Follow the specs more closely, switch to JWTs.jl, and fix the tests

Project.toml

@@ -1,30 +1,28 @@
 name = "SMARTBackendServices"
 uuid = "78af60b6-7677-4c75-8291-bd270d1b4390"
 authors = ["Dilum Aluthge", "contributors"]
-version = "1.0.1"
+version = "2.0.0"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
 HTTP = "cd3eb016-35fb-5094-929b-558a96fad6f3"
 HealthBase = "94e1309d-ccf4-42de-905f-515f1d7b1cae"
 JSON3 = "0f8b85d8-7281-11e9-16c2-39a750bddbf1"
-JSONWebTokens = "9b8beb19-0777-58c6-920b-28f749fee4d3"
+JWTs = "d850fbd6-035d-5a70-a269-1ca2e636ac6c"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
-TimeZones = "f269a46b-ccf7-5d73-abea-4c690281aa53"
 URIs = "5c2747f8-b7ea-4ff2-ba2e-563bfd36b1d4"
 
 [compat]
 HTTP = "0.9.3"
 HealthBase = "1.0.1"
 JSON3 = "1.5.1"
-JSONWebTokens = "0.3.4, 1"
-TimeZones = "1.5.3"
+JWTs = "0.2.4"
 URIs = "1.2"
 julia = "1.5"
 
 [extras]
-JSONWebTokens = "9b8beb19-0777-58c6-920b-28f749fee4d3"
+MbedTLS = "739be429-bea8-5141-9913-cc70e7f3736d"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["JSONWebTokens", "Test"]
+test = ["MbedTLS", "Test"]

docs/Project.toml

@@ -1,3 +1,6 @@
 [deps]
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
 SMARTBackendServices = "78af60b6-7677-4c75-8291-bd270d1b4390"
+
+[compat]
+Documenter = "1"

docs/make.jl

@@ -15,7 +15,6 @@ makedocs(;
         "Home" => "index.md",
         "API" => "api.md",
     ],
-    strict=true,
 )
 
 deploydocs(;

src/SMARTBackendServices.jl

@@ -4,9 +4,8 @@ import Dates
 import HTTP
 import HealthBase
 import JSON3
-import JSONWebTokens
+import JWTs
 import Random
-import TimeZones
 import URIs
 
 const get_fhir_access_token = HealthBase.get_fhir_access_token
@@ -19,6 +18,5 @@ include("types.jl")
 
 include("backend_services.jl")
 include("jwt.jl")
-include("timestamps.jl")
 
 end # module

src/backend_services.jl

@@ -1,45 +1,151 @@
-function _backend_services_create_jwt(config::BackendServicesConfig)
+function _backend_services_create_jwt(config::BackendServicesConfig, token_endpoint::AbstractString)
+    # Random string that uniquely identifies the JWT
     jti = Random.randstring(150)
 
-    now = TimeZones.now(TimeZones.localzone())
-    expiration_time = now + Dates.Minute(4)
-    expiration_time_seconds_since_epoch_utc = integer_seconds_since_the_epoch_utc(expiration_time)
-
+    # Expiration time (integer) in seconds since "epoch"
+    # SHALL be no more than 5 minutes in the future
+    expiration_time = Dates.now(Dates.UTC) + Dates.Minute(4)
+    expiration_time_seconds_since_epoch_utc = round(Int, Dates.datetime2unix(expiration_time))
+
     jwt_payload_claims_dict = Dict(
-        "iss" => config.iss,
-        "sub" => config.sub,
-        "aud" => config.token_endpoint,
+        "iss" => config.client_id,
+        "sub" => config.client_id,
+        "aud" => token_endpoint,
         "jti" => jti,
         "exp" => expiration_time_seconds_since_epoch_utc,
     )
-    jwt = JSONWebTokens.encode(config.private_key, jwt_payload_claims_dict)
+    jwt = JWTs.JWT(; payload = jwt_payload_claims_dict)
+
+    # Sign
+    JWTs.sign!(jwt, config.key, config.keyid)
+    @assert JWTs.issigned(jwt)
+    @assert JWTs.kid(jwt) == config.keyid
 
