websocket api recovery middleware (logging)

internal/websocket/app.go

@@ -16,7 +16,7 @@ type Server struct {
 func NewServer(addr string) *Server {
 	router := gin.New()
 
-	router.Use(gin.Recovery())
+	router.Use(RecoveryMiddleware())
 	router.Use(http.RequestIdMiddleware())
 	router.Use(http.CorrelationIdMiddleware())
 	router.Use(http.RequestJsonLogger())

internal/websocket/recovery.go

@@ -0,0 +1,89 @@
+package websocket
+
+import (
+	"bytes"
+	"fmt"
+	"github.com/gin-gonic/gin"
+	"github.com/twofas/2fas-server/internal/common/logging"
+	"io/ioutil"
+	"runtime"
+)
+
+func RecoveryMiddleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		defer func() {
+			if err := recover(); err != nil {
+				stack := stack(3)
+
+				logging.WithFields(logging.Fields{
+					"stack": string(stack),
+					"error": err,
+				}).Error("Panic")
+			}
+		}()
+
+		c.Next()
+	}
+}
+
+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 []byte("???")
+	}
+	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 []byte("???")
+	}
+
+	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 contain dot (e.g. code.google.com/...),
+	// so first eliminate the path prefix
+	if lastSlash := bytes.LastIndex(name, []byte("/")); lastSlash >= 0 {
+		name = name[lastSlash+1:]
+	}
+	if period := bytes.Index(name, []byte(".")); period >= 0 {
+		name = name[period+1:]
+	}
+	name = bytes.Replace(name, []byte("·"), []byte("."), -1)
+	return name
+}