// Notify the client of an error condition and log it for audit purposes.
func (wfe *WebFrontEndImpl) sendError(response http.ResponseWriter, msg string, detail interface{}, code int) {
problem := core.ProblemDetails{Detail: msg}
switch code {
case http.StatusPreconditionFailed:
fallthrough
case http.StatusForbidden:
problem.Type = core.UnauthorizedProblem
case http.StatusConflict:
fallthrough
case http.StatusMethodNotAllowed:
fallthrough
case http.StatusNotFound:
fallthrough
case http.StatusBadRequest:
fallthrough
case http.StatusLengthRequired:
problem.Type = core.MalformedProblem
default: // Either http.StatusInternalServerError or an unexpected code
problem.Type = core.ServerInternalProblem
}
// Only audit log internal errors so users cannot purposefully cause
// auditable events.
if problem.Type == core.ServerInternalProblem {
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
wfe.log.Audit(fmt.Sprintf("Internal error - %s - %s", msg, detail))
} else if statusCodeFromError(detail) != http.StatusInternalServerError {
// If not an internal error and problem is a custom error type
problem.Detail += fmt.Sprintf(" :: %s", detail)
}
problemDoc, err := json.Marshal(problem)
if err != nil {
// AUDIT[ Error Conditions ] 9cc4d537-8534-4970-8665-4b382abe82f3
wfe.log.Audit(fmt.Sprintf("Could not marshal error message: %s - %+v", err, problem))
problemDoc = []byte("{\"detail\": \"Problem marshalling error message.\"}")
}
// Paraphrased from
// https://golang.org/src/net/http/server.go#L1272
response.Header().Set("Content-Type", "application/problem+json")
response.WriteHeader(code)
response.Write(problemDoc)
wfe.stats.Inc(fmt.Sprintf("WFE.HTTP.ErrorCodes.%d", code), 1, 1.0)
problemSegments := strings.Split(string(problem.Type), ":")
if len(problemSegments) > 0 {
wfe.stats.Inc(fmt.Sprintf("WFE.HTTP.ProblemTypes.%s", problemSegments[len(problemSegments)-1]), 1, 1.0)
}
}