Trouble with getbyhostname()

Hi,
I am having trouble with getbyhostname().I works sometimes but on
other occasions it crashes.
IPADDRESS is a string say "192.123.12.1"

(gdb)
Client::SendSocket (this=0xbfa9493c, QuerBuf=@0xbfa948c4,
IPADDRESS=@0xbfa948d4) at Client.cc:141
141 h = gethostbyname(IPADDRESS.c_str());
(gdb)
*** glibc detected *** /home/workspace/DNSResolver1/checkstring:
free(): invalid next size (normal): 0x0804eb38 ***
======= Backtrace: =========
/lib/tls/i686/cmov/libc.so.6[0xb7db1d65]
/lib/tls/i686/cmov/libc.so.6(cfree+0x90)[0xb7db5800]
/lib/tls/i686/cmov/libc.so.6(fclose+0x134)[0xb7da06f4]
/lib/tls/i686/cmov/libc.so.6[0xb7e2a73d]
/lib/tls/i686/cmov/libc.so.6(__res_ninit+0x25)[0xb7e2ae65]
/lib/tls/i686/cmov/libc.so.6(__res_maybe_init+0x7b)[0xb7e2c30b]
/lib/tls/i686/cmov/libc.so.6(__nss_hostname_digits_dots+0x2d)
[0xb7e2dcdd]
/lib/tls/i686/cmov/libc.so.6(gethostbyname+0x9a)[0xb7e3227a]

(E-Mail Removed) wrote:
> Hi,
> I am having trouble with getbyhostname().I works sometimes but on
> other occasions it crashes.
> IPADDRESS is a string say "192.123.12.1"

Well, gethostbyname really does work, honest. So you will have to send
us a snippet of your code if you want advice on what is wrong with it.

Robert

>
> (gdb)
> Client::SendSocket (this=0xbfa9493c, QuerBuf=@0xbfa948c4,
> IPADDRESS=@0xbfa948d4) at Client.cc:141
> 141 h = gethostbyname(IPADDRESS.c_str());
> (gdb)
> *** glibc detected *** /home/workspace/DNSResolver1/checkstring:
> free(): invalid next size (normal): 0x0804eb38 ***
> ======= Backtrace: =========
> /lib/tls/i686/cmov/libc.so.6[0xb7db1d65]
> /lib/tls/i686/cmov/libc.so.6(cfree+0x90)[0xb7db5800]
> /lib/tls/i686/cmov/libc.so.6(fclose+0x134)[0xb7da06f4]
> /lib/tls/i686/cmov/libc.so.6[0xb7e2a73d]
> /lib/tls/i686/cmov/libc.so.6(__res_ninit+0x25)[0xb7e2ae65]
> /lib/tls/i686/cmov/libc.so.6(__res_maybe_init+0x7b)[0xb7e2c30b]
> /lib/tls/i686/cmov/libc.so.6(__nss_hostname_digits_dots+0x2d)
> [0xb7e2dcdd]
> /lib/tls/i686/cmov/libc.so.6(gethostbyname+0x9a)[0xb7e3227a]

Uhm... not being a programmer, or anything, but isn't gethostbyname used
for resolving names into adresses and not the other way around?

(E-Mail Removed) wrote:
> Hi,
> I am having trouble with getbyhostname().I works sometimes but on
> other occasions it crashes.
> IPADDRESS is a string say "192.123.12.1"
>
> (gdb)
> Client::SendSocket (this=0xbfa9493c, QuerBuf=@0xbfa948c4,
> IPADDRESS=@0xbfa948d4) at Client.cc:141
> 141 h = gethostbyname(IPADDRESS.c_str());
> (gdb)
> *** glibc detected *** /home/workspace/DNSResolver1/checkstring:
> free(): invalid next size (normal): 0x0804eb38 ***
> ======= Backtrace: =========
> /lib/tls/i686/cmov/libc.so.6[0xb7db1d65]
> /lib/tls/i686/cmov/libc.so.6(cfree+0x90)[0xb7db5800]
> /lib/tls/i686/cmov/libc.so.6(fclose+0x134)[0xb7da06f4]
> /lib/tls/i686/cmov/libc.so.6[0xb7e2a73d]
> /lib/tls/i686/cmov/libc.so.6(__res_ninit+0x25)[0xb7e2ae65]
> /lib/tls/i686/cmov/libc.so.6(__res_maybe_init+0x7b)[0xb7e2c30b]
> /lib/tls/i686/cmov/libc.so.6(__nss_hostname_digits_dots+0x2d)
> [0xb7e2dcdd]
> /lib/tls/i686/cmov/libc.so.6(gethostbyname+0x9a)[0xb7e3227a]

Jurgen Haan <(E-Mail Removed)> wrote:
> Uhm... not being a programmer, or anything, but isn't gethostbyname
> used for resolving names into adresses and not the other way around?

Yes, but for the last decade or so just about everyone's
gethostbyname() is willing to take-in an IPv4 address as a
dotted-decimal string.

However, for the last, oh five years or so, people should be migrating
to getaddrinfo() rather than gethostbyname()...

rick jones
--
denial, anger, bargaining, depression, acceptance, rebirth...
where do you want to be today?
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

Rick Jones <(E-Mail Removed)> writes:

>Jurgen Haan <(E-Mail Removed)> wrote:
>> Uhm... not being a programmer, or anything, but isn't gethostbyname
>> used for resolving names into adresses and not the other way around?

>Yes, but for the last decade or so just about everyone's
>gethostbyname() is willing to take-in an IPv4 address as a
>dotted-decimal string.

>However, for the last, oh five years or so, people should be migrating
>to getaddrinfo() rather than gethostbyname()...

Which unfortunately has ( or maybe had) a problem in that it would not use
the local hosts file but went out to the dns server for everything.



>rick jones
>--
>denial, anger, bargaining, depression, acceptance, rebirth...
> where do you want to be today?
>these opinions are mine, all mine; HP might not want them anyway...
>feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

Unruh <unruh-(E-Mail Removed)> wrote:
> Rick Jones <(E-Mail Removed)> writes:
> >However, for the last, oh five years or so, people should be
> >migrating to getaddrinfo() rather than gethostbyname()...

> Which unfortunately has ( or maybe had) a problem in that it would
> not use the local hosts file but went out to the dns server for
> everything.

I would expect that is had rather than has as I've been using it
without reported trouble (of that sort at least) in netperf for a few
years now.

rick jones
--
denial, anger, bargaining, depression, acceptance, rebirth...
where do you want to be today?
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...