From 4b5d4da6f6a863638c8100cde5af834a83ac8956 Mon Sep 17 00:00:00 2001
From: Josh Gao <jmgao@google.com>
Date: Wed, 7 Jun 2017 12:11:19 -0700
Subject: [PATCH] adb: remove SendConnectOnHost.

This logic appears to be racy, and it shouldn't actually be needed, if
our devices follow the USB spec. Use libusb_set_interface_alt_setting
on device initialization as well, to add one more thing that should
reset the data toggles.

Bug: http://b/32952319
Test: python test_device.py
Change-Id: I392198af3d72c524b893e5056afa2b4617cea49c
---
 adb/adb.cpp               | 15 +--------------
 adb/adb.h                 |  3 ---
 adb/client/usb_libusb.cpp |  7 +++++++
 adb/transport.cpp         |  7 -------
 adb/transport.h           |  2 --
 adb/transport_usb.cpp     | 10 +---------
 6 files changed, 9 insertions(+), 35 deletions(-)

diff --git a/adb/adb.cpp b/adb/adb.cpp
index 8c24bbba3..6b30be884 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -257,19 +257,6 @@ void send_connect(atransport* t) {
     send_packet(cp, t);
 }
 
-#if ADB_HOST
-
-void SendConnectOnHost(atransport* t) {
-    // Send an empty message before A_CNXN message. This is because the data toggle of the ep_out on
-    // host and ep_in on device may not be the same.
-    apacket* p = get_apacket();
-    CHECK(p);
-    send_packet(p, t);
-    send_connect(t);
-}
-
-#endif
-
 // qual_overwrite is used to overwrite a qualifier string.  dst is a
 // pointer to a char pointer.  It is assumed that if *dst is non-NULL, it
 // was malloc'ed and needs to freed.  *dst will be set to a dup of src.
@@ -370,7 +357,7 @@ void handle_packet(apacket *p, atransport *t)
         if (p->msg.arg0){
             send_packet(p, t);
 #if ADB_HOST
-            SendConnectOnHost(t);
+            send_connect(t);
 #endif
         } else {
             t->SetConnectionState(kCsOffline);
diff --git a/adb/adb.h b/adb/adb.h
index 6a9897f63..a4d233ead 100644
--- a/adb/adb.h
+++ b/adb/adb.h
@@ -224,9 +224,6 @@ void handle_online(atransport *t);
 void handle_offline(atransport *t);
 
 void send_connect(atransport *t);
-#if ADB_HOST
-void SendConnectOnHost(atransport* t);
-#endif
 
 void parse_banner(const std::string&, atransport* t);
 
diff --git a/adb/client/usb_libusb.cpp b/adb/client/usb_libusb.cpp
index 7025f283c..81201995a 100644
--- a/adb/client/usb_libusb.cpp
+++ b/adb/client/usb_libusb.cpp
@@ -333,6 +333,13 @@ static void process_device(libusb_device* device) {
             return;
         }
 
+        rc = libusb_set_interface_alt_setting(handle.get(), interface_num, 0);
+        if (rc != 0) {
+            LOG(WARNING) << "failed to set interface alt setting for device '" << device_serial
+                         << "'" << libusb_error_name(rc);
+            return;
+        }
+
         for (uint8_t endpoint : {bulk_in, bulk_out}) {
             rc = libusb_clear_halt(handle.get(), endpoint);
             if (rc != 0) {
diff --git a/adb/transport.cpp b/adb/transport.cpp
index 34cc026a5..089a1ecf4 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -1101,11 +1101,4 @@ std::shared_ptr<RSA> atransport::NextKey() {
     keys_.pop_front();
     return result;
 }
-bool atransport::SetSendConnectOnError() {
-    if (has_send_connect_on_error_) {
-        return false;
-    }
-    has_send_connect_on_error_ = true;
-    return true;
-}
 #endif
diff --git a/adb/transport.h b/adb/transport.h
index 79e307561..8c101fdc5 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -122,7 +122,6 @@ class atransport {
 
 #if ADB_HOST
     std::shared_ptr<RSA> NextKey();
-    bool SetSendConnectOnError();
 #endif
 
     char token[TOKEN_SIZE] = {};
@@ -181,7 +180,6 @@ private:
     std::atomic<ConnectionState> connection_state_;
 #if ADB_HOST
     std::deque<std::shared_ptr<RSA>> keys_;
-    bool has_send_connect_on_error_ = false;
 #endif
 
     DISALLOW_COPY_AND_ASSIGN(atransport);
diff --git a/adb/transport_usb.cpp b/adb/transport_usb.cpp
index 6768d31a1..fdecccfc3 100644
--- a/adb/transport_usb.cpp
+++ b/adb/transport_usb.cpp
@@ -103,13 +103,6 @@ static int remote_read(apacket* p, atransport* t) {
 
 err_msg:
     p->msg.command = 0;
-    if (t->GetConnectionState() == kCsOffline) {
-        // If the data toggle of ep_out on device and ep_in on host are not the same, we may receive
-        // an error message. In this case, resend one A_CNXN message to connect the device.
-        if (t->SetSendConnectOnError()) {
-            SendConnectOnHost(t);
-        }
-    }
     return 0;
 }
 
@@ -162,8 +155,7 @@ static int remote_write(apacket *p, atransport *t)
     return 0;
 }
 
-static void remote_close(atransport *t)
-{
+static void remote_close(atransport* t) {
     usb_close(t->usb);
     t->usb = 0;
 }