Sanitize and parse URL in Lua

sanitize_url.lua

 
function sanitize_url(url)
 
  if url:match("[%s%c]") then
     error "url contains spaces or ctrl chars"
  end 
  local proto,tail=url:match('^(%a+)://(.+)')
  if not proto then
    tail=url
    proto="http"
  end   
 
  local host,colon,port, path_sep,path=tail:match('(^[%a%d-.]+)(:?)(%d*)(/?)([%w%p%?]*)')
  if colon==":" and #port==0 then
    error "url format: colon without port number"
  end
  if #path>0 and  #path_sep==0 then
    error "url format: missing /"
  end
  if not host then 
    error "url format: no host"
  end    
  
  print(string.format("Host=%s Path=%s Port=%s",host,path or "",port or ""))
 
  return {
     proto=proto, 
     host=host,
     port=port or "",
     path=path or "" 
  }
 
end