KBS: return more context about RCAR/Attestation error

[Xynnn007]

cc @mythi

[mythi]

I'm not sure if this is going to help. With the following:

diff --git a/attestation-agent/kbs_protocol/src/client/mod.rs b/attestation-agent/kbs_protocol/src/client/mod.rs
index 5febb69..fdb7f23 100644
--- a/attestation-agent/kbs_protocol/src/client/mod.rs
+++ b/attestation-agent/kbs_protocol/src/client/mod.rs
@@ -48,7 +48,7 @@ pub struct KbsClient<T> {
     pub(crate) token: Option<Token>,
 }
 
-pub const KBS_PROTOCOL_VERSION: &str = "0.1.1";
+pub const KBS_PROTOCOL_VERSION: &str = "0.2.0";
 
 pub const KBS_GET_RESOURCE_MAX_ATTEMPT: u64 = 3;
 
diff --git a/attestation-agent/kbs_protocol/src/client/rcar_client.rs b/attestation-agent/kbs_protocol/src/client/rcar_client.rs
index fc160af..1a4a5e7 100644
--- a/attestation-agent/kbs_protocol/src/client/rcar_client.rs
+++ b/attestation-agent/kbs_protocol/src/client/rcar_client.rs
@@ -447,6 +447,7 @@ mod test {
             Err(e) => {
                 // Skip the test if the kbs server returned ProtocolVersion error. Any other
                 // error is treated as a failure.
+                println!("{:#?}", e);
                 assert!(e
                     .to_string()
                     .contains("KBS Client Protocol Version Mismatch"));

I get:

RcarHandshake(
    "KBS request unauthorized, ErrorInformation: ErrorInformation { error_type: \"https://github.com/confidential-containers/kbs/errors/AttestationError\", detail: \"Attestation error\" }",
)

[Xynnn007]

Updated. Now the client side would see

RcarHandshake(
    "KBS request unauthorized, ErrorInformation: ErrorInformation { error_type: \"https://github.com/confidential-containers/kbs/errors/AttestationError\", detail: \"Attestation error: RCAR handshake Auth failed: KBS Client Protocol Version Mismatch: expect =0.1.1 while the request is 0.2.0\" }",
)

[mythi]

LGTM, thanks!

[fitzthum]

LGTM