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session.go
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session.go
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package ssh
import (
"fmt"
"strings"
bosherr "github.com/cloudfoundry/bosh-utils/errors"
boshsys "github.com/cloudfoundry/bosh-utils/system"
boshdir "github.com/cloudfoundry/bosh-cli/director"
)
type SessionImpl struct {
connOpts ConnectionOpts
sessOpts SessionImplOpts
result boshdir.SSHResult
privKeyFile boshsys.File
knownHostsFile boshsys.File
fs boshsys.FileSystem
}
type SessionImplOpts struct {
ForceTTY bool
}
func NewSessionImpl(
connOpts ConnectionOpts,
sessOpts SessionImplOpts,
result boshdir.SSHResult,
fs boshsys.FileSystem,
) *SessionImpl {
return &SessionImpl{connOpts: connOpts, sessOpts: sessOpts, result: result, fs: fs}
}
func (r *SessionImpl) Start() ([]string, error) {
var err error
r.privKeyFile, err = r.makePrivKeyFile()
if err != nil {
return nil, err
}
r.knownHostsFile, err = r.makeKnownHostsFile()
if err != nil {
_ = r.fs.RemoveAll(r.privKeyFile.Name())
return nil, err
}
// Options are used for both ssh and scp
cmdOpts := []string{}
if r.sessOpts.ForceTTY {
cmdOpts = append(cmdOpts, "-tt")
}
cmdOpts = append(cmdOpts, []string{
"-o", "ServerAliveInterval=30",
"-o", "ForwardAgent=no",
"-o", "PasswordAuthentication=no",
"-o", "IdentitiesOnly=yes",
"-o", "IdentityFile=" + r.privKeyFile.Name(),
"-o", "StrictHostKeyChecking=yes",
"-o", "UserKnownHostsFile=" + r.knownHostsFile.Name(),
}...)
gwUsername, gwHost, gwPrivKeyPath := r.gwOpts(r.connOpts, r.result)
if len(r.connOpts.SOCKS5Proxy) > 0 {
proxyOpt := fmt.Sprintf(
"ProxyCommand=nc -X 5 -x %s %%h %%p",
strings.TrimPrefix(r.connOpts.SOCKS5Proxy, "socks5://"),
)
cmdOpts = append(cmdOpts, "-o", proxyOpt)
} else if len(gwHost) > 0 {
gwCmdOpts := []string{
"-o", "ServerAliveInterval=30",
"-o", "ForwardAgent=no",
"-o", "ClearAllForwardings=yes",
// Strict host key checking for a gateway is not necessary
// since ProxyCommand is only used for forwarding TCP and
// agent forwarding is disabled
"-o", "StrictHostKeyChecking=no",
"-o", "UserKnownHostsFile=/dev/null",
}
if len(gwPrivKeyPath) > 0 {
gwCmdOpts = append(
gwCmdOpts,
"-o", "PasswordAuthentication=no",
"-o", "IdentitiesOnly=yes",
"-o", "IdentityFile="+gwPrivKeyPath,
)
}
proxyOpt := fmt.Sprintf(
// Always force TTY for gateway ssh
"ProxyCommand=ssh -tt -W %%h:%%p -l %s %s %s",
gwUsername,
gwHost,
strings.Join(gwCmdOpts, " "),
)
cmdOpts = append(cmdOpts, "-o", proxyOpt)
}
cmdOpts = append(cmdOpts, r.connOpts.RawOpts...)
return cmdOpts, nil
}
func (r *SessionImpl) Finish() error {
// Make sure to try to delete all files regardless of errors
privKeyErr := r.fs.RemoveAll(r.privKeyFile.Name())
knownHostsErr := r.fs.RemoveAll(r.knownHostsFile.Name())
if privKeyErr != nil {
return privKeyErr
}
if knownHostsErr != nil {
return knownHostsErr
}
return nil
}
func (r SessionImpl) makePrivKeyFile() (boshsys.File, error) {
file, err := r.fs.TempFile("ssh-priv-key")
if err != nil {
return nil, bosherr.WrapErrorf(err, "Creating temp file for SSH private key")
}
_, err = file.Write([]byte(r.connOpts.PrivateKey))
if err != nil {
_ = r.fs.RemoveAll(file.Name())
return nil, bosherr.WrapErrorf(err, "Writing SSH private key")
}
return file, nil
}
func (r SessionImpl) makeKnownHostsFile() (boshsys.File, error) {
file, err := r.fs.TempFile("ssh-known-hosts")
if err != nil {
return nil, bosherr.WrapErrorf(err, "Creating temp file for SSH known hosts")
}
var content string
for _, host := range r.result.Hosts {
if len(host.HostPublicKey) > 0 {
content += fmt.Sprintf("%s %s\n", host.Host, host.HostPublicKey)
}
}
if len(content) > 0 {
_, err := file.Write([]byte(content))
if err != nil {
_ = r.fs.RemoveAll(file.Name())
return nil, bosherr.WrapErrorf(err, "Writing SSH known hosts")
}
}
return file, nil
}
func (r SessionImpl) gwOpts(connOpts ConnectionOpts, result boshdir.SSHResult) (string, string, string) {
if connOpts.GatewayDisable {
return "", "", ""
}
// Take server provided gateway options
username := result.GatewayUsername
host := result.GatewayHost
if len(connOpts.GatewayUsername) > 0 {
username = connOpts.GatewayUsername
}
if len(connOpts.GatewayHost) > 0 {
host = connOpts.GatewayHost
}
privKeyPath := connOpts.GatewayPrivateKeyPath
return username, host, privKeyPath
}