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package caddyhttp
import (
"fmt"
mathrand "math/rand"
"path"
"runtime"
"strings"
"bitbucket.org/lightcodelabs/caddy2"
)
// Error is a convenient way for a Handler to populate the
// essential fields of a HandlerError. If err is itself a
// HandlerError, then any essential fields that are not
// set will be populated.
func Error(statusCode int, err error) HandlerError {
const idLen = 9
if he, ok := err.(HandlerError); ok {
if he.ID == "" {
he.ID = randString(idLen, true)
}
if he.Trace == "" {
he.Trace = trace()
}
if he.StatusCode == 0 {
he.StatusCode = statusCode
}
return he
}
return HandlerError{
ID: randString(idLen, true),
StatusCode: statusCode,
Err: err,
Trace: trace(),
}
}
// HandlerError is a serializable representation of
// an error from within an HTTP handler.
type HandlerError struct {
Err error // the original error value and message
StatusCode int // the HTTP status code to associate with this error
Message string // an optional message that can be shown to the user
Recommendations []string // an optional list of things to try to resolve the error
ID string // generated; for identifying this error in logs
Trace string // produced from call stack
}
func (e HandlerError) Error() string {
var s string
if e.ID != "" {
s += fmt.Sprintf("{id=%s}", e.ID)
}
if e.Trace != "" {
s += " " + e.Trace
}
if e.StatusCode != 0 {
s += fmt.Sprintf(": HTTP %d", e.StatusCode)
}
if e.Err != nil {
s += ": " + e.Err.Error()
}
return strings.TrimSpace(s)
}
// randString returns a string of n random characters.
// It is not even remotely secure OR a proper distribution.
// But it's good enough for some things. It excludes certain
// confusing characters like I, l, 1, 0, O, etc. If sameCase
// is true, then uppercase letters are excluded.
func randString(n int, sameCase bool) string {
if n <= 0 {
return ""
}
dict := []byte("abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRTUVWXY23456789")
if sameCase {
dict = []byte("abcdefghijkmnpqrstuvwxyz0123456789")
}
b := make([]byte, n)
for i := range b {
b[i] = dict[mathrand.Int63()%int64(len(dict))]
}
return string(b)
}
func trace() string {
if pc, file, line, ok := runtime.Caller(2); ok {
filename := path.Base(file)
pkgAndFuncName := path.Base(runtime.FuncForPC(pc).Name())
return fmt.Sprintf("%s (%s:%d)", pkgAndFuncName, filename, line)
}
return ""
}
// ErrRehandle is a special error value that Handlers should return
// from their ServeHTTP() method if the request is to be re-processed.
// This error value is a sentinel value that should not be wrapped or
// modified.
var ErrRehandle = fmt.Errorf("rehandling request")
// ErrorCtxKey is the context key to use when storing
// an error (for use with context.Context).
const ErrorCtxKey = caddy2.CtxKey("handler_chain_error")
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