Refine statuses (#26)

Remote media is now dereferenced and attached properly to incoming federated statuses.
    Mentions are now dereferenced and attached properly to incoming federated statuses.
    Small fixes to status visibility.
    Allow URL params for filtering statuses:

	// ExcludeRepliesKey is for specifying whether to exclude replies in a list of returned statuses by an account.
      	// PinnedKey is for specifying whether to include pinned statuses in a list of returned statuses by an account.
      	// MaxIDKey is for specifying the maximum ID of the status to retrieve.
      	// MediaOnlyKey is for specifying that only statuses with media should be returned in a list of returned statuses by an account.

    Add endpoint for fetching an account's statuses.

internal/transport/controller.go

@@ -21,6 +21,7 @@ package transport
 import (
 	"crypto"
 	"fmt"
+	"sync"
 
 	"github.com/go-fed/activity/pub"
 	"github.com/go-fed/httpsig"
@@ -30,7 +31,7 @@ import (
 
 // Controller generates transports for use in making federation requests to other servers.
 type Controller interface {
-	NewTransport(pubKeyID string, privkey crypto.PrivateKey) (pub.Transport, error)
+	NewTransport(pubKeyID string, privkey crypto.PrivateKey) (Transport, error)
 }
 
 type controller struct {
@@ -51,7 +52,7 @@ func NewController(config *config.Config, clock pub.Clock, client pub.HttpClient
 }
 
 // NewTransport returns a new http signature transport with the given public key id (a URL), and the given private key.
-func (c *controller) NewTransport(pubKeyID string, privkey crypto.PrivateKey) (pub.Transport, error) {
+func (c *controller) NewTransport(pubKeyID string, privkey crypto.PrivateKey) (Transport, error) {
 	prefs := []httpsig.Algorithm{httpsig.RSA_SHA256, httpsig.RSA_SHA512}
 	digestAlgo := httpsig.DigestSha256
 	getHeaders := []string{"(request-target)", "host", "date"}
@@ -67,5 +68,17 @@ func (c *controller) NewTransport(pubKeyID string, privkey crypto.PrivateKey) (p
 		return nil, fmt.Errorf("error creating post signer: %s", err)
 	}
 
-	return pub.NewHttpSigTransport(c.client, c.appAgent, c.clock, getSigner, postSigner, pubKeyID, privkey), nil
+	sigTransport := pub.NewHttpSigTransport(c.client, c.appAgent, c.clock, getSigner, postSigner, pubKeyID, privkey)
+
+	return &transport{
+		client:       c.client,
+		appAgent:     c.appAgent,
+		gofedAgent:   "(go-fed/activity v1.0.0)",
+		clock:        c.clock,
+		pubKeyID:     pubKeyID,
+		privkey:      privkey,
+		sigTransport: sigTransport,
+		getSigner:    getSigner,
+		getSignerMu:  &sync.Mutex{},
+	}, nil
 }

internal/transport/transport.go

@@ -0,0 +1,77 @@
+package transport
+
+import (
+	"context"
+	"crypto"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"sync"
+
+	"github.com/go-fed/activity/pub"
+	"github.com/go-fed/httpsig"
+)
+
+// Transport wraps the pub.Transport interface with some additional
+// functionality for fetching remote media.
+type Transport interface {
+	pub.Transport
+	DereferenceMedia(c context.Context, iri *url.URL, expectedContentType string) ([]byte, error)
+}
+
+// transport implements the Transport interface
+type transport struct {
+	client       pub.HttpClient
+	appAgent     string
+	gofedAgent   string
+	clock        pub.Clock
+	pubKeyID     string
+	privkey      crypto.PrivateKey
+	sigTransport *pub.HttpSigTransport
+	getSigner    httpsig.Signer
+	getSignerMu  *sync.Mutex
+}
+
+func (t *transport) BatchDeliver(c context.Context, b []byte, recipients []*url.URL) error {
+	return t.sigTransport.BatchDeliver(c, b, recipients)
+}
+
+func (t *transport) Deliver(c context.Context, b []byte, to *url.URL) error {
+	return t.sigTransport.Deliver(c, b, to)
+}
+
+func (t *transport) Dereference(c context.Context, iri *url.URL) ([]byte, error) {
+	return t.sigTransport.Dereference(c, iri)
+}
+
+func (t *transport) DereferenceMedia(c context.Context, iri *url.URL, expectedContentType string) ([]byte, error) {
+	req, err := http.NewRequest("GET", iri.String(), nil)
+	if err != nil {
+		return nil, err
+	}
+	req = req.WithContext(c)
+	if expectedContentType == "" {
+		req.Header.Add("Accept", "*/*")
+	} else {
+		req.Header.Add("Accept", expectedContentType)
+	}
+	req.Header.Add("Date", t.clock.Now().UTC().Format("Mon, 02 Jan 2006 15:04:05")+" GMT")
+	req.Header.Add("User-Agent", fmt.Sprintf("%s %s", t.appAgent, t.gofedAgent))
+	req.Header.Set("Host", iri.Host)
+	t.getSignerMu.Lock()
+	err = t.getSigner.SignRequest(t.privkey, t.pubKeyID, req, nil)
+	t.getSignerMu.Unlock()
+	if err != nil {
+		return nil, err
+	}
+	resp, err := t.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("GET request to %s failed (%d): %s", iri.String(), resp.StatusCode, resp.Status)
+	}
+	return ioutil.ReadAll(resp.Body)
+}