-    return jwt
+    return string(jwt)
 end
 
+# Obtain the token endpoint from the well-known URIs
+# Ref: https://www.hl7.org/fhir/smart-app-launch/backend-services.html#retrieve-well-knownsmart-configuration
+function _token_endpoint_wellknown(config::BackendServicesConfig)
+    # Request the SMART configuration file
+    _config_response = HTTP.request(
+        "GET",
+        joinpath(config.base_url, ".well-known/smart-configuration");
+        # In principle, it should be possible to omit the header
+        # (and servers may ignore it anyway)
+        # Ref: https://www.hl7.org/fhir/smart-app-launch/conformance.html#using-well-known
+        headers = ("Accept" => "application/json",),
+        # Old servers might still only support the /metadata endpoint (even though its use for SMART capabilities is deprecated)
+        # Hence we do not throw an exception if the request fails but try the /metadata endpoint first
+        # Ref: https://hl7.org/fhir/smart-app-launch/1.0.0/conformance/index.html#declaring-support-for-oauth2-endpoints
+        # Ref: https://www.hl7.org/fhir/smart-app-launch/conformance.html#smart-on-fhir-oauth-authorization-endpoints-and-capabilities
+        status_exception = false,
+    )
+
+    # Exit gracefully (return `nothing`) if the server does not convey its SMART capabilities using well-known URIs
+    if _config_response.status != 200
+        return nothing
+    end
+
+    # Extract the token endpoint from the JSON response
+    config_response = JSON3.read(_config_response.body)
+    get(config_response, :token_endpoint) do
+        error(
+            "SMART configuration: Violation of the FHIR specification. The mandatory `token_endpoint` is missing from the Well-Known Uniform Resource Identifiers (URIs) JSON document.",
+        )
+    end::String
+end
+
+# Obtain the token endpoint from the CapabilityStatement at the /metadata endpoint
+# Note: Declaring SMART capabilities using the /metadata endpoint is deprecated but old servers might still not support the well-known URIs
+# Ref: https://hl7.org/fhir/smart-app-launch/1.0.0/conformance/index.html#declaring-support-for-oauth2-endpoints
+function _token_endpoint_metadata(config::BackendServicesConfig)
+    # Request the CapabilityStatement
+    _metadata_response = HTTP.request(
+        "GET",
+        joinpath(config.base_url, "metadata");
+        # We only support FHIR version R4
+        # Ref: https://hl7.org/fhir/R4/versioning.html#mt-version
+        headers = ("Accept" => "application/fhir+json; fhirVersion=4.0"),
+        # We throw our own, hopefully more descriptive, exception if necessary
+        status_exception = false,
+    )
+
+    # Exit gracefully (return `nothing`) if the server does not convey its SMART capabilities at the /metadata endpoint
+    if _metadata_response.status != 200
+        return nothing
+    end
+
+    # Extract the token endpoint from the JSON response
+    # Ref: https://hl7.org/fhir/smart-app-launch/1.0.0/conformance/index.html#declaring-support-for-oauth2-endpoints
+    # Ref: https://hl7.org/fhir/R4/capabilitystatement.html
+    compat_statement = JSON3.read(_metadata_response.body)
+    rest = get(compat_statement, :rest, nothing)
+    if rest !== nothing
+        for rest in compat_statement.rest
+            security = get(rest, :security, nothing)
+            if security !== nothing
+                extensions = get(security, :extension, nothing)
+                if extensions !== nothing
+                    for extension in extensions
+                        if get(extension, :url, nothing) ===
+                           "http://fhir-registry.smarthealthit.org/StructureDefinition/oauth-uris"
+                            for url_value in extension.extension
+                                if url_value.url === "token"
+                                    return url_value.valueUri::String
+                                end
+                            end
+                        end
+                    end
+                end
+            end
+        end
+    end
+
+    error(
+        "SMART configuration: Violation of the FHIR specification. The mandatory `token` url of the OAuth2 token endpoint is missing from the FHIR CompatibilityStatement.",
+    )
+end
+
+# Ref: https://www.hl7.org/fhir/smart-app-launch/backend-services.html
 """
     backend_services(config::BackendServicesConfig)
 """
 function backend_services(config::BackendServicesConfig)
-    jwt = _backend_services_create_jwt(config)
+    # Obtain the token endpoint: Try first the well-known URI and then the /metadata endpoint (deprecated)
+    # On Julia >= 1.7 this can be simplified to
+    # token_endpoint = @something _token_endpoint_wellknown(config) _token_endpoint_metadata(config) error("...")
+    token_endpoint = _token_endpoint_wellknown(config)
+    if token_endpoint === nothing
+        token_endpoint = _token_endpoint_metadata(config)
+        if token_endpoint === nothing
+            # Ref: https://www.hl7.org/fhir/smart-app-launch/conformance.html#smart-on-fhir-oauth-authorization-endpoints-and-capabilities
+            # Ref: https://hl7.org/fhir/smart-app-launch/1.0.0/conformance/index.html#smart-on-fhir-oauth-authorization-endpoints
+            error(
+                "SMART configuration: Violation of the FHIR specification. The FHIR server does neither convey its SMART capabilities using a Well-Known Uniform Resource Identifiers (URIs) JSON file nor its CapabilityStatement.",
+            )
+        end
+    end
+
+    # Obtain the access token
+    # Ref: https://www.hl7.org/fhir/smart-app-launch/backend-services.html#obtain-access-token
+    # Create JWT
+    jwt = _backend_services_create_jwt(config, token_endpoint)
 
