From 249dba391d9ed5dafcc361346dbe73faeb35f06c Mon Sep 17 00:00:00 2001
From: Frank Denis <github@pureftpd.org>
Date: Thu, 25 Apr 2024 12:43:29 +0200
Subject: [PATCH] Support gzip compression to fetch source files

---
 dnscrypt-proxy/sources.go    |  2 +-
 dnscrypt-proxy/xtransport.go | 29 ++++++++++++++++++++++++++---
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/dnscrypt-proxy/sources.go b/dnscrypt-proxy/sources.go
index 30bd3cb4..2bf83415 100644
--- a/dnscrypt-proxy/sources.go
+++ b/dnscrypt-proxy/sources.go
@@ -131,7 +131,7 @@ func (source *Source) parseURLs(urls []string) {
 }
 
 func fetchFromURL(xTransport *XTransport, u *url.URL) ([]byte, error) {
-	bin, _, _, _, err := xTransport.Get(u, "", DefaultTimeout)
+	bin, _, _, _, err := xTransport.GetWithCompression(u, "", DefaultTimeout)
 	return bin, err
 }
 
diff --git a/dnscrypt-proxy/xtransport.go b/dnscrypt-proxy/xtransport.go
index e0efd780..249a514e 100644
--- a/dnscrypt-proxy/xtransport.go
+++ b/dnscrypt-proxy/xtransport.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"compress/gzip"
 	"context"
 	"crypto/sha512"
 	"crypto/tls"
@@ -482,6 +483,7 @@ func (xTransport *XTransport) Fetch(
 	contentType string,
 	body *[]byte,
 	timeout time.Duration,
+	compress bool,
 ) ([]byte, int, *tls.ConnectionState, time.Duration, error) {
 	if timeout <= 0 {
 		timeout = xTransport.timeout
@@ -530,6 +532,9 @@ func (xTransport *XTransport) Fetch(
 		)
 		return nil, 0, nil, 0, err
 	}
+	if compress && body == nil {
+		header["Accept-Encoding"] = []string{"gzip"}
+	}
 	req := &http.Request{
 		Method: method,
 		URL:    url,
@@ -596,7 +601,17 @@ func (xTransport *XTransport) Fetch(
 		}
 	}
 	tls := resp.TLS
-	bin, err := io.ReadAll(io.LimitReader(resp.Body, MaxHTTPBodyLength))
+
+	var bodyReader io.ReadCloser = resp.Body
+	if compress && resp.Header.Get("Content-Encoding") == "gzip" {
+		bodyReader, err = gzip.NewReader(io.LimitReader(resp.Body, MaxHTTPBodyLength))
+		if err != nil {
+			return nil, statusCode, tls, rtt, err
+		}
+		defer bodyReader.Close()
+	}
+
+	bin, err := io.ReadAll(io.LimitReader(bodyReader, MaxHTTPBodyLength))
 	if err != nil {
 		return nil, statusCode, tls, rtt, err
 	}
@@ -604,12 +619,20 @@ func (xTransport *XTransport) Fetch(
 	return bin, statusCode, tls, rtt, err
 }
 
+func (xTransport *XTransport) GetWithCompression(
+	url *url.URL,
+	accept string,
+	timeout time.Duration,
+) ([]byte, int, *tls.ConnectionState, time.Duration, error) {
+	return xTransport.Fetch("GET", url, accept, "", nil, timeout, true)
+}
+
 func (xTransport *XTransport) Get(
 	url *url.URL,
 	accept string,
 	timeout time.Duration,
 ) ([]byte, int, *tls.ConnectionState, time.Duration, error) {
-	return xTransport.Fetch("GET", url, accept, "", nil, timeout)
+	return xTransport.Fetch("GET", url, accept, "", nil, timeout, false)
 }
 
 func (xTransport *XTransport) Post(
@@ -619,7 +642,7 @@ func (xTransport *XTransport) Post(
 	body *[]byte,
 	timeout time.Duration,
 ) ([]byte, int, *tls.ConnectionState, time.Duration, error) {
-	return xTransport.Fetch("POST", url, accept, contentType, body, timeout)
+	return xTransport.Fetch("POST", url, accept, contentType, body, timeout, false)
 }
 
 func (xTransport *XTransport) dohLikeQuery(