59 lines
1.5 KiB
Go
59 lines
1.5 KiB
Go
package docker
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import (
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"encoding/json"
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"errors"
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"net/http"
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"regexp"
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"strings"
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)
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var ErrNoMorePages = errors.New("no more pages")
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// Matches an RFC 5988 (https://tools.ietf.org/html/rfc5988#section-5)
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// Link header. For example,
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//
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// <http://registry.example.com/v2/_catalog?n=5&last=tag5>; type="application/json"; rel="next"
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//
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// The URL is _supposed_ to be wrapped by angle brackets `< ... >`,
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// but e.g., quay.io does not include them. Similarly, params like
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// `rel="next"` may not have quoted values in the wild.
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var nextLinkRE = regexp.MustCompile(`^ *<?([^;>]+)>? *(?:;[^;]*)*; *rel="?next"?(?:;.*)?`)
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func getNextLink(resp *http.Response) (string, error) {
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for _, link := range resp.Header[http.CanonicalHeaderKey("Link")] {
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parts := nextLinkRE.FindStringSubmatch(link)
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if parts != nil {
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return parts[1], nil
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}
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}
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return "", ErrNoMorePages
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}
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// getPaginatedJSON accepts a string and a pointer, and returns the
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// next page URL while updating pointed-to variable with a parsed JSON
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// value. When there are no more pages it returns `ErrNoMorePages`.
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func (r *Registry) getPaginatedJSON(url string, response interface{}) (string, error) {
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resp, err := r.Client.Get(url)
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if err != nil {
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return "", err
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}
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defer resp.Body.Close()
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decoder := json.NewDecoder(resp.Body)
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err = decoder.Decode(response)
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if err != nil {
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return "", err
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}
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next, err := getNextLink(resp)
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if err != nil {
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return "", err
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}
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if !strings.HasPrefix(next, r.URL) {
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next = r.URL + next
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}
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return next, nil
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}
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