[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

internal/processing/admin/domainpermission.go

@@ -0,0 +1,335 @@
+// 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"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"mime/multipart"
+	"net/http"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// apiDomainPerm is a cheeky shortcut for returning
+// the API version of the given domain permission
+// (*gtsmodel.DomainBlock or *gtsmodel.DomainAllow),
+// or an appropriate error if something goes wrong.
+func (p *Processor) apiDomainPerm(
+	ctx context.Context,
+	domainPermission gtsmodel.DomainPermission,
+	export bool,
+) (*apimodel.DomainPermission, gtserror.WithCode) {
+	apiDomainPerm, err := p.tc.DomainPermToAPIDomainPerm(ctx, domainPermission, export)
+	if err != nil {
+		err := gtserror.NewfAt(3, "error converting domain permission to api model: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return apiDomainPerm, nil
+}
+
+// DomainPermissionCreate creates an instance-level permission
+// targeting the given domain, and then processes any side
+// effects of the permission creation.
+//
+// If the same permission type already exists for the domain,
+// side effects will be retried.
+//
+// Return values for this function are the new or existing
+// domain permission, the ID of the admin action resulting
+// from this call, and/or an error if something goes wrong.
+func (p *Processor) DomainPermissionCreate(
+	ctx context.Context,
+	permissionType gtsmodel.DomainPermissionType,
+	adminAcct *gtsmodel.Account,
+	domain string,
+	obfuscate bool,
+	publicComment string,
+	privateComment string,
+	subscriptionID string,
+) (*apimodel.DomainPermission, string, gtserror.WithCode) {
+	switch permissionType {
+
+	// Explicitly block a domain.
+	case gtsmodel.DomainPermissionBlock:
+		return p.createDomainBlock(
+			ctx,
+			adminAcct,
+			domain,
+			obfuscate,
+			publicComment,
+			privateComment,
+			subscriptionID,
+		)
+
+	// Explicitly allow a domain.
+	case gtsmodel.DomainPermissionAllow:
+		return p.createDomainAllow(
+			ctx,
+			adminAcct,
+			domain,
+			obfuscate,
+			publicComment,
+			privateComment,
+			subscriptionID,
+		)
+
+	// Weeping, roaring, red-faced.
+	default:
+		err := gtserror.Newf("unrecognized permission type %d", permissionType)
+		return nil, "", gtserror.NewErrorInternalError(err)
+	}
+}
+
+// DomainPermissionDelete removes one domain block with the given ID,
+// and processes side effects of removing the block asynchronously.
+//
+// Return values for this function are the deleted domain block, the ID of the admin
+// action resulting from this call, and/or an error if something goes wrong.
+func (p *Processor) DomainPermissionDelete(
+	ctx context.Context,
+	permissionType gtsmodel.DomainPermissionType,
+	adminAcct *gtsmodel.Account,
+	domainBlockID string,
+) (*apimodel.DomainPermission, string, gtserror.WithCode) {
+	switch permissionType {
+
+	// Delete explicit domain block.
+	case gtsmodel.DomainPermissionBlock:
+		return p.deleteDomainBlock(
+			ctx,
+			adminAcct,
+			domainBlockID,
+		)
+
+	// Delete explicit domain allow.
+	case gtsmodel.DomainPermissionAllow:
+		return p.deleteDomainAllow(
+			ctx,
+			adminAcct,
+			domainBlockID,
+		)
+
+	// You do the hokey-cokey and you turn
+	// around, that's what it's all about.
+	default:
+		err := gtserror.Newf("unrecognized permission type %d", permissionType)
+		return nil, "", gtserror.NewErrorInternalError(err)
+	}
+}
+
+// DomainPermissionsImport handles the import of multiple
+// domain permissions, by calling the DomainPermissionCreate
+// function for each domain in the provided file. Will return
+// a slice of processed domain permissions.
+//
+// In the case of total failure, a gtserror.WithCode will be
+// returned so that the caller can respond appropriately. In
+// the case of partial or total success, a MultiStatus model
+// will be returned, which contains information about success
+// + failure count, so that the caller can retry any failures
+// as they wish.
+func (p *Processor) DomainPermissionsImport(
+	ctx context.Context,
+	permissionType gtsmodel.DomainPermissionType,
+	account *gtsmodel.Account,
+	domainsF *multipart.FileHeader,
+) (*apimodel.MultiStatus, gtserror.WithCode) {
+	// Ensure known permission type.
+	if permissionType != gtsmodel.DomainPermissionBlock &&
+		permissionType != gtsmodel.DomainPermissionAllow {
+		err := gtserror.Newf("unrecognized permission type %d", permissionType)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	// Open the provided file.
+	file, err := domainsF.Open()
+	if err != nil {
+		err = gtserror.Newf("error opening attachment: %w", err)
+		return nil, gtserror.NewErrorBadRequest(err, err.Error())
+	}
+	defer file.Close()
+
+	// Parse file as slice of domain blocks.
