/etc/hosts and getaddrinfo()

parthaswathi · 05-16-2007, 08:06 AM

Hi folks,

I am facing problem with getaddrinfo(), which is returning an error saying "Name or service is not known".
Even after giving an IPV6 address in /etc/hosts

The entry in /etc/hosts for the IPV6 address as below

dhoomsolaris fe80::214:4fff:fe61:3da6

The code looks like as below

memset (&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_flags = AI_PASSIVE | AI_ADDRCONFIG;
hints.ai_socktype = SOCK_STREAM;

errnum = getaddrinfo ("dhoomsolaris", SERVER_PORT, &hints, &res);
if (errnum) {
gai_strerror(errnum);
}
Please help in this, I will appreciate the same.

Regards,
Swathi

osor · 05-16-2007, 05:13 PM

This is very vague… What did you use for “hints.ai_flags”? Specifically, what is “hints.ai_flags & AI_NUMERICSERV”?

A short sample of code that exhibits the failure would prove helpful (remember to use [code] and [/code]).

parthaswathi · 05-16-2007, 10:48 PM

Quote:

Originally Posted by osor

This is very vague… What did you use for “hints.ai_flags”? Specifically, what is “hints.ai_flags & AI_NUMERICSERV”?

A short sample of code that exhibits the failure would prove helpful (remember to use [code] and [/code]).

Sorry for giving an incomplete information.

I have edited the question by providing enough information, can you please look into that and help me the same.

Regards,
Partha

osor · 05-17-2007, 03:48 PM

First off, it still isn’t a very complete sample of code (For example, if you get an error, gai_strerror(errnum) will show you nothing. Additionally, you never showed us the definition of SERVER_PORT. Additionally, you didn’t use [code] tags!).

Nevertheless, I think I can help you

. It seems to me the error is caused by the format of your /etc/hosts entry. The entry format is supposed to be (at least on linux, *BSD, and Mac):

Code:

ip_address canonical_hostname aliases

For example:

Code:

::1 localhost loopback

So your entry should be changed to something like:

Code:

fe80::214:4fff:fe61:3da6 dhoomsolaris

If it is still failing, you might have a problem with your numerical service (IIRC, you were previously using a numerical service). To circumvent this, you tell the resolver explicitly that you don’t need your service to be translated numerically. E.g.,

Code:

#define SERVER_PORT "80"

	memset (&hints, 0, sizeof(hints));
	hints.ai_family = AF_UNSPEC;
	hints.ai_flags = AI_PASSIVE | AI_ADDRCONFIG | AI_NUMERICSERV;
	hints.ai_socktype = SOCK_STREAM;

	int errnum = getaddrinfo ("dhoomsolaris", SERVER_PORT, &hints, &res);
	if (errnum)
		fprintf(stderr, "Name Resolution Failure: %s\n", gai_strerror(errnum));