distribution/registry/api/v2/urls.go
Sebastiaan van Stijn 3b391d3290
replace strings.Split(N) for strings.Cut() or alternatives
Go 1.18 and up now provides a strings.Cut() which is better suited for
splitting key/value pairs (and similar constructs), and performs better:

```go
func BenchmarkSplit(b *testing.B) {
	b.ReportAllocs()
	data := []string{"12hello=world", "12hello=", "12=hello", "12hello"}
	for i := 0; i < b.N; i++ {
		for _, s := range data {
			_ = strings.SplitN(s, "=", 2)[0]
		}
	}
}

func BenchmarkCut(b *testing.B) {
	b.ReportAllocs()
	data := []string{"12hello=world", "12hello=", "12=hello", "12hello"}
	for i := 0; i < b.N; i++ {
		for _, s := range data {
			_, _, _ = strings.Cut(s, "=")
		}
	}
}
```

    BenchmarkSplit
    BenchmarkSplit-10    	 8244206	       128.0 ns/op	     128 B/op	       4 allocs/op
    BenchmarkCut
    BenchmarkCut-10      	54411998	        21.80 ns/op	       0 B/op	       0 allocs/op

While looking at occurrences of `strings.Split()`, I also updated some for alternatives,
or added some constraints;

- for cases where an specific number of items is expected, I used `strings.SplitN()`
  with a suitable limit. This prevents (theoretical) unlimited splits.
- in some cases it we were using `strings.Split()`, but _actually_ were trying to match
  a prefix; for those I replaced the code to just match (and/or strip) the prefix.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2022-11-10 22:38:12 +01:00

