feat: add CaptchaDecodeError type and retry transient HTTP errors during captcha polling

internal/sarin/captcha.go

@@ -14,10 +14,10 @@ import (
 
 const (
 	captchaPollInterval = 1 * time.Second
-	captchaTimeout      = 120 * time.Second
+	captchaPollTimeout  = 120 * time.Second
 )
 
-var captchaHTTPClient = &http.Client{Timeout: captchaTimeout}
+var captchaHTTPClient = &http.Client{Timeout: 5 * time.Second}
 
 // solveCaptcha creates a task on the given captcha service and polls until it is solved,
 // returning the extracted token from the solution object.
@@ -31,8 +31,9 @@ var captchaHTTPClient = &http.Client{Timeout: captchaTimeout}
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func solveCaptcha(baseURL, apiKey string, task map[string]any, solutionKey string, taskIDIsString bool) (string, error) {
 	if apiKey == "" {
@@ -52,6 +53,7 @@ func solveCaptcha(baseURL, apiKey string, task map[string]any, solutionKey strin
 //
 // It can return the following errors:
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
 func captchaCreateTask(baseURL, apiKey string, task map[string]any) (string, error) {
 	body := map[string]any{
@@ -61,7 +63,7 @@ func captchaCreateTask(baseURL, apiKey string, task map[string]any) (string, err
 
 	data, err := json.Marshal(body)
 	if err != nil {
-		return "", types.NewCaptchaRequestError("createTask", err)
+		return "", types.NewCaptchaDecodeError("createTask", err)
 	}
 
 	resp, err := captchaHTTPClient.Post(
@@ -81,7 +83,7 @@ func captchaCreateTask(baseURL, apiKey string, task map[string]any) (string, err
 		TaskID           json.RawMessage `json:"taskId"`
 	}
 	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
-		return "", types.NewCaptchaRequestError("createTask", err)
+		return "", types.NewCaptchaDecodeError("createTask", err)
 	}
 
 	if result.ErrorID != 0 {
@@ -98,15 +100,15 @@ func captchaCreateTask(baseURL, apiKey string, task map[string]any) (string, err
 }
 
 // captchaPollResult polls the getTaskResult endpoint at captchaPollInterval until the task
-// is solved, an error is returned by the service, or the overall captchaTimeout is hit.
+// is solved, an error is returned by the service, or the overall captchaPollTimeout is hit.
 //
 // It can return the following errors:
-//   - types.CaptchaTimeoutError
-//   - types.CaptchaRequestError
+//   - types.CaptchaPollTimeoutError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
 //   - types.CaptchaSolutionKeyError
 func captchaPollResult(baseURL, apiKey, taskID, solutionKey string, taskIDIsString bool) (string, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), captchaTimeout)
+	ctx, cancel := context.WithTimeout(context.Background(), captchaPollTimeout)
 	defer cancel()
 
 	ticker := time.NewTicker(captchaPollInterval)
@@ -115,12 +117,18 @@ func captchaPollResult(baseURL, apiKey, taskID, solutionKey string, taskIDIsStri
 	for {
 		select {
 		case <-ctx.Done():
-			return "", types.NewCaptchaTimeoutError(taskID)
+			return "", types.NewCaptchaPollTimeoutError(taskID)
 		case <-ticker.C:
 			token, err := captchaGetTaskResult(baseURL, apiKey, taskID, solutionKey, taskIDIsString)
 			if errors.Is(err, types.ErrCaptchaProcessing) {
 				continue
 			}
+			// Retry on transient HTTP errors (timeouts, connection resets, etc.)
+			// instead of failing the entire solve. The poll loop timeout will
+			// eventually catch permanently unreachable services.
+			if _, ok := errors.AsType[types.CaptchaRequestError](err); ok {
+				continue
+			}
 			if err != nil {
 				return "", err
 			}
@@ -134,6 +142,7 @@ func captchaPollResult(baseURL, apiKey, taskID, solutionKey string, taskIDIsStri
 // It can return the following errors:
 //   - types.ErrCaptchaProcessing
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
 //   - types.CaptchaSolutionKeyError
 func captchaGetTaskResult(baseURL, apiKey, taskID, solutionKey string, taskIDIsString bool) (string, error) {
@@ -146,7 +155,7 @@ func captchaGetTaskResult(baseURL, apiKey, taskID, solutionKey string, taskIDIsS
 
 	data, err := json.Marshal(bodyMap)
 	if err != nil {
-		return "", types.NewCaptchaRequestError("getTaskResult", err)
+		return "", types.NewCaptchaDecodeError("getTaskResult", err)
 	}
 
 	resp, err := captchaHTTPClient.Post(
@@ -167,7 +176,7 @@ func captchaGetTaskResult(baseURL, apiKey, taskID, solutionKey string, taskIDIsS
 		Solution         map[string]any `json:"solution"`
 	}
 	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
-		return "", types.NewCaptchaRequestError("getTaskResult", err)
+		return "", types.NewCaptchaDecodeError("getTaskResult", err)
 	}
 
