http-wokou/pkg/controller.go

package httpserver

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"strings"

	"github.com/gin-gonic/gin"
)

// Implementing a 'set'
var NonmutableHeaders = map[string]struct{}{
	"Cookie":          struct{}{},
	"User-Agent":      struct{}{},
	"Accept-Encoding": struct{}{},
	"Referer":         struct{}{},
	"X-Proxy-Url":     struct{}{},
	"Host":            struct{}{},
}

type Controller struct {
	Config *HttpServerConfig
	Client *http.Client
}

type ProxyCookies struct {
	ck map[*url.URL][]*http.Cookie
}

func (p *ProxyCookies) SetCookies(u *url.URL, cookies []*http.Cookie) {
	p.ck[u] = cookies
}

func (p *ProxyCookies) Cookies(u *url.URL) []*http.Cookie {
	cookies, ok := p.ck[u]
	if !ok {
		return []*http.Cookie{
			nil,
		}
	} else {
		return cookies
	}
}

/*
Returns a new Controller struct to register routes to the gin router

	:param cfg: A pointer to an HttpServerConfig struct
*/
func NewController(cfg *HttpServerConfig) *Controller {
	ckJar := &ProxyCookies{}
	for idx := range cfg.CookieJar {
		ck := cfg.CookieJar[idx]
		url, err := url.Parse(ck.Domain)
		if err != nil {
			log.Fatal("required cookie could not be patsed: ", ck, err)
		}
		ckJar.SetCookies(url, ck)
	}

	return &Controller{Config: cfg, Client: &http.Client{Jar: ckJar}}
}

/*
This handler will be responsible for proxying out the GET requests that the server recieves
*/
func (c *Controller) Get(ctx *gin.Context) {

	url := fmt.Sprintf("https://%s%s", c.Config.AllowedDomain, ctx.Param("ProxiedPath"))
	req, err := http.NewRequest(ctx.Request.Method, url, ctx.Request.Body)
	if err != nil {
		ctx.JSON(500, map[string]string{
			"Error": "Error creating the request.",
			"Msg:":  err.Error(),
		})
		return
	}
	req.URL.Path = ctx.Param("ProxiedPath")
	req.Header.Add("User-Agent", c.Config.UserAgent)
	req.Header.Set("Referer", c.Config.AllowedDomain)
	if ctx.Param("ProxiedPath") == "/" {
		req.Header.Add("Location", "https://sem.bunnytools.shop/analytics/overview/")
	}
	if ctx.Param("ProxiedPath") == "/_compatibility/traffic/overview/" {
		req.Header.Add("Location", "https://sem.bunnytools.shop/analytics/traffic/overview/ebay.com")
	}
	for k, v := range ctx.Request.Header {
		_, ok := NonmutableHeaders[k]
		if !ok {
			req.Header.Add(k, v[0])
		}
	}
	fmt.Printf("%+v\n", req.Header)
	resp, err := c.Client.Do(req)
	if err != nil {
		ctx.JSON(500, map[string]string{
			"Error": "Error creating the request.",
			"Msg:":  err.Error(),
		})
		return
	}
	defer resp.Body.Close()
	b, err := io.ReadAll(resp.Body)
	if err != nil {
		ctx.JSON(500, map[string]string{
			"Error": "Error creating the request.",
			"Msg:":  err.Error(),
		})
		return
	}
	responseCookies := resp.Cookies()
	for idx := range responseCookies {
		url, err := url.Parse(ck.Domain)
		if err != nil {
			fmt.Printf("required cookie could not be patsed: %+v\n, error: %s\n", ck, err)
		}

		c.Client.Jar.SetCookies(url, responseCookies[idx])
	}

	newBody := strings.ReplaceAll(string(b), "\"srf-browser-unhappy\"", "\"srf-browser-unhappy\" style=\"display:none;\"")
	newBody = strings.ReplaceAll(newBody, "\"srf-navbar__right\"", "\"srf-navbar__right\" style=\"display:none;\"")
	newBody = strings.ReplaceAll(newBody, "<footer", "<footer style=\"display:none;\"")
	newBody = strings.ReplaceAll(newBody, "\"srf-report-sidebar-extras\"", "\"srf-report-sidebar-extra\" style=\"display:none;\"")
	newBody = strings.ReplaceAll(newBody, "www.semrush.com", "sem.bunnytools.shop")
	ctx.Data(resp.StatusCode, resp.Header.Get("Content-Type"), []byte(newBody))

}