Implement KVM websocket proxy in bmcweb

This patchset implements a KVM websocket proxy designed to interoperate
with phosphor-webui and KVM.  in short, IP address 127.0.0.1:5900 is
proxied to the websocket.  This allows someone to connect from a browser
session.

Requires patchset here for the phosphor-webui side:
https://gerrit.openbmc-project.xyz/#/c/openbmc/phosphor-webui/+/10268/
and requires the kvm patches here:
https://gerrit.openbmc-project.xyz/#/c/openbmc/meta-phosphor/+/13536/

Tested By:
Launched webui, observed KVM.  Moved mouse, and typed on keyboard,
changes appeared on host system.

Change-Id: I407488f4b16be208b188a0abc19954a0243af173
Signed-off-by: Ed Tanous <ed.tanous@intel.com>

1 files changed, 173 insertions, 0 deletions

diff --git a/include/kvm_websocket.hpp b/include/kvm_websocket.hpp
new file mode 100644
index 0000000000..aa2eaecc32
--- /dev/null
+++ b/include/kvm_websocket.hpp
@@ -0,0 +1,173 @@
+#pragma once
+#include <crow/app.h>
+#include <crow/websocket.h>
+#include <sys/socket.h>
+
+#include <boost/container/flat_map.hpp>
+#include <boost/container/flat_set.hpp>
+#include <webserver_common.hpp>
+
+namespace crow
+{
+namespace obmc_kvm
+{
+
+static std::unique_ptr<boost::asio::ip::tcp::socket> hostSocket;
+
+// TODO(ed) validate that these buffer sizes are sane
+static boost::beast::flat_static_buffer<1024U * 50U> outputBuffer;
+static boost::beast::flat_static_buffer<1024U> inputBuffer;
+
+static crow::websocket::Connection* session = nullptr;
+
+static bool doingWrite = false;
+
+inline void doWrite()
+{
+    if (doingWrite)
+    {
+        BMCWEB_LOG_DEBUG << "Already writing.  Bailing out";
+        return;
+    }
+    if (inputBuffer.size() == 0)
+    {
+        BMCWEB_LOG_DEBUG << "inputBuffer empty.  Bailing out";
+        return;
+    }
+
+    doingWrite = true;
+    hostSocket->async_write_some(
+        inputBuffer.data(),
+        [](boost::beast::error_code ec, std::size_t bytes_written) {
+            BMCWEB_LOG_DEBUG << "Wrote " << bytes_written << "bytes";
+            doingWrite = false;
+            inputBuffer.consume(bytes_written);
+
+            if (session == nullptr)
+            {
+                return;
+            }
+            if (ec == boost::asio::error::eof)
+            {
+                session->close("KVM socket port closed");
+                return;
+            }
+            if (ec)
+            {
+                session->close("Error in reading to host port");
+                BMCWEB_LOG_ERROR << "Error in KVM socket write " << ec;
+                return;
+            }
+            doWrite();
+        });
+}
+
+inline void doRead();
+
+inline void readDone(const boost::system::error_code& ec, std::size_t bytesRead)
+{
+    outputBuffer.commit(bytesRead);
+    BMCWEB_LOG_DEBUG << "read done.  Read " << bytesRead << " bytes";
+    if (ec)
+    {
+        BMCWEB_LOG_ERROR << "Couldn't read from KVM socket port: " << ec;
+        if (session != nullptr)
+        {
+            session->close("Error in connecting to KVM port");
+        }
+        return;
+    }
+    if (session == nullptr)
+    {
+        return;
+    }
+
+    boost::beast::string_view payload(
+        static_cast<const char*>(outputBuffer.data().data()), bytesRead);
+    BMCWEB_LOG_DEBUG << "Sending payload size " << payload.size();
+    session->sendBinary(payload);
+    outputBuffer.consume(bytesRead);
+
+    doRead();
+}
+
+inline void doRead()
+{
+    std::size_t bytes = outputBuffer.capacity() - outputBuffer.size();
+    BMCWEB_LOG_DEBUG << "Reading " << bytes << " from kvm socket";
+    hostSocket->async_read_some(
+        outputBuffer.prepare(outputBuffer.capacity() - outputBuffer.size()),
+        readDone);
+}
+
+inline void connectHandler(const boost::system::error_code& ec)
+{
+    if (ec)
+    {
+        BMCWEB_LOG_ERROR << "Couldn't connect to KVM socket port: " << ec;
+        if (session != nullptr)
+        {
+            session->close("Error in connecting to KVM port");
+        }
+        return;
+    }
+
+    doWrite();
+    doRead();
+}
+
+inline void requestRoutes(CrowApp& app)
+{
+    BMCWEB_ROUTE(app, "/kvm/0")
+        .websocket()
+        .onopen([](crow::websocket::Connection& conn) {
+            BMCWEB_LOG_DEBUG << "Connection " << &conn << " opened";
+
+            if (session != nullptr)
+            {
+                conn.close("User already connected");
+                return;
+            }
+
+            session = &conn;
+            if (hostSocket == nullptr)
+            {
+                boost::asio::ip::tcp::endpoint endpoint(
+                    boost::asio::ip::address::from_string("127.0.0.1"), 5900);
+
+                hostSocket = std::make_unique<boost::asio::ip::tcp::socket>(
+                    conn.get_io_context());
+                hostSocket->async_connect(endpoint, connectHandler);
+            }
+        })
+        .onclose(
+            [](crow::websocket::Connection& conn, const std::string& reason) {
+                session = nullptr;
+                hostSocket = nullptr;
+                inputBuffer.reset();
+                outputBuffer.reset();
+            })
+        .onmessage([](crow::websocket::Connection& conn,
+                      const std::string& data, bool is_binary) {
+            if (data.length() > inputBuffer.capacity())
+            {
+                BMCWEB_LOG_ERROR << "Buffer overrun when writing "
+                                 << data.length() << " bytes";
+                conn.close("Buffer overrun");
+                return;
+            }
+
+            BMCWEB_LOG_DEBUG << "Read " << data.size()
+                             << " bytes from websocket";
+            boost::asio::buffer_copy(inputBuffer.prepare(data.size()),
+                                     boost::asio::buffer(data));
+            BMCWEB_LOG_DEBUG << "commiting " << data.size()
+                             << " bytes from websocket";
+            inputBuffer.commit(data.size());
+
+            BMCWEB_LOG_DEBUG << "inputbuffer size " << inputBuffer.size();
+            doWrite();
+        });
+}
+} // namespace obmc_kvm
+} // namespace crow