promty/proxy/main.go

144 lines
3.4 KiB
Go

package main
import (
"bytes"
"compress/gzip"
"fmt"
"io"
"net/http"
"net/http/httputil"
"net/url"
"os"
"regexp"
"strings"
)
func main() {
proxy := &httputil.ReverseProxy{
Rewrite: func(r *httputil.ProxyRequest) {
host, _ := Yadro2Kernel(r.In.Host, true)
url, _ := url.Parse("https://" + host)
r.SetURL(url)
// We only support gzip decoding
r.Out.Header.Set("Accept-Encoding", "gzip")
},
ModifyResponse: func(r *http.Response) error {
// Disable security policy because of the domain restrictions.
r.Header.Del("Content-Security-Policy")
// Skip non-html pages.
contentType := r.Header.Get("Content-Type")
if !strings.HasPrefix(contentType, "text/") {
return nil
}
r.Header.Set("Content-Type", contentType+";charset=utf-8")
// Read response body into data. If body is encoded, decode it.
var data []byte
switch r.Header.Get("Content-Encoding") {
case "gzip":
reader, _ := gzip.NewReader(r.Body)
data, _ = io.ReadAll(reader)
r.Body.Close()
default:
data, _ = io.ReadAll(r.Body)
r.Body.Close()
}
// Rewrite 30x redirect location
locHeader := r.Header.Get("Location")
if locHeader != "" {
re := regexp.MustCompile(`https?:\/\/[A-Za-z\-\.]*.?kernel\.org\/`)
r.Header.Set("Location", string(re.ReplaceAllFunc([]byte(locHeader), func(original_raw []byte) []byte {
kernel := strings.ToLower(string(original_raw))
kernel = strings.TrimPrefix(kernel, "https://")
kernel = strings.TrimPrefix(kernel, "http://")
kernel = strings.TrimPrefix(kernel, "www.")
kernel = strings.TrimSuffix(kernel, "/")
yadro, exists := Kernel2Yadro(kernel)
if !exists {
fmt.Println("Missing:", kernel)
return original_raw
}
return []byte("http://" + yadro + "/") // TODO: https
})))
}
// Modify the response.
data = modifyResponse(data)
// Remove headers that mess with body encoding and set the body.
r.Header.Del("Content-Encoding")
r.Header.Del("Content-Length")
r.Body = io.NopCloser(bytes.NewReader(data))
return nil
},
}
http.ListenAndServe("0.0.0.0:80", proxy)
}
func replaceDomains(response []byte) []byte {
re := regexp.MustCompile(`(?i)[A-Za-z\-\.]*\.?kernel\.org`)
response = re.ReplaceAllFunc(response, func(original_raw []byte) []byte {
kernel := strings.ToLower(string(original_raw))
// Strip `www.`
kernel = strings.TrimPrefix(kernel, "www.")
yadro, exists := Kernel2Yadro(kernel)
if !exists {
fmt.Println("Missing:", kernel)
return original_raw
}
return []byte(yadro)
})
response = bytes.ReplaceAll(response, []byte("%3F"), []byte("?"))
response = bytes.ReplaceAll(response, []byte("%26"), []byte("&"))
response = bytes.ReplaceAll(response, []byte("https"), []byte("http")) // TODO: TEMP
return response
}
func translateWithPromtPuppies(response []byte) []byte {
// Don't try to translate empty body (30x, etc)
if len(response) == 0 {
return response
}
req, _ := http.NewRequest("POST", "http://caddy:9000/translate", bytes.NewReader(response))
req.Header.Add("Content-Type", "text/html")
resp, err := http.DefaultClient.Do(req)
if err != nil {
fmt.Fprintln(os.Stderr, "Error in first", err)
return []byte{0}
}
response, _ = io.ReadAll(resp.Body)
resp.Body.Close()
return response
}
func modifyResponse(response []byte) []byte {
response = translateWithPromtPuppies(response)
response = replaceDomains(response)
return response
}