feat(configtest,scan): detect known_hosts error (#1386)

scanner/debian.go

@@ -48,8 +48,7 @@ func detectDebian(c config.ServerInfo) (bool, osTypeInterface, error) {
 			return false, nil, nil
 		}
 		if r.ExitStatus == 255 {
-			deb := newDebian(c) // Panic occur when return value 2 is nil and 3 is non-nil
-			return false, deb, xerrors.Errorf("Unable to connect via SSH. Scan with -vvv option to print SSH debugging messages and check SSH settings. If you have never SSH to the host to be scanned, SSH to the host before scanning in order to add the HostKey. %s@%s port: %s\n%s", c.User, c.Host, c.Port, r)
+			return false, &unknown{base{ServerInfo: c}}, xerrors.Errorf("Unable to connect via SSH. Scan with -vvv option to print SSH debugging messages and check SSH settings.\n%s", r)
 		}
 		logging.Log.Debugf("Not Debian like Linux. %s", r)
 		return false, nil, nil

scanner/serverapi.go

@@ -5,6 +5,7 @@ import (
 	"math/rand"
 	"net/http"
 	"os"
+	"strings"
 	"time"
 
 	debver "github.com/knqyf263/go-deb-version"
@@ -286,6 +287,12 @@ func (s Scanner) detectServerOSes() (servers, errServers []osTypeInterface) {
 					logging.Log.Debugf("Panic: %s on %s", p, srv.ServerName)
 				}
 			}()
+			if err := checkHostinKnownHosts(srv); err != nil {
+				checkOS := unknown{base{ServerInfo: srv}}
+				checkOS.setErrs([]error{err})
+				osTypeChan <- &checkOS
+				return
+			}
 			osTypeChan <- s.detectOS(srv)
 		}(target)
 	}
@@ -296,12 +303,10 @@ func (s Scanner) detectServerOSes() (servers, errServers []osTypeInterface) {
 		case res := <-osTypeChan:
 			if 0 < len(res.getErrs()) {
 				errServers = append(errServers, res)
-				logging.Log.Errorf("(%d/%d) Failed: %s, err: %+v",
-					i+1, len(s.Targets), res.getServerInfo().ServerName, res.getErrs())
+				logging.Log.Errorf("(%d/%d) Failed: %s, err: %+v", i+1, len(s.Targets), res.getServerInfo().ServerName, res.getErrs())
 			} else {
 				servers = append(servers, res)
-				logging.Log.Infof("(%d/%d) Detected: %s: %s",
-					i+1, len(s.Targets), res.getServerInfo().ServerName, res.getDistro())
+				logging.Log.Infof("(%d/%d) Detected: %s: %s", i+1, len(s.Targets), res.getServerInfo().ServerName, res.getDistro())
 			}
 		case <-timeout:
 			msg := "Timed out while detecting servers"
@@ -327,6 +332,69 @@ func (s Scanner) detectServerOSes() (servers, errServers []osTypeInterface) {
 	return
 }
 
+func checkHostinKnownHosts(c config.ServerInfo) error {
+	if isLocalExec(c.Port, c.Host) {
+		return nil
+	}
+
+	args := []string{"-G"}
+	if len(c.SSHConfigPath) > 0 {
+		args = []string{"-G", "-F", c.SSHConfigPath}
+	}
+	r := localExec(c, fmt.Sprintf("ssh %s %s", strings.Join(args, " "), c.Host), noSudo)
+	if !r.isSuccess() {
+		return xerrors.Errorf("Failed to print SSH configuration. err: %w", r.Error)
+	}
+
+	var (
+		hostname         string
+		globalKnownHosts string
+		userKnownHosts   string
+	)
+	for _, line := range strings.Split(r.Stdout, "\n") {
+		if strings.HasPrefix(line, "hostname ") {
+			hostname = strings.TrimPrefix(line, "hostname ")
+		} else if strings.HasPrefix(line, "globalknownhostsfile ") {
+			globalKnownHosts = strings.TrimPrefix(line, "globalknownhostsfile ")
+		} else if strings.HasPrefix(line, "userknownhostsfile ") {
+			userKnownHosts = strings.TrimPrefix(line, "userknownhostsfile ")
+		}
+	}
+
+	knownHostsPaths := []string{}
+	for _, knownHosts := range []string{userKnownHosts, globalKnownHosts} {
+		for _, knownHost := range strings.Split(knownHosts, " ") {
+			if knownHost != "" {
+				knownHostsPaths = append(knownHostsPaths, knownHost)
+			}
+		}
+	}
+	if len(knownHostsPaths) == 0 {
+		return xerrors.New("Failed to find any known_hosts to use. Please check the UserKnownHostsFile and GlobalKnownHostsFile settings for SSH.")
+	}
+
+	for _, knownHosts := range knownHostsPaths {
+		if c.Port != "" && c.Port != "22" {
+			cmd := fmt.Sprintf("ssh-keygen -F %s -f %s", fmt.Sprintf("\"[%s]:%s\"", c.Host, c.Port), knownHosts)
+			if r := localExec(c, cmd, noSudo); r.isSuccess() {
+				return nil
+			}
+		}
+		cmd := fmt.Sprintf("ssh-keygen -F %s -f %s", c.Host, knownHosts)
+		if r := localExec(c, cmd, noSudo); r.isSuccess() {
+			return nil
+		}
+	}
+
+	sshCmd := fmt.Sprintf("ssh -i %s %s@%s", c.KeyPath, c.User, c.Host)
+	sshKeyScancmd := fmt.Sprintf("ssh-keyscan -H %s >> %s", hostname, knownHostsPaths[0])
+	if c.Port != "" && c.Port != "22" {
+		sshCmd = fmt.Sprintf("ssh -i %s -p %s %s@%s", c.KeyPath, c.Port, c.User, c.Host)
+		sshKeyScancmd = fmt.Sprintf("ssh-keyscan -H -p %s %s >> %s", c.Port, hostname, knownHostsPaths[0])
+	}
+	return xerrors.Errorf("Failed to find the host in known_hosts. Plaese exec `$ %s` or `$ %s`", sshCmd, sshKeyScancmd)
+}
+
 func (s Scanner) detectContainerOSes(hosts []osTypeInterface) (actives, inactives []osTypeInterface) {
 	logging.Log.Info("Detecting OS of containers... ")
 	osTypesChan := make(chan []osTypeInterface, len(hosts))