From 782ce52a6ee75e46668e5cd417a7531053033922 Mon Sep 17 00:00:00 2001
From: Zhanglong Xia <zhanglongxia@google.com>
Date: Tue, 4 Jun 2019 22:29:18 +0800
Subject: [PATCH] [ncp] update static checking for diag output buffer size
 (#3891)

---
 src/ncp/ncp_base.hpp | 9 ++++++++-
 src/ncp/ncp_spi.cpp  | 4 +++-
 src/ncp/ncp_uart.cpp | 5 +++++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/ncp/ncp_base.hpp b/src/ncp/ncp_base.hpp
index 105cbf724..4f332c205 100644
--- a/src/ncp/ncp_base.hpp
+++ b/src/ncp/ncp_base.hpp
@@ -62,6 +62,12 @@ namespace Ncp {
 class NcpBase
 {
 public:
+    enum
+    {
+        kSpinelCmdHeaderSize = 2, ///< Size of spinel command header (in bytes).
+        kSpinelPropIdSize    = 3, ///< Size of spinel property identifier (in bytes).
+    };
+
     /**
      * This constructor creates and initializes an NcpBase instance.
      *
@@ -400,7 +406,8 @@ protected:
     otError HandlePropertySet_SPINEL_PROP_HOST_POWER_STATE(uint8_t aHeader);
 
 #if OPENTHREAD_ENABLE_DIAG
-    OT_STATIC_ASSERT(OPENTHREAD_CONFIG_DIAG_OUTPUT_BUFFER_SIZE <= OPENTHREAD_CONFIG_NCP_TX_BUFFER_SIZE,
+    OT_STATIC_ASSERT(OPENTHREAD_CONFIG_DIAG_OUTPUT_BUFFER_SIZE <=
+                         OPENTHREAD_CONFIG_NCP_TX_BUFFER_SIZE - kSpinelCmdHeaderSize - kSpinelPropIdSize,
                      "diag output buffer should be smaller than NCP UART tx buffer");
 
     otError HandlePropertySet_SPINEL_PROP_NEST_STREAM_MFG(uint8_t aHeader);
diff --git a/src/ncp/ncp_spi.cpp b/src/ncp/ncp_spi.cpp
index bdb0f4d43..931f7a9fa 100644
--- a/src/ncp/ncp_spi.cpp
+++ b/src/ncp/ncp_spi.cpp
@@ -47,7 +47,9 @@
 #if OPENTHREAD_ENABLE_NCP_SPI
 
 #if OPENTHREAD_ENABLE_DIAG
-OT_STATIC_ASSERT(OPENTHREAD_CONFIG_DIAG_OUTPUT_BUFFER_SIZE <= OPENTHREAD_CONFIG_NCP_SPI_BUFFER_SIZE,
+OT_STATIC_ASSERT(OPENTHREAD_CONFIG_DIAG_OUTPUT_BUFFER_SIZE <=
+                     OPENTHREAD_CONFIG_NCP_SPI_BUFFER_SIZE - ot::Ncp::NcpBase::kSpinelCmdHeaderSize -
+                         ot::Ncp::NcpBase::kSpinelPropIdSize - ot::Ncp::SpiFrame::kHeaderSize,
                  "diag output should be smaller than NCP SPI tx buffer");
 OT_STATIC_ASSERT(OPENTHREAD_CONFIG_DIAG_CMD_LINE_BUFFER_SIZE <= OPENTHREAD_CONFIG_NCP_SPI_BUFFER_SIZE,
                  "diag command line should be smaller than NCP SPI rx buffer");
diff --git a/src/ncp/ncp_uart.cpp b/src/ncp/ncp_uart.cpp
index 41d920d97..8eb16ae50 100644
--- a/src/ncp/ncp_uart.cpp
+++ b/src/ncp/ncp_uart.cpp
@@ -50,6 +50,11 @@
 #if OPENTHREAD_ENABLE_NCP_UART
 
 #if OPENTHREAD_ENABLE_DIAG
+OT_STATIC_ASSERT(OPENTHREAD_CONFIG_DIAG_OUTPUT_BUFFER_SIZE <= OPENTHREAD_CONFIG_NCP_UART_RX_BUFFER_SIZE -
+                                                                  ot::Ncp::NcpBase::kSpinelCmdHeaderSize -
+                                                                  ot::Ncp::NcpBase::kSpinelPropIdSize,
+                 "diag output should be smaller than NCP UART rx buffer");
+
 OT_STATIC_ASSERT(OPENTHREAD_CONFIG_DIAG_CMD_LINE_BUFFER_SIZE <= OPENTHREAD_CONFIG_NCP_UART_RX_BUFFER_SIZE,
                  "diag command line should be smaller than NCP UART rx buffer");
 #endif