manager: add hard-coded read checks

The host-client cannot try to read back more than this number of bytes
without hitting a memory overflow in phosphor-host-ipmid.  The method we
can call to dynamically receive that number isn't currently linking out
of the userlayer library.

Note: Once the configure_ac can find and provide the userlayer library
from phosphor-host-ipmid, we can remove the hard-coded 64 and 0xe.

Change-Id: I08f6bb59ce44279f76a494dccaa477ae75d532c4
Signed-off-by: Patrick Venture <venture@google.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/manager.cpp b/manager.cpp
index 712d7db..639ca2d 100644
--- a/manager.cpp
+++ b/manager.cpp
@@ -270,8 +270,23 @@ std::vector<uint8_t> BlobManager::read(uint16_t session, uint32_t offset,
         return std::vector<uint8_t>();
     }
 
+    /* TODO: Currently, configure_ac isn't finding libuserlayer, w.r.t the
+     * symbols I need.
+     */
+
+    /** The channel to use for now.
+     * TODO: We will receive this information through the IPMI message call.
+     */
+    // const int ipmiChannel = ipmi::currentChNum;
+    /** This information is transport specific.
+     * TODO: We need a way to know this dynamically.
+     * on BT, 4 bytes of header, and 1 reply code.
+     */
+    // uint32_t maxTransportSize = ipmi::getChannelMaxTransferSize(ipmiChannel);
+
     /* Try reading from it. */
-    return info->handler->read(session, offset, requestedSize);
+    return info->handler->read(session, offset,
+                               std::min(maximumReadSize, requestedSize));
 }
 
 bool BlobManager::write(uint16_t session, uint32_t offset,