Refactor: Simplify errors for wrapping

1 files changed, 80 insertions, 62 deletions

diff --git a/src/oauth.go b/src/oauth.go
index 6212124..5b7a5c4 100644
--- a/src/oauth.go
+++ b/src/oauth.go
@@ -12,6 +12,22 @@ import (
 	"strings"
 )
 
+type OAuthGenStateUnableError struct {
+	Err error
+}
+
+func (e *OAuthGenStateUnableError) Error() string {
+	return fmt.Sprintf("failed generating state with error %v", e.Err)
+}
+
+type OAuthGenVerifierUnableError struct {
+	Err error
+}
+
+func (e *OAuthGenVerifierUnableError) Error() string {
+	return fmt.Sprintf("failed generating verifier with error %v", e.Err)
+}
+
 // Generates a random base64 string to be used for state
 // https://datatracker.ietf.org/doc/html/draft-ietf-oauth-v2-1-04#section-4.1.1
 // "state":  OPTIONAL.  An opaque value used by the client to maintain
@@ -22,7 +38,7 @@ func genState() (string, error) {
 	randomBytes, err := MakeRandomByteSlice(32)
 
 	if err != nil {
-		return "", err
+		return "", &OAuthGenStateUnableError{Err: err}
 	}
 
 	// For consistency we also use raw url encoding here
@@ -48,7 +64,7 @@ func genChallengeS256(verifier string) string {
 func genVerifier() (string, error) {
 	randomBytes, err := MakeRandomByteSlice(32)
 	if err != nil {
-		return "", err
+		return "", &OAuthGenVerifierUnableError{Err: err}
 	}
 
 	return base64.RawURLEncoding.EncodeToString(randomBytes), nil
@@ -76,17 +92,27 @@ type EduVPNOAuthToken struct {
 	Expires int    `json:"expires_in"`
 }
 
+type OAuthFailedCallbackError struct {
+	Addr string
+	Err  error
+}
+
+func (e *OAuthFailedCallbackError) Error() string {
+	return fmt.Sprintf("failed callback %s with error %v", e.Addr, e.Err)
+}
+
 // Gets an authenticated HTTP client by obtaining refresh and access tokens
 func (eduvpn *EduVPNOAuthSession) getHTTPTokenClient() error {
 	eduvpn.context = context.Background()
 	mux := http.NewServeMux()
+	addr := "127.0.0.1:8000"
 	eduvpn.server = &http.Server{
-		Addr:    "127.0.0.1:8000",
+		Addr:    addr,
 		Handler: mux,
 	}
 	mux.HandleFunc("/callback", eduvpn.oauthCallback)
 	if err := eduvpn.server.ListenAndServe(); err != http.ErrServerClosed {
-		return detailedOAuthError{errCallbackServerError, fmt.Sprintf("oauth callback server error"), err}
+		return &OAuthFailedCallbackError{Addr: addr, Err: err}
 	}
 	return eduvpn.callbackError
 }
@@ -106,15 +132,16 @@ func (eduvpn *EduVPNOAuthSession) getTokens(authCode string) error {
 		"redirect_uri":  {"http://127.0.0.1:8000/callback"},
 	}
 	client := &http.Client{}
-	req, reqErr := http.NewRequest(http.MethodPost, eduvpn.VPNState.Endpoints.API.V3.Token, strings.NewReader(data.Encode()))
-	if reqErr != nil {
-		return reqErr
+	url := eduvpn.VPNState.Endpoints.API.V3.Token
+	req, reqErr := http.NewRequest(http.MethodPost, url, strings.NewReader(data.Encode()))
+	if reqErr != nil { // shouldn't happen
+		panic(reqErr)
 	}
 	req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
 	resp, reqErr := client.Do(req)
 
 	if reqErr != nil {
-		return reqErr
+		return &HTTPResourceError{URL: url, Err: reqErr}
 	}
 
 	// Close the response body at the end
@@ -123,14 +150,14 @@ func (eduvpn *EduVPNOAuthSession) getTokens(authCode string) error {
 	// Read the body
 	body, readErr := ioutil.ReadAll(resp.Body)
 	if readErr != nil {
-		return readErr
+		return &HTTPReadError{URL: url, Err: readErr}
 	}
 
 	tokenStructure := &EduVPNOAuthToken{}
 	jsonErr := json.Unmarshal(body, tokenStructure)
 
 	if jsonErr != nil {
-		return jsonErr
+		return &HTTPParseJsonError{URL: url, Body: string(body), Err: jsonErr}
 	}
 
 	eduvpn.VPNState.OAuthToken = tokenStructure
@@ -138,13 +165,39 @@ func (eduvpn *EduVPNOAuthSession) getTokens(authCode string) error {
 	return nil
 }
 
