fix: review comments

easy two-liner to pass `oidcc-userinfo-post-header` test in conformance
suite.

frontend/src/lib/hooks/oidc.ts

@@ -1,55 +1,40 @@
-export type OIDCValues = {
-  scope: string;
-  response_type: string;
-  client_id: string;
-  redirect_uri: string;
-  state: string;
-  nonce: string;
-};
+import { z } from "zod";
 
-interface IuseOIDCParams {
-  values: OIDCValues;
-  compiled: string;
+export const oidcParamsSchema = z.object({
+  scope: z.string().nonempty(),
+  response_type: z.string().nonempty(),
+  client_id: z.string().nonempty(),
+  redirect_uri: z.string().nonempty(),
+  state: z.string().optional(),
+  nonce: z.string().optional(),
+  code_challenge: z.string().optional(),
+  code_challenge_method: z.string().optional(),
+});
+
+export const useOIDCParams = (
+  params: URLSearchParams,
+): {
+  values: z.infer<typeof oidcParamsSchema>;
+  issues: string[];
   isOidc: boolean;
-  missingParams: string[];
-}
+  compiled: string;
+} => {
+  const obj = Object.fromEntries(params.entries());
+  const parsed = oidcParamsSchema.safeParse(obj);
 
-const optionalParams: string[] = ["state", "nonce"];
-
-export function useOIDCParams(params: URLSearchParams): IuseOIDCParams {
-  let compiled: string = "";
-  let isOidc = false;
-  const missingParams: string[] = [];
-
-  const values: OIDCValues = {
-    scope: params.get("scope") ?? "",
-    response_type: params.get("response_type") ?? "",
-    client_id: params.get("client_id") ?? "",
-    redirect_uri: params.get("redirect_uri") ?? "",
-    state: params.get("state") ?? "",
-    nonce: params.get("nonce") ?? "",
+  if (parsed.success) {
+    return {
+      values: parsed.data,
+      issues: [],
+      isOidc: true,
+      compiled: new URLSearchParams(parsed.data).toString(),
     };
-
-  for (const key of Object.keys(values)) {
-    if (!values[key as keyof OIDCValues]) {
-      if (!optionalParams.includes(key)) {
-        missingParams.push(key);
-      }
-    }
-  }
-
-  if (missingParams.length === 0) {
-    isOidc = true;
-  }
-
-  if (isOidc) {
-    compiled = new URLSearchParams(values).toString();
   }
 
   return {
-    values,
-    compiled,
-    isOidc,
-    missingParams,
+    issues: parsed.error.issues.map((issue) => issue.path.toString()),
+    values: {} as z.infer<typeof oidcParamsSchema>,
+    isOidc: false,
+    compiled: "",
   };
-}
+};

frontend/src/pages/authorize-page.tsx

@@ -72,36 +72,27 @@ export const AuthorizePage = () => {
   const scopeMap = createScopeMap(t);
 
   const searchParams = new URLSearchParams(search);
-  const {
-    values: props,
-    missingParams,
-    isOidc,
-    compiled: compiledOIDCParams,
-  } = useOIDCParams(searchParams);
-  const scopes = props.scope ? props.scope.split(" ").filter(Boolean) : [];
+  const oidcParams = useOIDCParams(searchParams);
 
   const getClientInfo = useQuery({
-    queryKey: ["client", props.client_id],
+    queryKey: ["client", oidcParams.values.client_id],
     queryFn: async () => {
-      const res = await fetch(`/api/oidc/clients/${props.client_id}`);
+      const res = await fetch(
+        `/api/oidc/clients/${encodeURIComponent(oidcParams.values.client_id)}`,
+      );
       const data = await getOidcClientInfoSchema.parseAsync(await res.json());
       return data;
     },
-    enabled: isOidc,
+    enabled: oidcParams.isOidc,
   });
 
   const authorizeMutation = useMutation({
     mutationFn: () => {
       return axios.post("/api/oidc/authorize", {
-        scope: props.scope,
-        response_type: props.response_type,
-        client_id: props.client_id,
-        redirect_uri: props.redirect_uri,
-        state: props.state,
-        nonce: props.nonce,
+        ...oidcParams.values,
       });
     },
-    mutationKey: ["authorize", props.client_id],
+    mutationKey: ["authorize", oidcParams.values.client_id],
     onSuccess: (data) => {
       toast.info(t("authorizeSuccessTitle"), {
         description: t("authorizeSuccessSubtitle"),
@@ -115,17 +106,17 @@ export const AuthorizePage = () => {
     },
   });
 
-  if (missingParams.length > 0) {
+  if (oidcParams.issues.length > 0) {
     return (
       <Navigate
-        to={`/error?error=${encodeURIComponent(t("authorizeErrorMissingParams", { missingParams: missingParams.join(", ") }))}`}
+        to={`/error?error=${encodeURIComponent(t("authorizeErrorMissingParams", { missingParams: oidcParams.issues.join(", ") }))}`}
         replace
       />
     );
   }
 
   if (!isLoggedIn) {
-    return <Navigate to={`/login?${compiledOIDCParams}`} replace />;
+    return <Navigate to={`/login?${oidcParams.compiled}`} replace />;
   }
 
   if (getClientInfo.isLoading) {
@@ -152,6 +143,9 @@ export const AuthorizePage = () => {
     );
   }
 
