Add Telegram support (#762)

* add telegram support

* format message

* remove debug print

* fix linting error

* add telegram to discover; group message by 10

* use chatID instead of channel

* apply refactor

* remove reduntant space

report/telegram.go

@@ -0,0 +1,77 @@
+package report
+
+import (
+	"bytes"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/future-architect/vuls/config"
+	"github.com/future-architect/vuls/models"
+)
+
+// TelegramWriter sends report to Telegram
+type TelegramWriter struct{}
+
+func (w TelegramWriter) Write(rs ...models.ScanResult) (err error) {
+	conf := config.Conf.Telegram
+	for _, r := range rs {
+		msgs := []string{fmt.Sprintf("*%s*\n%s\n%s\n%s",
+			r.ServerInfo(),
+			r.ScannedCves.FormatCveSummary(),
+			r.ScannedCves.FormatFixedStatus(r.Packages),
+			r.FormatUpdatablePacksSummary())}
+		for _, vinfo := range r.ScannedCves {
+			maxCvss := vinfo.MaxCvssScore()
+			severity := strings.ToUpper(maxCvss.Value.Severity)
+			if severity == "" {
+				severity = "?"
+			}
+			msgs = append(msgs, fmt.Sprintf(`[%s](https://nvd.nist.gov/vuln/detail/%s) _%s %s %s_\n%s`,
+				vinfo.CveID,
+				vinfo.CveID,
+				strconv.FormatFloat(maxCvss.Value.Score, 'f', 1, 64),
+				severity,
+				maxCvss.Value.Vector,
+				vinfo.Summaries(config.Conf.Lang, r.Family)[0].Value))
+			if len(msgs) == 5 {
+				if err = sendMessage(conf.ChatID, conf.Token, strings.Join(msgs, "\n\n")); err != nil {
+					return err
+				}
+				msgs = []string{}
+			}
+		}
+		if len(msgs) != 0 {
+			if err = sendMessage(conf.ChatID, conf.Token, strings.Join(msgs, "\n\n")); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func sendMessage(chatID, token, message string) error {
+	uri := fmt.Sprintf("https://api.telegram.org/bot%s/sendMessage", token)
+	payload := `{"text": "` + strings.Replace(message, `"`, `\"`, -1) + `", "chat_id": "` + chatID + `", "parse_mode": "Markdown" }`
+	req, err := http.NewRequest("POST", uri, bytes.NewBuffer([]byte(payload)))
+	req.Header.Add("Content-Type", "application/json")
+	if err != nil {
+		return err
+	}
+	client := &http.Client{}
+	resp, err := client.Do(req)
+	if checkResponse(resp) != nil && err != nil {
+		fmt.Println(err)
+		return err
+	}
+	defer resp.Body.Close()
+	return nil
+}
+
+func checkResponse(r *http.Response) error {
+	if c := r.StatusCode; 200 <= c && c <= 299 {
+		return nil
+	}
+	return fmt.Errorf("API call to %s failed: %s", r.Request.URL.String(), r.Status)
+}