Include output from 'netsh' if requested operation fails or times out

2 files changed, 75 insertions, 4 deletions

diff --git a/windows/windns/src/windns/netsh.cpp b/windows/windns/src/windns/netsh.cpp
index af65ace2a9..fc46d824c2 100644
--- a/windows/windns/src/windns/netsh.cpp
+++ b/windows/windns/src/windns/netsh.cpp
@@ -1,21 +1,69 @@
 #include "stdafx.h"
 #include "netsh.h"
 #include "libcommon/applicationrunner.h"
+#include "libcommon/string.h"
 #include <sstream>
 #include <stdexcept>
 
 namespace
 {
 
+std::vector<std::string> BlockToRows(const std::string &textBlock)
+{
+	//
+	// TODO: Formalize and move to libcommon.
+	// There is a recurring need to split a text block into lines, ignoring blank lines.
+	//
+	// Also, changing the encoding back and forth is terribly wasteful.
+	// Should look into replacing all of this with Boost some day.
+	//
+
+	const auto wideTextBlock = common::string::ToWide(textBlock);
+	const auto wideRows = common::string::Tokenize(wideTextBlock, L"\r\n");
+
+	std::vector<std::string> result;
+
+	result.reserve(wideRows.size());
+
+	std::transform(wideRows.begin(), wideRows.end(), std::back_inserter(result), [](const std::wstring &str)
+	{
+		return common::string::ToAnsi(str);
+	});
+
+	return result;
+}
+
+__declspec(noreturn) void ThrowWithDetails(std::string &&error, common::ApplicationRunner &netsh)
+{
+	std::vector<std::string> details { "Failed to capture output from 'netsh'" };
+
+	std::string output;
+
+	static const size_t MAX_CHARS = 2048;
+	static const size_t TIMEOUT_MILLISECONDS = 2000;
+
+	if (netsh.read(output, MAX_CHARS, TIMEOUT_MILLISECONDS))
+	{
+		auto outputRows = BlockToRows(output);
+
+		if (false == outputRows.empty())
+		{
+			details = std::move(outputRows);
+		}
+	}
+
+	throw NetShError(std::move(error), std::move(details));
+}
+
 void ValidateShellOut(common::ApplicationRunner &netsh)
 {
-	static const uint32_t TIMEOUT_TWO_SECONDS = 2000;
+	static const size_t TIMEOUT_MILLISECONDS = 2000;
 
 	DWORD returnCode;
 
-	if (false == netsh.join(returnCode, TIMEOUT_TWO_SECONDS))
+	if (false == netsh.join(returnCode, TIMEOUT_MILLISECONDS))
 	{
-		throw std::runtime_error("'netsh' did not complete in a timely manner");
+		ThrowWithDetails("'netsh' did not complete in a timely manner", netsh);
 	}
 
 	if (returnCode != 0)
@@ -24,7 +72,7 @@ void ValidateShellOut(common::ApplicationRunner &netsh)
 
 		ss << "'netsh' failed the requested operation. Error: " << returnCode;
 
-		throw std::runtime_error(ss.str());
+		ThrowWithDetails(ss.str(), netsh);
 	}
 }
 
diff --git a/windows/windns/src/windns/netsh.h b/windows/windns/src/windns/netsh.h
index d299cf6f87..7aa5b800f0 100644
--- a/windows/windns/src/windns/netsh.h
+++ b/windows/windns/src/windns/netsh.h
@@ -2,6 +2,7 @@
 
 #include <string>
 #include <cstdint>
+#include <stdexcept>
 
 class NetSh
 {
@@ -24,3 +25,25 @@ private:
 
 	NetSh();
 };
+
+class NetShError : public std::exception
+{
+public:
+
+	NetShError(std::string &&error, std::vector<std::string> &&details)
+		: std::exception(error.c_str())
+		, m_error(std::move(error))
+		, m_details(std::move(details))
+	{
+	}
+
+	const std::vector<std::string> &details()
+	{
+		return m_details;
+	}
+
+private:
+
+	const std::string m_error;
+	const std::vector<std::string> m_details;
+};