 	if result.ErrorID != 0 {
@@ -199,8 +208,9 @@ const twoCaptchaBaseURL = "https://api.2captcha.com"
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func twoCaptchaSolveRecaptchaV2(apiKey, websiteURL, websiteKey string) (string, error) {
 	return solveCaptcha(twoCaptchaBaseURL, apiKey, map[string]any{
@@ -216,8 +226,9 @@ func twoCaptchaSolveRecaptchaV2(apiKey, websiteURL, websiteKey string) (string,
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func twoCaptchaSolveRecaptchaV3(apiKey, websiteURL, websiteKey, pageAction string) (string, error) {
 	task := map[string]any{
@@ -237,8 +248,9 @@ func twoCaptchaSolveRecaptchaV3(apiKey, websiteURL, websiteKey, pageAction strin
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func twoCaptchaSolveTurnstile(apiKey, websiteURL, websiteKey, cData string) (string, error) {
 	task := map[string]any{
@@ -261,8 +273,9 @@ const antiCaptchaBaseURL = "https://api.anti-captcha.com"
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func antiCaptchaSolveRecaptchaV2(apiKey, websiteURL, websiteKey string) (string, error) {
 	return solveCaptcha(antiCaptchaBaseURL, apiKey, map[string]any{
@@ -279,8 +292,9 @@ func antiCaptchaSolveRecaptchaV2(apiKey, websiteURL, websiteKey string) (string,
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func antiCaptchaSolveRecaptchaV3(apiKey, websiteURL, websiteKey, pageAction string) (string, error) {
 	task := map[string]any{
@@ -301,8 +315,9 @@ func antiCaptchaSolveRecaptchaV3(apiKey, websiteURL, websiteKey, pageAction stri
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func antiCaptchaSolveHCaptcha(apiKey, websiteURL, websiteKey string) (string, error) {
 	return solveCaptcha(antiCaptchaBaseURL, apiKey, map[string]any{
@@ -318,8 +333,9 @@ func antiCaptchaSolveHCaptcha(apiKey, websiteURL, websiteKey string) (string, er
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func antiCaptchaSolveTurnstile(apiKey, websiteURL, websiteKey, cData string) (string, error) {
 	task := map[string]any{
@@ -342,8 +358,9 @@ const capSolverBaseURL = "https://api.capsolver.com"
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func capSolverSolveRecaptchaV2(apiKey, websiteURL, websiteKey string) (string, error) {
 	return solveCaptcha(capSolverBaseURL, apiKey, map[string]any{
@@ -359,8 +376,9 @@ func capSolverSolveRecaptchaV2(apiKey, websiteURL, websiteKey string) (string, e
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func capSolverSolveRecaptchaV3(apiKey, websiteURL, websiteKey, pageAction string) (string, error) {
 	task := map[string]any{
@@ -380,8 +398,9 @@ func capSolverSolveRecaptchaV3(apiKey, websiteURL, websiteKey, pageAction string
 // It can return the following errors:
 //   - types.ErrCaptchaKeyEmpty
 //   - types.CaptchaRequestError
+//   - types.CaptchaDecodeError
 //   - types.CaptchaAPIError
-//   - types.CaptchaTimeoutError
+//   - types.CaptchaPollTimeoutError
 //   - types.CaptchaSolutionKeyError
 func capSolverSolveTurnstile(apiKey, websiteURL, websiteKey, cData string) (string, error) {
 	task := map[string]any{

internal/types/errors.go

@@ -520,15 +520,35 @@ func (e CaptchaRequestError) Unwrap() error {
 	return e.Err
 }
 
-type CaptchaTimeoutError struct {
+type CaptchaDecodeError struct {
+	Endpoint string
+	Err      error
+}
+
+func NewCaptchaDecodeError(endpoint string, err error) CaptchaDecodeError {
+	if err == nil {
+		err = errNoError
+	}
+	return CaptchaDecodeError{Endpoint: endpoint, Err: err}
+}
+
+func (e CaptchaDecodeError) Error() string {
+	return fmt.Sprintf("captcha %s decode failed: %v", e.Endpoint, e.Err)
+}
+
+func (e CaptchaDecodeError) Unwrap() error {
+	return e.Err
+}
+
+type CaptchaPollTimeoutError struct {
 	TaskID string
 }
 
-func NewCaptchaTimeoutError(taskID string) CaptchaTimeoutError {
-	return CaptchaTimeoutError{TaskID: taskID}
+func NewCaptchaPollTimeoutError(taskID string) CaptchaPollTimeoutError {
+	return CaptchaPollTimeoutError{TaskID: taskID}
 }
 
-func (e CaptchaTimeoutError) Error() string {
+func (e CaptchaPollTimeoutError) Error() string {
 	return fmt.Sprintf("captcha solving timed out (taskId: %s)", e.TaskID)
 }