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Unlike a plain `net/http/client.Do()`, requests made through client/request use the `sendRequest` function, which parses the server response, and may convert non-transport errors into errors (through `cli.checkResponseErr()`). This means that we cannot assume that no reader was opened if an error is returned. This patch changes various locations where `ensureReaderClosed` was only called in the non-error situation, and uses a `defer` to make sure it's always called. `ensureReaderClosed` itself already checks if the response's body was set, so in situations where the error was due to a transport error, calling `ensureReaderClosed` should be a no-op. Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
64 lines
2 KiB
Go
64 lines
2 KiB
Go
package client // import "github.com/docker/docker/client"
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import (
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"context"
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"net/http"
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"path"
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"github.com/docker/docker/api/types"
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"github.com/docker/docker/errdefs"
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)
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// Ping pings the server and returns the value of the "Docker-Experimental",
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// "Builder-Version", "OS-Type" & "API-Version" headers. It attempts to use
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// a HEAD request on the endpoint, but falls back to GET if HEAD is not supported
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// by the daemon.
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func (cli *Client) Ping(ctx context.Context) (types.Ping, error) {
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var ping types.Ping
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// Using cli.buildRequest() + cli.doRequest() instead of cli.sendRequest()
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// because ping requests are used during API version negotiation, so we want
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// to hit the non-versioned /_ping endpoint, not /v1.xx/_ping
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req, err := cli.buildRequest("HEAD", path.Join(cli.basePath, "/_ping"), nil, nil)
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if err != nil {
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return ping, err
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}
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serverResp, err := cli.doRequest(ctx, req)
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if err == nil {
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defer ensureReaderClosed(serverResp)
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switch serverResp.statusCode {
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case http.StatusOK, http.StatusInternalServerError:
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// Server handled the request, so parse the response
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return parsePingResponse(cli, serverResp)
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}
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}
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req, err = cli.buildRequest("GET", path.Join(cli.basePath, "/_ping"), nil, nil)
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if err != nil {
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return ping, err
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}
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serverResp, err = cli.doRequest(ctx, req)
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defer ensureReaderClosed(serverResp)
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if err != nil {
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return ping, err
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}
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return parsePingResponse(cli, serverResp)
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}
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func parsePingResponse(cli *Client, resp serverResponse) (types.Ping, error) {
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var ping types.Ping
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if resp.header == nil {
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err := cli.checkResponseErr(resp)
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return ping, errdefs.FromStatusCode(err, resp.statusCode)
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}
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ping.APIVersion = resp.header.Get("API-Version")
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ping.OSType = resp.header.Get("OSType")
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if resp.header.Get("Docker-Experimental") == "true" {
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ping.Experimental = true
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}
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if bv := resp.header.Get("Builder-Version"); bv != "" {
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ping.BuilderVersion = types.BuilderVersion(bv)
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}
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err := cli.checkResponseErr(resp)
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return ping, errdefs.FromStatusCode(err, resp.statusCode)
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}
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