+  const scopes =
+    oidcParams.values.scope.split(" ").filter((s) => s.trim() !== "") || [];
+
   return (
     <Card>
       <CardHeader className="mb-2">

frontend/src/pages/login-page.tsx

@@ -51,15 +51,12 @@ export const LoginPage = () => {
   const formId = useId();
 
   const searchParams = new URLSearchParams(search);
-  const {
-    values: props,
-    isOidc,
-    compiled: compiledOIDCParams,
-  } = useOIDCParams(searchParams);
+  const redirectUri = searchParams.get("redirect_uri") || undefined;
+  const oidcParams = useOIDCParams(searchParams);
 
   const [isOauthAutoRedirect, setIsOauthAutoRedirect] = useState(
     providers.find((provider) => provider.id === oauthAutoRedirect) !==
-      undefined && props.redirect_uri,
+      undefined && redirectUri !== undefined,
   );
 
   const oauthProviders = providers.filter(
@@ -78,7 +75,7 @@ export const LoginPage = () => {
   } = useMutation({
     mutationFn: (provider: string) =>
       axios.get(
-        `/api/oauth/url/${provider}${props.redirect_uri ? `?redirect_uri=${encodeURIComponent(props.redirect_uri)}` : ""}`,
+        `/api/oauth/url/${provider}${redirectUri ? `?redirect_uri=${encodeURIComponent(redirectUri)}` : ""}`,
       ),
     mutationKey: ["oauth"],
     onSuccess: (data) => {
@@ -109,8 +106,12 @@ export const LoginPage = () => {
     mutationKey: ["login"],
     onSuccess: (data) => {
       if (data.data.totpPending) {
+        if (oidcParams.isOidc) {
+          window.location.replace(`/totp?${oidcParams.compiled}`);
+          return;
+        }
         window.location.replace(
-          `/totp${props.redirect_uri ? `?redirect_uri=${encodeURIComponent(props.redirect_uri)}` : ""}`,
+          `/totp${redirectUri ? `?redirect_uri=${encodeURIComponent(redirectUri)}` : ""}`,
         );
         return;
       }
@@ -120,12 +121,12 @@ export const LoginPage = () => {
       });
 
       redirectTimer.current = window.setTimeout(() => {
-        if (isOidc) {
-          window.location.replace(`/authorize?${compiledOIDCParams}`);
+        if (oidcParams.isOidc) {
+          window.location.replace(`/authorize?${oidcParams.compiled}`);
           return;
         }
         window.location.replace(
-          `/continue${props.redirect_uri ? `?redirect_uri=${encodeURIComponent(props.redirect_uri)}` : ""}`,
+          `/continue${redirectUri ? `?redirect_uri=${encodeURIComponent(redirectUri)}` : ""}`,
         );
       }, 500);
     },
@@ -144,7 +145,7 @@ export const LoginPage = () => {
       !isLoggedIn &&
       isOauthAutoRedirect &&
       !hasAutoRedirectedRef.current &&
-      props.redirect_uri
+      redirectUri !== undefined
     ) {
       hasAutoRedirectedRef.current = true;
       oauthMutate(oauthAutoRedirect);
@@ -155,7 +156,7 @@ export const LoginPage = () => {
     hasAutoRedirectedRef,
     oauthAutoRedirect,
     isOauthAutoRedirect,
-    props.redirect_uri,
+    redirectUri,
   ]);
 
   useEffect(() => {
@@ -170,14 +171,14 @@ export const LoginPage = () => {
     };
   }, [redirectTimer, redirectButtonTimer]);
 
-  if (isLoggedIn && isOidc) {
-    return <Navigate to={`/authorize?${compiledOIDCParams}`} replace />;
+  if (isLoggedIn && oidcParams.isOidc) {
+    return <Navigate to={`/authorize?${oidcParams.compiled}`} replace />;
   }
 
-  if (isLoggedIn && props.redirect_uri !== "") {
+  if (isLoggedIn && redirectUri !== undefined) {
     return (
       <Navigate
-        to={`/continue${props.redirect_uri ? `?redirect_uri=${encodeURIComponent(props.redirect_uri)}` : ""}`}
+        to={`/continue${redirectUri ? `?redirect_uri=${encodeURIComponent(redirectUri)}` : ""}`}
         replace
       />
     );

frontend/src/pages/totp-page.tsx

@@ -27,11 +27,8 @@ export const TotpPage = () => {
   const redirectTimer = useRef<number | null>(null);
 
   const searchParams = new URLSearchParams(search);
-  const {
-    values: props,
-    isOidc,
-    compiled: compiledOIDCParams,
-  } = useOIDCParams(searchParams);
+  const redirectUri = searchParams.get("redirect_uri") || undefined;
+  const oidcParams = useOIDCParams(searchParams);
 
   const totpMutation = useMutation({
     mutationFn: (values: TotpSchema) => axios.post("/api/user/totp", values),
@@ -42,13 +39,13 @@ export const TotpPage = () => {
       });
 
