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Copy pathblockpage.go
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280 lines (245 loc) · 7.38 KB
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8000
/div>
package main
import (
"bytes"
"context"
"encoding/json"
"errors"
"fmt"
"html/template"
"io"
"io/ioutil"
"log"
"net"
"net/http"
"strconv"
"strings"
"go.starlark.net/starlark"
)
// Functions for displaying block pages.
// transparent1x1 is a single-pixel transparent GIF file.
const transparent1x1 = "GIF89a\x10\x00\x10\x00\x80\xff\x00\xc0\xc0\xc0\x00\x00\x00!\xf9\x04\x01\x00\x00\x00\x00,\x00\x00\x00\x00\x10\x00\x10\x00\x00\x02\x0e\x84\x8f\xa9\xcb\xed\x0f\xa3\x9c\xb4\u068b\xb3>\x05\x00;"
func (c *config) loadBlockPage(path string) error {
if strings.HasPrefix(path, "http") {
c.BlockTemplate = nil
c.BlockpageURL = path
return nil
}
bt := template.New("blockpage")
content, err := ioutil.ReadFile(path)
if err != nil {
return fmt.Errorf("error loading block page template: %v", err)
}
_, err = bt.Parse(string(content))
if err != nil {
return fmt.Errorf("error parsing block page template: %v", err)
}
c.BlockTemplate = bt
c.BlockpageURL = ""
return nil
}
type blockData struct {
URL string
Categories string
Conditions string
User string
Tally string
Scores string
RuleDescription string
Referer string
Request *http.Request
Response *http.Response
}
func (c *config) aclDescription(name string) string {
cat, ok := c.Categories[name]
if ok {
return cat.description
}
d, ok := c.ACLs.Descriptions[name]
if ok {
return d
}
return name
}
// Convert rule conditions into category descriptions as much as possible.
func (c *config) aclDescriptions(rule ACLActionRule) []string {
var categories []string
for _, acl := range rule.Needed {
categories = append(categories, c.aclDescription(acl))
}
for _, acl := range rule.Disallowed {
categories = append(categories, "not "+c.aclDescription(acl))
}
return categories
}
// showBlockPage shows a block page for a page that was blocked by an ACL.
func showBlockPage(w http.ResponseWriter, r *http.Request, resp *http.Response, user string, tally map[rule]int, scores map[string]int, rule ACLActionRule, extraData any) {
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("X-Redwood-Block-Page", "403 Access Denied")
c := getConfig()
switch {
case c.BlockTemplate != nil:
data := blockData{
URL: r.URL.String(),
Conditions: rule.Conditions(),
User: user,
Tally: listTally(stringTally(tally)),
Scores: listTally(scores),
Categories: strings.Join(c.aclDescriptions(rule), ", "),
RuleDescription: rule.Description,
Referer: r.Referer(),
Request: r,
Response: resp,
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.WriteHeader(http.StatusForbidden)
err := c.BlockTemplate.Execute(w, data)
if err != nil {
log.Println("Error filling in block page template:", err)
}
case c.BlockpageURL != "":
clientIP := r.RemoteAddr
if host, _, err := net.SplitHostPort(clientIP); err == nil {
clientIP = host
}
if e, ok := extraData.(starlark.Value); ok {
j, err := starlark.Call(&starlark.Thread{Name: "json.encode"}, starlarkJSONEncode, starlark.Tuple{e}, nil)
if err == nil {
if j, ok := j.(starlark.String); ok {
extraData = json.RawMessage(j)
}
}
}
d := map[string]any{
"url": r.URL.String(),
"rule": rule,
"user": user,
"tally": stringTally(tally),
"scores": scores,
"categories": c.aclDescriptions(rule),
"method": r.Method,
"client-ip": clientIP,
"referer": r.Referer(),
"request-header": r.Header,
"log-data": extraData,
}
if resp != nil {
d["response-header"] = resp.Header
