client/request.go
package client // import "github.com/docker/docker/client"
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"net"
"net/http"
"net/url"
"os"
"reflect"
"strings"
"github.com/docker/docker/api/types"
"github.com/docker/docker/api/types/versions"
"github.com/docker/docker/errdefs"
"github.com/pkg/errors"
)
// serverResponse is a wrapper for http API responses.
type serverResponse struct {
body io.ReadCloser
header http.Header
statusCode int
reqURL *url.URL
}
// head sends an http request to the docker API using the method HEAD.
func (cli *Client) head(ctx context.Context, path string, query url.Values, headers http.Header) (serverResponse, error) {
return cli.sendRequest(ctx, http.MethodHead, path, query, nil, headers)
}
// get sends an http request to the docker API using the method GET with a specific Go context.
func (cli *Client) get(ctx context.Context, path string, query url.Values, headers http.Header) (serverResponse, error) {
return cli.sendRequest(ctx, http.MethodGet, path, query, nil, headers)
}
// post sends an http request to the docker API using the method POST with a specific Go context.
func (cli *Client) post(ctx context.Context, path string, query url.Values, obj interface{}, headers http.Header) (serverResponse, error) {
body, headers, err := encodeBody(obj, headers)
if err != nil {
return serverResponse{}, err
}
return cli.sendRequest(ctx, http.MethodPost, path, query, body, headers)
}
func (cli *Client) postRaw(ctx context.Context, path string, query url.Values, body io.Reader, headers http.Header) (serverResponse, error) {
return cli.sendRequest(ctx, http.MethodPost, path, query, body, headers)
}
func (cli *Client) put(ctx context.Context, path string, query url.Values, obj interface{}, headers http.Header) (serverResponse, error) {
body, headers, err := encodeBody(obj, headers)
if err != nil {
return serverResponse{}, err
}
return cli.putRaw(ctx, path, query, body, headers)
}
// putRaw sends an http request to the docker API using the method PUT.
func (cli *Client) putRaw(ctx context.Context, path string, query url.Values, body io.Reader, headers http.Header) (serverResponse, error) {
// PUT requests are expected to always have a body (apparently)
// so explicitly pass an empty body to sendRequest to signal that
// it should set the Content-Type header if not already present.
if body == nil {
body = http.NoBody
}
return cli.sendRequest(ctx, http.MethodPut, path, query, body, headers)
}
// delete sends an http request to the docker API using the method DELETE.
func (cli *Client) delete(ctx context.Context, path string, query url.Values, headers http.Header) (serverResponse, error) {
return cli.sendRequest(ctx, http.MethodDelete, path, query, nil, headers)
}
func encodeBody(obj interface{}, headers http.Header) (io.Reader, http.Header, error) {
if obj == nil {
return nil, headers, nil
}
// encoding/json encodes a nil pointer as the JSON document `null`,
// irrespective of whether the type implements json.Marshaler or encoding.TextMarshaler.
// That is almost certainly not what the caller intended as the request body.
if reflect.TypeOf(obj).Kind() == reflect.Ptr && reflect.ValueOf(obj).IsNil() {
return nil, headers, nil
}
body, err := encodeData(obj)
if err != nil {
return nil, headers, err
}
if headers == nil {
headers = make(map[string][]string)
}
headers["Content-Type"] = []string{"application/json"}
return body, headers, nil
}
func (cli *Client) buildRequest(ctx context.Context, method, path string, body io.Reader, headers http.Header) (*http.Request, error) {
req, err := http.NewRequestWithContext(ctx, method, path, body)
if err != nil {
return nil, err
}
req = cli.addHeaders(req, headers)
req.URL.Scheme = cli.scheme
req.URL.Host = cli.addr
if cli.proto == "unix" || cli.proto == "npipe" {
// Override host header for non-tcp connections.
req.Host = DummyHost
}
if body != nil && req.Header.Get("Content-Type") == "" {
req.Header.Set("Content-Type", "text/plain")
}
return req, nil
}
func (cli *Client) sendRequest(ctx context.Context, method, path string, query url.Values, body io.Reader, headers http.Header) (serverResponse, error) {
req, err := cli.buildRequest(ctx, method, cli.getAPIPath(ctx, path, query), body, headers)
if err != nil {
return serverResponse{}, err
}
resp, err := cli.doRequest(req)
switch {
case errors.Is(err, context.Canceled):
return serverResponse{}, errdefs.Cancelled(err)
case errors.Is(err, context.DeadlineExceeded):
return serverResponse{}, errdefs.Deadline(err)
case err == nil:
err = cli.checkResponseErr(resp)
}
return resp, errdefs.FromStatusCode(err, resp.statusCode)
}
// FIXME(thaJeztah): Should this actually return a serverResp when a connection error occurred?
func (cli *Client) doRequest(req *http.Request) (serverResponse, error) {
serverResp := serverResponse{statusCode: -1, reqURL: req.URL}
resp, err := cli.client.Do(req)
if err != nil {
if cli.scheme != "https" && strings.Contains(err.Error(), "malformed HTTP response") {
return serverResp, errConnectionFailed{fmt.Errorf("%v.\n* Are you trying to connect to a TLS-enabled daemon without TLS?", err)}
}
if cli.scheme == "https" && strings.Contains(err.Error(), "bad certificate") {
return serverResp, errConnectionFailed{errors.Wrap(err, "the server probably has client authentication (--tlsverify) enabled; check your TLS client certification settings")}
}
// Don't decorate context sentinel errors; users may be comparing to
// them directly.