     body_params = Dict{String, String}()
     body_params["grant_type"] = "client_credentials"
     body_params["client_assertion_type"] = "urn:ietf:params:oauth:client-assertion-type:jwt-bearer"
     body_params["client_assertion"] = jwt
-
-    if config.scope !== nothing
-        body_params["scope"] = config.scope
-    end
+    body_params["scope"] = config.scope
 
     _response = HTTP.request(
         "POST",
-        config.token_endpoint;
-        headers = Dict("Content-Type" => "application/x-www-form-urlencoded"),
+        token_endpoint;
+        headers = ("Content-Type" => "application/x-www-form-urlencoded",),
         body = URIs.escapeuri(body_params),
     )
 
-    access_token_response = JSON3.read(String(_response.body))
+    access_token_response = JSON3.read(_response.body)
     access_token = access_token_response.access_token
 
     access_token_is_jwt, access_token_jwt_decoded = try_decode_jwt(access_token)

src/jwt.jl

@@ -1,6 +1,6 @@
 function try_decode_jwt(contents::AbstractString)
     try
-        jwt_decoded = JSONWebTokens.decode(JSONWebTokens.None(), contents)
+        jwt_decoded = JWTs.claims(JWTs.JWT(; jwt = contents))
         return true, jwt_decoded
     catch
     end

src/types.jl

@@ -1,21 +1,19 @@
 """
-    BackendServicesConfig{PK}(; kwargs...)
+    BackendServicesConfig{T <: JWTs.JWK}(; kwargs...)
 
 ## Required Keyword Arguments:
-- `iss::String`
-- `private_key::PK`
-- `sub::String`
-- `token_endpoint::String`
-
-## Optional Keyword Arguments:
-- `scope::Union{String, Nothing}`. Default value: `nothing`.
+- `base_url`::String
+- `client_id::String`
+- `scope::String`
+- `key::T`
+- `keyid::String`
 """
-Base.@kwdef struct BackendServicesConfig{PK <: JSONWebTokens.Encoding}
-    iss::String
-    private_key::PK
-    scope::Union{String, Nothing} = nothing
-    sub::String
-    token_endpoint::String
+Base.@kwdef struct BackendServicesConfig{T <: JWTs.JWK}
+    base_url::String
+    client_id::String
+    scope::String
+    key::T
+    keyid::String
 end
 
 Base.@kwdef struct BackendServicesResult

test/basic.jl

@@ -1,21 +1,55 @@
-token_endpoint = "https://launch.smarthealthit.org/v/r4/auth/token"
+# This test uses the public https://launch.smarthealthit.org test server
+#
+# In the webinterface, select "Launch Type": "Backend Service"
+# and then switch to the "Client Registration & Validation" tab
+#
+# There you can register a client (with randomly generated ID),
+# possibly restricted to some scope,
+# with a JWK set of public keys for authentication.
+#
+# Use the base URL at the bottom of the page to connect to the
+# server with the stated client ID, scope, and keys. 
+#
+# A private key together with a public JWK set can be generated
+# e.g. with https://mkjwk.org/ (alternatively, you can e.g.
+# generate the key with openssl and create the JWK set manually):
+# 1. Select "Key Use": "Signature"
+# 2. Select "Algorithm": "RS384"
+# 3. Specify a key id (or let it be generated automatically)
+# 4. Check "Show X.509"
+# 5. Press "Generate"
+# 6. Update the `keyid` below
+# 7. Save the private key (in X.509 format) as ./key/private.pem
 