       redirectTimer.current = window.setTimeout(() => {
-        if (isOidc) {
-          window.location.replace(`/authorize?${compiledOIDCParams}`);
+        if (oidcParams.isOidc) {
+          window.location.replace(`/authorize?${oidcParams.compiled}`);
           return;
         }
 
         window.location.replace(
-          `/continue${props.redirect_uri ? `?redirect_uri=${encodeURIComponent(props.redirect_uri)}` : ""}`,
+          `/continue${redirectUri ? `?redirect_uri=${encodeURIComponent(redirectUri)}` : ""}`,
         );
       }, 500);
     },

internal/assets/migrations/000007_oidc_pkce.down.sql

@@ -0,0 +1 @@
+ALTER TABLE "oidc_codes" DROP COLUMN "code_challenge";

internal/assets/migrations/000007_oidc_pkce.up.sql

@@ -0,0 +1 @@
+ALTER TABLE "oidc_codes" ADD COLUMN "code_challenge" TEXT DEFAULT "";

internal/controller/context_controller_test.go

@@ -10,10 +10,12 @@ import (
 	"github.com/steveiliop56/tinyauth/internal/config"
 	"github.com/steveiliop56/tinyauth/internal/controller"
 	"github.com/steveiliop56/tinyauth/internal/utils"
+	"github.com/steveiliop56/tinyauth/internal/utils/tlog"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestContextController(t *testing.T) {
+	tlog.NewTestLogger().Init()
 	controllerConfig := controller.ContextControllerConfig{
 		Providers: []controller.Provider{
 			{

internal/controller/health_controller_test.go

@@ -8,10 +8,12 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/steveiliop56/tinyauth/internal/controller"
+	"github.com/steveiliop56/tinyauth/internal/utils/tlog"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestHealthController(t *testing.T) {
+	tlog.NewTestLogger().Init()
 	tests := []struct {
 		description string
 		path        string

internal/controller/oidc_controller.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/go-querystring/query"
+
 	"github.com/steveiliop56/tinyauth/internal/service"
 	"github.com/steveiliop56/tinyauth/internal/utils"
 	"github.com/steveiliop56/tinyauth/internal/utils/tlog"
@@ -34,6 +35,7 @@ type TokenRequest struct {
 	RefreshToken string `form:"refresh_token" url:"refresh_token"`
 	ClientSecret string `form:"client_secret" url:"client_secret"`
 	ClientID     string `form:"client_id" url:"client_id"`
+	CodeVerifier string `form:"code_verifier" url:"code_verifier"`
 }
 
 type CallbackError struct {
@@ -69,6 +71,7 @@ func (controller *OIDCController) SetupRoutes() {
 	oidcGroup.POST("/authorize", controller.Authorize)
 	oidcGroup.POST("/token", controller.Token)
 	oidcGroup.GET("/userinfo", controller.Userinfo)
+	oidcGroup.POST("/userinfo", controller.Userinfo)
 }
 
 func (controller *OIDCController) GetClientInfo(c *gin.Context) {
@@ -308,6 +311,16 @@ func (controller *OIDCController) Token(c *gin.Context) {
 			return
 		}
 
+		ok := controller.oidc.ValidatePKCE(entry.CodeChallenge, req.CodeVerifier)
+
+		if !ok {
+			tlog.App.Warn().Msg("PKCE validation failed")
+			c.JSON(400, gin.H{
+				"error": "invalid_grant",
+			})
+			return
+		}
+
 		tokenRes, err := controller.oidc.GenerateAccessToken(c, client, entry)
 
 		if err != nil {
@@ -364,14 +377,15 @@ func (controller *OIDCController) Userinfo(c *gin.Context) {
 		return
 	}
 
+	var token string
+
 	authorization := c.GetHeader("Authorization")
-
-	tokenType, token, ok := strings.Cut(authorization, " ")
-
+	if authorization != "" {
+		tokenType, bearerToken, ok := strings.Cut(authorization, " ")
 		if !ok {
-		tlog.App.Warn().Msg("OIDC userinfo accessed without authorization header")
+			tlog.App.Warn().Msg("OIDC userinfo accessed with malformed authorization header")
 			c.JSON(401, gin.H{
-			"error": "invalid_grant",
+				"error": "invalid_request",
 			})
 			return
 		}
@@ -379,7 +393,32 @@ func (controller *OIDCController) Userinfo(c *gin.Context) {
 		if strings.ToLower(tokenType) != "bearer" {
 			tlog.App.Warn().Msg("OIDC userinfo accessed with invalid token type")
 			c.JSON(401, gin.H{
-			"error": "invalid_grant",
+				"error": "invalid_request",
+			})
+			return
+		}
+
+		token = bearerToken
+	} else if c.Request.Method == http.MethodPost {
+		if c.ContentType() != "application/x-www-form-urlencoded" {
+			tlog.App.Warn().Msg("OIDC userinfo POST accessed with invalid content type")
+			c.JSON(400, gin.H{
+				"error": "invalid_request",
+			})
+			return
+		}
+		token = c.PostForm("access_token")
+		if token == "" {
+			tlog.App.Warn().Msg("OIDC userinfo POST accessed without access_token in body")
+			c.JSON(401, gin.H{
+				"error": "invalid_request",
+			})
+			return
+		}
+	} else {
+		tlog.App.Warn().Msg("OIDC userinfo accessed without authorization header")
+		c.JSON(401, gin.H{
+			"error": "invalid_request",
 		})
 		return
 	}

