lib/ur: Implement crash (panic) reporting (fixes #959) (#5702)

* lib/ur: Implement crash (panic) reporting (fixes #959) This implements a simple crash reporting method. It piggybacks on the panic log files created by the monitor process, picking these up and uploading them from the usage reporting routine. A new config value points to the crash receiver base URL, which defaults to "https://crash.syncthing.net/newcrash" (following the pattern of "https://data.syncthing.net/newdata" for usage reports, but allowing us to separate the service as required).
2019-06-11 08:19:11 +02:00
parent 93e57bd357
commit 42ce6be9b9
19 changed files with 1925 additions and 19 deletions
--- a/cmd/stcrashreceiver/stcrashreceiver.go
+++ b/cmd/stcrashreceiver/stcrashreceiver.go
@@ -0,0 +1,135 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+// Command stcrashreceiver is a trivial HTTP server that allows two things:
+//
+// - uploading files (crash reports) named like a SHA256 hash using a PUT request
+// - checking whether such file exists using a HEAD request
+//
+// Typically this should be deployed behind something that manages HTTPS.
+package main
+
+import (
+	"flag"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+const maxRequestSize = 1 << 20 // 1 MiB
+
+func main() {
+	dir := flag.String("dir", ".", "Directory to store reports in")
+	dsn := flag.String("dsn", "", "Sentry DSN")
+	listen := flag.String("listen", ":22039", "HTTP listen address")
+	flag.Parse()
+
+	cr := &crashReceiver{
+		dir: *dir,
+		dsn: *dsn,
+	}
+
+	log.SetOutput(os.Stdout)
+	if err := http.ListenAndServe(*listen, cr); err != nil {
+		log.Fatalln("HTTP serve:", err)
+	}
+}
+
+type crashReceiver struct {
+	dir string
+	dsn string
+}
+
+func (r *crashReceiver) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	// The final path component should be a SHA256 hash in hex, so 64 hex
+	// characters. We don't care about case on the request but use lower
+	// case internally.
+	base := strings.ToLower(path.Base(req.URL.Path))
+	if len(base) != 64 {
+		http.Error(w, "Bad request", http.StatusBadRequest)
+		return
+	}
+	for _, c := range base {
+		if c >= 'a' && c <= 'f' {
+			continue
+		}
+		if c >= '0' && c <= '9' {
+			continue
+		}
+		http.Error(w, "Bad request", http.StatusBadRequest)
+		return
+	}
+
+	switch req.Method {
+	case http.MethodHead:
+		r.serveHead(base, w, req)
+	case http.MethodPut:
+		r.servePut(base, w, req)
+	default:
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+	}
+}
+
+// serveHead responds to HEAD requests by checking if the named report
+// already exists in the system.
+func (r *crashReceiver) serveHead(base string, w http.ResponseWriter, _ *http.Request) {
+	path := filepath.Join(r.dirFor(base), base)
+	if _, err := os.Lstat(path); err != nil {
+		http.Error(w, "Not found", http.StatusNotFound)
+	}
+	// 200 OK
+}
+
+// servePut accepts and stores the given report.
+func (r *crashReceiver) servePut(base string, w http.ResponseWriter, req *http.Request) {
+	path := filepath.Join(r.dirFor(base), base)
+	fullPath := filepath.Join(r.dir, path)
+
+	// Ensure the destination directory exists
+	if err := os.MkdirAll(filepath.Dir(fullPath), 0755); err != nil {
+		log.Printf("Creating directory for report %s: %v", base, err)
+		http.Error(w, "Internal server error", http.StatusInternalServerError)
+		return
+	}
+
+	// Read at most maxRequestSize of report data.
+	log.Println("Receiving report", base)
+	lr := io.LimitReader(req.Body, maxRequestSize)
+	bs, err := ioutil.ReadAll(lr)
+	if err != nil {
+		log.Println("Reading report:", err)
+		http.Error(w, "Internal server error", http.StatusInternalServerError)
+		return
+	}
+
+	// Create an output file
+	err = ioutil.WriteFile(fullPath, bs, 0644)
+	if err != nil {
+		log.Printf("Creating file for report %s: %v", base, err)
+		http.Error(w, "Internal server error", http.StatusInternalServerError)
+		return
+	}
+
+	// Send the report to Sentry
+	if r.dsn != "" {
+		go func() {
+			// There's no need for the client to have to wait for this part.
+			if err := sendReport(r.dsn, path, bs); err != nil {
+				log.Println("Failed to send report:", err)
+			}
+		}()
+	}
+}
+
+// 01234567890abcdef... => 01/23
+func (r *crashReceiver) dirFor(base string) string {
+	return filepath.Join(base[0:2], base[2:4])
+}