-client_id = "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.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.7YooXIb64Y3_j38n-Gqwa1PqXc-hz-4xJAJF5oqxJVo"
+# Settings of the registered client
+base_url = "https://launch.smarthealthit.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"
+client_id = "3n43riWosf7geBkZBuybgvH3MZ7XHCnsQ2w60TIl51kvCohhypVi76GKjPcYZqeKww5xghfkXON9CWZe24dcD51vgFsxQpWyKu231uazer9562RAUvTFY9Qmswad33zvXomNT9WpAfNvtNcvhOzOwdrZZ1mYCV5pHfZYYXJHvPz7mnGvrnnvHUW1VAMayZf38dM8cY3M7v5hhb2OXabgtXBTabx8Ho2rGOcaKZGcDpds8kfcaIfDJIoJD6F72MCS2PpB8UoM2tsJFANMwUCiTEoMnluu3JbPOkfy5HvcepmXaVfC5PeyF7LLTHg8ePTP1WQXODudt8biepUmdsv9eT3JmPYIw4KCnGlLvO8WFKrQqwz18KO4DjScHILUjQzDfGGjjXBUZ5v6mKoHuvEyI1ijBCPp4NvP29cEUQjcxHI22SKnkVfLXEK7w1mdRlvjAFOuMvJoERMb9Hg63OP3iGBn112r0XUhHjGuzEb9hNc63kkUXIHkDqD1PKaTxoRq1afGsta4Itr36mJQT4OwcwelKuX2F32guPzovGA5wIbG5I6iopp6a7inIeIgg84wH5DVPwRGr5Tr4GBtxphtnSr9tWzDA0noX9VhF4AehYMdG2xtbVGmkERRs0PKGHpQUYXZ7YDkxkzKwnveok4lJS73fRitWcgBZi1TaVWZPOVs2rlXVDW57k87h1rzaofgvYFpfGOdfHmP87o2VXAQ8XYnW8THoLxwcdICnV9mY0xZ8YnuKR38XvEiPlxax5ZF77YQ5sPbFy53Ru6Ci2Dly6vU9quuTVK3MJaQI1IUfRqLQFwUivtXl7iFDH0mPWQUs5skRzXKQEcnLVR2fU0TVt39MX5WnSPgoeNVwxt84hsseOKbFJzZmGXSjScbFLDqUN3DKH07KHKOs0eMIYGw0dnnlvjlQM4NTlgTyogIfgBwLfCeXuTdEHBXkImNCDDqNKsxVS9irVCWvZcDTxjrY7nt1fPW3WoGfGVjxm2q5ao71bmMHIrxHuuOwk1G1C1z"
+scope = "system/*.rs"
 
-smart_config = BackendServicesConfig(;
-    iss = "https://whatever.smart/our-sample-backend-service",
-    sub = client_id,
-    private_key = JSONWebTokens.RS384(test_private_key),
-    scope = "system/*.*",
-    token_endpoint = token_endpoint,
-)
+# Signing key (RS384 algorithm, i.e., SHA384 hash function)
+key = JWTs.JWKRSA(MbedTLS.MD_SHA384, MbedTLS.parse_keyfile(joinpath(@__DIR__, "key", "private.pem")))
+keyid = "Yb09hTDCqmo0UttScFOf37Vzx19jiDlbnzYQYAv6uXk"
 
-smart_result = backend_services(smart_config)
+smart_config = BackendServicesConfig(; base_url, client_id, key, keyid, scope)
 
+smart_result = backend_services(smart_config)
 @test smart_result isa SMARTBackendServices.BackendServicesResult
 
 access_token = get_fhir_access_token(smart_result)
-
 @test access_token isa AbstractString
-
 @test length(access_token) > 1
+
+@testset "token_endpoint" begin
+    # Correct settings
+    token_endpoint_wellknown = SMARTBackendServices._token_endpoint_wellknown(smart_config)
+    @test token_endpoint_wellknown isa String
+    token_endpoint_metadata = SMARTBackendServices._token_endpoint_metadata(smart_config)
+    @test token_endpoint_metadata isa String
+    @test token_endpoint_metadata === token_endpoint_wellknown
+
+    # Incorrect base url
+    config = BackendServicesConfig(; base_url = "https://google.com", client_id, key, keyid, scope)
+    @test SMARTBackendServices._token_endpoint_wellknown(config) === nothing
+    @test SMARTBackendServices._token_endpoint_metadata(config) === nothing
+    @test_throws ErrorException("SMART configuration: Violation of the FHIR specification. The FHIR server does neither convey its SMART capabilities using a Well-Known Uniform Resource Identifiers (URIs) JSON file nor its CapabilityStatement.") backend_services(config)
+end