Maven/cmd/mavend/netscan.go

package main

import (
	"context"
	"fmt"
	"log"
	"strings"
	"time"

	"github.com/kami/maven/internal/config"
	"github.com/kami/maven/internal/netscan"
)

// scanBudget — the whole spoken scan, end to end. A voice turn that takes
// longer than this has already failed as a turn, so the scan returns whatever
// it found rather than keeping him waiting.
const scanBudget = 20 * time.Second

// scanReadOut — how many hosts she names out loud. The rest are a count: a
// spoken list of twenty IP addresses is not an answer.
const scanReadOut = 6

// netWiring — the LAN scanner, when the `netscan` block is enabled. nil ⇒ Maven
// never puts a discovery packet on the network.
//
// Unlike the house, a scan is a READ, so it is a query source rather than an
// act: there is no allowlist row and no confirm turn, because nothing changes.
// What makes that safe is that the range is not an argument — see
// internal/netscan's package comment.
type netWiring struct {
	scanner *netscan.Scanner
	subnets []string
}

// wireNetScan builds the scanner. nil unless the block is enabled and valid.
func wireNetScan(cfg *config.Config) *netWiring {
	nc, ok := cfg.NetScanner()
	if !ok {
		return nil
	}
	if err := netscan.Validate(nc); err != nil {
		// config.validate already ran this, so reaching here is a programming
		// error rather than a config one. Not fatal: the scanner off is a
		// working Maven.
		log.Printf("netscan: not wired: %v", err)
		return nil
	}
	return &netWiring{scanner: netscan.New(nc), subnets: nc.Subnets}
}

// scanSummary answers "какие устройства в сети?" in one line.
func (w *netWiring) scanSummary(ctx context.Context) (string, bool) {
	if w == nil {
		return "", false
	}
	ctx, cancel := context.WithTimeout(ctx, scanBudget)
	defer cancel()
	hosts, err := w.scanner.Scan(ctx)
	if err != nil {
		log.Printf("netscan: scan: %v", err)
		return "не получилось просканировать сеть.", true
	}
	if len(hosts) == 0 {
		return "в сети никого не нашла.", true
	}
	shown := hosts
	if len(shown) > scanReadOut {
		shown = shown[:scanReadOut]
	}
	parts := make([]string, 0, len(shown))
	for _, h := range shown {
		s := h.Addr
		if len(h.Ports) > 0 {
			ps := make([]string, 0, len(h.Ports))
			for _, p := range h.Ports {
				ps = append(ps, fmt.Sprintf("%d", p))
			}
			s += " (" + strings.Join(ps, ", ") + ")"
		}
		parts = append(parts, s)
	}
	out := fmt.Sprintf("нашла %d %s: %s", len(hosts), hostWord(len(hosts)), strings.Join(parts, "; "))
	if len(hosts) > len(shown) {
		out += fmt.Sprintf(" и ещё %d", len(hosts)-len(shown))
	}
	return out + ".", true
}

// hostWord — Russian counts inflect the noun: 1 устройство, 2-4 устройства,
// 5+ устройств, and the teens are all the last form.
func hostWord(n int) string {
	if n%100 >= 11 && n%100 <= 14 {
		return "устройств"
	}
	switch n % 10 {
	case 1:
		return "устройство"
	case 2, 3, 4:
		return "устройства"
	default:
		return "устройств"
	}
}

// isNetworkQuery recognises a question about the LAN, narrowly. It needs a
// network word AND an ask: "интернет не работает" is a complaint, not a request
// to scan, and a scan she runs unasked is exactly the noisy behaviour the
// bounds exist to prevent.
func isNetworkQuery(u string) bool {
	s := strings.ToLower(strings.TrimSpace(u))
	if s == "" {
		return false
	}
	network := false
	for _, w := range []string{"в сети", "в сетке", "сеть", "сети", "локальн", "wifi", "wi-fi", "вайфай"} {
		if strings.Contains(s, w) {
			network = true
			break
		}
	}
	if !network {
		return false
	}
	// An explicit ask to scan, or a phrase that can only be about the LAN.
	// "кто в сети" carries no device noun but means nothing else.
	for _, w := range []string{"просканируй", "сканируй", "скан", "просканир", "кто в сети", "кто в сетке"} {
		if strings.Contains(s, w) {
			return true
		}
	}
	ask := strings.Contains(s, "?") || homeWord(s, "какие") || homeWord(s, "кто") ||
		homeWord(s, "что") || homeWord(s, "сколько") || strings.Contains(s, "покажи")
	if !ask {
		return false
	}
	for _, w := range []string{"устройств", "хост", "компьютер", "машин", "адрес"} {
		if strings.Contains(s, w) {
			return true
		}
	}
	return false
}