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handler.go
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handler.go
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package main
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"os"
"os/exec"
"regexp"
"strings"
)
var errInvalidMethod = errors.New("invalid method")
var errInvalidInput = errors.New("invalid input")
var errMissingField = errors.New("missing field")
var errUserNotFound = errors.New("user not found")
var errParsing = errors.New("failed to parse keybase output")
var errKeybaseNotRunning = errors.New("keybase is not running")
var errKeybaseNotLoggedIn = errors.New("keybase is not logged in")
type errUnexpected struct {
value string
}
func (err *errUnexpected) Error() string {
return fmt.Sprintf("unexpected error: %s", err.value)
}
func execRunner(cmd *exec.Cmd) error {
return cmd.Run()
}
// reUsernameQuery matches valid username queries
var reUsernameQuery = regexp.MustCompile(`^[a-zA-Z0-9_\-.:@]{1,256}$`)
// checkUsernameQuery returns the query if it's valid to use
// We return the valid string so that it can be used as a separate
// pre-validated variable which makes it less likely that the validation will
// be accidentally removed in the future, as opposed to if we just continued
// using the input variable after validating it.
func checkUsernameQuery(s string) (string, error) {
if s == "" {
return "", errMissingField
}
if !reUsernameQuery.MatchString(s) {
return "", errInvalidInput
}
return s, nil
}
// newHandler returns a request handler.
func newHandler() *handler {
return &handler{
Run: execRunner,
FindKeybaseBinary: func() (string, error) {
return findKeybaseBinary(keybaseBinary)
},
}
}
type handler struct {
// Run wraps the equivalent of cmd.Run(), allowing for mocking
Run func(cmd *exec.Cmd) error
// FindCmd returns the path of the keybase binary if it can find it
FindKeybaseBinary func() (string, error)
}
// Handle accepts a request, handles it, and returns an optional result if there was no error
func (h *handler) Handle(req *Request) (interface{}, error) {
switch req.Method {
case "chat":
return nil, h.handleChat(req)
case "query":
return h.handleQuery(req)
}
return nil, errInvalidMethod
}
// handleChat sends a chat message to a user.
func (h *handler) handleChat(req *Request) error {
if req.Body == "" {
return errMissingField
}
idQuery, err := checkUsernameQuery(req.To)
if err != nil {
return err
}
binPath, err := h.FindKeybaseBinary()
if err != nil {
return err
}
var out bytes.Buffer
cmd := exec.Command(binPath, "chat", "send", "--private", idQuery)
cmd.Env = append(os.Environ(), "KEYBASE_LOG_FORMAT=plain")
cmd.Stdin = strings.NewReader(req.Body)
cmd.Stdout = &out
cmd.Stderr = &out
if err := h.Run(cmd); err != nil {
return parseError(&out, err)
}
return nil
}
type resultQuery struct {
Username string `json:"username"`
}
// parseQuery reads the stderr from a keybase query command and returns a result
func parseQuery(r io.Reader) (*resultQuery, error) {
scanner := bufio.NewScanner(r)
var lastErrLine string
for scanner.Scan() {
// Find a line that looks like... "[INFO] 001 Identifying someuser"
line := strings.TrimSpace(scanner.Text())
parts := strings.Split(line, " ")
if len(parts) < 4 {
continue
}
// Short circuit errors
if parts[0] == "[ERRO]" {
lastErrLine = strings.Join(parts[2:], " ")
if lastErrLine == "Not found" {
return nil, errUserNotFound
}
continue
}
if parts[2] != "Identifying" {
continue
}
resp := &resultQuery{
Username: parts[3],
}
return resp, nil
}
if err := scanner.Err(); err != nil {
return nil, scanner.Err()
}
// This could happen if the keybase service is broken
return nil, &errUnexpected{lastErrLine}
}
// parseError reads stderr output and returns an error made from it. If it
// fails to parse an error, it returns the fallback error.
func parseError(r io.Reader, fallback error) error {
scanner := bufio.NewScanner(r)
// Find the final error
var lastErr error
for scanner.Scan() {
// Should be of the form "[ERRO] 001 Not found" or "...: No resolution found"
line := strings.TrimSpace(scanner.Text())
if line == "" {
continue
}
// Check some error states we know about:
if strings.Contains(line, "Keybase isn't running.") {
return errKeybaseNotRunning
}
if strings.Contains(line, "You are not logged into Keybase.") {
return errKeybaseNotLoggedIn
}
parts := strings.SplitN(line, " ", 3)
if len(parts) < 3 {
continue
}
if parts[0] != "[ERRO]" {
continue
}
if strings.HasSuffix(parts[2], "No resolution found") {
return errUserNotFound
}
if strings.HasPrefix(parts[2], "Not found") {
return errUserNotFound
}
lastErr = fmt.Errorf(parts[2])
}
if lastErr != nil {
return lastErr
}
return fallback
}
// handleQuery searches whether a user is present in Keybase.
func (h *handler) handleQuery(req *Request) (*resultQuery, error) {
idQuery, err := checkUsernameQuery(req.To)
if err != nil {
return nil, err
}
binPath, err := h.FindKeybaseBinary()
if err != nil {
return nil, err
}
// Unfortunately `keybase id ...` does not support JSON output, so we parse the output
var out bytes.Buffer
cmd := exec.Command(binPath, "id", idQuery)
cmd.Env = append(os.Environ(), "KEYBASE_LOG_FORMAT=plain")
cmd.Stdout = &out
cmd.Stderr = &out
if err := h.Run(cmd); err != nil {
return nil, parseError(&out, err)
}
return parseQuery(&out)
}