From c4bf992c0cd1f5623c6240244162384732206fe2 Mon Sep 17 00:00:00 2001
From: Geoffrey McRae <geoff@hostfission.com>
Date: Sun, 17 May 2020 11:13:08 +1000
Subject: [PATCH] [client/host] added enforcement of KVMFR versioning

---
 VERSION                       |  2 +-
 c-host/src/app.c              |  8 +++++++-
 client/src/main.c             | 16 +++++++++++++++-
 common/include/common/KVMFR.h | 10 ++++++++++
 repos/LGMP                    |  2 +-
 5 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/VERSION b/VERSION
index 138cdb95..8d242dc5 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-B1-187-gcfd8126e5d+1
\ No newline at end of file
+B1-188-gdcce288a98+1
\ No newline at end of file
diff --git a/c-host/src/app.c b/c-host/src/app.c
index 1860d4ba..6ca67085 100644
--- a/c-host/src/app.c
+++ b/c-host/src/app.c
@@ -413,8 +413,14 @@ int app_main(int argc, char * argv[])
   DEBUG_INFO("IVSHMEM Address  : 0x%" PRIXPTR, (uintptr_t)shmDev.mem);
   DEBUG_INFO("Max Pointer Size : %u KiB", (unsigned int)MAX_POINTER_SIZE / 1024);
 
+  KVMFR udata = {
+    .magic   = KVMFR_MAGIC,
+    .version = KVMFR_VERSION
+  };
+
   LGMP_STATUS status;
-  if ((status = lgmpHostInit(shmDev.mem, shmDev.size, &app.lgmp)) != LGMP_OK)
+  if ((status = lgmpHostInit(shmDev.mem, shmDev.size, &app.lgmp,
+          sizeof(udata), (uint8_t *)&udata)) != LGMP_OK)
   {
     DEBUG_ERROR("lgmpHostInit Failed: %s", lgmpStatusString(status));
     goto fail;
diff --git a/client/src/main.c b/client/src/main.c
index 478aa22b..c1ae6e9f 100644
--- a/client/src/main.c
+++ b/client/src/main.c
@@ -1446,7 +1446,11 @@ static int lg_run()
   LGMP_STATUS status;
   while(true)
   {
-    if ((status = lgmpClientInit(state.shm.mem, state.shm.size, &state.lgmp)) == LGMP_OK)
+    uint32_t udataSize;
+    KVMFR *udata;
+
+    if ((status = lgmpClientInit(state.shm.mem, state.shm.size, &state.lgmp,
+            &udataSize, (uint8_t **)&udata)) == LGMP_OK)
       break;
 
     if (status == LGMP_ERR_INVALID_SESSION || status == LGMP_ERR_INVALID_MAGIC)
@@ -1455,6 +1459,16 @@ static int lg_run()
       continue;
     }
 
+    if (udataSize != sizeof(KVMFR) ||
+        memcmp(udata->magic, KVMFR_MAGIC, sizeof(udata->magic)) != 0 ||
+        udata->version != KVMFR_VERSION)
+    {
+      DEBUG_ERROR("The host application is not compatible with this client");
+      DEBUG_ERROR("Expected KVMFR version %d\n", KVMFR_VERSION);
+      DEBUG_ERROR("This is not a Looking Glass error, do not report this");
+      return -1;
+    }
+
     DEBUG_ERROR("lgmpClientInit Failed: %s", lgmpStatusString(status));
     return -1;
   }
diff --git a/common/include/common/KVMFR.h b/common/include/common/KVMFR.h
index ab9a24a7..701ccd36 100644
--- a/common/include/common/KVMFR.h
+++ b/common/include/common/KVMFR.h
@@ -50,6 +50,16 @@ typedef enum CursorType
 }
 CursorType;
 
+#define KVMFR_MAGIC   "KVMFR---"
+#define KVMFR_VERSION 1
+
+typedef struct KVMFR
+{
+  char     magic[8];
+  uint32_t version;
+}
+KVMFR;
+
 typedef struct KVMFRCursor
 {
   int16_t    x, y;        // cursor x & y position
diff --git a/repos/LGMP b/repos/LGMP
index 1d412a1c..61c9178c 160000
--- a/repos/LGMP
+++ b/repos/LGMP
@@ -1 +1 @@
-Subproject commit 1d412a1cf572a341d0d0c9c2714f1107d5376647
+Subproject commit 61c9178c87df46f39a817e63eb85afe2a131e51d