Definition for SOL Context Class

SOL context class provides interfaces for operations on a SOL
payload instance, to send data to a remote console and receive SOL
payload from a remote console, retry SOL payload. It manages the
sequence numbers related to the SOL and the retry count.

Change-Id: If3926a98bf9435779f4d6d7d564f48c576bf1f24
Signed-off-by: Tom Joseph <tomjoseph@in.ibm.com>

2 files changed, 191 insertions, 1 deletions

diff --git a/Makefile.am b/Makefile.am
index da9d488..f9fb32d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -41,7 +41,8 @@ netipmid_SOURCES = \
 	crypt_algo.hpp \
 	crypt_algo.cpp \
 	sol/console_buffer.hpp \
-	sd_event_loop.hpp
+	sd_event_loop.hpp \
+	sol/sol_context.hpp
 
 netipmid_CPPFLAGS = -DNET_IPMID_LIB_PATH=\"/usr/lib/net-ipmid/\"
 netipmid_LDFLAGS = $(SYSTEMD_LIBS) $(CRYPTO_LIBS) $(libmapper_LIBS) $(LIBADD_DLOPEN) -export-dynamic
diff --git a/sol/sol_context.hpp b/sol/sol_context.hpp
new file mode 100644
index 0000000..81ad19b
--- /dev/null
+++ b/sol/sol_context.hpp
@@ -0,0 +1,189 @@
+#pragma once
+
+#include "console_buffer.hpp"
+#include "session.hpp"
+
+namespace sol
+{
+
+namespace internal
+{
+
+/** @struct SequenceNumbers
+ *
+ *  SOL sequence numbers. At the session level, SOL Payloads share the session
+ *  sequence numbers for authenticated and unauthenticated packets with other
+ *  packets under the IPMI session. At the payload level, SOL packets include
+ *  their own message sequence numbers that are used for tracking missing and
+ *  retried SOL messages. The sequence numbers must be non-zero. Retried
+ *  packets use the same sequence number as the first packet.
+ */
+struct SequenceNumbers
+{
+    static constexpr uint8_t MAX_SOL_SEQUENCE_NUMBER = 0x10;
+
+    /** @brief Get the SOL sequence number.
+     *
+     *  @param[in] inbound - true for inbound sequence number and false for
+     *                       outbound sequence number
+     *
+     *  @return sequence number
+     */
+    auto get(bool inbound = true) const
+    {
+        return inbound ? in : out;
+    }
+
+    /** @brief Increment the inbound SOL sequence number. */
+    void incInboundSeqNum()
+    {
+        if ((++in) == MAX_SOL_SEQUENCE_NUMBER)
+        {
+            in = 1;
+        }
+    }
+
+    /** @brief Increment the outbound SOL sequence number.
+     *
+     *  @return outbound sequence number to populate the SOL payload.
+     */
+    auto incOutboundSeqNum()
+    {
+        if ((++out) == MAX_SOL_SEQUENCE_NUMBER)
+        {
+            out = 1;
+        }
+
+        return out;
+    }
+
+    private:
+        uint8_t in = 1;     //!< Inbound sequence number.
+        uint8_t out = 0;    //!< Outbound sequence number, since the first
+                            //!< operation is increment, it is initialised to 0
+};
+
+} // namespace internal
+
+/** @class Context
+ *
+ *  Context keeps the state of the SOL session. The information needed to
+ *  maintain the state of the SOL is part of this class. This class provides
+ *  interfaces to handle incoming SOL payload, send response and send outbound
+ *  SOL payload.
+ */
+class Context
+{
+    public:
+        Context() = default;
+        ~Context() = default;
+        Context(const Context&) = delete;
+        Context& operator=(const Context&) = delete;
+        Context(Context&&) = default;
+        Context& operator=(Context&&) = default;
+
+        /** @brief Context Constructor.
+         *
+         *  This is issued by the SOL Manager when a SOL payload instance is
+         *  started for the activate payload command.
+         *
+         *  @param[in] maxRetryCount  - Retry count max value.
+         *  @param[in] sendThreshold - Character send threshold.
+         *  @param[in] instance - SOL payload instance.
+         *  @param[in] sessionID - BMC session ID.
+         */
+        Context(uint8_t maxRetryCount,
+                uint8_t sendThreshold,
+                uint8_t instance,
+                session::SessionID sessionID):
+            maxRetryCount(maxRetryCount),
+            retryCounter(maxRetryCount),
+            sendThreshold(sendThreshold),
+            payloadInstance(instance),
+            sessionID(sessionID) {}
+
+        static constexpr auto clear = true;
+        static constexpr auto noClear = false;
+
+        /** @brief Retry count max value. */
+        const uint8_t maxRetryCount = 0;
+
+        /** @brief Retry counter. */
+        uint8_t retryCounter = 0;
+
+        /** @brief Character send threshold. */
+        const uint8_t sendThreshold = 0;
+
+        /** @brief SOL payload instance. */
+        const uint8_t payloadInstance = 0;
+
+        /** @brief Session ID. */
+        const session::SessionID sessionID = 0;
+
+        /** @brief Process the Inbound SOL payload.
+         *
+         *  The SOL payload from the remote console is processed and the
+         *  acknowledgment handling is done.
+         *
+         *  @param[in] seqNum - Packet sequence number.
+         *  @param[in] ackSeqNum - Packet ACK/NACK sequence number.
+         *  @param[in] count - Accepted character count.
+         *  @param[in] operation - ACK is false, NACK is true
+         *  @param[in] input - Incoming SOL character data.
+         */
+        void processInboundPayload(uint8_t seqNum,
+                                   uint8_t ackSeqNum,
+                                   uint8_t count,
+                                   bool status,
+                                   const Buffer& input);
+
+        /** @brief Send the outbound SOL payload.
+         *
+         *  @return zero on success and negative value if condition for sending
+         *          the payload fails.
+         */
+        int sendOutboundPayload();
+
+        /** @brief Resend the SOL payload.
+         *
+         *  @param[in] clear - if true then send the payload and clear the
+         *                     cached payload, if false only send the payload.
+         */
+        void resendPayload(bool clear);
+
+    private:
+        /** @brief Expected character count.
+         *
+         *  Expected Sequence number and expected character count is set before
+         *  sending the SOL payload. The check is done against these values when
+         *  an incoming SOL payload is received.
+         */
+        size_t expectedCharCount = 0;
+
+        /** @brief Inbound and Outbound sequence numbers. */
+        internal::SequenceNumbers seqNums;
+
+        /** @brief Copy of the last sent SOL payload.
+         *
+         *  A copy of the SOL payload is kept here, so that when a retry needs
+         *  to be attempted the payload is sent again.
+         */
+        Buffer payloadCache;
+
+        /**
+         * @brief Send Response for Incoming SOL payload.
+         *
+         * @param[in] ackSeqNum - Packet ACK/NACK Sequence Number.
+         * @param[in] count - Accepted Character Count.
+         * @param[in] ack - Set ACK/NACK in the Operation.
+         */
+        void prepareResponse(uint8_t ackSeqNum, uint8_t count, bool ack);
+
+        /** @brief Send the outgoing SOL payload.
+         *
+         *  @param[in] out - buffer containing the SOL payload.
+         */
+        void sendPayload(const Buffer& out) const;
+};
+
+} // namespace sol