topology-map/internal/mikrotik/mikrotik.go

package mikrotik

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"

	"git.faercol.me/faercol/topology-map/internal/config"
	"git.faercol.me/faercol/topology-map/internal/models"
)

const arpRoute = "/rest/ip/arp"

func buildQueryURL(targetIP, route string) string {
	return "http://" + targetIP + route
}

type MikrotikClient struct {
	httpClt *http.Client
	targets []config.MikrotikConfig
}

func NewMikrotikClient(targets []config.MikrotikConfig) *MikrotikClient {
	return &MikrotikClient{
		httpClt: http.DefaultClient,
		targets: targets,
	}
}

func (c *MikrotikClient) doQuery(target config.MikrotikConfig, route string) ([]byte, error) {
	query, err := http.NewRequest(http.MethodGet, buildQueryURL(target.IPAddress, route), nil)
	if err != nil {
		return nil, err
	}
	query.SetBasicAuth(target.User, target.Password)

	resp, err := c.httpClt.Do(query)
	if err != nil {
		return nil, err
	}

	return io.ReadAll(resp.Body)
}

func (c *MikrotikClient) getARPCacheForTarget(target config.MikrotikConfig) ([]models.ARPRecord, error) {
	data, err := c.doQuery(target, arpRoute)
	if err != nil {
		return nil, err
	}

	var resp []models.ARPRecord
	if err := json.Unmarshal(data, &resp); err != nil {
		return nil, err
	}
	return resp, nil
}

func (c *MikrotikClient) GetARPRecords() ([]*models.ARPRecord, error) {
	arpCache := map[string]models.ARPRecord{}

	for _, t := range c.targets {
		records, err := c.getARPCacheForTarget(t)
		if err != nil {
			return nil, fmt.Errorf("failed to get ARP data for device %s: %w", t.IPAddress, err)
		}
		for _, r := range records {
			arpCache[r.MacAddress] = r
		}
	}

	var res []*models.ARPRecord
	for _, r := range arpCache {
		res = append(res, &r)
	}
	return res, nil
}