Commit initial versions of percent_encode and percent_decode

lib/http_tools.sh

@@ -490,6 +490,63 @@ get_header_value () {
 	return 0
 }
 
+#######################################################################
+# This function percent-encodes all characters except the "Unreserved 
+# Characters" defined in section 2.3 of RFC 3986.
+#
+# See: https://gist.github.com/cdown/1163649
+#      https://en.wikipedia.org/wiki/Percent-encoding
+#######################################################################
+percent_encode () {
+    # percent_encode <string>
+
+	# make sure there is one (and only one) command-line argument
+	if [ $# -ne 1 ]; then
+		echo "ERROR: $FUNCNAME: incorrect number of arguments: $# (1 required)" >&2
+		return 2
+	fi
+
+	# this implementation assumes a particular collating sequence
+	local LC_COLLATE=C
+
+	local length
+	local c
+
+	length="${#1}"
+	for (( i = 0; i < length; i++ )); do
+		c="${1:i:1}"
+		case "$c" in
+			[a-zA-Z0-9.~_-]) printf "$c" ;;
+			*) printf '%%%02X' "'$c"
+		esac
+	done
+}
+
+#######################################################################
+# This function percent-decodes all percent-encoded characters.
+#######################################################################
+percent_decode () {
+    # percent_decode <string>
+
+	# make sure there is one (and only one) command-line argument
+	if [ $# -ne 1 ]; then
+		echo "ERROR: $FUNCNAME: incorrect number of arguments: $# (1 required)" >&2
+		return 2
+	fi
+
+	local encoded_string
+
+	# the percent_encode function doesn't convert spaces to
+	# plus signs (+) but the input string to the percent_decode 
+	# function may have been encoded in some other manner so we
+	# first decode plus signs (+) into spaces
+    encoded_string="${1//+/ }"
+
+    printf '%b' "${encoded_string//%/\\x}"
+}
+
+# DEPRECATED: Use percent_encode and percent_decode instead.
+#
 # URL encoder/decoder
 # see: https://gist.github.com/cdown/1163649
 url_encode () {