+type OAuthFailedCallbackParameterError struct {
+	Parameter string
+	URL       string
+}
+
+func (e *OAuthFailedCallbackParameterError) Error() string {
+	return fmt.Sprintf("failed retrieving parameter %s in url %s", e.Parameter, e.URL)
+}
+
+type OAuthFailedCallbackStateMatchError struct {
+	State         string
+	ExpectedState string
+}
+
+func (e *OAuthFailedCallbackStateMatchError) Error() string {
+	return fmt.Sprintf("failed matching state, got %s, want %s", e.State, e.ExpectedState)
+}
+
+type OAuthFailedCallbackGetTokensError struct {
+	Err error
+}
+
+func (e *OAuthFailedCallbackGetTokensError) Error() string {
+	return fmt.Sprintf("failed getting tokens with error %v", e.Err)
+}
+
 //
 //// The callback to retrieve the authorization code: https://datatracker.ietf.org/doc/html/draft-ietf-oauth-v2-1-04#section-1.3.1
 func (eduvpn *EduVPNOAuthSession) oauthCallback(w http.ResponseWriter, req *http.Request) {
 	// Extract the authorization code
 	code, success := req.URL.Query()["code"]
 	if !success {
-		eduvpn.callbackError = detailedOAuthError{errCallbackGetAuthCodeError, fmt.Sprintf("oauth auth code cannot be retrieved"), nil}
+		eduvpn.callbackError = &OAuthFailedCallbackParameterError{Parameter: "code", URL: req.URL.String()}
 		go eduvpn.server.Shutdown(eduvpn.context)
 		return
 	}
@@ -155,14 +208,14 @@ func (eduvpn *EduVPNOAuthSession) oauthCallback(w http.ResponseWriter, req *http
 	// https://datatracker.ietf.org/doc/html/draft-ietf-oauth-v2-1-04#section-7.15
 	state, success := req.URL.Query()["state"]
 	if !success {
-		eduvpn.callbackError = detailedOAuthError{errCallbackGetStateError, fmt.Sprintf("oauth state cannot be retrieved"), nil}
+		eduvpn.callbackError = &OAuthFailedCallbackParameterError{Parameter: "state", URL: req.URL.String()}
 		go eduvpn.server.Shutdown(eduvpn.context)
 		return
 	}
 	// The state is the first entry
 	extractedState := state[0]
 	if extractedState != eduvpn.state {
-		eduvpn.callbackError = detailedOAuthError{errCallbackVerifyStateMatchError, fmt.Sprintf("oauth state does not match"), nil}
+		eduvpn.callbackError = &OAuthFailedCallbackStateMatchError{State: extractedState, ExpectedState: eduvpn.state}
 		go eduvpn.server.Shutdown(eduvpn.context)
 		return
 	}
@@ -172,7 +225,7 @@ func (eduvpn *EduVPNOAuthSession) oauthCallback(w http.ResponseWriter, req *http
 	err := eduvpn.getTokens(extractedCode)
 
 	if err != nil {
-		eduvpn.callbackError = detailedOAuthError{errCallbackGetTokenExchangeError, fmt.Sprintf("oauth failed to get token in exchange"), err}
+		eduvpn.callbackError = &OAuthFailedCallbackGetTokensError{Err: err}
 		go eduvpn.server.Shutdown(eduvpn.context)
 		return
 	}
@@ -197,6 +250,14 @@ func constructURL(baseURL string, parameters map[string]string) (string, error)
 	return url.String(), nil
 }
 
+type OAuthFailedInitializeError struct {
+	Err error
+}
+
+func (e *OAuthFailedInitializeError) Error() string {
+	return fmt.Sprintf("failed initializing OAuth with error %v", e.Err)
+}
+
 // Initializes the OAuth for eduvpn.
 // It needs a vpn state that was gotten from `Register`
 // It returns the authurl for the browser and an error if present
@@ -208,13 +269,13 @@ func InitializeOAuth(vpnState *EduVPNState) (string, error) {
 	// Generate the state
 	state, stateErr := genState()
 	if stateErr != nil {
-		return "", detailedOAuthError{errGenStateError, fmt.Sprintf("oauth failed to gen random bytes for state"), stateErr}
+		return "", &OAuthFailedInitializeError{Err: stateErr}
 	}
 
 	// Generate the verifier and challenge
-	verifier, err := genVerifier()
-	if err != nil {
-		return "", detailedOAuthError{errGenVerifierError, fmt.Sprintf("oauth failed to verifier"), err}
+	verifier, verifierErr := genVerifier()
+	if verifierErr != nil {
+		return "", &OAuthFailedInitializeError{Err: verifierErr}
 	}
 	challenge := genChallengeS256(verifier)
 
@@ -230,7 +291,7 @@ func InitializeOAuth(vpnState *EduVPNState) (string, error) {
 
 	authURL, urlErr := constructURL(vpnState.Endpoints.API.V3.Authorization, parameters)
 
-	if urlErr != nil {
+	if urlErr != nil { // shouldn't happen
 		panic(urlErr)
 	}
 
@@ -249,46 +310,3 @@ func FinishOAuth(vpnState *EduVPNState) error {
 	}
 	return vpnState.OAuthSession.getHTTPTokenClient()
 }
-
-// OAuthErrorCode Simplified error code for public interface.
-type OAuthErrorCode = VPNErrorCode
-type OAuthError = VPNError
-
-// detailedOAuthErrorCode used for unit tests.
-type detailedOAuthErrorCode = detailedVPNErrorCode
-type detailedOAuthError = detailedVPNError
-
-const (
-	ErrGenError OAuthErrorCode = iota + 1
-	ErrCallbackTokenError
-)
-
-const (
-	errGenStateError detailedOAuthErrorCode = iota + 1
-	errGenVerifierError
-	errCallbackServerError
-	errCallbackGetAuthCodeError
-	errCallbackGetStateError
-	errCallbackVerifyStateMatchError
-	errCallbackGetTokenExchangeError
-)
-
-func (err detailedOAuthError) ToOAuthError() OAuthError {
-	return RequestError{err.Code.ToOAuthErrorCode(), err}
-}
-
-func (code detailedOAuthErrorCode) ToOAuthErrorCode() OAuthErrorCode {
-	switch code {
-	case errGenStateError:
-	case errGenVerifierError:
-		return ErrGenError
-
-	case errCallbackServerError:
-	case errCallbackGetAuthCodeError:
-	case errCallbackGetStateError:
-	case errCallbackVerifyStateMatchError:
-	case errCallbackGetTokenExchangeError:
-		return ErrCallbackTokenError
-	}
-	panic("invalid detailedOAuthErrorCode")
-}