254 lines
6.8 KiB
Go

package v2
import (
"fmt"
"net/http"
"net/url"
"strings"
"github.com/distribution/distribution/v3/reference"
"github.com/gorilla/mux"
)
// URLBuilder creates registry API urls from a single base endpoint. It can be
// used to create urls for use in a registry client or server.
//
// All urls will be created from the given base, including the api version.
// For example, if a root of "/foo/" is provided, urls generated will be fall
// under "/foo/v2/...". Most application will only provide a schema, host and
// port, such as "https://localhost:5000/".
type URLBuilder struct {
root *url.URL // url root (ie http://localhost/)
router *mux.Router
relative bool
}
// NewURLBuilder creates a URLBuilder with provided root url object.
func NewURLBuilder(root *url.URL, relative bool) *URLBuilder {
return &URLBuilder{
root: root,
router: Router(),
relative: relative,
}
}
// NewURLBuilderFromString works identically to NewURLBuilder except it takes
// a string argument for the root, returning an error if it is not a valid
// url.
func NewURLBuilderFromString(root string, relative bool) (*URLBuilder, error) {
u, err := url.Parse(root)
if err != nil {
return nil, err
}
return NewURLBuilder(u, relative), nil
}
// NewURLBuilderFromRequest uses information from an *http.Request to
// construct the root url.
func NewURLBuilderFromRequest(r *http.Request, relative bool) *URLBuilder {
var (
scheme = "http"
host = r.Host
)
if r.TLS != nil {
scheme = "https"
} else if len(r.URL.Scheme) > 0 {
scheme = r.URL.Scheme
}
// Handle forwarded headers
// Prefer "Forwarded" header as defined by rfc7239 if given
// see https://tools.ietf.org/html/rfc7239
if forwarded := r.Header.Get("Forwarded"); len(forwarded) > 0 {
forwardedHeader, _, err := parseForwardedHeader(forwarded)
if err == nil {
if fproto := forwardedHeader["proto"]; len(fproto) > 0 {
scheme = fproto
}
if fhost := forwardedHeader["host"]; len(fhost) > 0 {
host = fhost
}
}
} else {
if forwardedProto := r.Header.Get("X-Forwarded-Proto"); len(forwardedProto) > 0 {
scheme = forwardedProto
}
if forwardedHost := r.Header.Get("X-Forwarded-Host"); len(forwardedHost) > 0 {
// According to the Apache mod_proxy docs, X-Forwarded-Host can be a
// comma-separated list of hosts, to which each proxy appends the
// requested host. We want to grab the first from this comma-separated
// list.
host, _, _ = strings.Cut(forwardedHost, ",")
host = strings.TrimSpace(host)
}
}
basePath := routeDescriptorsMap[RouteNameBase].Path
requestPath := r.URL.Path
index := strings.Index(requestPath, basePath)
u := &url.URL{
Scheme: scheme,
Host: host,
}
if index > 0 {
// N.B. index+1 is important because we want to include the trailing /
u.Path = requestPath[0 : index+1]
}
return NewURLBuilder(u, relative)
}
// BuildBaseURL constructs a base url for the API, typically just "/v2/".
func (ub *URLBuilder) BuildBaseURL() (string, error) {
route := ub.cloneRoute(RouteNameBase)
baseURL, err := route.URL()
if err != nil {
return "", err
}
return baseURL.String(), nil
}
// BuildCatalogURL constructs a url get a catalog of repositories
func (ub *URLBuilder) BuildCatalogURL(values ...url.Values) (string, error) {
route := ub.cloneRoute(RouteNameCatalog)
catalogURL, err := route.URL()
if err != nil {
return "", err
}
return appendValuesURL(catalogURL, values...).String(), nil
}
// BuildTagsURL constructs a url to list the tags in the named repository.
func (ub *URLBuilder) BuildTagsURL(name reference.Named, values ...url.Values) (string, error) {
route := ub.cloneRoute(RouteNameTags)
tagsURL, err := route.URL("name", name.Name())
if err != nil {
return "", err
}
return appendValuesURL(tagsURL, values...).String(), nil
}
// BuildManifestURL constructs a url for the manifest identified by name and
// reference. The argument reference may be either a tag or digest.
func (ub *URLBuilder) BuildManifestURL(ref reference.Named) (string, error) {
route := ub.cloneRoute(RouteNameManifest)
tagOrDigest := ""
switch v := ref.(type) {
case reference.Tagged:
tagOrDigest = v.Tag()
case reference.Digested:
tagOrDigest = v.Digest().String()
default:
return "", fmt.Errorf("reference must have a tag or digest")
}
manifestURL, err := route.URL("name", ref.Name(), "reference", tagOrDigest)
if err != nil {
return "", err
}
return manifestURL.String(), nil
}
// BuildBlobURL constructs the url for the blob identified by name and dgst.
func (ub *URLBuilder) BuildBlobURL(ref reference.Canonical) (string, error) {
route := ub.cloneRoute(RouteNameBlob)
layerURL, err := route.URL("name", ref.Name(), "digest", ref.Digest().String())
if err != nil {
return "", err
}
return layerURL.String(), nil
}
// BuildBlobUploadURL constructs a url to begin a blob upload in the
// repository identified by name.
func (ub *URLBuilder) BuildBlobUploadURL(name reference.Named, values ...url.Values) (string, error) {
route := ub.cloneRoute(RouteNameBlobUpload)
uploadURL, err := route.URL("name", name.Name())
if err != nil {
return "", err
}
return appendValuesURL(uploadURL, values...).String(), nil
}
// BuildBlobUploadChunkURL constructs a url for the upload identified by uuid,
// including any url values. This should generally not be used by clients, as
// this url is provided by server implementations during the blob upload
// process.
func (ub *URLBuilder) BuildBlobUploadChunkURL(name reference.Named, uuid string, values ...url.Values) (string, error) {
route := ub.cloneRoute(RouteNameBlobUploadChunk)
uploadURL, err := route.URL("name", name.Name(), "uuid", uuid)
if err != nil {
return "", err
}
return appendValuesURL(uploadURL, values...).String(), nil
}
// clondedRoute returns a clone of the named route from the router. Routes
// must be cloned to avoid modifying them during url generation.
func (ub *URLBuilder) cloneRoute(name string) clonedRoute {
route := new(mux.Route)
root := new(url.URL)
*route = *ub.router.GetRoute(name) // clone the route
*root = *ub.root
return clonedRoute{Route: route, root: root, relative: ub.relative}
}
type clonedRoute struct {
*mux.Route
root *url.URL
relative bool
}
func (cr clonedRoute) URL(pairs ...string) (*url.URL, error) {
routeURL, err := cr.Route.URL(pairs...)
if err != nil {
return nil, err
}
if cr.relative {
return routeURL, nil
}
if routeURL.Scheme == "" && routeURL.User == nil && routeURL.Host == "" {
routeURL.Path = routeURL.Path[1:]
}
url := cr.root.ResolveReference(routeURL)
url.Scheme = cr.root.Scheme
return url, nil
}
// appendValuesURL appends the parameters to the url.
func appendValuesURL(u *url.URL, values ...url.Values) *url.URL {
merged := u.Query()
for _, v := range values {
for k, vv := range v {
merged[k] = append(merged[k], vv...)
}
}
u.RawQuery = merged.Encode()
return u
}