[lwip-devel] [patch #6900] IP Address Conversion Functions

[Chris N. Strahm]

URL:
  <http://savannah.nongnu.org/patch/?6900>

                 Summary: IP Address Conversion Functions
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: cstrahm
            Submitted on: Tue 25 Aug 2009 02:30:46 AM GMT
                Category: None
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None

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Details:

Nice idea. A bug or patch entry at savannah makes sure this doesn't get
forgotten. Thanks.
Simon


Chris Strahm wrote:
> Perhaps I have missed a function that may already exist, if not I guess
this
> would be a request for a new feature/function.
>
> When displaying an IP address as a string this kind of call is often made:
>
> printf("Starting lwIP, StaticIP %s\n", inet_ntoa(*(struct
> in_addr*)&netadr.ip));
>
> The function inet_ntoa() takes a "struct in_addr" parameter.
>
> However the "netadr.ip" value here contains a "struct ip_addr".  Since
they
> are not the same, all the above type casting is done to force it to work.
> This causes a warning everywhere from GCC about alignment etc.
>
> A better way to do this is to create a new function such as:
>
> // display ip_addr value as string
> char *ip_ntoa(struct ip_addr adr) {
>  struct in_addr ip;
>  ip.s_addr = adr.addr;
>  return(inet_ntoa(ip));
> } // ip_ntoa
>
> So the above call with the new function is then:
>
> printf("Starting lwIP, StaticIP %s\n", ip_ntoa(netadr.ip));
>
> This eliminates all the type casting and warnings.  Since lwIP has both
> "struct in_addr" and "struct ip_addr" used throughout, it seems like
having
> a str conversion routine for each type would make sense.
>
> I added ip_ntoa() to the ip_addr.c and ip_addr.h files which makes it easy
> to use anywhere.
>
> Chris.





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