Bug #78479 [Com]: gethostbyname can incorrectly return 0.0.0.0
Edit report at https://bugs.php.net/bug.php?id=78479&edit=1
ID: 78479
Comment by: zhangwenchao001 at gmail dot com
Reported by: ryan at arctype dot co
Summary: gethostbyname can incorrectly return 0.0.0.0
Status: Open
Type: Bug
Package: *Network Functions
Operating System: Ubuntu Linux
PHP Version: master-Git-2019-08-30 (Git)
Block user comment: N
Private report: N
New Comment:
# chaochao @ KVM-Ubuntu in ~ [9:36:43]
$ php -a
Interactive mode enabled
php > echo gethostbyname("downloads.wordpress.org");
198.143.164.250
I have IPv4/IPv6, found no problems.
Previous Comments:
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[2019-08-30 21:17:20] ryan at arctype dot co
Description:
------------
Consider:
<?php echo gethostbyname("www.google.com"); ?>
38.7.248.176
<?php echo gethostbyname("downloads.wordpress.org"); ?>
0.0.0.0
;; ANSWER SECTION:
www.google.com. 229 IN A 216.58.193.196
;; ANSWER SECTION:
downloads.wordpress.org. 300 IN A 198.143.164.250
The DNS on the host is running fine, DNS for downloads.wordpress.org is ok. We are however running
on a dual-stack ipv4/v6 host.
www.google.com has an AAAA record, downloads.wordpress.org does not.
I suspect that gethostbyname() is returning an AAAA record from the system call to gethostbyname(3),
which returns a struct hostent:
struct hostent {
char *h_name; /* official name of host */
char **h_aliases; /* alias list */
int h_addrtype; /* host address type */
int h_length; /* length of address */
char **h_addr_list; /* list of addresses */
}
While the PHP docs explicitly state that PHP's gethostbyname() returns the IPv4 address, the
implementation does not restrict or check if the system call actually returns an AF_INET h_addrtype
instead of AF_INET6, always assuming a v4 and copying sizeof(in_addr): https://github.com/php/php-src/blob/master/ext/standard/dns.c#L272
According to the Linux man pages, "The gethostbyname*(), gethostbyaddr*(), herror(), and
hstrerror() functions are obsolete. Applications should use getaddrinfo(3), getnameinfo(3), and
gai_strerror(3) instead."
"The gethostbyaddr() function returns a structure of type hostent for the given host
address addr of length len and address type type. Valid address types are AF_INET and
AF_INET6."
This problem has manifested elsewhere in this Wordpress bug report from a dual-stack host: https://core.trac.wordpress.org/ticket/38291
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Edit this bug report at https://bugs.php.net/bug.php?id=78479&edit=1
Thread (6 messages)