internal/controller/oidc_controller_test.go

@@ -1,6 +1,8 @@
 package controller_test
 
 import (
+	"crypto/sha256"
+	"encoding/base64"
 	"encoding/json"
 	"net/http/httptest"
 	"net/url"
@@ -15,11 +17,13 @@ import (
 	"github.com/steveiliop56/tinyauth/internal/controller"
 	"github.com/steveiliop56/tinyauth/internal/repository"
 	"github.com/steveiliop56/tinyauth/internal/service"
+	"github.com/steveiliop56/tinyauth/internal/utils/tlog"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestOIDCController(t *testing.T) {
+	tlog.NewTestLogger().Init()
 	tempDir := t.TempDir()
 
 	oidcServiceCfg := service.OIDCServiceConfig{
@@ -431,6 +435,349 @@ func TestOIDCController(t *testing.T) {
 				assert.False(t, ok, "Did not expect email claim in userinfo response")
 			},
 		},
+		{
+			description: "Ensure userinfo forbids access with no authorization header",
+			middlewares: []gin.HandlerFunc{},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				req := httptest.NewRequest("GET", "/api/oidc/userinfo", nil)
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 401, recorder.Code)
+
+				var res map[string]any
+				err := json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+				assert.Equal(t, "invalid_request", res["error"])
+			},
+		},
+		{
+			description: "Ensure userinfo forbids access with malformed authorization header",
+			middlewares: []gin.HandlerFunc{},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				req := httptest.NewRequest("GET", "/api/oidc/userinfo", nil)
+				req.Header.Set("Authorization", "Bearer")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 401, recorder.Code)
+
+				var res map[string]any
+				err := json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+				assert.Equal(t, "invalid_request", res["error"])
+			},
+		},
+		{
+			description: "Ensure userinfo forbids access with invalid token type",
+			middlewares: []gin.HandlerFunc{},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				req := httptest.NewRequest("GET", "/api/oidc/userinfo", nil)
+				req.Header.Set("Authorization", "Basic some-token")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 401, recorder.Code)
+
+				var res map[string]any
+				err := json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+				assert.Equal(t, "invalid_request", res["error"])
+			},
+		},
+		{
+			description: "Ensure userinfo forbids access with empty bearer token",
+			middlewares: []gin.HandlerFunc{},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				req := httptest.NewRequest("GET", "/api/oidc/userinfo", nil)
+				req.Header.Set("Authorization", "Bearer ")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 401, recorder.Code)
+
+				var res map[string]any
+				err := json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+				assert.Equal(t, "invalid_grant", res["error"])
+			},
+		},
+		{
+			description: "Ensure userinfo POST rejects missing access token in body",
+			middlewares: []gin.HandlerFunc{},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				req := httptest.NewRequest("POST", "/api/oidc/userinfo", strings.NewReader(""))
+				req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 401, recorder.Code)
+
+				var res map[string]any
+				err := json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+				assert.Equal(t, "invalid_request", res["error"])
+			},
+		},
+		{
+			description: "Ensure userinfo POST rejects wrong content type",
+			middlewares: []gin.HandlerFunc{},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				req := httptest.NewRequest("POST", "/api/oidc/userinfo", strings.NewReader(`{"access_token":"some-token"}`))
+				req.Header.Set("Content-Type", "application/json")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 400, recorder.Code)
+
+				var res map[string]any
+				err := json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+				assert.Equal(t, "invalid_request", res["error"])
+			},
+		},
+		{
+			description: "Ensure userinfo accepts access token via POST body",
+			middlewares: []gin.HandlerFunc{
+				simpleCtx,
+			},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				tokenTest, found := getTestByDescription("Ensure we can get a token with a valid request")
+				assert.True(t, found, "Token test not found")
+				tokenRecorder := httptest.NewRecorder()
+				tokenTest(t, router, tokenRecorder)
+
+				var tokenRes map[string]any
+				err := json.Unmarshal(tokenRecorder.Body.Bytes(), &tokenRes)
+				assert.NoError(t, err)
+
+				accessToken := tokenRes["access_token"].(string)
+				assert.NotEmpty(t, accessToken)
+
+				body := url.Values{}
+				body.Set("access_token", accessToken)
+				req := httptest.NewRequest("POST", "/api/oidc/userinfo", strings.NewReader(body.Encode()))
+				req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 200, recorder.Code)
+
+				var userInfoRes map[string]any
+				err = json.Unmarshal(recorder.Body.Bytes(), &userInfoRes)
+				assert.NoError(t, err)
+
+				_, ok := userInfoRes["sub"]
+				assert.True(t, ok, "Expected sub claim in userinfo response")
+			},
+		},
+		{
+			description: "Ensure plain PKCE succeeds",
+			middlewares: []gin.HandlerFunc{
+				simpleCtx,
+			},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				reqBody := service.AuthorizeRequest{
+					Scope:         "openid",
+					ResponseType:  "code",
+					ClientID:      "some-client-id",
+					RedirectURI:   "https://test.example.com/callback",
+					State:         "some-state",
+					Nonce:         "some-nonce",
+					CodeChallenge: "some-challenge",
+					// Not setting a code challenge method should default to "plain"
+					CodeChallengeMethod: "",
+				}
+				reqBodyBytes, err := json.Marshal(reqBody)
+				assert.NoError(t, err)
+
+				req := httptest.NewRequest("POST", "/api/oidc/authorize", strings.NewReader(string(reqBodyBytes)))
+				req.Header.Set("Content-Type", "application/json")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 200, recorder.Code)
+
+				var res map[string]any
+				err = json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+
+				redirectURI := res["redirect_uri"].(string)
+				url, err := url.Parse(redirectURI)
+				assert.NoError(t, err)
+
+				queryParams := url.Query()
+				assert.Equal(t, queryParams.Get("state"), "some-state")
+
+				code := queryParams.Get("code")
+				assert.NotEmpty(t, code)
+
+				// Now exchange the code for a token
+				recorder = httptest.NewRecorder()
