[feature] add worker task serialization logic (#2989)

* improved server shutdown with more precise shutdown of modules + deferring of ALL of it

* move delivery and workers into separate files

* add worker task model and Serialize() / Deserialize() methods for message types

* start adding message serialize / deserialize tests

* start adding test cases

* update body rewinding to rely on standard library mechanism of r.GetBody()

* remove request rewinding (http.Client{} should already handle this)

* standard library already handles rewinding

* improved code comment

* move the newPOST() function contents to prepare(), fits better with current API

* add Serialize() / Deserialize() implementations for Delivery{} type

* finish writing FromClientAPI sserialize / deserialize tests

* start adding FromFediAPI{} serialize / deserialize test cases

* fix FromFediAPI{} tests

* add tests for delivery message type

* fix repeat code

* missing license header

* use testrig status and accounts for marshal / unmarshaling tests

* add a specific test for checking account RSA keys are preserved

1 files changed, 55 insertions, 0 deletions

diff --git a/internal/httpclient/transport.go b/internal/httpclient/transport.go
new file mode 100644
index 000000000..350d24fab
--- /dev/null
+++ b/internal/httpclient/transport.go
@@ -0,0 +1,55 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package httpclient
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+)
+
+// SignFunc is a function signature that provides request signing.
+type SignFunc func(r *http.Request) error
+
+// signingtransport wraps an http.Transport{}
+// (RoundTripper implementer) to check request
+// context for a signing function and using for
+// all subsequent trips through RoundTrip().
+type signingtransport struct{ http.Transport }
+
+func (t *signingtransport) RoundTrip(r *http.Request) (*http.Response, error) {
+	// Ensure updated host always set.
+	r.Header.Set("Host", r.URL.Host)
+
+	if sign := gtscontext.HTTPClientSignFunc(r.Context()); sign != nil {
+		// Reset signing header fields
+		now := time.Now().UTC()
+		r.Header.Set("Date", now.Format("Mon, 02 Jan 2006 15:04:05")+" GMT")
+		r.Header.Del("Signature")
+		r.Header.Del("Digest")
+
+		// Sign the outgoing request.
+		if err := sign(r); err != nil {
+			return nil, err
+		}
+	}
+
+	// Pass to underlying transport.
+	return t.Transport.RoundTrip(r)
+}