Initial commit

This adds a rudimentary `chaos` package for querying broadband info, and
a Prometheus exporter.

chaos.go

@@ -0,0 +1,166 @@
+// Package chaos provides access to Andrews and Arnold's CHAOS v2 API.
+package chaos
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+)
+
+const defaultEndpoint = "https://chaos2.aa.net.uk"
+
+// API provides the accessors for querying the CHAOS service.
+type API struct {
+	Endpoint string
+	login    url.Values
+}
+
+// New takes an Auth with API credentials and returns an API object.
+func New(auth Auth) *API {
+	return &API{Endpoint: defaultEndpoint, login: auth.form()}
+}
+
+// Auth is the authentication credentials for the API.
+//
+// The API requires either account authentication (AccountNumber and AccountPassword) or control authentication (ControlLogin and ControlPassword.)
+//
+// ControlLogin may also be passed when using account authentication.
+type Auth struct {
+	AccountNumber   string
+	AccountPassword string
+	ControlLogin    string
+	ControlPassword string
+}
+
+// Construct form values for sending as authentication data.
+func (a Auth) form() url.Values {
+	f := url.Values{}
+	if a.AccountNumber != "" {
+		f.Set("account_number", a.AccountNumber)
+	}
+	if a.AccountPassword != "" {
+		f.Set("account_password", a.AccountPassword)
+	}
+	if a.ControlLogin != "" {
+		f.Set("control_login", a.ControlLogin)
+	}
+	if a.ControlPassword != "" {
+		f.Set("control_password", a.ControlPassword)
+	}
+	return f
+}
+
+func (api API) makeRequest(url string) ([]byte, error) {
+	client := &http.Client{
+		Timeout: 10 * time.Second,
+	}
+
+	req, err := http.NewRequest("POST", api.Endpoint+url, strings.NewReader(api.login.Encode()))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	body, err := ioutil.ReadAll(resp.Body)
+	defer resp.Body.Close()
+	if err != nil {
+		return nil, fmt.Errorf("error reading response body: %w", err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("bad response code: %d", resp.StatusCode)
+	}
+
+	return body, nil
+}
+
+// The API returns timestamps in the format "YYYY-mm-dd HH:mm:ss" rather than RFC3389.
+//
+// Use a custom type to unmarshal JSON to this format.
+type chaosTime struct {
+	time.Time
+}
+
+func (t *chaosTime) UnmarshalJSON(b []byte) error {
+	s := strings.Trim(string(b), `"`)
+	// The API returns times in UK local rather than UTC
+	loc, err := time.LoadLocation("Europe/London")
+	if err != nil {
+		loc = time.Local
+	}
+	nt, err := time.ParseInLocation("2006-01-02 15:04:05", s, loc)
+	if err != nil {
+		return err
+	}
+	t.Time = nt
+	return nil
+}
+
+// BroadbandInfo represents information about a broadband line.
+type BroadbandInfo struct {
+	ID             int       `json:"id,string"`
+	Login          string    `json:"login"`
+	Postcode       string    `json:"postcode"`
+	TXRate         int       `json:"tx_rate,string"`
+	RXRate         int       `json:"rx_rate,string"`
+	TXRateAdjusted int       `json:"tx_rate_adjusted,string"`
+	QuotaMonthly   int       `json:"quota_monthly,string"`
+	QuotaRemaining int       `json:"quota_remaining,string"`
+	QuotaTimestamp chaosTime `json:"quota_timestamp"`
+}
+
+// BroadbandInfo fetches broadband info.
+func (api API) BroadbandInfo() ([]BroadbandInfo, error) {
+	resp, err := api.makeRequest("/broadband/info")
+	if err != nil {
+		return nil, err
+	}
+	r := struct {
+		Info  []BroadbandInfo `json:"info"`
+		Error string          `json:"error"`
+	}{}
+	err = json.Unmarshal(resp, &r)
+	if err != nil {
+		return nil, fmt.Errorf("BroadbandInfo JSON decode: %w", err)
+	}
+	if r.Error != "" {
+		return nil, errors.New(r.Error)
+	}
+	return r.Info, nil
+}
+
+// BroadbandQuota is quota.
+type BroadbandQuota struct {
+	ID             int       `json:"id,string"`
+	QuotaMonthly   int       `json:"quota_monthly"`
+	QuotaRemaining int       `json:"quota_remaining,string"`
+	QuotaTimestamp chaosTime `json:"quota_timestamp,string"`
+}
+
+// BroadbandQuota fetches the broadband quota.
+func (api API) BroadbandQuota() ([]BroadbandQuota, error) {
+	resp, err := api.makeRequest("/broadband/quota")
+	if err != nil {
+		return nil, err
+	}
+	r := struct {
+		Quota []BroadbandQuota `json:"quota"`
+		Error string           `json:"error"`
+	}{}
+	err = json.Unmarshal(resp, &r)
+	if err != nil {
+		return nil, fmt.Errorf("BroadbandQuota JSON decode: %w", err)
+	}
+	if r.Error != "" {
+		return nil, errors.New(r.Error)
+	}
+	return r.Quota, nil
+}