+				tokenReqBody := controller.TokenRequest{
+					GrantType:    "authorization_code",
+					Code:         code,
+					RedirectURI:  "https://test.example.com/callback",
+					CodeVerifier: "some-challenge",
+				}
+				reqBodyEncoded, err := query.Values(tokenReqBody)
+				assert.NoError(t, err)
+
+				req = httptest.NewRequest("POST", "/api/oidc/token", strings.NewReader(reqBodyEncoded.Encode()))
+				req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+				req.SetBasicAuth("some-client-id", "some-client-secret")
+				router.ServeHTTP(recorder, req)
+
+				assert.Equal(t, 200, recorder.Code)
+			},
+		},
+		{
+			description: "Ensure S256 PKCE succeeds",
+			middlewares: []gin.HandlerFunc{
+				simpleCtx,
+			},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				hasher := sha256.New()
+				hasher.Write([]byte("some-challenge"))
+				codeChallenge := hasher.Sum(nil)
+				codeChallengeEncoded := base64.RawURLEncoding.EncodeToString(codeChallenge)
+				reqBody := service.AuthorizeRequest{
+					Scope:               "openid",
+					ResponseType:        "code",
+					ClientID:            "some-client-id",
+					RedirectURI:         "https://test.example.com/callback",
+					State:               "some-state",
+					Nonce:               "some-nonce",
+					CodeChallenge:       codeChallengeEncoded,
+					CodeChallengeMethod: "S256",
+				}
+				reqBodyBytes, err := json.Marshal(reqBody)
+				assert.NoError(t, err)
+
+				req := httptest.NewRequest("POST", "/api/oidc/authorize", strings.NewReader(string(reqBodyBytes)))
+				req.Header.Set("Content-Type", "application/json")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 200, recorder.Code)
+
+				var res map[string]any
+				err = json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+
+				redirectURI := res["redirect_uri"].(string)
+				url, err := url.Parse(redirectURI)
+				assert.NoError(t, err)
+
+				queryParams := url.Query()
+				assert.Equal(t, queryParams.Get("state"), "some-state")
+
+				code := queryParams.Get("code")
+				assert.NotEmpty(t, code)
+
+				// Now exchange the code for a token
+				recorder = httptest.NewRecorder()
+				tokenReqBody := controller.TokenRequest{
+					GrantType:    "authorization_code",
+					Code:         code,
+					RedirectURI:  "https://test.example.com/callback",
+					CodeVerifier: "some-challenge",
+				}
+				reqBodyEncoded, err := query.Values(tokenReqBody)
+				assert.NoError(t, err)
+
+				req = httptest.NewRequest("POST", "/api/oidc/token", strings.NewReader(reqBodyEncoded.Encode()))
+				req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+				req.SetBasicAuth("some-client-id", "some-client-secret")
+				router.ServeHTTP(recorder, req)
+
+				assert.Equal(t, 200, recorder.Code)
+			},
+		},
+		{
+			description: "Ensure request with invalid PKCE fails",
+			middlewares: []gin.HandlerFunc{
+				simpleCtx,
+			},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				hasher := sha256.New()
+				hasher.Write([]byte("some-challenge"))
+				codeChallenge := hasher.Sum(nil)
+				codeChallengeEncoded := base64.RawURLEncoding.EncodeToString(codeChallenge)
+				reqBody := service.AuthorizeRequest{
+					Scope:               "openid",
+					ResponseType:        "code",
+					ClientID:            "some-client-id",
+					RedirectURI:         "https://test.example.com/callback",
+					State:               "some-state",
+					Nonce:               "some-nonce",
+					CodeChallenge:       codeChallengeEncoded,
+					CodeChallengeMethod: "S256",
+				}
+				reqBodyBytes, err := json.Marshal(reqBody)
+				assert.NoError(t, err)
+
+				req := httptest.NewRequest("POST", "/api/oidc/authorize", strings.NewReader(string(reqBodyBytes)))
+				req.Header.Set("Content-Type", "application/json")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 200, recorder.Code)
+
+				var res map[string]any
+				err = json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+
+				redirectURI := res["redirect_uri"].(string)
+				url, err := url.Parse(redirectURI)
+				assert.NoError(t, err)
+
+				queryParams := url.Query()
+				assert.Equal(t, queryParams.Get("state"), "some-state")
+
+				code := queryParams.Get("code")
+				assert.NotEmpty(t, code)
+
+				// Now exchange the code for a token
+				recorder = httptest.NewRecorder()
+				tokenReqBody := controller.TokenRequest{
+					GrantType:    "authorization_code",
+					Code:         code,
+					RedirectURI:  "https://test.example.com/callback",
+					CodeVerifier: "some-challenge-1",
+				}
+				reqBodyEncoded, err := query.Values(tokenReqBody)
+				assert.NoError(t, err)
+
+				req = httptest.NewRequest("POST", "/api/oidc/token", strings.NewReader(reqBodyEncoded.Encode()))
+				req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+				req.SetBasicAuth("some-client-id", "some-client-secret")
+				router.ServeHTTP(recorder, req)
+
+				assert.Equal(t, 400, recorder.Code)
+			},
+		},
+		{
+			description: "Ensure request with invalid challenge method fails",
+			middlewares: []gin.HandlerFunc{
+				simpleCtx,
+			},
+			run: func(t *testing.T, router *gin.Engine, recorder *httptest.ResponseRecorder) {
+				hasher := sha256.New()
+				hasher.Write([]byte("some-challenge"))
+				codeChallenge := hasher.Sum(nil)
+				codeChallengeEncoded := base64.RawURLEncoding.EncodeToString(codeChallenge)
+				reqBody := service.AuthorizeRequest{
+					Scope:               "openid",
+					ResponseType:        "code",
+					ClientID:            "some-client-id",
+					RedirectURI:         "https://test.example.com/callback",
+					State:               "some-state",
+					Nonce:               "some-nonce",
+					CodeChallenge:       codeChallengeEncoded,
+					CodeChallengeMethod: "foo",
+				}
+				reqBodyBytes, err := json.Marshal(reqBody)
+				assert.NoError(t, err)
+
+				req := httptest.NewRequest("POST", "/api/oidc/authorize", strings.NewReader(string(reqBodyBytes)))
+				req.Header.Set("Content-Type", "application/json")
+				router.ServeHTTP(recorder, req)
+				assert.Equal(t, 200, recorder.Code)
+
+				var res map[string]any
+				err = json.Unmarshal(recorder.Body.Bytes(), &res)
+				assert.NoError(t, err)
+
+				redirectURI := res["redirect_uri"].(string)
+				url, err := url.Parse(redirectURI)
+				assert.NoError(t, err)
+
+				queryParams := url.Query()
+				error := queryParams.Get("error")
+				assert.NotEmpty(t, error)
+			},
+		},
 	}
 
