Add WebUSB descriptors

Most code taken from https://github.com/devanlai/dap42 and https://github.com/devanlai/dapboot

webusb.c

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+/*
+ * Copyright (c) 2016, Devan Lai
+ *
+ * Permission to use, copy, modify, and/or distribute this software
+ * for any purpose with or without fee is hereby granted, provided
+ * that the above copyright notice and this permission notice
+ * appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+ * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+ * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <string.h>
+
+#include "util.h"
+#include "webusb.h"
+#include "usb21_standard.h"
+
+const struct webusb_platform_descriptor webusb_platform_capability_descriptor = {
+	.bLength = WEBUSB_PLATFORM_DESCRIPTOR_SIZE,
+	.bDescriptorType = USB_DT_DEVICE_CAPABILITY,
+	.bDevCapabilityType = USB_DC_PLATFORM,
+	.bReserved = 0,
+	.platformCapabilityUUID = WEBUSB_UUID,
+	.bcdVersion = 0x0100,
+	.bVendorCode = WEBUSB_VENDOR_CODE,
+	.iLandingPage = 1
+};
+
+static const char* webusb_https_url;
+
+static int webusb_control_vendor_request(usbd_device *usbd_dev,
+									 struct usb_setup_data *req,
+									 uint8_t **buf, uint16_t *len,
+									 usbd_control_complete_callback* complete) {
+	(void)complete;
+	(void)usbd_dev;
+
+	if (req->bRequest != WEBUSB_VENDOR_CODE) {
+		return USBD_REQ_NEXT_CALLBACK;
+	}
+
+	int status = USBD_REQ_NOTSUPP;
+	switch (req->wIndex) {
+		case WEBUSB_REQ_GET_URL: {
+			struct webusb_url_descriptor* url = (struct webusb_url_descriptor*)(*buf);
+			uint16_t index = req->wValue;
+			if (index == 0) {
+				return USBD_REQ_NOTSUPP;
+			}
+
+			if (index == 1) {
+				size_t url_len = strlen(webusb_https_url);
+				url->bLength = WEBUSB_DT_URL_DESCRIPTOR_SIZE + url_len;
+				url->bDescriptorType = WEBUSB_DT_URL;
+				url->bScheme = WEBUSB_URL_SCHEME_HTTPS;
+				memcpy(&url->URL, webusb_https_url, url_len);
+				*len = MIN(*len, url->bLength);
+				status = USBD_REQ_HANDLED;
+			} else {
+				// TODO: stall instead?
+				status = USBD_REQ_NOTSUPP;
+			}
+			break;
+		}
+		default: {
+			status = USBD_REQ_NOTSUPP;
+			break;
+		}
+	}
+
+	return status;
+}
+
+static void webusb_set_config(usbd_device* usbd_dev, uint16_t wValue) {
+	(void)wValue;
+	usbd_register_control_callback(
+		usbd_dev,
+		USB_REQ_TYPE_VENDOR | USB_REQ_TYPE_DEVICE,
+		USB_REQ_TYPE_TYPE | USB_REQ_TYPE_RECIPIENT,
+		webusb_control_vendor_request);
+}
+
+void webusb_setup(usbd_device* usbd_dev, const char* https_url) {
+	webusb_https_url = https_url;
+
+	usbd_register_set_config_callback(usbd_dev, webusb_set_config);
+}

webusb.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2016, Devan Lai
+ *
+ * Permission to use, copy, modify, and/or distribute this software
+ * for any purpose with or without fee is hereby granted, provided
+ * that the above copyright notice and this permission notice
+ * appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+ * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+ * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef WEBUSB_H_INCLUDED
+#define WEBUSB_H_INCLUDED
+
+#include <libopencm3/usb/usbd.h>
+#include "webusb_defs.h"
+
+// Arbitrary
+#define WEBUSB_VENDOR_CODE 0x01
+
+extern const struct webusb_platform_descriptor webusb_platform_capability_descriptor;
+extern void webusb_setup(usbd_device* usbd_dev,
+							const char** https_urls, size_t num_https_urls);
+
+#endif

webusb_defs.h

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+/*
+ * Copyright (c) 2016, Devan Lai
+ *
+ * Permission to use, copy, modify, and/or distribute this software
+ * for any purpose with or without fee is hereby granted, provided
+ * that the above copyright notice and this permission notice
+ * appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+ * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+ * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef WEBUSB_DEFS_H_INCLUDED
+#define WEBUSB_DEFS_H_INCLUDED
+
+#include <stdint.h>
+
+#define WEBUSB_REQ_GET_URL             0x02
+
+#define WEBUSB_DT_DESCRIPTOR_SET_HEADER 0
+#define WEBUSB_DT_CONFIGURATION_SUBSET_HEADER 1
+#define WEBUSB_DT_FUNCTION_SUBSET_HEADER 2
+#define WEBUSB_DT_URL 3
+
+#define WEBUSB_URL_SCHEME_HTTP 0
+#define WEBUSB_URL_SCHEME_HTTPS 1
+
+struct webusb_platform_descriptor {
+	uint8_t bLength;
+	uint8_t bDescriptorType;
+	uint8_t bDevCapabilityType;
+	uint8_t bReserved;
+	uint8_t platformCapabilityUUID[16];
+	uint16_t bcdVersion;
+	uint8_t bVendorCode;
+	uint8_t iLandingPage;
+} __attribute__((packed));
+
+#define WEBUSB_PLATFORM_DESCRIPTOR_SIZE sizeof(struct webusb_platform_descriptor)
+
+// from https://wicg.github.io/webusb/#webusb-platform-capability-descriptor
+// see also this (for endianness explanation)
+// https://github.com/WICG/webusb/issues/115#issuecomment-352206549
+#define WEBUSB_UUID {0x38, 0xB6, 0x08, 0x34, 0xA9, 0x09, 0xA0, 0x47,0x8B, 0xFD, 0xA0, 0x76, 0x88, 0x15, 0xB6, 0x65}
+
+struct webusb_url_descriptor {
+	uint8_t bLength;
+	uint8_t bDescriptorType;
+	uint8_t bScheme;
+	char URL[];
+} __attribute__((packed));
+
+#define WEBUSB_DT_URL_DESCRIPTOR_SIZE 3
+
+#endif