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package middleware // import "github.com/docker/docker/api/server/middleware"
import (
"context"
"fmt"
"net/http"
"runtime"
"github.com/docker/docker/api"
"github.com/docker/docker/api/server/httputils"
"github.com/docker/docker/api/types/versions"
)
// VersionMiddleware is a middleware that
// validates the client and server versions.
type VersionMiddleware struct {
serverVersion string
// defaultAPIVersion is the default API version provided by the API server,
// specified as "major.minor". It is usually configured to the latest API
// version [github.com/docker/docker/api.DefaultVersion].
//
// API requests for API versions greater than this version are rejected by
// the server and produce a [versionUnsupportedError].
defaultAPIVersion string
// minAPIVersion is the minimum API version provided by the API server,
// specified as "major.minor".
//
// API requests for API versions lower than this version are rejected by
// the server and produce a [versionUnsupportedError].
minAPIVersion string
}
// NewVersionMiddleware creates a VersionMiddleware with the given versions.
func NewVersionMiddleware(serverVersion, defaultAPIVersion, minAPIVersion string) (*VersionMiddleware, error) {
if versions.LessThan(defaultAPIVersion, api.MinSupportedAPIVersion) || versions.GreaterThan(defaultAPIVersion, api.DefaultVersion) {
return nil, fmt.Errorf("invalid default API version (%s): must be between %s and %s", defaultAPIVersion, api.MinSupportedAPIVersion, api.DefaultVersion)
}
if versions.LessThan(minAPIVersion, api.MinSupportedAPIVersion) || versions.GreaterThan(minAPIVersion, api.DefaultVersion) {
return nil, fmt.Errorf("invalid minimum API version (%s): must be between %s and %s", minAPIVersion, api.MinSupportedAPIVersion, api.DefaultVersion)
}
if versions.GreaterThan(minAPIVersion, defaultAPIVersion) {
return nil, fmt.Errorf("invalid API version: the minimum API version (%s) is higher than the default version (%s)", minAPIVersion, defaultAPIVersion)
}
return &VersionMiddleware{
serverVersion: serverVersion,
defaultAPIVersion: defaultAPIVersion,
minAPIVersion: minAPIVersion,
}, nil
}
type versionUnsupportedError struct {
version, minVersion, maxVersion string
}
func (e versionUnsupportedError) Error() string {
if e.minVersion != "" {
return fmt.Sprintf("client version %s is too old. Minimum supported API version is %s, please upgrade your client to a newer version", e.version, e.minVersion)
}
return fmt.Sprintf("client version %s is too new. Maximum supported API version is %s", e.version, e.maxVersion)
}
func (e versionUnsupportedError) InvalidParameter() {}
// WrapHandler returns a new handler function wrapping the previous one in the request chain.
func (v VersionMiddleware) WrapHandler(handler func(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error) func(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
return func(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
w.Header().Set("Server", fmt.Sprintf("Docker/%s (%s)", v.serverVersion, runtime.GOOS))
w.Header().Set("API-Version", v.defaultAPIVersion)
w.Header().Set("OSType", runtime.GOOS)
apiVersion := vars["version"]
if apiVersion == "" {
apiVersion = v.defaultAPIVersion
}
if versions.LessThan(apiVersion, v.minAPIVersion) {
return versionUnsupportedError{version: apiVersion, minVersion: v.minAPIVersion}
}
if versions.GreaterThan(apiVersion, v.defaultAPIVersion) {
return versionUnsupportedError{version: apiVersion, maxVersion: v.defaultAPIVersion}
}
ctx = context.WithValue(ctx, httputils.APIVersionKey{}, apiVersion)
return handler(ctx, w, r, vars)
}
}
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