 	app := bootstrap.NewBootstrapApp(config.Config{})

internal/controller/proxy_controller_test.go

@@ -17,6 +17,7 @@ import (
 )
 
 func TestProxyController(t *testing.T) {
+	tlog.NewTestLogger().Init()
 	tempDir := t.TempDir()
 
 	authServiceCfg := service.AuthServiceConfig{
@@ -390,8 +391,6 @@ func TestProxyController(t *testing.T) {
 		},
 	}
 
-	tlog.NewSimpleLogger().Init()
-
 	oauthBrokerCfgs := make(map[string]config.OAuthServiceConfig)
 
 	app := bootstrap.NewBootstrapApp(config.Config{})

internal/controller/resources_controller_test.go

@@ -8,11 +8,13 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/steveiliop56/tinyauth/internal/controller"
+	"github.com/steveiliop56/tinyauth/internal/utils/tlog"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestResourcesController(t *testing.T) {
+	tlog.NewTestLogger().Init()
 	tempDir := t.TempDir()
 
 	resourcesControllerCfg := controller.ResourcesControllerConfig{

internal/controller/user_controller_test.go

@@ -22,6 +22,7 @@ import (
 )
 
 func TestUserController(t *testing.T) {
+	tlog.NewTestLogger().Init()
 	tempDir := t.TempDir()
 
 	authServiceCfg := service.AuthServiceConfig{
@@ -274,8 +275,6 @@ func TestUserController(t *testing.T) {
 		},
 	}
 
-	tlog.NewSimpleLogger().Init()
-
 	oauthBrokerCfgs := make(map[string]config.OAuthServiceConfig)
 
 	app := bootstrap.NewBootstrapApp(config.Config{})

internal/controller/well_known_controller_test.go

@@ -13,11 +13,13 @@ import (
 	"github.com/steveiliop56/tinyauth/internal/controller"
 	"github.com/steveiliop56/tinyauth/internal/repository"
 	"github.com/steveiliop56/tinyauth/internal/service"
+	"github.com/steveiliop56/tinyauth/internal/utils/tlog"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestWellKnownController(t *testing.T) {
+	tlog.NewTestLogger().Init()
 	tempDir := t.TempDir()
 
 	oidcServiceCfg := service.OIDCServiceConfig{

internal/middleware/context_middleware.go

@@ -24,6 +24,7 @@ var (
 		"GET /api/oidc/clients",
 		"POST /api/oidc/token",
 		"GET /api/oidc/userinfo",
+		"POST /api/oidc/userinfo",
 		"GET /resources",
 		"POST /api/user/login",
 		"GET /.well-known/openid-configuration",

