that gets extended for larger messages. Since the reply often is indeed
larger than the request, this is indeed often the case for CoAP over
TCP.
Note: Right now, no CoAP over TCP implementation is upstream. However,
getting rid of incorrect assumptions now will make life easier
later on.
Some calls to `coap_build_hdr()` were done with the target buffer for
the header and the source buffer for the token overlapping:
They reuse the buffer that held the request to assemble the response in.
We cannot use `memcpy()` in this case to copy the token into the target
buffer, as source and destination would (fully) overlap.
This commit makes reusing the request buffer for the response a special
case: `memcpy()` is only used to copy the token if source and
destination address of the token differ.
An alternative fix would have been to use `memmove()` unconditionally.
But `memmove()` does not make any assumption about the layout of target
and source buffer, while we know that the token either will already be
at the right position (when reusing the request buffer for the response)
or be in a non-overlapping buffer (when generating a fresh token). This
approach is more efficient than `memmove()`.
19487: nanocoap: implement extended tokens (RFC 8974) r=benpicco a=benpicco
19808: boards: add ESP32-S3-USB-OTG support r=benpicco a=gschorcht
### Contribution description
This PR provides the support for the [ESP32-S3-USB-OTG](https://docs.espressif.com/projects/espressif-esp-dev-kits/en/latest/esp32s3/esp32-s3-usb-otg/user_guide.html) board.
The SD card can only be used in SPI mode at the moment. As soon as PR #19786 is merged, the SD/MMC support can be enabled and the SD card can then be used in SD mode with 4-bit data bus width.
The display uses uses the ST7789 driver IC that is compatible with the ST7735. For that purpose the ST7735 driver is extended by a pseudomodule definition `st7789` for the ST7789 which is enabled by the board and enables automatically the `st7789` (e57c48a33ee2a869c15603788e5306ba066f91cf). Vise versa, board's `Makefile.dep` enables automatically the `st7789` pseudomodule if the `st7735` is used. The pseudomodule `st7789` is just used to increase the upper limit for supported lines. This change is also part of PR #19807.
~The PR includes a very small documentation fix for ESP32-S3-DevKit board that was noticed during the development of this board definition (1155b6ac1b8efa39d8a0bd7150e602095159fdc1).~
### Testing procedure
The board has been tested with all basic tests for supported hardware including `tests/driver/st3375`:
- [x] tests/drivers/st3375
- [x] tests/periph/gpio
- [x] tests/periph/pwm
- [x] tests/periph/spi
- [x] tests/periph/uart
- [x] tests/sys/usbus_cdc_ecm
### Issues/PRs references
Co-authored-by: Benjamin Valentin <benpicco@beuth-hochschule.de>
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
