[feature] Add /api/v1/admin/debug/apurl endpoint (#2359)

internal/processing/admin/debug_apurl.go

@@ -0,0 +1,126 @@
+// 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 admin
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/url"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// DebugAPUrl performs a GET to the given url, using the
+// signature of the given admin account. The GET will
+// have Accept set to the ActivityPub content types.
+//
+// Only urls with schema http or https are allowed.
+//
+// Calls to blocked domains are not allowed, not only
+// because it's unfair to call them when they can't
+// call us, but because it probably won't work anyway
+// if they try to dereference the calling account.
+//
+// Errors returned from this function should be fairly
+// verbose, to help with debugging.
+func (p *Processor) DebugAPUrl(
+	ctx context.Context,
+	adminAcct *gtsmodel.Account,
+	urlStr string,
+) (*apimodel.DebugAPUrlResponse, gtserror.WithCode) {
+	// Validate URL.
+	if urlStr == "" {
+		err := gtserror.New("empty URL")
+		return nil, gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	url, err := url.Parse(urlStr)
+	if err != nil {
+		err := gtserror.Newf("invalid URL: %w", err)
+		return nil, gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	if url == nil || (url.Scheme != "http" && url.Scheme != "https") {
+		err = gtserror.New("invalid URL scheme, acceptable schemes are http or https")
+		return nil, gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	// Ensure URL not blocked.
+	blocked, err := p.state.DB.IsDomainBlocked(ctx, url.Host)
+	if err != nil {
+		err = gtserror.Newf("db error checking for domain block: %w", err)
+		return nil, gtserror.NewErrorInternalError(err, err.Error())
+	}
+
+	if blocked {
+		err = gtserror.Newf("target domain %s is blocked", url.Host)
+		return nil, gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	// All looks fine. Prepare the transport and (signed) GET request.
+	tsport, err := p.transportController.NewTransportForUsername(ctx, adminAcct.Username)
+	if err != nil {
+		err = gtserror.Newf("error creating transport: %w", err)
+		return nil, gtserror.NewErrorInternalError(err, err.Error())
+	}
+
+	req, err := http.NewRequestWithContext(
+		// Caller will want a snappy
+		// response so don't retry.
+		gtscontext.SetFastFail(ctx),
+		http.MethodGet, urlStr, nil,
+	)
+	if err != nil {
+		err = gtserror.Newf("error creating request: %w", err)
+		return nil, gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+
+	req.Header.Add("Accept", string(apiutil.AppActivityLDJSON)+","+string(apiutil.AppActivityJSON))
+	req.Header.Add("Accept-Charset", "utf-8")
+	req.Header.Set("Host", url.Host)
+
+	// Perform the HTTP request,
+	// and return everything.
+	rsp, err := tsport.GET(req)
+	if err != nil {
+		err = gtserror.Newf("error doing dereference: %w", err)
+		return nil, gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+	defer rsp.Body.Close()
+
+	b, err := io.ReadAll(rsp.Body)
+	if err != nil {
+		err := gtserror.Newf("error reading response body bytes: %w", err)
+		return nil, gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+
+	debugResponse := &apimodel.DebugAPUrlResponse{
+		RequestURL:      urlStr,
+		RequestHeaders:  req.Header,
+		ResponseHeaders: rsp.Header,
+		ResponseCode:    rsp.StatusCode,
+		ResponseBody:    string(b),
+	}
+
+	return debugResponse, nil
+}