federated authentication better logging + tidying (#232)

* change trace logging in authenticator

* messing about

* lil changes

* go fmt

* error fix

* Fix broken test

internal/api/s2s/user/common.go

@@ -0,0 +1,59 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
+
+   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 user
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+// ActivityPubAcceptHeaders represents the Accept headers mentioned here:
+// https://www.w3.org/TR/activitypub/#retrieving-objects
+var ActivityPubAcceptHeaders = []string{
+	`application/activity+json`,
+	`application/ld+json; profile="https://www.w3.org/ns/activitystreams"`,
+}
+
+// populateContext transfers the signature verifier and signature from the gin context to the request context
+func populateContext(c *gin.Context) context.Context {
+	ctx := c.Request.Context()
+
+	verifier, signed := c.Get(string(util.APRequestingPublicKeyVerifier))
+	if signed {
+		ctx = context.WithValue(ctx, util.APRequestingPublicKeyVerifier, verifier)
+	}
+
+	signature, signed := c.Get(string(util.APRequestingPublicKeySignature))
+	if signed {
+		ctx = context.WithValue(ctx, util.APRequestingPublicKeySignature, signature)
+	}
+
+	return ctx
+}
+
+func negotiateFormat(c *gin.Context) (string, error) {
+	format := c.NegotiateFormat(ActivityPubAcceptHeaders...)
+	if format == "" {
+		return "", fmt.Errorf("no format can be offered for Accept headers %s", c.Request.Header.Get("Accept"))
+	}
+	return format, nil
+}