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Re: [Oorexx-devel] About SockGetHostByAddr question for AIX 6.1
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From: Rainer T. <ta...@ta...> - 2011-03-14 09:15:47
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Hello,<br>
this is the AIX definition:<br>
<br>
Technical Reference:
Communications, Volume 2<br>
<br>
gethostbyaddr Subroutine<br>
<br>
Purpose<br>
<br>
Gets network host entry by address.<br>
<br>
Library<br>
<br>
Standard C Library (libc.a)<br>
(libbind)<br>
(libnis)<br>
(liblocal)<br>
<br>
Syntax<br>
<br>
#include <netdb.h><br>
<br>
struct hostent *gethostbyaddr ( Address, Length, Type)<br>
<br>
const void *Address, size_t Length, int Type;<br>
<br>
Description<br>
<br>
The gethostbyaddr subroutine is threadsafe in AIX 4.3 and
later. However, the return value points to static data<br>
that is overwritten by subsequent calls. This data must be
copied to be saved for use by subsequent calls.<br>
<br>
The gethostbyaddr subroutine retrieves information about a
host using the host address as a search key. Unless<br>
specified, the gethostbyaddr subroutine uses the default name
services ordering, that is, it will query DNS/BIND,<br>
NIS, then the local /etc/hosts file.<br>
<br>
When using DNS/BIND name service resolution, if the file
/etc/resolv.conf exists, the gethostbyaddr subroutine<br>
queries the domain name server. The gethostbyaddr subroutine
recognizes domain name servers as described in RFC<br>
883.<br>
<br>
When using NIS for name resolution, if the getdomainname
subroutine is successful and yp_bind indicates NIS is<br>
running, then the gethostbyaddr subroutine queries NIS.<br>
<br>
The gethostbyaddr subroutine also searches the local
/etc/hosts file when indicated to do so.<br>
<br>
The gethostbyaddr returns a pointer to a hostent structure,
which contains information obtained from one of the<br>
name resolutions services. The hostent structure is defined
in the netdb.h file.<br>
<br>
The environment variable, NSORDER can be set to override the
default name services ordering and the order<br>
specified in the /etc/netsvc.conf file.<br>
<br>
Parameters<br>
<br>
Address<br>
Specifies a host address. The host address is passed as
a pointer to the binary format address.<br>
Length<br>
Specifies the length of host address.<br>
Type<br>
Specifies the domain type of the host address. It can be
either AF_INET or AF_INET6.<br>
<br>
Return Values<br>
<br>
The gethostbyaddr subroutine returns a pointer to a hostent
structure upon success.<br>
<br>
If an error occurs or if the end of the file is reached, the
gethostbyaddr subroutine returns a NULL pointer and<br>
sets h_errno to indicate the error.<br>
<br>
Error Codes<br>
<br>
The gethostbyaddr subroutine is unsuccessful if any of the
following errors occur:<br>
Error<br>
Description<br>
HOST_NOT_FOUND<br>
The host specified by the Name parameter is not found.<br>
TRY_AGAIN<br>
The local server does not receive a response from an
authoritative server. Try again later.<br>
NO_RECOVERY<br>
This error code indicates an unrecoverable error.<br>
NO_ADDRESS<br>
The requested Address parameter is valid but does not
have a name at the name server.<br>
SERVICE_UNAVAILABLE<br>
None of the name services specified are running or
available.<br>
<br>
Files<br>
/etc/hosts<br>
Contains the host-name database.<br>
/etc/resolv.conf<br>
Contains the name server and domain name information.<br>
/etc/netsvc.conf<br>
Contains the name of the services ordering.<br>
/usr/include/netdb.h<br>
Contains the network database structure.<br>
<br>
Related Information<br>
<br>
The endhostent subroutine, gethostbyname subroutine,
sethostent subroutine, gethostent subroutine, inet_addr<br>
subroutine.<br>
<br>
Sockets Overview, and Network Address Translation in AIX 5L
Version 5.3 Communications Programming Concepts.<br>
<br>
<br>
Here is a sample for AIX (32/64 bit):<br>
<br>
#include <stdio.h><br>
#include <stdlib.h><br>
#include <unistd.h><br>
#include <netdb.h><br>
#include <arpa/inet.h><br>
#include <sys/socket.h><br>
<br>
int main(void)<br>
{<br>
struct hostent * pHostEnt;<br>
in_addr ia;<br>
char *addr;<br>
<br>
pHostEnt = gethostbyname("test.foo.org");<br>
ia.s_addr = (*(int *)pHostEnt->h_addr);<br>
addr = inet_ntoa(ia);<br>
printf("addr: %s\n", addr);<br>
<br>
pHostEnt = gethostbyaddr((char *) &ia.s_addr, sizeof(addr),
AF_INET);<br>
if (!pHostEnt)<br>
{<br>
printf("error gethostbyaddr: %d\n", h_errno);<br>
}<br>
else<br>
{<br>
printf("h_name: %s\n", pHostEnt->h_name);<br>
}<br>
return(0);<br>
}<br>
<br>
output:<br>
<br>
# ./textme2<br>
addr: 10.10.10.10<br>
h_name: test.foo.org<br>
<br>
<br>
On 12.03.2011 19:08, Jean-Louis Faucher wrote:
<blockquote
cite="mid:AANLkTimb0ZF_CPJ3o0DZ_OpUBq92SmKz-LeS=n3Eq=_6...@ma..."
type="cite">Hi<br>
<br>
I had a look at<br>
<a moz-do-not-send="true"
href="https://sourceforge.net/projects/oorexx/forums/forum/408477/topic/4404931"
target="_blank">https://sourceforge.net/projects/oorexx/forums/forum/408477/topic/4404931</a><br>
<br>
I see no difference in code beetween 320 and 410 which could
explain the failure.<br>
But there is a difference in test case : 64 bits vs 32 bits. And I
wonder if the declaration of addr is ok :<br>
<br>
long addr;<br>
addr = inet_addr(argv[0].strptr);<br>
pHostEnt = gethostbyaddr((char*)&addr,sizeof(addr),domain);<br>
<br>
According to this Unix spec <br>
<a moz-do-not-send="true"
href="http://pubs.opengroup.org/onlinepubs/009695399/functions/gethostbyaddr.html"
target="_blank">http://pubs.opengroup.org/onlinepubs/009695399/functions/gethostbyaddr.html</a><br>
addr should be of type <br>
struct in_addr<br>
which includes at least the member <br>
in_addr_t s_addr<br>
whose type is equivalent to the type uint32_t (they say).<br>
<br>
struct in_addr addr;<br>
addr.s_addr=inet_addr("1.2.3.4");<br>
<br>
Could the declaration long addr be the problem ?<br>
I tested under MacOsX 64 bits, it's not a problem.<br>
Don't know for AIX 6.1<br>
<br>
Jean-Louis<br>
<br>
</blockquote>
Bye<br>
Rainer <br>
<blockquote
cite="mid:AANLkTimb0ZF_CPJ3o0DZ_OpUBq92SmKz-LeS=n3Eq=_6...@ma..."
type="cite">
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