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|
package onionloc
import (
"net/http"
"strings"
"golang.org/x/net/html"
)
const (
HTTPHeaderName = "Onion-Location"
)
func HTTP(rsp *http.Response) (string, bool) {
v, ok := rsp.Header[HTTPHeaderName]
if !ok {
return "", false
}
if len(v) != 1 {
return "", false
}
return v[0], true
}
func HTML(rsp *http.Response) (string, bool) {
z := html.NewTokenizer(rsp.Body)
for {
tt := z.Next()
if tt == html.ErrorToken {
return "", false // EOF and other errors
}
switch tt {
case html.StartTagToken, html.SelfClosingTagToken:
t := z.Token()
// Looking for the html meta tag, see:
// https://www.w3schools.com/tags/tag_meta.asp
//
// We expect two attributes: "key" and "content"
if strings.ToLower(t.Data) != "meta" {
break
}
if len(t.Attr) != 2 {
break
}
// We're looking for the "http-equiv" key, see:
// https://www.w3schools.com/tags/att_meta_http_equiv.asp
//
// In particular with the value "onion-location", see:
// https://community.torproject.org/onion-services/advanced/onion-location/
//
// If we have all this and a following content
// attribute, that is the Onion-Location URL that this
// page advertises. We make no attempt to validate
// whether the content value is really an onion address.
attr := t.Attr[0]
if strings.ToLower(attr.Key) != "http-equiv" {
break
}
if strings.ToLower(attr.Val) != "onion-location" {
break
}
attr = t.Attr[1]
if strings.ToLower(attr.Key) != "content" {
break
}
return attr.Val, true
default:
}
}
}
|