}
data, err := json.Marshal(d)
if err != nil {
log.Println("Error generating JSON info for block page:", err)
http.Error(w, "", http.StatusForbidden)
return
}
blockReq, err := http.NewRequestWithContext(r.Context(), "POST", c.BlockpageURL, bytes.NewReader(data))
if err != nil {
if !errors.Is(err, context.Canceled) {
log.Printf("Error fetching blockpage from %s: %v", c.BlockpageURL, err)
}
http.Error(w, "", http.StatusForbidden)
return
}
blockReq.Header.Set("Content-Type", "application/json")
blockResp, err := transportWithExtraRootCerts.RoundTrip(blockReq)
if err != nil {
if !errors.Is(err, context.Canceled) {
log.Printf("Error fetching blockpage from %s: %v", c.BlockpageURL, err)
}
http.Error(w, "", http.StatusForbidden)
return
}
defer blockResp.Body.Close()
removeHopByHopHeaders(blockResp.Header)
if blockResp.ContentLength > 0 {
w.Header().Set("Content-Length", strconv.FormatInt(blockResp.ContentLength, 10))
}
if blockResp.StatusCode == http.StatusOK {
blockResp.StatusCode = http.StatusForbidden
}
copyResponseHeader(w, blockResp)
_, err = io.Copy(w, blockResp.Body)
if err != nil {
panic(http.ErrAbortHandler)
}
default:
http.Error(w, "", http.StatusForbidden)
return
}
}
// showInvisibleBlock blocks the request with an invisible image.
func showInvisibleBlock(w http.ResponseWriter) {
w.Header().Set("Content-Type", "image/gif")
w.Header().Set("Access-Control-Allow-Origin", "*")
w.WriteHeader(http.StatusForbidden)
fmt.Fprint(w, transparent1x1)
}
func (c *config) loadErrorPage(path string) error {
if strings.HasPrefix(path, "http") {
c.ErrorTemplate = nil
c.ErrorURL = path
return nil
}
bt := template.New("errorpage")
content, err := ioutil.ReadFile(path)
if err != nil {
return fmt.Errorf("error loading error page template: %v", err)
}
_, err = bt.Parse(string(content))
if err != nil {
return fmt.Errorf("error parsing error page template: %v", err)
}
c.ErrorTemplate = bt
c.ErrorURL = ""
return nil
}
// showErrorPage shows an error page for a request that failed (as we were
// fetching it from the origin server).
func showErrorPage(w http.ResponseWriter, r *http.Request, pageError error) {
w.Header().Set("Access-Control-Allow-Origin", "*")
c := getConfig()
d := map[string]any{
"url": r.URL.String(),
"error": pageError.Error(),
}
if dnsError, ok := errors.AsType[*net.DNSError](pageError); ok {
d["dns error"] = dnsError
}
w.Header().Set("Connection", "close")
switch {
case c.ErrorTemplate != nil:
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.WriteHeader(http.StatusBadGateway)
err := c.ErrorTemplate.Execute(w, d)
if err != nil {
log.Println("Error filling in error page template:", err)
panic(http.ErrAbortHandler)
}
case c.ErrorURL != "":
data, err := json.Marshal(d)
if err != nil {
log.Println("Error generating JSON info for error page:", err)
http.Error(w, pageError.Error(), http.StatusBadGateway)
return
}
errorResp, err := clientWithExtraRootCerts.Post(c.ErrorURL, "application/json", bytes.NewReader(data))
if err != nil {
log.Printf("Error fetching error page from %s: %v", c.ErrorURL, err)
http.Error(w, pageError.Error(), http.StatusBadGateway)
return
}
defer errorResp.Body.Close()
removeHopByHopHeaders(errorResp.Header)
if errorResp.ContentLength > 0 {
w.Header().Set("Content-Length", strconv.FormatInt(errorResp.ContentLength, 10))
}
errorResp.StatusCode = http.StatusBadGateway
copyResponseHeader(w, errorResp)
_, err = io.Copy(w, errorResp.Body)
if err != nil {
panic(http.ErrAbortHandler)
}
default:
http.Error(w, pageError.Error(), http.StatusBadGateway)
return
}
}