http-wokou/pkg/cache.go

/*
		GNU GENERAL PUBLIC LICENSE
                 Version 3, 29 June 2007

 Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

 http-wokou, An HTTP Proxying framework for bypassing DNS Security
 Copyright (C) 2024 Russell Hrubesky, ChiralWorks Software LLC

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU 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 General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.

*/

package httpserver

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"

	"github.com/patrickmn/go-cache"
)

type CachedResource struct {
	Data    []byte
	Headers *http.Header
	Ctype   string
	Rcode   int
}

func NewCachedResource(data []byte, headers *http.Header, rcode int) *CachedResource {
	return &CachedResource{
		Data:    data,
		Headers: headers,
		Rcode:   rcode,
	}
}

func (c *Controller) CacheResource(key string, resource *CachedResource) {
	fmt.Printf("Cached resource for: %s\n", key)
	c.cache.Set(key, resource, cache.DefaultExpiration)
}

func (c *Controller) GetResource(key string) *CachedResource {
	resource, found := c.cache.Get(key)
	if found {
		fmt.Printf("Cache Hit! Found resource for URI: %s\n", key)
		return resource.(*CachedResource)
	}
	return nil
}

type RouteMapping struct {
	DomainName string   `json:"domain_name"`
	UriPaths   []string `json:"uri_paths"`
	RouteSet   map[string]struct{}
}

type RouteMap struct {
	Mappings map[string]string `json:"mappings"`
	Shotgun  map[string]string `json:"shotgun"`
	MapCache *cache.Cache
}

type RouteMapper interface {
	mapUriToDomain(string, string)
	GetMappedDomain(string) (string, bool)
	ExportRouteMaps(string)
}

/*
Set a route to exist for the URI to the specific domain

	:param uri: the URI to set the route for
	:param domain: the domain name to resolve the uri to
*/
func (r *RouteMap) MapUriToDomain(uri string, domain string) {
	r.MapCache.Set(uri, domain, cache.DefaultExpiration)

}

// returns the domain/url that the uri belongs to as defined in the routemap
func (r *RouteMap) GetMappedDomain(uri string) (string, bool) {
	dname, ok := r.MapCache.Get(uri)
	if ok {
		return fmt.Sprint(dname), true

	}

	for k, v := range r.Shotgun {

		if strings.Contains(uri, k) {
			return v, true
		}
	}

	return "", false
}

// This populates the cache in a RouteMap with the data from the config file
func (r *RouteMap) populateRouteMaps() {
	for k, v := range r.Mappings {
		r.MapUriToDomain(k, v)
	}
}

// Exports the cache into a JSON-friendly data structure (so that it can be written to the file system)
func (r *RouteMap) ExportRouteMap(loc string) {
	routeMapOut := &RouteMap{
		Mappings: map[string]string{},
		Shotgun:  map[string]string{},
	}

	cachedRoutes := r.MapCache.Items()
	for k, v := range cachedRoutes {
		routeMapOut.Mappings[k] = fmt.Sprint(v.Object)
	}
	for k, v := range r.Shotgun {
		routeMapOut.Shotgun[k] = v
	}

	b, err := json.Marshal(routeMapOut)
	if err != nil {
		log.Fatal("failed to marshal struct: ", err)
	}
	os.WriteFile(loc, b, os.ModePerm)

}