116 lines
3.7 KiB
Go
116 lines
3.7 KiB
Go
package pub
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import (
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"net/http"
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"github.com/superseriousbusiness/activity/streams"
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)
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var ErrNotFound = errors.New("go-fed/activity: ActivityStreams data not found")
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// HandlerFunc determines whether an incoming HTTP request is an ActivityStreams
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// GET request, and if so attempts to serve ActivityStreams data.
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//
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// If an error is returned, then the calling function is responsible for writing
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// to the ResponseWriter as part of error handling.
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//
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// If 'isASRequest' is false and there is no error, then the calling function
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// may continue processing the request, and the HandlerFunc will not have
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// written anything to the ResponseWriter. For example, a webpage may be served
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// instead.
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//
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// If 'isASRequest' is true and there is no error, then the HandlerFunc
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// successfully served the request and wrote to the ResponseWriter.
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//
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// Callers are responsible for authorized access to this resource.
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type HandlerFunc func(c context.Context, w http.ResponseWriter, r *http.Request) (isASRequest bool, err error)
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// NewActivityStreamsHandler creates a HandlerFunc to serve ActivityStreams
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// requests which are coming from other clients or servers that wish to obtain
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// an ActivityStreams representation of data.
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//
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// Strips retrieved ActivityStreams values of sensitive fields ('bto' and 'bcc')
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// before responding with them. Sets the appropriate HTTP status code for
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// Tombstone Activities as well.
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//
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// Defaults to supporting content to be retrieved by HTTPS only.
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func NewActivityStreamsHandler(db Database, clock Clock) HandlerFunc {
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return NewActivityStreamsHandlerScheme(db, clock, "https")
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}
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// NewActivityStreamsHandlerScheme creates a HandlerFunc to serve
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// ActivityStreams requests which are coming from other clients or servers that
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// wish to obtain an ActivityStreams representation of data provided by the
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// specified protocol scheme.
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//
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// Strips retrieved ActivityStreams values of sensitive fields ('bto' and 'bcc')
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// before responding with them. Sets the appropriate HTTP status code for
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// Tombstone Activities as well.
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//
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// Specifying the "scheme" allows for retrieving ActivityStreams content with
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// identifiers such as HTTP, HTTPS, or other protocol schemes.
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//
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// Returns ErrNotFound when the database does not retrieve any data and no
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// errors occurred during retrieval.
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func NewActivityStreamsHandlerScheme(db Database, clock Clock, scheme string) HandlerFunc {
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return func(c context.Context, w http.ResponseWriter, r *http.Request) (isASRequest bool, err error) {
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// Do nothing if it is not an ActivityPub GET request
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if !isActivityPubGet(r) {
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return
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}
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isASRequest = true
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id := requestId(r, scheme)
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var unlock func()
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// Lock and obtain a copy of the requested ActivityStreams value
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unlock, err = db.Lock(c, id)
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if err != nil {
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return
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}
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// WARNING: Unlock not deferred
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t, err := db.Get(c, id)
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unlock() // unlock even on error
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if err != nil {
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return
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}
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// Unlock must have been called by this point and in every
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// branch above
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if t == nil {
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err = ErrNotFound
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return
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}
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// Remove sensitive fields.
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clearSensitiveFields(t)
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// Serialize the fetched value.
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m, err := streams.Serialize(t)
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if err != nil {
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return
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}
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raw, err := json.Marshal(m)
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if err != nil {
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return
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}
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// Construct the response.
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addResponseHeaders(w.Header(), clock, raw)
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// Write the response.
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if streams.IsOrExtendsActivityStreamsTombstone(t) {
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w.WriteHeader(http.StatusGone)
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} else {
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w.WriteHeader(http.StatusOK)
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}
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n, err := w.Write(raw)
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if err != nil {
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return
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} else if n != len(raw) {
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err = fmt.Errorf("only wrote %d of %d bytes", n, len(raw))
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return
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}
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return
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}
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}
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