[BUG][Dart] Basic and Bearer auth interceptors case-sensitive scheme comparison

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• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

The OpenAPI specification defines the "scheme" property as:

The name of the HTTP Authorization scheme to be used in the Authorization header as defined in RFC7235. The values used SHOULD be registered in the IANA Authentication Scheme registry.

According to RFC7235 the name of the HTTP Authorization scheme must be a case-insensitive token:

It uses a case-insensitive token as a means to identify the authentication scheme, followed by additional information necessary for achieving authentication via that scheme.

RFC7617 - Basic Auth also agrees that the scheme must be a case-insensitive token:

Note that both scheme and parameter names are matched case-insensitively.

RFC6750 - Bearer Auth is contradicting because:

Unless otherwise noted, all the protocol parameter names and values are case sensitive.

and it also defines it as "Bearer".

The BasicAuthInterceptor and BearerAuthInterceptor only compare with "basic" and "bearer" which is against the specification and does not work for example when the OpenAPI specification was generated by Smithy.

openapi-generator version

openapi-generator-cli-7.0.1.jar

OpenAPI declaration file content or url

{
  "openapi": "3.0.2",
  "info": {
    "title": "Sample",
    "version": "1.0.0"
  },
  "paths": {
    "/hello": {
      "get": {
        "operationId": "Hello",
        "parameters": [
          {
            "name": "Name",
            "in": "query",
            "schema": {
              "type": "string"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Hello 200 response",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object",
                  "properties": {
                    "greeting": {
                      "type": "string"
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "Name": {
        "type": "string"
      },
      "HelloResponseContent": {
        "type": "object",
        "properties": {
          "greeting": {
            "type": "string"
          }
        }
      }
    },
    "securitySchemes": {
      "smithy.api.httpBearerAuth": {
        "type": "http",
        "description": "HTTP Bearer authentication",
        "scheme": "Bearer"
      }
    }
  },
  "security": [
    {
      "smithy.api.httpBearerAuth": []
    }
  ]
}

Generation Details

Steps to reproduce

Related issues/PRs

Suggest a fix

In order to compare the strings in a case-insensitive manner, make sure that both values are in lowercase.

Start with modules/openapi-generator/src/main/resources/dart/libraries/dio/auth/basic_auth.mustache and bearer_auth.mustache, then generate a Dart Dio client from the supplied OpenAPI declaration. Check how each interceptor compares the Authorization scheme; done means Basic and Bearer schemes work regardless of capitalization, with generated output covering the reported Smithy-style value.