122 lines
3.3 KiB
Go
122 lines
3.3 KiB
Go
// Copyright (c) 2020-2022 The Decred developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package webapi
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import (
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"bytes"
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"fmt"
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"net"
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"net/http"
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"net/http/httputil"
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"os"
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"runtime"
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"strings"
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"github.com/decred/slog"
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"github.com/gin-gonic/gin"
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)
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// Recovery returns a middleware that recovers from any panics which occur in
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// request handlers. It logs the panic, a stack trace, and the full request
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// details. It also ensure the client receives a 500 response rather than no
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// response at all.
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func Recovery(log slog.Logger) gin.HandlerFunc {
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return func(c *gin.Context) {
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defer func() {
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if err := recover(); err != nil {
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// Check for a broken connection, as it is not really a
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// condition that warrants a panic stack trace.
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var brokenPipe bool
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if ne, ok := err.(*net.OpError); ok {
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if se, ok := ne.Err.(*os.SyscallError); ok {
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if strings.Contains(strings.ToLower(se.Error()), "broken pipe") ||
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strings.Contains(strings.ToLower(se.Error()), "connection reset by peer") {
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brokenPipe = true
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}
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}
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}
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httpRequest, _ := httputil.DumpRequest(c.Request, true)
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if brokenPipe {
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log.Errorf("%s\n%s", err, httpRequest)
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} else {
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log.Errorf("panic recovered: %s\n\n%s\n\n%s",
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err, formattedStack(), httpRequest)
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}
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if brokenPipe {
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// If the connection is dead, we can't write a status to it.
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_ = c.Error(err.(error))
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c.Abort()
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} else {
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c.AbortWithStatus(http.StatusInternalServerError)
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}
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}
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}()
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c.Next()
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}
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}
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// formattedStack returns a nicely formatted stack frame.
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func formattedStack() []byte {
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buf := new(bytes.Buffer)
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// As we loop, we open files and read them. These variables record the
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// currently loaded file.
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var lines [][]byte
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var lastFile string
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for i := 3; ; i++ {
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pc, file, line, ok := runtime.Caller(i)
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if !ok {
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break
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}
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// Print this much at least. If we can't find the source, it won't show.
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fmt.Fprintf(buf, "%s:%d (0x%x)\n", file, line, pc)
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if file != lastFile {
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data, err := os.ReadFile(file)
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if err != nil {
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continue
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}
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lines = bytes.Split(data, []byte{'\n'})
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lastFile = file
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}
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fmt.Fprintf(buf, "\t%s: %s\n", function(pc), source(lines, line))
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}
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return buf.Bytes()
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}
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// source returns a space-trimmed slice of the n'th line.
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func source(lines [][]byte, n int) []byte {
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n-- // in stack trace, lines are 1-indexed but our array is 0-indexed
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if n < 0 || n >= len(lines) {
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return []byte("???")
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}
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return bytes.TrimSpace(lines[n])
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}
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// function returns, if possible, the name of the function containing the PC.
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func function(pc uintptr) []byte {
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fn := runtime.FuncForPC(pc)
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if fn == nil {
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return []byte("???")
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}
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name := []byte(fn.Name())
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// The name includes the path name to the package, which is unnecessary
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// since the file name is already included. Plus, it has center dots.
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// That is, we see
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// runtime/debug.*T·ptrmethod
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// and want
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// *T.ptrmethod
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// Also the package path might contain dot (e.g. code.google.com/...),
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// so first eliminate the path prefix
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if lastSlash := bytes.LastIndex(name, []byte("/")); lastSlash >= 0 {
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name = name[lastSlash+1:]
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}
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if period := bytes.Index(name, []byte(".")); period >= 0 {
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name = name[period+1:]
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}
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name = bytes.Replace(name, []byte("·"), []byte("."), -1)
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return name
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}
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