probelabs/goreplay · error

handle buffer timeout error: %q, interface: %q

Error message

handle buffer timeout error: %q, interface: %q

What it means

After applying options, PcapHandle sets the read timeout via inactive.SetTimeout(config.BufferTimeout), defaulting it to 2000ms when zero. Failure is wrapped as "handle buffer timeout error: <err>, interface: <name>". It means libpcap rejected the timeout value on the inactive handle (e.g. negative duration).

Source

Thrown at internal/capture/capture.go:461

		snap = 64<<10 + 200
	}

	err = inactive.SetSnapLen(snap)
	if err != nil {
		return nil, fmt.Errorf("snapshot length error: %q, interface: %q", err, ifi.Name)
	}
	if l.config.BufferSize > 0 {
		err = inactive.SetBufferSize(int(l.config.BufferSize))
		if err != nil {
			return nil, fmt.Errorf("handle buffer size error: %q, interface: %q", err, ifi.Name)
		}
	}
	if l.config.BufferTimeout == 0 {
		l.config.BufferTimeout = 2000 * time.Millisecond
	}
	err = inactive.SetTimeout(l.config.BufferTimeout)
	if err != nil {
		return nil, fmt.Errorf("handle buffer timeout error: %q, interface: %q", err, ifi.Name)
	}
	handle, err = inactive.Activate()
	if err != nil {
		return nil, fmt.Errorf("PCAP Activate device error: %q, interface: %q", err, ifi.Name)
	}

	bpfFilter := l.config.BPFFilter
	if bpfFilter == "" {
		bpfFilter = l.Filter(ifi)
	}
	fmt.Println("Interface:", ifi.Name, ". BPF Filter:", bpfFilter)
	err = handle.SetBPFFilter(bpfFilter)
	if err != nil {
		handle.Close()
		return nil, fmt.Errorf("BPF filter error: %q%s, interface: %q", err, bpfFilter, ifi.Name)
	}
	return
}

View on GitHub (pinned to 251e45abd2)

Solutions

1. Validate BufferTimeout is non-negative (and non-zero so the 2000ms default applies) before calling PcapHandle
2. Reset the config value to 0 to use the built-in 2000ms default
3. Fix duration parsing (use time.ParseDuration) so the value cannot be negative
4. Wrap the call and surface the wrapped %q error for the underlying libpcap cause

Example fix

// before
cfg.BufferTimeout = -1 * time.Second // invalid
// after
if cfg.BufferTimeout < 0 { cfg.BufferTimeout = 0 } // -> default 2000ms

if cfg.BufferTimeout < 0 {
    return fmt.Errorf("BufferTimeout must be >= 0, got %v", cfg.BufferTimeout)
}

if err != nil && strings.Contains(err.Error(), "handle buffer timeout error") {
    log.Warnf("timeout rejected, using default: %v", err)
    cfg.BufferTimeout = 0
    handle, err = l.PcapHandle(ifi)
}

When it happens

Trigger: Calling PcapHandle with l.config.BufferTimeout negative (e.g. from a misparsed config like "-5s") or otherwise invalid so SetTimeout fails before Activate.

Common situations: YAML/JSON parsing quirks producing negative durations; manually computing milliseconds and passing a negative int; confusion between time.Duration units when constructing the config programmatically.

Understand the failure class

• Timeouts: ETIMEDOUT, deadlines, and hung requests — what actually expires when a request times out.

Related errors

• inactive handle error: %q, interface: %q
• %q: supported timestamps: %q, interface: %q
• promiscuous mode error: %q, interface: %q
• snapshot length error: %q, interface: %q
• monitor mode error: %q, interface: %q

AI-assisted analysis of probelabs/goreplay@251e45abd2 (2026-09-02). Data as JSON: /api/errors/d6926a4d49200c71. Report an issue: GitHub.