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Recovery

// Copyright 2014 Manu Martinez-Almeida.  All rights reserved.
// Use of this source code is governed by a MIT style
// license that can be found in the LICENSE file.

package gin

import (
"bytes"
"fmt"
"io"
"io/ioutil"
"log"
"net"
"net/http"
"net/http/httputil"
"os"
"runtime"
"strings"
"time"
)

var (
dunno = []byte("???")
centerDot = []byte("·")
dot = []byte(".")
slash = []byte("/")
)

// RecoveryFunc defines the function passable to CustomRecovery.
type RecoveryFunc func(c *Context, err interface{})

// Recovery returns a middleware that recovers from any panics and writes a 500 if there was one.
func Recovery() HandlerFunc {
return RecoveryWithWriter(DefaultErrorWriter)
}

//CustomRecovery returns a middleware that recovers from any panics and calls the provided handle func to handle it.
func CustomRecovery(handle RecoveryFunc) HandlerFunc {
return RecoveryWithWriter(DefaultErrorWriter, handle)
}

// RecoveryWithWriter returns a middleware for a given writer that recovers from any panics and writes a 500 if there was one.
func RecoveryWithWriter(out io.Writer, recovery ...RecoveryFunc) HandlerFunc {
if len(recovery) > 0 {
return CustomRecoveryWithWriter(out, recovery[0])
}
return CustomRecoveryWithWriter(out, defaultHandleRecovery)
}

// CustomRecoveryWithWriter returns a middleware for a given writer that recovers from any panics and calls the provided handle func to handle it.
func CustomRecoveryWithWriter(out io.Writer, handle RecoveryFunc) HandlerFunc {
var logger *log.Logger
if out != nil {
logger = log.New(out, "\n\n\x1b[31m", log.LstdFlags)
}
return func(c *Context) {
defer func() {
if err := recover(); err != nil {
// Check for a broken connection, as it is not really a
// condition that warrants a panic stack trace.
var brokenPipe bool
if ne, ok := err.(*net.OpError); ok {
if se, ok := ne.Err.(*os.SyscallError); ok {
if strings.Contains(strings.ToLower(se.Error()), "broken pipe") || strings.Contains(strings.ToLower(se.Error()), "connection reset by peer") {
brokenPipe = true
}
}
}
if logger != nil {
stack := stack(3)
httpRequest, _ := httputil.DumpRequest(c.Request, false)
headers := strings.Split(string(httpRequest), "\r\n")
for idx, header := range headers {
current := strings.Split(header, ":")
if current[0] == "Authorization" {
headers[idx] = current[0] + ": *"
}
}
headersToStr := strings.Join(headers, "\r\n")
if brokenPipe {
logger.Printf("%s\n%s%s", err, headersToStr, reset)
} else if IsDebugging() {
logger.Printf("[Recovery] %s panic recovered:\n%s\n%s\n%s%s",
timeFormat(time.Now()), headersToStr, err, stack, reset)
} else {
logger.Printf("[Recovery] %s panic recovered:\n%s\n%s%s",
timeFormat(time.Now()), err, stack, reset)
}
}
if brokenPipe {
// If the connection is dead, we can't write a status to it.
c.Error(err.(error)) // nolint: errcheck
c.Abort()
} else {
handle(c, err)
}
}
}()
c.Next()
}
}

func defaultHandleRecovery(c *Context, err interface{}) {
c.AbortWithStatus(http.StatusInternalServerError)
}

// stack returns a nicely formatted stack frame, skipping skip frames.
func stack(skip int) []byte {
buf := new(bytes.Buffer) // the returned data
// As we loop, we open files and read them. These variables record the currently
// loaded file.
var lines [][]byte
var lastFile string
for i := skip; ; i++ { // Skip the expected number of frames
pc, file, line, ok := runtime.Caller(i)
if !ok {
break
}
// Print this much at least. If we can't find the source, it won't show.
fmt.Fprintf(buf, "%s:%d (0x%x)\n", file, line, pc)
if file != lastFile {
data, err := ioutil.ReadFile(file)
if err != nil {
continue
}
lines = bytes.Split(data, []byte{'\n'})
lastFile = file
}
fmt.Fprintf(buf, "\t%s: %s\n", function(pc), source(lines, line))
}
return buf.Bytes()
}

// source returns a space-trimmed slice of the n'th line.
func source(lines [][]byte, n int) []byte {
n-- // in stack trace, lines are 1-indexed but our array is 0-indexed
if n < 0 || n >= len(lines) {
return dunno
}
return bytes.TrimSpace(lines[n])
}

// function returns, if possible, the name of the function containing the PC.
func function(pc uintptr) []byte {
fn := runtime.FuncForPC(pc)
if fn == nil {
return dunno
}
name := []byte(fn.Name())
// The name includes the path name to the package, which is unnecessary
// since the file name is already included. Plus, it has center dots.
// That is, we see
// runtime/debug.*T·ptrmethod
// and want
// *T.ptrmethod
// Also the package path might contains dot (e.g. code.google.com/...),
// so first eliminate the path prefix
if lastSlash := bytes.LastIndex(name, slash); lastSlash >= 0 {
name = name[lastSlash+1:]
}
if period := bytes.Index(name, dot); period >= 0 {
name = name[period+1:]
}
name = bytes.Replace(name, centerDot, dot, -1)
return name
}

func timeFormat(t time.Time) string {
timeString := t.Format("2006/01/02 - 15:04:05")
return timeString
}