[feature] Allow exposing allows, implement `/api/v1/domain_blocks` and `/api/v1/domain_allows` (#4169)

- adds config flags `instance-expose-allowlist` and `instance-expose-allowlist-web` to allow instance admins to expose their allowlist via the web + api.
- renames `instance-expose-suspended` and `instance-expose-suspended-web` to  `instance-expose-blocklist` and `instance-expose-blocklist-web`.
- deprecates the `suspended` filter on `/api/v1/instance/peers` endpoint and adds `blocked` and `allowed` filters
- adds the `flat` query param to `/api/v1/instance/peers` to allow forcing return of a flat list of domains
- implements `/api/v1/instance/domain_blocks` and `/api/v1/instance/domain_allows` endpoints with or without auth depending on config
- rejigs the instance about page to include a general section on domain permissions, with block and allow subsections (and appropriate links)

Closes https://codeberg.org/superseriousbusiness/gotosocial/issues/3847
Closes https://codeberg.org/superseriousbusiness/gotosocial/issues/4150

Prerequisite to https://codeberg.org/superseriousbusiness/gotosocial/issues/3711

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4169
Co-authored-by: tobi <tobi.smethurst@protonmail.com>
Co-committed-by: tobi <tobi.smethurst@protonmail.com>

1 files changed, 136 insertions, 0 deletions

diff --git a/internal/web/domainperms.go b/internal/web/domainperms.go
new file mode 100644
index 000000000..24608e1fd
--- /dev/null
+++ b/internal/web/domainperms.go
@@ -0,0 +1,136 @@
+// 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 web
+
+import (
+	"context"
+	"errors"
+
+	apimodel "code.superseriousbusiness.org/gotosocial/internal/api/model"
+	apiutil "code.superseriousbusiness.org/gotosocial/internal/api/util"
+	"code.superseriousbusiness.org/gotosocial/internal/config"
+	"code.superseriousbusiness.org/gotosocial/internal/gtserror"
+	"github.com/gin-gonic/gin"
+)
+
+const (
+	domainBlocklistPath = aboutPath + "/domain_blocks"
+	domainAllowlistPath = aboutPath + "/domain_allows"
+)
+
+func (m *Module) domainBlocklistGETHandler(c *gin.Context) {
+	instance, errWithCode := m.processor.InstanceGetV1(c.Request.Context())
+	if errWithCode != nil {
+		apiutil.WebErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	// Return instance we already got from the db,
+	// don't try to fetch it again when erroring.
+	instanceGet := func(ctx context.Context) (*apimodel.InstanceV1, gtserror.WithCode) {
+		return instance, nil
+	}
+
+	// We only serve text/html at this endpoint.
+	if _, err := apiutil.NegotiateAccept(c, apiutil.TextHTML); err != nil {
+		errWithCode := gtserror.NewErrorNotAcceptable(err, err.Error())
+		apiutil.WebErrorHandler(c, errWithCode, instanceGet)
+		return
+	}
+
+	if !config.GetInstanceExposeBlocklistWeb() {
+		const errText = "this instance does not expose its blocklist via the web"
+		errWithCode := gtserror.NewErrorUnauthorized(errors.New(errText), errText)
+		apiutil.WebErrorHandler(c, errWithCode, instanceGet)
+		return
+	}
+
+	domainBlocks, errWithCode := m.processor.InstancePeersGet(
+		c.Request.Context(),
+		true,  // Include blocked.
+		false, // Don't include allowed.
+		false, // Don't include open.
+		false, // Don't flatten list.
+		false, // Don't include severity.
+	)
+	if errWithCode != nil {
+		apiutil.WebErrorHandler(c, errWithCode, instanceGet)
+		return
+	}
+
+	page := apiutil.WebPage{
+		Template:    "domain-blocklist.tmpl",
+		Instance:    instance,
+		OGMeta:      apiutil.OGBase(instance),
+		Stylesheets: []string{cssFA},
+		Extra:       map[string]any{"blocklist": domainBlocks},
+	}
+
+	apiutil.TemplateWebPage(c, page)
+}
+
+func (m *Module) domainAllowlistGETHandler(c *gin.Context) {
+	instance, errWithCode := m.processor.InstanceGetV1(c.Request.Context())
+	if errWithCode != nil {
+		apiutil.WebErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	// Return instance we already got from the db,
+	// don't try to fetch it again when erroring.
+	instanceGet := func(ctx context.Context) (*apimodel.InstanceV1, gtserror.WithCode) {
+		return instance, nil
+	}
+
+	// We only serve text/html at this endpoint.
+	if _, err := apiutil.NegotiateAccept(c, apiutil.TextHTML); err != nil {
+		errWithCode := gtserror.NewErrorNotAcceptable(err, err.Error())
+		apiutil.WebErrorHandler(c, errWithCode, instanceGet)
+		return
+	}
+
+	if !config.GetInstanceExposeAllowlistWeb() {
+		const errText = "this instance does not expose its allowlist via the web"
+		errWithCode := gtserror.NewErrorUnauthorized(errors.New(errText), errText)
+		apiutil.WebErrorHandler(c, errWithCode, instanceGet)
+		return
+	}
+
+	domainAllows, errWithCode := m.processor.InstancePeersGet(
+		c.Request.Context(),
+		false, // Don't include blocked.
+		true,  // Include allowed.
+		false, // Don't include open.
+		false, // Don't flatten list.
+		false, // Don't include severity.
+	)
+	if errWithCode != nil {
+		apiutil.WebErrorHandler(c, errWithCode, instanceGet)
+		return
+	}
+
+	page := apiutil.WebPage{
+		Template:    "domain-allowlist.tmpl",
+		Instance:    instance,
+		OGMeta:      apiutil.OGBase(instance),
+		Stylesheets: []string{cssFA},
+		Extra:       map[string]any{"allowlist": domainAllows},
+	}
+
+	apiutil.TemplateWebPage(c, page)
+}