mirror of
https://github.com/superseriousbusiness/gotosocial.git
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106 lines
3.1 KiB
Go
106 lines
3.1 KiB
Go
// GoToSocial
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// Copyright (C) GoToSocial Authors admin@gotosocial.org
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// SPDX-License-Identifier: AGPL-3.0-or-later
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package headerfilter
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import (
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"fmt"
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"net/http"
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"sync/atomic"
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"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
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"github.com/superseriousbusiness/gotosocial/internal/headerfilter"
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)
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// Cache provides a means of caching headerfilter.Filters in
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// memory to reduce load on an underlying storage mechanism.
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type Cache struct {
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// current cached header filters slice.
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ptr atomic.Pointer[headerfilter.Filters]
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}
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// RegularMatch performs .RegularMatch() on cached headerfilter.Filters, loading using callback if necessary.
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func (c *Cache) RegularMatch(h http.Header, load func() ([]*gtsmodel.HeaderFilter, error)) (string, string, error) {
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// Load ptr value.
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ptr := c.ptr.Load()
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if ptr == nil {
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// Cache is not hydrated.
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// Load filters from callback.
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filters, err := loadFilters(load)
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if err != nil {
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return "", "", err
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}
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// Store the new
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// header filters.
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ptr = &filters
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c.ptr.Store(ptr)
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}
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// Deref and perform match.
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return ptr.RegularMatch(h)
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}
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// InverseMatch performs .InverseMatch() on cached headerfilter.Filters, loading using callback if necessary.
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func (c *Cache) InverseMatch(h http.Header, load func() ([]*gtsmodel.HeaderFilter, error)) (string, string, error) {
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// Load ptr value.
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ptr := c.ptr.Load()
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if ptr == nil {
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// Cache is not hydrated.
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// Load filters from callback.
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filters, err := loadFilters(load)
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if err != nil {
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return "", "", err
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}
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// Store the new
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// header filters.
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ptr = &filters
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c.ptr.Store(ptr)
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}
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// Deref and perform match.
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return ptr.InverseMatch(h)
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}
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// Clear will drop the currently loaded filters,
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// triggering a reload on next call to ._Match().
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func (c *Cache) Clear() { c.ptr.Store(nil) }
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// loadFilters will load filters from given load callback, creating and parsing raw filters.
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func loadFilters(load func() ([]*gtsmodel.HeaderFilter, error)) (headerfilter.Filters, error) {
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// Load filters from callback.
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hdrFilters, err := load()
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if err != nil {
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return nil, fmt.Errorf("error reloading cache: %w", err)
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}
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// Allocate new header filter slice to store expressions.
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filters := make(headerfilter.Filters, 0, len(hdrFilters))
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// Add all raw expression to filter slice.
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for _, filter := range hdrFilters {
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if err := filters.Append(filter.Header, filter.Regex); err != nil {
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return nil, fmt.Errorf("error appending exprs: %w", err)
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}
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}
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return filters, nil
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}
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