From 3b8cd67dff9d39cb29da2d600a6849842e224506 Mon Sep 17 00:00:00 2001
From: Josh Gao <jmgao@google.com>
Date: Fri, 6 Sep 2019 14:42:06 -0700
Subject: [PATCH] Add stub code to read MS OS 2.0 descriptors.

Linux doesn't seem to actually support emitting them, so we can't check
that they're actually there, but commit the code to read them so that
if and when Linux gets support, it's easier to check.

This also adds some error checking for ill-formed binary object store
entries.

Test: check_ms_os_desc
Change-Id: I4baf6a16f0f96acbec468b843db65d4ab3a589fe
---
 adb/tools/check_ms_os_desc.cpp | 47 +++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/adb/tools/check_ms_os_desc.cpp b/adb/tools/check_ms_os_desc.cpp
index d4cfb6183..8743ff725 100644
--- a/adb/tools/check_ms_os_desc.cpp
+++ b/adb/tools/check_ms_os_desc.cpp
@@ -158,6 +158,49 @@ static void check_ms_os_desc_v1(libusb_device_handle* device_handle, const std::
     errx(1, "failed to find v1 MS OS descriptor specifying WinUSB for device %s", serial.c_str());
 }
 
+static void check_ms_os_desc_v2(libusb_device_handle* device_handle, const std::string& serial) {
+    libusb_bos_descriptor* bos;
+    int rc = libusb_get_bos_descriptor(device_handle, &bos);
+
+    if (rc != 0) {
+        fprintf(stderr, "failed to get bos descriptor for device %s\n", serial.c_str());
+        return;
+    }
+
+    for (size_t i = 0; i < bos->bNumDeviceCaps; ++i) {
+        libusb_bos_dev_capability_descriptor* desc = bos->dev_capability[i];
+        if (desc->bDescriptorType != LIBUSB_DT_DEVICE_CAPABILITY) {
+            errx(1, "invalid BOS descriptor type: %d", desc->bDescriptorType);
+        }
+
+        if (desc->bDevCapabilityType != 0x05 /* PLATFORM */) {
+            fprintf(stderr, "skipping non-platform dev capability: %#02x\n",
+                    desc->bDevCapabilityType);
+            continue;
+        }
+
+        if (desc->bLength < sizeof(*desc) + 16) {
+            errx(1, "received device capability descriptor not long enough to contain a UUID?");
+        }
+
+        char uuid[16];
+        memcpy(uuid, desc->dev_capability_data, 16);
+
+        constexpr uint8_t ms_os_uuid[16] = {0xD8, 0xDD, 0x60, 0xDF, 0x45, 0x89, 0x4C, 0xC7,
+                                            0x9C, 0xD2, 0x65, 0x9D, 0x9E, 0x64, 0x8A, 0x9F};
+        if (memcmp(uuid, ms_os_uuid, 16) != 0) {
+            fprintf(stderr, "skipping unknown UUID\n");
+            continue;
+        }
+
+        size_t data_length = desc->bLength - sizeof(*desc) - 16;
+        fprintf(stderr, "found MS OS 2.0 descriptor, length = %zu\n", data_length);
+
+        // Linux does not appear to support MS OS 2.0 Descriptors.
+        // TODO: If and when it does, verify that we're emitting them properly.
+    }
+}
+
 int main(int argc, char** argv) {
     libusb_context* ctx;
     if (libusb_init(&ctx) != 0) {
@@ -208,8 +251,10 @@ int main(int argc, char** argv) {
         check_ms_os_desc_v1(device_handle, *serial);
         fprintf(stderr, "found v1 OS descriptor for device %s\n", serial->c_str());
 
-        // TODO: Read BOS for MS OS Descriptor 2.0 descriptors:
+        // Read BOS for MS OS Descriptor 2.0 descriptors:
         // http://download.microsoft.com/download/3/5/6/3563ED4A-F318-4B66-A181-AB1D8F6FD42D/MS_OS_2_0_desc.docx
+        fprintf(stderr, "fetching v2 OS descriptor from device %s\n", serial->c_str());
+        check_ms_os_desc_v2(device_handle, *serial);
 
         found = true;
     }