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package client
import (
"fmt"
"io"
"os"
"github.com/mimecast/dtail/internal/config"
"github.com/mimecast/dtail/internal/io/dlog"
"github.com/mimecast/dtail/internal/ssh"
gossh "golang.org/x/crypto/ssh"
)
// noopCloser lets callers unconditionally defer closer.Close() when a code
// path does not own a real resource (e.g. no agent available).
type noopCloserFunc struct{}
func (noopCloserFunc) Close() error { return nil }
var noAuthCloser io.Closer = noopCloserFunc{}
var (
privateKeySigner = ssh.PrivateKeySigner
agentSigners = ssh.AgentSignersWithKeyIndex
)
// InitSSHAuthMethods initialises all known SSH auth methods on the client side.
// The returned io.Closer owns any ssh-agent connection acquired while building
// the auth methods and must be closed by the caller once all SSH handshakes
// that consume the returned auth methods have completed. The closer is always
// non-nil so callers can unconditionally `defer closer.Close()`.
func InitSSHAuthMethods(sshAuthMethods []gossh.AuthMethod,
hostKeyCallback gossh.HostKeyCallback, trustAllHosts bool,
privateKeyPath string, agentKeyIndex int) ([]gossh.AuthMethod, HostKeyCallback, io.Closer) {
if len(sshAuthMethods) > 0 {
simpleCallback, err := NewSimpleCallback()
if err != nil {
dlog.Client.FatalPanic(err)
}
return sshAuthMethods, simpleCallback, noAuthCloser
}
return initKnownHostsAuthMethods(trustAllHosts, privateKeyPath, agentKeyIndex)
}
func initKnownHostsAuthMethods(trustAllHosts bool,
privateKeyPath string, agentKeyIndex int) ([]gossh.AuthMethod, HostKeyCallback, io.Closer) {
knownHostsFile := fmt.Sprintf("%s/.ssh/known_hosts", os.Getenv("HOME"))
if config.Env("DTAIL_INTEGRATION_TEST_RUN_MODE") {
// In case of integration test, override known hosts file path.
knownHostsFile = "./known_hosts"
}
knownHostsCallback, err := NewKnownHostsCallback(knownHostsFile, trustAllHosts)
if err != nil {
dlog.Client.FatalPanic(knownHostsFile, err)
}
dlog.Client.Debug("initKnownHostsAuthMethods", "Added known hosts file path", knownHostsFile)
if config.Env("DTAIL_INTEGRATION_TEST_RUN_MODE") {
if privateKeyPath == "" {
privateKeyPath = "./id_rsa"
}
GeneratePrivatePublicKeyPairIfNotExists(privateKeyPath, 4096)
}
sshAuthMethods, agentCloser := collectKnownHostsAuthMethods(privateKeyPath, agentKeyIndex)
if len(sshAuthMethods) == 0 {
_ = agentCloser.Close()
dlog.Client.FatalPanic("Unable to find private SSH key information")
}
return sshAuthMethods, knownHostsCallback, agentCloser
}
func collectKnownHostsAuthMethods(privateKeyPath string, agentKeyIndex int) ([]gossh.AuthMethod, io.Closer) {
signers, agentCloser := collectKnownHostsSigners(privateKeyPath, agentKeyIndex)
if len(signers) == 0 {
return nil, agentCloser
}
return []gossh.AuthMethod{gossh.PublicKeys(signers...)}, agentCloser
}
func collectKnownHostsSigners(privateKeyPath string, agentKeyIndex int) ([]gossh.Signer, io.Closer) {
var signers []gossh.Signer
home := os.Getenv("HOME")
defaultPrivateKeyPaths := []string{
home + "/.ssh/id_rsa",
home + "/.ssh/id_dsa",
home + "/.ssh/id_ecdsa",
home + "/.ssh/id_ed25519",
}
if config.Env("DTAIL_INTEGRATION_TEST_RUN_MODE") {
defaultPrivateKeyPaths = append([]string{"./id_rsa"}, defaultPrivateKeyPaths...)
}
if privateKeyPath == "" {
privateKeyPath = defaultPrivateKeyPaths[0]
}
addedPrivateKeyPaths := make(map[string]bool, len(defaultPrivateKeyPaths)+1)
addedPublicKeys := make(map[string]bool, len(defaultPrivateKeyPaths)+1)
addSigner := func(source string, signer gossh.Signer) {
if signer == nil {
return
}
pubKey := string(signer.PublicKey().Marshal())
if addedPublicKeys[pubKey] {
dlog.Client.Debug("initKnownHostsAuthMethods", "Skipping duplicate signer", source)
return
}
addedPublicKeys[pubKey] = true
signers = append(signers, signer)
dlog.Client.Debug("initKnownHostsAuthMethods", "Added signer", source)
}
addPrivateKeySigner := func(path string) {
if path == "" {
return
}
if addedPrivateKeyPaths[path] {
return
}
signer, err := privateKeySigner(path)
if err != nil {
dlog.Client.Debug("initKnownHostsAuthMethods", "Unable to load private key signer", path, err)
return
}
addedPrivateKeyPaths[path] = true
addSigner(path, signer)
}
// First, the explicit auth key path (or default ~/.ssh/id_rsa).
addPrivateKeySigner(privateKeyPath)
// Second, SSH agent (YubiKey-backed keys are typically exposed here).
// The agent signers sign lazily over the agent connection, so its
// io.Closer must live until the caller is done with the signers.
loadedAgentSigners, agentCloser, err := agentSigners(agentKeyIndex)
if err != nil {
dlog.Client.Debug("initKnownHostsAuthMethods", "Unable to load SSH agent signers", err)
}
if agentCloser == nil {
agentCloser = noAuthCloser
}
for i, signer := range loadedAgentSigners {
addSigner(fmt.Sprintf("agent:%d:%d", agentKeyIndex, i), signer)
}
// Third, additional default private key paths.
for _, path := range defaultPrivateKeyPaths {
addPrivateKeySigner(path)
}
return signers, agentCloser
}
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