distribution/registry/handlers/catalog.go

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package handlers
import (
"encoding/json"
"fmt"
"io"
"net/http"
"net/url"
"strconv"
"github.com/distribution/distribution/v3/registry/api/errcode"
"github.com/distribution/distribution/v3/registry/storage/driver"
"github.com/gorilla/handlers"
)
const defaultReturnedEntries = 100
func catalogDispatcher(ctx *Context, r *http.Request) http.Handler {
catalogHandler := &catalogHandler{
Context: ctx,
}
return handlers.MethodHandler{
http.MethodGet: http.HandlerFunc(catalogHandler.GetCatalog),
}
}
type catalogHandler struct {
*Context
}
type catalogAPIResponse struct {
Repositories []string `json:"repositories"`
}
func (ch *catalogHandler) GetCatalog(w http.ResponseWriter, r *http.Request) {
moreEntries := true
q := r.URL.Query()
lastEntry := q.Get("last")
entries := defaultReturnedEntries
maximumConfiguredEntries := ch.App.Config.Catalog.MaxEntries
// parse n, if n is negative abort with an error
if n := q.Get("n"); n != "" {
parsedMax, err := strconv.Atoi(n)
if err != nil || parsedMax < 0 {
ch.Errors = append(ch.Errors, errcode.ErrorCodePaginationNumberInvalid.WithDetail(map[string]string{"n": n}))
return
}
// if a client requests more than it's allowed to receive
if parsedMax > maximumConfiguredEntries {
ch.Errors = append(ch.Errors, errcode.ErrorCodePaginationNumberInvalid.WithDetail(map[string]int{"n": parsedMax}))
return
}
entries = parsedMax
}
// then enforce entries to be between 0 & maximumConfiguredEntries
// max(0, min(entries, maximumConfiguredEntries))
if entries < 0 || entries > maximumConfiguredEntries {
entries = maximumConfiguredEntries
}
repos := make([]string, entries)
filled := 0
// entries is guaranteed to be >= 0 and < maximumConfiguredEntries
if entries == 0 {
moreEntries = false
} else {
returnedRepositories, err := ch.App.registry.Repositories(ch.Context, repos, lastEntry)
if err != nil {
_, pathNotFound := err.(driver.PathNotFoundError)
if err != io.EOF && !pathNotFound {
ch.Errors = append(ch.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
return
}
// err is either io.EOF or not PathNotFoundError
moreEntries = false
}
filled = returnedRepositories
}
w.Header().Set("Content-Type", "application/json")
// Add a link header if there are more entries to retrieve
if moreEntries {
lastEntry = repos[filled-1]
urlStr, err := createLinkEntry(r.URL.String(), entries, lastEntry)
if err != nil {
ch.Errors = append(ch.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
return
}
w.Header().Set("Link", urlStr)
}
enc := json.NewEncoder(w)
if err := enc.Encode(catalogAPIResponse{
Repositories: repos[0:filled],
}); err != nil {
ch.Errors = append(ch.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
return
}
}
// Use the original URL from the request to create a new URL for
// the link header
func createLinkEntry(origURL string, maxEntries int, lastEntry string) (string, error) {
calledURL, err := url.Parse(origURL)
if err != nil {
return "", err
}
v := url.Values{}
v.Add("n", strconv.Itoa(maxEntries))
v.Add("last", lastEntry)
calledURL.RawQuery = v.Encode()
calledURL.Fragment = ""
urlStr := fmt.Sprintf("<%s>; rel=\"next\"", calledURL.String())
return urlStr, nil
}