From 87da9084e60499b0b62e19c4b2a9275f5cd4f99d Mon Sep 17 00:00:00 2001
From: DL6ER <dl6er@dl6er.de>
Date: Sat, 10 Aug 2019 13:33:30 +0200
Subject: [PATCH] Use compression (if available) when downloading the ad lists.

Signed-off-by: DL6ER <dl6er@dl6er.de>
---
 gravity.sh | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/gravity.sh b/gravity.sh
index 5095c2b7..1153466d 100755
--- a/gravity.sh
+++ b/gravity.sh
@@ -457,7 +457,7 @@ parseList() {
 # Download specified URL and perform checks on HTTP status and file content
 gravity_DownloadBlocklistFromUrl() {
   local url="${1}" cmd_ext="${2}" agent="${3}" adlistID="${4}" saveLocation="${5}" target="${6}"
-  local heisenbergCompensator="" patternBuffer str httpCode success=""
+  local heisenbergCompensator="" patternBuffer str httpCode success="" compression
 
   # Create temp file to store content on disk instead of RAM
   patternBuffer=$(mktemp -p "/tmp" --suffix=".phgpb")
@@ -505,8 +505,18 @@ gravity_DownloadBlocklistFromUrl() {
     echo -ne "  ${INFO} ${str} Pending..."
     cmd_ext="--resolve $domain:$port:$ip $cmd_ext"
   fi
+
+  # Use compression to reduce the amount of data that is transfered
+  # between the Pi-hole and the ad list provider. Use this feature
+  # only if it is supported by the locally available version of curl
+  if curl -V | grep -q "Features:.* libz"; then
+    compression="--compressed"
+  else
+    compression=""
+  fi
+
   # shellcheck disable=SC2086
-  httpCode=$(curl -s -L ${cmd_ext} ${heisenbergCompensator} -w "%{http_code}" -A "${agent}" "${url}" -o "${patternBuffer}" 2> /dev/null)
+  httpCode=$(curl -s -L ${compression} ${cmd_ext} ${heisenbergCompensator} -w "%{http_code}" -A "${agent}" "${url}" -o "${patternBuffer}" 2> /dev/null)
 
   case $url in
     # Did we "download" a local file?