doi: add new doi backend

Add a new backend to support mounting datasets published with a digital
object identifier (DOI).

backend/doi/invenio.go

@@ -0,0 +1,164 @@
+// Implementation for InvenioRDM
+
+package doi
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/url"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/rclone/rclone/backend/doi/api"
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/lib/rest"
+)
+
+var invenioRecordRegex = regexp.MustCompile(`\/records?\/(.+)`)
+
+// Returns true if resolvedURL is likely a DOI hosted on an InvenioRDM intallation
+func activateInvenio(ctx context.Context, srv *rest.Client, pacer *fs.Pacer, resolvedURL *url.URL) (isActive bool) {
+	_, _, err := resolveInvenioEndpoint(ctx, srv, pacer, resolvedURL)
+	return err == nil
+}
+
+// Resolve the main API endpoint for a DOI hosted on an InvenioRDM installation
+func resolveInvenioEndpoint(ctx context.Context, srv *rest.Client, pacer *fs.Pacer, resolvedURL *url.URL) (provider Provider, endpoint *url.URL, err error) {
+	var res *http.Response
+	opts := rest.Opts{
+		Method:  "GET",
+		RootURL: resolvedURL.String(),
+	}
+	err = pacer.Call(func() (bool, error) {
+		res, err = srv.Call(ctx, &opts)
+		return shouldRetry(ctx, res, err)
+	})
+	if err != nil {
+		return "", nil, err
+	}
+
+	// First, attempt to grab the API URL from the headers
+	var linksetURL *url.URL
+	links := parseLinkHeader(res.Header.Get("Link"))
+	for _, link := range links {
+		if link.Rel == "linkset" && link.Type == "application/linkset+json" {
+			parsed, err := url.Parse(link.Href)
+			if err == nil {
+				linksetURL = parsed
+				break
+			}
+		}
+	}
+
+	if linksetURL != nil {
+		endpoint, err = checkInvenioAPIURL(ctx, srv, pacer, linksetURL)
+		if err == nil {
+			return Invenio, endpoint, nil
+		}
+		fs.Logf(nil, "using linkset URL failed: %s", err.Error())
+	}
+
+	// If there is no linkset header, try to grab the record ID from the URL
+	recordID := ""
+	resURL := res.Request.URL
+	match := invenioRecordRegex.FindStringSubmatch(resURL.EscapedPath())
+	if match != nil {
+		recordID = match[1]
+		guessedURL := res.Request.URL.ResolveReference(&url.URL{
+			Path: "/api/records/" + recordID,
+		})
+		endpoint, err = checkInvenioAPIURL(ctx, srv, pacer, guessedURL)
+		if err == nil {
+			return Invenio, endpoint, nil
+		}
+		fs.Logf(nil, "guessing the URL failed: %s", err.Error())
+	}
+
+	return "", nil, fmt.Errorf("could not resolve the Invenio API endpoint for '%s'", resolvedURL.String())
+}
+
+func checkInvenioAPIURL(ctx context.Context, srv *rest.Client, pacer *fs.Pacer, resolvedURL *url.URL) (endpoint *url.URL, err error) {
+	var result api.InvenioRecordResponse
+	opts := rest.Opts{
+		Method:  "GET",
+		RootURL: resolvedURL.String(),
+	}
+	err = pacer.Call(func() (bool, error) {
+		res, err := srv.CallJSON(ctx, &opts, nil, &result)
+		return shouldRetry(ctx, res, err)
+	})
+	if err != nil {
+		return nil, err
+	}
+	if result.Links.Self == "" {
+		return nil, fmt.Errorf("could not parse API response from '%s'", resolvedURL.String())
+	}
+	return url.Parse(result.Links.Self)
+}
+
+// invenioProvider implements the doiProvider interface for InvenioRDM installations
+type invenioProvider struct {
+	f *Fs
+}
+
+// ListEntries returns the full list of entries found at the remote, regardless of root
+func (ip *invenioProvider) ListEntries(ctx context.Context) (entries []*Object, err error) {
+	// Use the cache if populated
+	cachedEntries, found := ip.f.cache.GetMaybe("files")
+	if found {
+		parsedEntries, ok := cachedEntries.([]Object)
+		if ok {
+			for _, entry := range parsedEntries {
+				newEntry := entry
+				entries = append(entries, &newEntry)
+			}
+			return entries, nil
+		}
+	}
+
+	filesURL := ip.f.endpoint.JoinPath("files")
+	var result api.InvenioFilesResponse
+	opts := rest.Opts{
+		Method: "GET",
+		Path:   strings.TrimLeft(filesURL.EscapedPath(), "/"),
+	}
+	err = ip.f.pacer.Call(func() (bool, error) {
+		res, err := ip.f.srv.CallJSON(ctx, &opts, nil, &result)
+		return shouldRetry(ctx, res, err)
+	})
+	if err != nil {
+		return nil, fmt.Errorf("readDir failed: %w", err)
+	}
+	for _, file := range result.Entries {
+		modTime, modTimeErr := time.Parse(time.RFC3339, file.Updated)
+		if modTimeErr != nil {
+			fs.Logf(ip.f, "error: could not parse last update time %v", modTimeErr)
+			modTime = timeUnset
+		}
+		entry := &Object{
+			fs:          ip.f,
+			remote:      file.Key,
+			contentURL:  file.Links.Content,
+			size:        file.Size,
+			modTime:     modTime,
+			contentType: file.MimeType,
+			md5:         strings.TrimPrefix(file.Checksum, "md5:"),
+		}
+		entries = append(entries, entry)
+	}
+	// Populate the cache
+	cacheEntries := []Object{}
+	for _, entry := range entries {
+		cacheEntries = append(cacheEntries, *entry)
+	}
+	ip.f.cache.Put("files", cacheEntries)
+	return entries, nil
+}
+
+func newInvenioProvider(f *Fs) doiProvider {
+	return &invenioProvider{
+		f: f,
+	}
+}