From 034920eca21bc25899565484928ee72025e21ff8 Mon Sep 17 00:00:00 2001
From: Wiktor Golgowski <wiktor.golgowski@linux.intel.com>
Date: Thu, 30 Apr 2020 11:09:35 +0200
Subject: [PATCH] Use chip id-based UUID for Service Root.
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If the sysfs-provided chip id is available, it will be used as
payload to generate Service Root UUID from hardcoded namespace.

Tested:
Generated UUID is consistent between BMC image reflashes.
If the sysfs node is not available, code falls back to randomly
generated UUID.

Signed-off-by: Wiktor Gołgowski <wiktor.golgowski@linux.intel.com>
---
 include/persistent_data.hpp | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/include/persistent_data.hpp b/include/persistent_data.hpp
index 24f7afd..8826b06 100644
--- a/include/persistent_data.hpp
+++ b/include/persistent_data.hpp
@@ -25,6 +25,10 @@ class ConfigFile
   public:
     // todo(ed) should read this from a fixed location somewhere, not CWD
     static constexpr const char* filename = "bmcweb_persistent_data.json";
+    static constexpr const char* chipIdSysfsNode = "/sys/devices/platform"
+    "/ahb/ahb:apb/1e6e2000.syscon/1e6e2000.syscon:misc_control/chip_id";
+    static constexpr const char* UuidNs = "{b7b0553a-54cc-4162-982d-"
+    "944847ed76f5}";
 
     ConfigFile()
     {
@@ -144,9 +148,31 @@ class ConfigFile
 
         if (systemUuid.empty())
         {
-            systemUuid =
-                boost::uuids::to_string(boost::uuids::random_generator()());
-            needWrite = true;
+            // Try to retrieve chip id-based uuid.
+            std::ifstream chipIdFile(chipIdSysfsNode);
+            if (chipIdFile.is_open())
+            {
+                std::string chipId;
+                std::getline(chipIdFile, chipId);
+                if (!chipId.empty())
+                {
+                    boost::uuids::name_generator_sha1 gen(
+                        boost::uuids::string_generator()(UuidNs));
+                    systemUuid = boost::uuids::to_string(gen(chipId.c_str()));
+                    needWrite = true;
+                }
+                else
+                {
+                    BMCWEB_LOG_ERROR << "Cannot get chip id-based System UUID.";
+                }
+            }
+            // If the above fails, generate random uuid.
+            if (systemUuid.empty())
+            {
+                systemUuid =
+                    boost::uuids::to_string(boost::uuids::random_generator()());
+                needWrite = true;
+            }
         }
         if (fileRevision < jsonRevision)
         {
-- 
2.17.1