func handleTCPConnection(logger log.Logger, conn net.Conn, sshConfig *ssh.ServerConfig, system datamodel.System) {
// Open SSH connection
sshConn, channels, requests, err := ssh.NewServerConn(conn, sshConfig)
if err != nil {
logger.Warn("SSH handshake failed")
return
}
// Get user if exists, otherwise return error
users, _ := system.Users()
user, _ := users.Get(sshConn.Permissions.Extensions["username"])
logger.Debug("Handshake successful")
defer sshConn.Conn.Close()
// Discard requests
go ssh.DiscardRequests(requests)
for ch := range channels {
t := ch.ChannelType()
if t != "session" && t != "kappa-client" {
logger.Info("UnknownChannelType", "type", t)
ch.Reject(ssh.UnknownChannelType, t)
break
}
// Accept channel
channel, requests, err := ch.Accept()
if err != nil {
logger.Warn("Error creating channel")
continue
}
if t == "session" {
go handleSessionRequests(logger, channel, requests, system, user)
} else if t == "kappa-client" {
go handleChannelRequests(logger, channel, requests, system, user)
}
}
}
func NewSSHServer(logger log.Logger, sys datamodel.System, privateKey ssh.Signer, roots *x509.CertPool) (server SSHServer, err error) {
// Get user store
users, err := sys.Users()
// Create server config
sshConfig := &ssh.ServerConfig{
NoClientAuth: false,
PublicKeyCallback: func(conn ssh.ConnMetadata, key ssh.PublicKey) (perm *ssh.Permissions, err error) {
// Get user if exists, otherwise return error
user, err := users.Get(conn.User())
if err != nil {
return
}
// Check keyring for public key
if keyring := user.KeyRing(); !keyring.Contains(key.Marshal()) {
err = fmt.Errorf("invalid public key")
return
}
// Add pubkey and username to permissions
perm = &ssh.Permissions{
Extensions: map[string]string{
"pubkey": string(key.Marshal()),
"username": conn.User(),
},
}
return
},
AuthLogCallback: func(conn ssh.ConnMetadata, method string, err error) {
if err != nil {
logger.Info("Login attempt", "user", conn.User(), "method", method, "error", err.Error())
} else {
logger.Info("Successful login", "user", conn.User(), "method", method)
}
},
}
sshConfig.AddHostKey(privateKey)
// Get ssh bind addr
bind := viper.GetString("SSHListen")
if bind == "" {
err = fmt.Errorf("Empty SSH bind address")
return
}
// Open SSH socket
logger.Info("Starting SSH server", "addr", bind)
sshAddr, err := net.ResolveTCPAddr("tcp", bind)
if err != nil {
err = fmt.Errorf("Invalid tcp address")
return
}
// Create listener
listener, err := net.ListenTCP("tcp", sshAddr)
if err != nil {
return
}
server.logger = logger
server.sshConfig = sshConfig
server.listener = listener
server.system = sys
return
}