kbs_protocol: Return unquoted string from attestation()

Currently the String returned from attestation() is quoted, because
Value["token"] is a Value, and to_string() returns the "string representation"
of the Value instead of the contained string. Introduce a struct representing
the data returned from /attest, and deserialize into that so that we return the
correct, raw string.

Signed-off-by: Jeremi Piotrowski <[email protected]>

attestation-agent/kbs_protocol/src/lib.rs

@@ -116,8 +116,8 @@ impl KbsProtocolWrapper {
         match attest_response.status() {
             reqwest::StatusCode::OK => {
                 self.authenticated = true;
-                let token = attest_response.json::<serde_json::Value>().await?["token"].to_string();
-                Ok(token)
+                let resp = attest_response.json::<AttestationResponseData>().await?;
+                Ok(resp.token)
             }
             reqwest::StatusCode::UNAUTHORIZED => {
                 let error_info = attest_response.json::<ErrorInformation>().await?;

attestation-agent/kbs_protocol/src/types.rs

@@ -40,6 +40,12 @@ pub struct Challenge {
     pub extra_params: String,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct AttestationResponseData {
+    // Attestation token in JWT format
+    pub token: String,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct Response {
     pub protected: String,