if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
return serverResp, err
}
if uErr, ok := err.(*url.Error); ok {
if nErr, ok := uErr.Err.(*net.OpError); ok {
if os.IsPermission(nErr.Err) {
return serverResp, errConnectionFailed{errors.Wrapf(err, "permission denied while trying to connect to the Docker daemon socket at %v", cli.host)}
}
}
}
if nErr, ok := err.(net.Error); ok {
// FIXME(thaJeztah): any net.Error should be considered a connection error (but we should include the original error)?
if nErr.Timeout() {
return serverResp, ErrorConnectionFailed(cli.host)
}
if strings.Contains(nErr.Error(), "connection refused") || strings.Contains(nErr.Error(), "dial unix") {
return serverResp, ErrorConnectionFailed(cli.host)
}
}
// Although there's not a strongly typed error for this in go-winio,
// lots of people are using the default configuration for the docker
// daemon on Windows where the daemon is listening on a named pipe
// `//./pipe/docker_engine, and the client must be running elevated.
// Give users a clue rather than the not-overly useful message
// such as `error during connect: Get http://%2F%2F.%2Fpipe%2Fdocker_engine/v1.26/info:
// open //./pipe/docker_engine: The system cannot find the file specified.`.
// Note we can't string compare "The system cannot find the file specified" as
// this is localised - for example in French the error would be
// `open //./pipe/docker_engine: Le fichier spécifié est introuvable.`
if strings.Contains(err.Error(), `open //./pipe/docker_engine`) {
// Checks if client is running with elevated privileges
if f, elevatedErr := os.Open(`\\.\PHYSICALDRIVE0`); elevatedErr != nil {
err = errors.Wrap(err, "in the default daemon configuration on Windows, the docker client must be run with elevated privileges to connect")
} else {
_ = f.Close()
err = errors.Wrap(err, "this error may indicate that the docker daemon is not running")
}
}
return serverResp, errConnectionFailed{errors.Wrap(err, "error during connect")}
}
if resp != nil {
serverResp.statusCode = resp.StatusCode
serverResp.body = resp.Body
serverResp.header = resp.Header
}
return serverResp, nil
}
func (cli *Client) checkResponseErr(serverResp serverResponse) error {
if serverResp.statusCode >= 200 && serverResp.statusCode < 400 {
return nil
}
var body []byte
var err error
if serverResp.body != nil {
bodyMax := 1 * 1024 * 1024 // 1 MiB
bodyR := &io.LimitedReader{
R: serverResp.body,
N: int64(bodyMax),
}
body, err = io.ReadAll(bodyR)
if err != nil {
return err
}
if bodyR.N == 0 {
return fmt.Errorf("request returned %s with a message (> %d bytes) for API route and version %s, check if the server supports the requested API version", http.StatusText(serverResp.statusCode), bodyMax, serverResp.reqURL)
}
}
if len(body) == 0 {
return fmt.Errorf("request returned %s for API route and version %s, check if the server supports the requested API version", http.StatusText(serverResp.statusCode), serverResp.reqURL)
}
var daemonErr error
if serverResp.header.Get("Content-Type") == "application/json" && (cli.version == "" || versions.GreaterThan(cli.version, "1.23")) {
var errorResponse types.ErrorResponse
if err := json.Unmarshal(body, &errorResponse); err != nil {
return errors.Wrap(err, "Error reading JSON")
}
daemonErr = errors.New(strings.TrimSpace(errorResponse.Message))
} else {
daemonErr = errors.New(strings.TrimSpace(string(body)))
}
return errors.Wrap(daemonErr, "Error response from daemon")
}
func (cli *Client) addHeaders(req *http.Request, headers http.Header) *http.Request {
// Add CLI Config's HTTP Headers BEFORE we set the Docker headers
// then the user can't change OUR headers
for k, v := range cli.customHTTPHeaders {
if versions.LessThan(cli.version, "1.25") && http.CanonicalHeaderKey(k) == "User-Agent" {
continue
}
req.Header.Set(k, v)
}
for k, v := range headers {
req.Header[http.CanonicalHeaderKey(k)] = v
}
if cli.userAgent != nil {
if *cli.userAgent == "" {
req.Header.Del("User-Agent")
} else {
req.Header.Set("User-Agent", *cli.userAgent)
}
}
return req
}
func encodeData(data interface{}) (*bytes.Buffer, error) {
params := bytes.NewBuffer(nil)
if data != nil {
if err := json.NewEncoder(params).Encode(data); err != nil {
return nil, err
}
}
return params, nil
}
func ensureReaderClosed(response serverResponse) {
if response.body != nil {
// Drain up to 512 bytes and close the body to let the Transport reuse the connection
_, _ = io.CopyN(io.Discard, response.body, 512)
_ = response.body.Close()
}
}