blob: b9642cf1547df1f11d026b960de4c47a9a84331a [file] [log] [blame]
package main
import (
"context"
"fmt"
"strings"
"github.com/golang/glog"
"github.com/ziutek/telnet"
"golang.org/x/net/trace"
)
type cliClient struct {
conn *telnet.Conn
username string
password string
loggedIn bool
promptHostname string
}
func newCliClient(c *telnet.Conn, username, password string) *cliClient {
return &cliClient{
conn: c,
username: username,
password: password,
}
}
func (c *cliClient) readUntil(ctx context.Context, delims ...string) (string, error) {
chStr := make(chan string, 1)
chErr := make(chan error, 1)
go func() {
s, err := c.conn.ReadUntil(delims...)
if err != nil {
chErr <- err
return
}
chStr <- string(s)
}()
select {
case <-ctx.Done():
return "", fmt.Errorf("context done")
case err := <-chErr:
c.trace(ctx, "readUntil failed: %v", err)
return "", err
case s := <-chStr:
c.trace(ctx, "readUntil <- %q", s)
return s, nil
}
}
func (c *cliClient) readString(ctx context.Context, delim byte) (string, error) {
chStr := make(chan string, 1)
chErr := make(chan error, 1)
go func() {
s, err := c.conn.ReadString(delim)
if err != nil {
chErr <- err
return
}
chStr <- s
}()
select {
case <-ctx.Done():
return "", fmt.Errorf("context done")
case err := <-chErr:
c.trace(ctx, "readString failed: %v", err)
return "", err
case s := <-chStr:
c.trace(ctx, "readString <- %q", s)
return s, nil
}
}
func (c *cliClient) writeLine(ctx context.Context, s string) error {
n, err := c.conn.Write([]byte(s + "\n"))
if got, want := n, len(s)+1; got != want {
err = fmt.Errorf("wrote %d bytes out of %d", got, want)
}
if err != nil {
c.trace(ctx, "writeLine failed: %v", err)
return err
}
c.trace(ctx, "writeLine -> %q", s)
return nil
}
func (c *cliClient) trace(ctx context.Context, f string, parts ...interface{}) {
tr, ok := trace.FromContext(ctx)
if !ok {
fmted := fmt.Sprintf(f, parts...)
glog.Infof("[no trace] %s", fmted)
return
}
tr.LazyPrintf(f, parts...)
}
func (c *cliClient) logIn(ctx context.Context) error {
if c.loggedIn {
return nil
}
// Provide username.
prompt, err := c.readString(ctx, ':')
if err != nil {
return fmt.Errorf("could not read username prompt: %v", err)
}
if !strings.HasSuffix(prompt, "User:") {
return fmt.Errorf("invalid username prompt: %v", err)
}
if err := c.writeLine(ctx, c.username); err != nil {
return fmt.Errorf("could not write username: %v")
}
// Provide password.
prompt, err = c.readString(ctx, ':')
if err != nil {
return fmt.Errorf("could not read password prompt: %v", err)
}
if !strings.HasSuffix(prompt, "Password:") {
return fmt.Errorf("invalid password prompt: %v", err)
}
if err := c.writeLine(ctx, c.password); err != nil {
return fmt.Errorf("could not write password: %v")
}
// Get unprivileged prompt.
prompt, err = c.readString(ctx, '>')
if err != nil {
return fmt.Errorf("could not read unprivileged prompt: %v", err)
}
parts := strings.Split(prompt, "\r\n")
c.promptHostname = strings.TrimSuffix(parts[len(parts)-1], ">")
// Enable privileged mode.
if err := c.writeLine(ctx, "enable"); err != nil {
return fmt.Errorf("could not write enable: %v")
}
// Provide password (again)
prompt, err = c.readString(ctx, ':')
if err != nil {
return fmt.Errorf("could not read password prompt: %v", err)
}
if !strings.HasSuffix(prompt, "Password:") {
return fmt.Errorf("invalid password prompt: %v", err)
}
if err := c.writeLine(ctx, c.password); err != nil {
return fmt.Errorf("could not write password: %v")
}
// Get privileged prompt.
prompt, err = c.readString(ctx, '#')
if err != nil {
return fmt.Errorf("could not read privileged prompt: %v", err)
}
if !strings.HasSuffix(prompt, c.promptHostname+"#") {
return fmt.Errorf("unexpected privileged prompt: %v", prompt)
}
// Disable pager.
if err := c.writeLine(ctx, "terminal length 0"); err != nil {
return fmt.Errorf("could not diable pager: %v", err)
}
prompt, err = c.readString(ctx, '#')
if err != nil {
return fmt.Errorf("could not disable pager: %v", err)
}
if !strings.HasSuffix(prompt, c.promptHostname+"#") {
return fmt.Errorf("unexpected privileged prompt: %v", prompt)
}
// Success!
c.loggedIn = true
c.trace(ctx, "logged into %v", c.promptHostname)
return nil
}
func (c *cliClient) runCommand(ctx context.Context, command string) ([]string, string, error) {
if err := c.logIn(ctx); err != nil {
return nil, "", fmt.Errorf("could not log in: %v", err)
}
// First, synchronize to prompt.
attempts := 3
for {
c.writeLine(ctx, "")
line, err := c.readString(ctx, '\n')
if err != nil {
return nil, "", fmt.Errorf("while synchronizing to prompt: %v", err)
}
line = strings.Trim(line, "\r\n")
if strings.HasSuffix(line, c.promptHostname+"#") {
break
}
attempts -= 1
if attempts == 0 {
return nil, "", fmt.Errorf("could not find prompt, last result %q", line)
}
}
// Send comand.
c.writeLine(ctx, command)
// First, read until prompt again.
if _, err := c.readUntil(ctx, c.promptHostname+"#"); err != nil {
return nil, "", fmt.Errorf("could not get command hostname echo: %v", err)
}
loopback, err := c.readUntil(ctx, "\r\n")
if err != nil {
return nil, "", fmt.Errorf("could not get command loopback: %v", err)
}
loopback = strings.Trim(loopback, "\r\n")
c.trace(ctx, "effective command: %q", loopback)
// Read until we have a standalone prompt with no newline afterwards.
data, err := c.readUntil(ctx, c.promptHostname+"#")
if err != nil {
return nil, "", fmt.Errorf("could not get command results: %v", err)
}
lines := []string{}
for _, line := range strings.Split(data, "\r\n") {
if line == c.promptHostname+"#" {
break
}
lines = append(lines, line)
}
c.trace(ctx, "command %q returned lines: %v", command, lines)
return lines, loopback, nil
}