+	domainPerms := make([]*apimodel.DomainPermission, 0)
+	if err := json.NewDecoder(file).Decode(&domainPerms); err != nil {
+		err = gtserror.Newf("error parsing attachment as domain permissions: %w", err)
+		return nil, gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	count := len(domainPerms)
+	if count == 0 {
+		err = gtserror.New("error importing domain permissions: 0 entries provided")
+		return nil, gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	// Try to process each domain permission, differentiating
+	// between successes and errors so that the caller can
+	// try failed imports again if desired.
+	multiStatusEntries := make([]apimodel.MultiStatusEntry, 0, count)
+
+	for _, domainPerm := range domainPerms {
+		var (
+			domain         = domainPerm.Domain.Domain
+			obfuscate      = domainPerm.Obfuscate
+			publicComment  = domainPerm.PublicComment
+			privateComment = domainPerm.PrivateComment
+			subscriptionID = "" // No sub ID for imports.
+			errWithCode    gtserror.WithCode
+		)
+
+		domainPerm, _, errWithCode = p.DomainPermissionCreate(
+			ctx,
+			permissionType,
+			account,
+			domain,
+			obfuscate,
+			publicComment,
+			privateComment,
+			subscriptionID,
+		)
+
+		var entry *apimodel.MultiStatusEntry
+
+		if errWithCode != nil {
+			entry = &apimodel.MultiStatusEntry{
+				// Use the failed domain entry as the resource value.
+				Resource: domain,
+				Message:  errWithCode.Safe(),
+				Status:   errWithCode.Code(),
+			}
+		} else {
+			entry = &apimodel.MultiStatusEntry{
+				// Use successfully created API model domain block as the resource value.
+				Resource: domainPerm,
+				Message:  http.StatusText(http.StatusOK),
+				Status:   http.StatusOK,
+			}
+		}
+
+		multiStatusEntries = append(multiStatusEntries, *entry)
+	}
+
+	return apimodel.NewMultiStatus(multiStatusEntries), nil
+}
+
+// DomainPermissionsGet returns all existing domain
+// permissions of the requested type. If export is
+// true, the format will be suitable for writing out
+// to an export.
+func (p *Processor) DomainPermissionsGet(
+	ctx context.Context,
+	permissionType gtsmodel.DomainPermissionType,
+	account *gtsmodel.Account,
+	export bool,
+) ([]*apimodel.DomainPermission, gtserror.WithCode) {
+	var (
+		domainPerms []gtsmodel.DomainPermission
+		err         error
+	)
+
+	switch permissionType {
+	case gtsmodel.DomainPermissionBlock:
+		var blocks []*gtsmodel.DomainBlock
+
+		blocks, err = p.state.DB.GetDomainBlocks(ctx)
+		if err != nil {
+			break
+		}
+
+		for _, block := range blocks {
+			domainPerms = append(domainPerms, block)
+		}
+
+	case gtsmodel.DomainPermissionAllow:
+		var allows []*gtsmodel.DomainAllow
+
+		allows, err = p.state.DB.GetDomainAllows(ctx)
+		if err != nil {
+			break
+		}
+
+		for _, allow := range allows {
+			domainPerms = append(domainPerms, allow)
+		}
+
+	default:
+		err = errors.New("unrecognized permission type")
+	}
+
+	if err != nil {
+		err := gtserror.Newf("error getting %ss: %w", permissionType.String(), err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	apiDomainPerms := make([]*apimodel.DomainPermission, len(domainPerms))
+	for i, domainPerm := range domainPerms {
+		apiDomainBlock, errWithCode := p.apiDomainPerm(ctx, domainPerm, export)
+		if errWithCode != nil {
+			return nil, errWithCode
+		}
+
+		apiDomainPerms[i] = apiDomainBlock
+	}
+
+	return apiDomainPerms, nil
+}
+
+// DomainPermissionGet returns one domain
+// permission with the given id and type.
+//
+// If export is true, the format will be
+// suitable for writing out to an export.
+func (p *Processor) DomainPermissionGet(
+	ctx context.Context,
+	permissionType gtsmodel.DomainPermissionType,
+	id string,
+	export bool,
+) (*apimodel.DomainPermission, gtserror.WithCode) {
+	var (
+		domainPerm gtsmodel.DomainPermission
+		err        error
+	)
+
+	switch permissionType {
+	case gtsmodel.DomainPermissionBlock:
+		domainPerm, err = p.state.DB.GetDomainBlockByID(ctx, id)
+	case gtsmodel.DomainPermissionAllow:
+		domainPerm, err = p.state.DB.GetDomainAllowByID(ctx, id)
+	default:
+		err = gtserror.New("unrecognized permission type")
+	}
+
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			err = fmt.Errorf("no domain %s exists with id %s", permissionType.String(), id)
+			return nil, gtserror.NewErrorNotFound(err, err.Error())
+		}
+
+		err = gtserror.Newf("error getting domain %s with id %s: %w", permissionType.String(), id, err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return p.apiDomainPerm(ctx, domainPerm, export)
+}