Redfish Aggregation: Router to satellite resources

Adds ability to route requests to either native resources or
resources that belong to a satellite BMC as part of Redfish
Aggregation.  A prefix in the URI denotes if the resource is actually
from a satellite BMC.  Prefixes are only used to denote satellite
resources.  The URI of resources on the local/aggregating BMC will
remain unchanged.

Prefixes are separated from the resource ID by an underscore.  This
means that underscores cannot be used in the prefix name itself.
The prefixes used by satellite BMCs are revealed via D-Bus as well as
the config information needed to connect to that BMC.

Requests for satellite resources will not be handled locally.

Care should be taken to not name any local resources in a way that
could cause a collision (e.g. having a Chassis object named
"aggregated0_1U" on the aggregating BMC).

The patch only covers routing requests.  Requests to collection URIs
like /redfish/v1/Chassis will only return resources on the local BMC.
A future patch will cover adding satellite resources to collections.

Also note that URIs returned in the responses will not have the proper
prefix included.  Fixing these URIs will be addressed in future
patches.

A number of TODO comments are included in the code to indicate that
this functionality (collections and URI fixup) still needs to be
implemented.

Example URIs w/o Redfish Aggregation:
/redfish/v1/Chassis/1U/
/redfish/v1/Systems/system/
/redfish/v1/Managers/bmc/

Example URIs after enabling Redfish Aggregation if the associated
resources are located on the local/aggregating BMC:
/redfish/v1/Chassis/1U/
/redfish/v1/Systems/system/
/redfish/v1/Managers/bmc/

Example URIs if resources are instead located on a satellite BMC
named "aggregated0":
/redfish/v1/Chassis/aggregated0_1U/
/redfish/v1/Systems/aggregated0_system/
/redfish/v1/Managers/aggregated0_bmc/

Tested:
I was able to query supported resources located on the local BMC
as well as on a satellite BMC.  Requests with unknown prefixes return
a 404.  Requests to resource collections only return the resources
that are located on the aggregating BMC.

Signed-off-by: Carson Labrado <clabrado@google.com>
Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I87a3deb730bda95e72ecd3144ea40b0e5ee7d491

1 files changed, 5 insertions, 0 deletions

diff --git a/http/http_response.hpp b/http/http_response.hpp
index 38bebb5c8a..dd1f37aea2 100644
--- a/http/http_response.hpp
+++ b/http/http_response.hpp
@@ -122,6 +122,11 @@ struct Response
         return stringResponse->body();
     }
 
+    std::string_view getHeaderValue(std::string_view key) const
+    {
+        return stringResponse->base()[key];
+    }
+
     void keepAlive(bool k)
     {
         stringResponse->keep_alive(k);