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client: don't marshal typed nils in request body

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The internal Client request methods which accept an object as a body use
nil to signal that the request should not have a body. But it is easy to
accidentally pass a typed-nil value as the object, e.g. if the object
comes from a function argument or struct field of a concrete type. The
result is that these requests will, surprisingly, have a JSON body of
`null`. Treat typed-nil pointers the same as untyped nils for the
purposes of determining whether or not the request should include a
body.

Stop assuming that POST requests should always have a body. POST /commit
does not require a body, for example.

Signed-off-by: Cory Snider <csnider@mirantis.com>
This commit is contained in:
Cory Snider 2023-05-17 14:36:08 -04:00
parent f70d9933d1
commit 3ceb3810d7
1 changed files with 15 additions and 7 deletions
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22
client/request.go
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@ -10,6 +10,7 @@ import (
"net/http"
"net/url"
"os"
"reflect"
"strings"
"github.com/docker/docker/api/types"
@ -54,11 +55,17 @@ func (cli *Client) put(ctx context.Context, path string, query url.Values, obj i
if err != nil {
return serverResponse{}, err
}
return cli.sendRequest(ctx, http.MethodPut, path, query, body, headers)
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 map[string][]string) (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)
}
@ -73,6 +80,12 @@ func encodeBody(obj interface{}, headers headers) (io.Reader, headers, 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 {
@ -86,11 +99,6 @@ func encodeBody(obj interface{}, headers headers) (io.Reader, headers, error) {
}
func (cli *Client) buildRequest(method, path string, body io.Reader, headers headers) (*http.Request, error) {
expectedPayload := (method == http.MethodPost || method == http.MethodPut)
if expectedPayload && body == nil {
body = bytes.NewReader([]byte{})
}
req, err := http.NewRequest(method, path, body)
if err != nil {
return nil, err
@ -106,7 +114,7 @@ func (cli *Client) buildRequest(method, path string, body io.Reader, headers hea
req.URL.Host = cli.addr
req.URL.Scheme = cli.scheme
if expectedPayload && req.Header.Get("Content-Type") == "" {
if body != nil && req.Header.Get("Content-Type") == "" {
req.Header.Set("Content-Type", "text/plain")
}
return req, nil