internal/repository/models.go

@@ -12,6 +12,7 @@ type OidcCode struct {
 	ClientID      string
 	ExpiresAt     int64
 	Nonce         string
+	CodeChallenge string
 }
 
 type OidcToken struct {

internal/repository/oidc_queries.sql.go

@@ -17,11 +17,12 @@ INSERT INTO "oidc_codes" (
     "redirect_uri",
     "client_id",
     "expires_at",
-    "nonce"
+    "nonce",
+    "code_challenge"
 ) VALUES (
-    ?, ?, ?, ?, ?, ?, ?
+    ?, ?, ?, ?, ?, ?, ?, ?
 )
-RETURNING sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce
+RETURNING sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce, code_challenge
 `
 
 type CreateOidcCodeParams struct {
@@ -32,6 +33,7 @@ type CreateOidcCodeParams struct {
 	ClientID      string
 	ExpiresAt     int64
 	Nonce         string
+	CodeChallenge string
 }
 
 func (q *Queries) CreateOidcCode(ctx context.Context, arg CreateOidcCodeParams) (OidcCode, error) {
@@ -43,6 +45,7 @@ func (q *Queries) CreateOidcCode(ctx context.Context, arg CreateOidcCodeParams)
 		arg.ClientID,
 		arg.ExpiresAt,
 		arg.Nonce,
+		arg.CodeChallenge,
 	)
 	var i OidcCode
 	err := row.Scan(
@@ -53,6 +56,7 @@ func (q *Queries) CreateOidcCode(ctx context.Context, arg CreateOidcCodeParams)
 		&i.ClientID,
 		&i.ExpiresAt,
 		&i.Nonce,
+		&i.CodeChallenge,
 	)
 	return i, err
 }
@@ -156,7 +160,7 @@ func (q *Queries) CreateOidcUserInfo(ctx context.Context, arg CreateOidcUserInfo
 const deleteExpiredOidcCodes = `-- name: DeleteExpiredOidcCodes :many
 DELETE FROM "oidc_codes"
 WHERE "expires_at" < ?
-RETURNING sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce
+RETURNING sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce, code_challenge
 `
 
 func (q *Queries) DeleteExpiredOidcCodes(ctx context.Context, expiresAt int64) ([]OidcCode, error) {
@@ -176,6 +180,7 @@ func (q *Queries) DeleteExpiredOidcCodes(ctx context.Context, expiresAt int64) (
 			&i.ClientID,
 			&i.ExpiresAt,
 			&i.Nonce,
+			&i.CodeChallenge,
 		); err != nil {
 			return nil, err
 		}
@@ -286,7 +291,7 @@ func (q *Queries) DeleteOidcUserInfo(ctx context.Context, sub string) error {
 const getOidcCode = `-- name: GetOidcCode :one
 DELETE FROM "oidc_codes"
 WHERE "code_hash" = ?
-RETURNING sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce
+RETURNING sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce, code_challenge
 `
 
 func (q *Queries) GetOidcCode(ctx context.Context, codeHash string) (OidcCode, error) {
@@ -300,6 +305,7 @@ func (q *Queries) GetOidcCode(ctx context.Context, codeHash string) (OidcCode, e
 		&i.ClientID,
 		&i.ExpiresAt,
 		&i.Nonce,
+		&i.CodeChallenge,
 	)
 	return i, err
 }
@@ -307,7 +313,7 @@ func (q *Queries) GetOidcCode(ctx context.Context, codeHash string) (OidcCode, e
 const getOidcCodeBySub = `-- name: GetOidcCodeBySub :one
 DELETE FROM "oidc_codes"
 WHERE "sub" = ?
-RETURNING sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce
+RETURNING sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce, code_challenge
 `
 
 func (q *Queries) GetOidcCodeBySub(ctx context.Context, sub string) (OidcCode, error) {
@@ -321,12 +327,13 @@ func (q *Queries) GetOidcCodeBySub(ctx context.Context, sub string) (OidcCode, e
 		&i.ClientID,
 		&i.ExpiresAt,
 		&i.Nonce,
+		&i.CodeChallenge,
 	)
 	return i, err
 }
 
 const getOidcCodeBySubUnsafe = `-- name: GetOidcCodeBySubUnsafe :one
-SELECT sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce FROM "oidc_codes"
+SELECT sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce, code_challenge FROM "oidc_codes"
 WHERE "sub" = ?
 `
 
@@ -341,12 +348,13 @@ func (q *Queries) GetOidcCodeBySubUnsafe(ctx context.Context, sub string) (OidcC
 		&i.ClientID,
 		&i.ExpiresAt,
 		&i.Nonce,
+		&i.CodeChallenge,
 	)
 	return i, err
 }
 
 const getOidcCodeUnsafe = `-- name: GetOidcCodeUnsafe :one
-SELECT sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce FROM "oidc_codes"
+SELECT sub, code_hash, scope, redirect_uri, client_id, expires_at, nonce, code_challenge FROM "oidc_codes"
 WHERE "code_hash" = ?
 `
 
