Remove wget usage and dependency

There is only a single wget call in the installer, at the beginning of a pipe where curl may be the more natural choice. Since curl is a dependency already, this commit replaces the only wget call with curl and hence removes wget from installer dependencies.

Additionally, all curl calls get additional flags:
-s: The "silent" flag is now consequently used to suppress all processing output. It is not necessarily required when the STDOUT is a pipe or command substitution, but it does not hurt.
-S: Even when the curl output is piped, it may be helpful to have errors visible via STDERR, for debugging and being transparent about actual connection/download errors. This flag preserves error messages but does not send them to STDOUT, hence the data processed in the pipe or command substitution is not affected.
-f: There are cases where webservers return a 40x HTML document which is then printed to STDOUT by curl, like a 20x document, and hence unintentionally processed by the end of the pipe or command substitution. Usually this just cases a syntax error, but in theory it can have any unintended or even dangerous effect. The "fail" flag assures that 40x responses are printed as shortened error messages to STDERR and nothing is output to STDOUT. It should be hence seen as mandatory flag whenever curl is called to not print something to console but the output is processed.
-L: wget follows redirects automatically, curl requires the "-L" flag for this. For the wget => curl migration it is hence added to not change the behaviour.

Signed-off-by: MichaIng <micha@dietpi.com>

auto_install/install.sh

@@ -7,7 +7,7 @@
 #
 # Install with this command (from your Pi):
 #
-# curl -L https://install.pivpn.io | bash
+# curl -sSfL https://install.pivpn.io | bash
 # Make sure you have `curl` installed
 
 
@@ -34,7 +34,7 @@ PKG_INSTALL="${PKG_MANAGER} --yes --no-install-recommends install"
 PKG_COUNT="${PKG_MANAGER} -s -o Debug::NoLocking=true upgrade | grep -c ^Inst || true"
 
 # Dependencies that are required by the script, regardless of the VPN protocol chosen
-BASE_DEPS=(git tar wget curl grep dnsutils whiptail net-tools bsdmainutils)
+BASE_DEPS=(git tar curl grep dnsutils whiptail net-tools bsdmainutils)
 
 # Dependencies that where actually installed by the script. For example if the script requires
 # grep and dnsutils but dnsutils is already installed, we save grep here. This way when uninstalling
@@ -389,7 +389,7 @@ verifyFreeDiskSpace(){
 		echo "::: You only have ${existing_free_kilobytes} KiloBytes free."
 		echo "::: If this is a new install on a Raspberry Pi you may need to expand your disk."
 		echo "::: Try running 'sudo raspi-config', and choose the 'expand file system option'"
-		echo "::: After rebooting, run this installation again. (curl -L https://install.pivpn.io | bash)"
+		echo "::: After rebooting, run this installation again. (curl -sSfL https://install.pivpn.io | bash)"
 
 		echo "Insufficient free space, exiting..."
 		exit 1
@@ -1623,7 +1623,7 @@ askCustomDomain(){
 askPublicIPOrDNS(){
 	if ! IPv4pub=$(dig +short myip.opendns.com @208.67.222.222) || ! validIP "$IPv4pub"; then
 		echo "dig failed, now trying to curl checkip.amazonaws.com"
-		if ! IPv4pub=$(curl -s https://checkip.amazonaws.com) || ! validIP "$IPv4pub"; then
+		if ! IPv4pub=$(curl -sSf https://checkip.amazonaws.com) || ! validIP "$IPv4pub"; then
 			echo "checkip.amazonaws.com failed, please check your internet connection/DNS"
 			exit 1
 		fi
@@ -1832,7 +1832,7 @@ confOpenVPN(){
 	fi
 
 	# Get easy-rsa
-	wget -qO- "${easyrsaRel}" | $SUDO tar xz --one-top-level=/etc/openvpn/easy-rsa --strip-components 1
+	curl -sSfL "${easyrsaRel}" | $SUDO tar xz --one-top-level=/etc/openvpn/easy-rsa --strip-components 1
 	if ! test -s /etc/openvpn/easy-rsa/easyrsa; then
 		echo "$0: ERR: Failed to download EasyRSA."
 		exit 1