{"record":{"id":"a647c36668b4af2f","repo":"cloudflare/cloudflared","slug":"error-finishing-traceroute-w","errorCode":null,"errorMessage":"error finishing traceroute: %w","messagePattern":"error finishing traceroute: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"diagnostic/network/collector_utils.go","lineNumber":35,"sourceCode":"\t}\n\n\tif err := command.Start(); err != nil {\n\t\treturn nil, \"\", fmt.Errorf(\"error starting traceroute: %w\", err)\n\t}\n\n\t// Tee the output to a string to have the raw information\n\t// in case the decode call fails\n\t// This error is handled only after the Wait call below returns\n\t// otherwise the process can become a zombie\n\tbuf := bytes.NewBuffer([]byte{})\n\ttee := io.TeeReader(stdout, buf)\n\thops, err := Decode(tee, decodeLine)\n\t// regardless of success of the decoding\n\t// consume all output to have available in buf\n\t_, _ = io.ReadAll(tee)\n\n\tif werr := command.Wait(); werr != nil {\n\t\treturn nil, \"\", fmt.Errorf(\"error finishing traceroute: %w\", werr)\n\t}\n\n\tif err != nil {\n\t\treturn nil, buf.String(), err\n\t}\n\n\treturn hops, buf.String(), nil\n}\n\nfunc Decode(reader io.Reader, decodeLine DecodeLineFunc) ([]*Hop, error) {\n\tscanner := bufio.NewScanner(reader)\n\tscanner.Split(bufio.ScanLines)\n\n\tvar hops []*Hop\n\n\tfor scanner.Scan() {\n\t\ttext := scanner.Text()\n\t\tif text == \"\" {","sourceCodeStart":17,"sourceCodeEnd":53,"githubUrl":"https://github.com/cloudflare/cloudflared/blob/2253eeeb25a44a713a4b60b8ba1e1b3f377d1a0f/diagnostic/network/collector_utils.go#L17-L53","documentation":"After streaming traceroute output, decodeNetworkOutputToFile calls command.Wait() to reap the process. If traceroute exits with a non-zero status or Wait fails, this wrapped error is returned. A common cause is traceroute being unable to reach the target or lacking privileges, though note decoding errors are checked only after Wait succeeds.","triggerScenarios":"The traceroute process terminates abnormally: exits non-zero (unreachable host with certain flags, ICMP permission failure, killed by signal), or Wait itself fails after the process already had its resources collected.","commonSituations":"traceroute run without CAP_NET_RAW/setuid in containers (permission denied sending probes); network unreachable for the target; traceroute killed by timeout/signal handling; duplicate Wait calls in modified code.","solutions":["Inspect the wrapped exit error (exec.ExitError) for traceroute's exit code and stderr.","Run traceroute manually with the same arguments and user to reproduce (e.g. permission denied sending probes).","Grant CAP_NET_RAW (setcap cap_net_raw+ep on the traceroute binary) or run in a privileged network context.","Retry collection; if the target is unreachable, treat as an environmental finding rather than a code bug."],"exampleFix":"// before\n# traceroute: icmp socket Permission denied\n$ cloudflared diag ...\n// after\n$ sudo setcap cap_net_raw+ep $(which traceroute)\n$ cloudflared diag ...","handlingStrategy":"try-catch","validationCode":"// pre-check traceroute privileges\nif _, err := os.Stat(\"/proc/net/raw\"); err != nil {\n\t// raw sockets may be unavailable\n}\nerr := exec.Command(\"traceroute\", \"-n\", \"-m\", \"1\", \"127.0.0.1\").Run()","typeGuard":null,"tryCatchPattern":"hops, _, err := network.Collect(ctx, cfg)\nvar ee *exec.ExitError\nif errors.As(err, &ee) {\n\t// traceroute exited non-zero: check ee.ExitCode and the tee'd raw output\n}","preventionTips":["Grant CAP_NET_RAW / setcap cap_net_raw+ep on the traceroute binary","Confirm the target host is reachable before running network diagnostics","Avoid killing the process mid-trace; use context timeouts generously","Run traceroute manually with the same user to verify the environment"],"tags":["diagnostics","network","traceroute","process"],"backgroundTag":"command-failed","analyzedSha":"2253eeeb25a44a713a4b60b8ba1e1b3f377d1a0f","analyzedAt":"2026-09-06T04:14:33.757Z","contentChangedAt":"2026-09-06T04:14:33.757Z","schemaVersion":2},"datasetVersion":"2026-09-14T00:17:10.932Z"}