Re: [lwip-users] pylwIP - problems compiling on ubuntu 10.04

[Mason]

Mason wrote:

> Simon Goldschmidt wrote:
> 
>> Amir Shalem wrote:
>>
>>> 3. missing ENSRNOTFOUND
>>> lwip/src/api/netdb.c:203: error: 'ENSRNOTFOUND' undeclared
>>
>> I think I remember this being reported on one of the lists.
> 
> http://lists.gnu.org/archive/html/lwip-users/2011-08/msg00013.html
> 
>> I guess there's an include missing on linux to the file that provides
>> this error code.
> 
> It's not standard, as far as I could tell.
> So it should be defined by lwip headers.
> I can provide a patch this afternoon.
> 
>> If not, you can just define the error codes
>> yourself. However, in this case, the correct solution would probably
>> be to split the definition of error codes in arch.h so that lwIP can
>> provide the 'h_errno' error codes (for DNS) while not providing the
>> 'errno' error codes.
> 
> I'll look into it.

Of all the ENSR* definitions, only ENSRNOTFOUND is used, inside
lwip_gethostbyname_r

Before gethostbyname became obsolete in Issue 7 [1], POSIX had
this to say about netdb.h [2] and gethostbyname [3] in Issue 6.

[1] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netdb.h.html
[2] http://pubs.opengroup.org/onlinepubs/009695399/basedefs/netdb.h.html
[3] http://pubs.opengroup.org/onlinepubs/009695399/functions/gethostbyname.html

<quote>

ERRORS

These functions shall fail in the following cases.
The gethostbyaddr() and gethostbyname() functions shall set h_errno to
the value shown in the list below. Any changes to errno are unspecified.

[HOST_NOT_FOUND]
    No such host is known.
[NO_DATA]
    The server recognized the request and the name, but no address is 
available. Another type of request to the name server for the domain might 
return an answer.
[NO_RECOVERY]
    An unexpected server failure occurred which cannot be recovered.
[TRY_AGAIN]
    A temporary and possibly transient error occurred, such as a failure of a 
server to respond.

When the <netdb.h> header is included, h_errno shall be available as
a modifiable lvalue of type int. It is unspecified whether h_errno is
a macro or an identifier declared with external linkage.

The <netdb.h> header shall define the following macros for use as
error values for gethostbyaddr() and gethostbyname():

    HOST_NOT_FOUND
    NO_DATA
    NO_RECOVERY
    TRY_AGAIN

</quote>

These error value are correctly defined in src/include/lwip/arch.h

#ifndef LWIP_DNS_API_DEFINE_ERRORS
#define LWIP_DNS_API_DEFINE_ERRORS 1
#endif

#if LWIP_DNS_API_DEFINE_ERRORS
/** Errors used by the DNS API functions, h_errno can be one of them */
#define EAI_NONAME      200
#define EAI_SERVICE     201
#define EAI_FAIL        202
#define EAI_MEMORY      203

#define HOST_NOT_FOUND  210
#define NO_DATA         211
#define NO_RECOVERY     212
#define TRY_AGAIN       213
#endif /* LWIP_DNS_API_DEFINE_ERRORS */


I propose simply using HOST_NOT_FOUND to fix the problem:


--- netdb.c.orig        2011-05-06 10:51:25.000000000 +0200
+++ netdb.c     2011-10-18 14:58:58.312500000 +0200
@@ -198,11 +198,11 @@

   /* query host IP address */
   err = netconn_gethostbyname(name, &(h->addr));
   if (err != ERR_OK) {
     LWIP_DEBUGF(DNS_DEBUG, ("lwip_gethostbyname(%s) failed, err=%d\n", name, 
err));
-    *h_errnop = ENSRNOTFOUND;
+    *h_errnop = HOST_NOT_FOUND;
     return -1;
   }

   /* copy the hostname into buf */
   MEMCPY(hostname, name, namelen);


--- arch.h.orig 2011-05-06 10:51:26.000000000 +0200
+++ arch.h      2011-10-18 15:00:20.828125000 +0200
@@ -202,31 +202,10 @@
 #define  EDQUOT         122  /* Quota exceeded */

 #define  ENOMEDIUM      123  /* No medium found */
 #define  EMEDIUMTYPE    124  /* Wrong medium type */

-
-#define ENSROK                    0 /* DNS server returned answer with no data 
*/
-#define ENSRNODATA              160 /* DNS server returned answer with no data 
*/
-#define ENSRFORMERR             161 /* DNS server claims query was 
misformatted */
-#define ENSRSERVFAIL            162 /* DNS server returned general failure */
-#define ENSRNOTFOUND            163 /* Domain name not found */
-#define ENSRNOTIMP              164 /* DNS server does not implement requested 
operation */
-#define ENSRREFUSED             165 /* DNS server refused query */
-#define ENSRBADQUERY            166 /* Misformatted DNS query */
-#define ENSRBADNAME             167 /* Misformatted domain name */
-#define ENSRBADFAMILY           168 /* Unsupported address family */
-#define ENSRBADRESP             169 /* Misformatted DNS reply */
-#define ENSRCONNREFUSED         170 /* Could not contact DNS servers */
-#define ENSRTIMEOUT             171 /* Timeout while contacting DNS servers */
-#define ENSROF                  172 /* End of file */
-#define ENSRFILE                173 /* Error reading file */
-#define ENSRNOMEM               174 /* Out of memory */
-#define ENSRDESTRUCTION         175 /* Application terminated lookup */
-#define ENSRQUERYDOMAINTOOLONG  176 /* Domain name is too long */
-#define ENSRCNAMELOOP           177 /* Domain name is too long */
-
 #ifndef errno
 extern int errno;
 #endif

 #endif /* LWIP_PROVIDE_ERRNO */


Simon, do you agree with the proposed fix?

-- 
Regards.