[fix] fixed substring detection to work in dash

- added missing 'local' keyword to function vars

proxy/files/entrypoint.sh

@@ -46,21 +46,41 @@ function log()
 # this is a helper function as dash does not support arrays
 function get_element()
 {    
-    element="$1"
-    seperator="$2"; shift; shift
-    array=$@
-    old_IFS=$IFS
+    local element="$1"; #index to return
+    local seperator="$2"; shift; shift
+    local array=$@
+    local old_IFS=$IFS
     IFS="$seperator"
     set -- $array
     while [ "$element" -gt 0 ]; do
         shift
         element=$(( element - 1 ))
     done
-    result=$1
+    local result=$1
     IFS=$old_IFS
     echo $result
 }
 
+# helper function to check if a string contains a substring in dash
+function contains()
+{
+    local string="$1"
+    local substring="$2"    
+    [ -z $(echo "$string" | sed "/$substring/d") ]
+}
+# helper function to check if string begins with substring in dash
+function begins_with()
+{
+    local string=$1
+    local substring=$2
+    [ -z $(echo "$string" | sed "/^$substring/d") ]
+}
+# extra function for readability
+function has_port()
+{
+    contains $1 ":"
+}
+
 function sleep_wait()
 {
     # waiting on sleep to be able to handle SIGTERM
@@ -126,7 +146,7 @@ function read_file()
 
 function rng()
 {
-    rng_n=$(od -An -N2 -d < /dev/urandom)
+    local rng_n=$(od -An -N2 -d < /dev/urandom)
     echo $rng_n
 }
 
@@ -140,7 +160,7 @@ function gen_server_config()
 
     # default to 8080 if server port is undefined
     local port=":8080";
-    [[ $server == *":"* ]] && port=""
+    has_port $server && port=""
     
     # no arrays in dash
     local subdomain=$(get_element $domain_count " " $domain_list)