@@ -361,6 +369,7 @@ func (q *Queries) GetOidcCodeUnsafe(ctx context.Context, codeHash string) (OidcC
 		&i.ClientID,
 		&i.ExpiresAt,
 		&i.Nonce,
+		&i.CodeChallenge,
 	)
 	return i, err
 }

internal/service/oidc_service.go

@@ -81,6 +81,8 @@ type AuthorizeRequest struct {
 	RedirectURI         string `json:"redirect_uri" binding:"required"`
 	State               string `json:"state"`
 	Nonce               string `json:"nonce"`
+	CodeChallenge       string `json:"code_challenge"`
+	CodeChallengeMethod string `json:"code_challenge_method"`
 }
 
 type OIDCServiceConfig struct {
@@ -293,6 +295,13 @@ func (service *OIDCService) ValidateAuthorizeParams(req AuthorizeRequest) error
 		return errors.New("invalid_request_uri")
 	}
 
+	// PKCE code challenge method if set
+	if req.CodeChallenge != "" && req.CodeChallengeMethod != "" {
+		if req.CodeChallengeMethod != "S256" && req.CodeChallengeMethod != "plain" {
+			return errors.New("invalid_request")
+		}
+	}
+
 	return nil
 }
 
@@ -306,8 +315,7 @@ func (service *OIDCService) StoreCode(c *gin.Context, sub string, code string, r
 	// Fixed 10 minutes
 	expiresAt := time.Now().Add(time.Minute * time.Duration(10)).Unix()
 
-	// Insert the code into the database
-	_, err := service.queries.CreateOidcCode(c, repository.CreateOidcCodeParams{
+	entry := repository.CreateOidcCodeParams{
 		Sub:      sub,
 		CodeHash: service.Hash(code),
 		// Here it's safe to split and trust the output since, we validated the scopes before
@@ -316,7 +324,19 @@ func (service *OIDCService) StoreCode(c *gin.Context, sub string, code string, r
 		ClientID:    req.ClientID,
 		ExpiresAt:   expiresAt,
 		Nonce:       req.Nonce,
-	})
+	}
+
+	if req.CodeChallenge != "" {
+		if req.CodeChallengeMethod == "S256" {
+			entry.CodeChallenge = req.CodeChallenge
+		} else {
+			entry.CodeChallenge = service.hashAndEncodePKCE(req.CodeChallenge)
+			tlog.App.Warn().Msg("Received plain PKCE code challenge, it's recommended to use S256 for better security")
+		}
+	}
+
+	// Insert the code into the database
+	_, err := service.queries.CreateOidcCode(c, entry)
 
 	return err
 }
@@ -728,3 +748,16 @@ func (service *OIDCService) GetJWK() ([]byte, error) {
 
 	return jwk.Public().MarshalJSON()
 }
+
+func (service *OIDCService) ValidatePKCE(codeChallenge string, codeVerifier string) bool {
+	if codeChallenge == "" {
+		return true
+	}
+	return codeChallenge == service.hashAndEncodePKCE(codeVerifier)
+}
+
+func (service *OIDCService) hashAndEncodePKCE(codeVerifier string) string {
+	hasher := sha256.New()
+	hasher.Write([]byte(codeVerifier))
+	return base64.RawURLEncoding.EncodeToString(hasher.Sum(nil))
+}

internal/utils/tlog/log_wrapper.go

@@ -55,6 +55,17 @@ func NewSimpleLogger() *Logger {
 	})
 }
 
+func NewTestLogger() *Logger {
+	return NewLogger(config.LogConfig{
+		Level: "trace",
+		Streams: config.LogStreams{
+			HTTP:  config.LogStreamConfig{Enabled: true},
+			App:   config.LogStreamConfig{Enabled: true},
+			Audit: config.LogStreamConfig{Enabled: true},
+		},
+	})
+}
+
 func (l *Logger) Init() {
 	Audit = l.Audit
 	HTTP = l.HTTP

sql/oidc_queries.sql

@@ -6,9 +6,10 @@ INSERT INTO "oidc_codes" (
     "redirect_uri",
     "client_id",
     "expires_at",
-    "nonce"
+    "nonce",
+    "code_challenge"
 ) VALUES (
-    ?, ?, ?, ?, ?, ?, ?
+    ?, ?, ?, ?, ?, ?, ?, ?
 )
 RETURNING *;
 

sql/oidc_schemas.sql

@@ -5,7 +5,8 @@ CREATE TABLE IF NOT EXISTS "oidc_codes" (
     "redirect_uri" TEXT NOT NULL,
     "client_id" TEXT NOT NULL,
     "expires_at" INTEGER NOT NULL,
-    "nonce" TEXT DEFAULT ""
+    "nonce" TEXT DEFAULT "",
+    "code_challenge" TEXT DEFAULT ""
 );
 
 CREATE TABLE IF NOT EXISTS "oidc_tokens" (

sqlc.yml

@@ -26,3 +26,5 @@ sql:
             go_type: "string"
           - column: "oidc_tokens.nonce"
             go_type: "string"
+          - column: "oidc_codes.code_challenge"
+            go_type: "string"