[feature] Implement explicit domain allows + allowlist federation mode (#2200)

* love like winter! wohoah, wohoah

* domain allow side effects

* tests! logging! unallow!

* document federation modes

* linty linterson

* test

* further adventures in documentation

* finish up domain block documentation (i think)

* change wording a wee little bit

* docs, example

* consolidate shared domainPermission code

* call mode once

* fetch federation mode within domain blocked func

* read domain perm import in streaming manner

* don't use pointer to slice for domain perms

* don't bother copying blocks + allows before deleting

* admonish!

* change wording just a scooch

* update docs

1 files changed, 295 insertions, 0 deletions

diff --git a/internal/api/client/admin/domainpermission.go b/internal/api/client/admin/domainpermission.go
new file mode 100644
index 000000000..80aa05041
--- /dev/null
+++ b/internal/api/client/admin/domainpermission.go
@@ -0,0 +1,295 @@
+// 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"
+	"errors"
+	"fmt"
+	"mime/multipart"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+)
+
+type singleDomainPermCreate func(
+	context.Context,
+	gtsmodel.DomainPermissionType, // block/allow
+	*gtsmodel.Account, // admin account
+	string, // domain
+	bool, // obfuscate
+	string, // publicComment
+	string, // privateComment
+	string, // subscriptionID
+) (*apimodel.DomainPermission, string, gtserror.WithCode)
+
+type multiDomainPermCreate func(
+	context.Context,
+	gtsmodel.DomainPermissionType, // block/allow
+	*gtsmodel.Account, // admin account
+	*multipart.FileHeader, // domains
+) (*apimodel.MultiStatus, gtserror.WithCode)
+
+// createDomainPemissions either creates a single domain
+// permission entry (block/allow) or imports multiple domain
+// permission entries (multiple blocks, multiple allows)
+// using the given functions.
+//
+// Handling the creation of both types of permissions in
+// one function in this way reduces code duplication.
+func (m *Module) createDomainPermissions(
+	c *gin.Context,
+	permType gtsmodel.DomainPermissionType,
+	single singleDomainPermCreate,
+	multi multiDomainPermCreate,
+) {
+	authed, err := oauth.Authed(c, true, true, true, true)
+	if err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if !*authed.User.Admin {
+		err := fmt.Errorf("user %s not an admin", authed.User.ID)
+		apiutil.ErrorHandler(c, gtserror.NewErrorForbidden(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if _, err := apiutil.NegotiateAccept(c, apiutil.JSONAcceptHeaders...); err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	importing, errWithCode := apiutil.ParseDomainPermissionImport(c.Query(apiutil.DomainPermissionImportKey), false)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	// Parse + validate form.
+	form := new(apimodel.DomainPermissionRequest)
+	if err := c.ShouldBind(form); err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorBadRequest(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if importing && form.Domains.Size == 0 {
+		err = errors.New("import was specified but list of domains is empty")
+	} else if form.Domain == "" {
+		err = errors.New("empty domain provided")
+	}
+
+	if err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorBadRequest(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if !importing {
+		// Single domain permission creation.
+		domainBlock, _, errWithCode := single(
+			c.Request.Context(),
+			permType,
+			authed.Account,
+			form.Domain,
+			form.Obfuscate,
+			form.PublicComment,
+			form.PrivateComment,
+			"", // No sub ID for single perm creation.
+		)
+
+		if errWithCode != nil {
+			apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+			return
+		}
+
+		c.JSON(http.StatusOK, domainBlock)
+		return
+	}
+
+	// We're importing multiple domain permissions,
+	// so we're looking at a multi-status response.
+	multiStatus, errWithCode := multi(
+		c.Request.Context(),
+		permType,
+		authed.Account,
+		form.Domains, // Pass the file through.
+	)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	// TODO: Return 207 and multiStatus data nicely
+	//       when supported by the admin panel.
+	if multiStatus.Metadata.Failure != 0 {
+		failures := make(map[string]any, multiStatus.Metadata.Failure)
+		for _, entry := range multiStatus.Data {
+			// nolint:forcetypeassert
+			failures[entry.Resource.(string)] = entry.Message
+		}
+
+		err := fmt.Errorf("one or more errors importing domain %ss: %+v", permType.String(), failures)
+		apiutil.ErrorHandler(c, gtserror.NewErrorUnprocessableEntity(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	// Success, return slice of newly-created domain perms.
+	domainPerms := make([]any, 0, multiStatus.Metadata.Success)
+	for _, entry := range multiStatus.Data {
+		domainPerms = append(domainPerms, entry.Resource)
+	}
+
+	c.JSON(http.StatusOK, domainPerms)
+}
+
+// deleteDomainPermission deletes a single domain permission (block or allow).
+func (m *Module) deleteDomainPermission(
+	c *gin.Context,
+	permType gtsmodel.DomainPermissionType, // block/allow
+) {
+	authed, err := oauth.Authed(c, true, true, true, true)
+	if err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if !*authed.User.Admin {
+		err := fmt.Errorf("user %s not an admin", authed.User.ID)
+		apiutil.ErrorHandler(c, gtserror.NewErrorForbidden(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if _, err := apiutil.NegotiateAccept(c, apiutil.JSONAcceptHeaders...); err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	domainPermID, errWithCode := apiutil.ParseID(c.Param(apiutil.IDKey))
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	domainPerm, _, errWithCode := m.processor.Admin().DomainPermissionDelete(
+		c.Request.Context(),
+		permType,
+		authed.Account,
+		domainPermID,
+	)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	c.JSON(http.StatusOK, domainPerm)
+}
+
+// getDomainPermission gets a single domain permission (block or allow).
+func (m *Module) getDomainPermission(
+	c *gin.Context,
+	permType gtsmodel.DomainPermissionType,
+) {
+	authed, err := oauth.Authed(c, true, true, true, true)
+	if err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if !*authed.User.Admin {
+		err := fmt.Errorf("user %s not an admin", authed.User.ID)
+		apiutil.ErrorHandler(c, gtserror.NewErrorForbidden(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if _, err := apiutil.NegotiateAccept(c, apiutil.JSONAcceptHeaders...); err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	domainPermID, errWithCode := apiutil.ParseID(c.Param(apiutil.IDKey))
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	export, errWithCode := apiutil.ParseDomainPermissionExport(c.Query(apiutil.DomainPermissionExportKey), false)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	domainPerm, errWithCode := m.processor.Admin().DomainPermissionGet(
+		c.Request.Context(),
+		permType,
+		domainPermID,
+		export,
+	)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	c.JSON(http.StatusOK, domainPerm)
+}
+
+// getDomainPermissions gets all domain permissions of the given type (block, allow).
+func (m *Module) getDomainPermissions(
+	c *gin.Context,
+	permType gtsmodel.DomainPermissionType,
+) {
+	authed, err := oauth.Authed(c, true, true, true, true)
+	if err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if !*authed.User.Admin {
+		err := fmt.Errorf("user %s not an admin", authed.User.ID)
+		apiutil.ErrorHandler(c, gtserror.NewErrorForbidden(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	if _, err := apiutil.NegotiateAccept(c, apiutil.JSONAcceptHeaders...); err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	export, errWithCode := apiutil.ParseDomainPermissionExport(c.Query(apiutil.DomainPermissionExportKey), false)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	domainPerm, errWithCode := m.processor.Admin().DomainPermissionsGet(
+		c.Request.Context(),
+		permType,
+		authed.Account,
+		export,
+	)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	c.JSON(http.StatusOK, domainPerm)
+}