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From: | Bei Guan |
Subject: | Re: [lwip-users] Re: Problem on using DNS function in app |
Date: | Fri, 19 Nov 2010 09:34:48 +0800 |
I assume you are initializing LWIP via a call to tcip_init()? If so, the DNS module should be correctly initialized, which eliminates one possible reason for an ERR_VAL result. Your parameters look OK, which rules out all the other "immediate error" results which can return ERR_VAL.(I've just filed a bug report, as the init/parameter error conditions are supposed to return ERR_ARG but are actually returning ERR_VAL.)ERR_VAL is also returned if there is an invalid response from the DNS sever. The comment in do_dns_found() suggests this could be a timeout or memory error, or the DNS server may have returned an error such as a nonexistent domain name.----- Original Message -----From: Bei GuanSent: Friday, November 19, 2010 4:25 AMSubject: [lwip-users] Re: Problem on using DNS function in appNow I can compile successfully. But there are some error and the value of the error is -9, which means "Illegal value".
My code:
char hname[]="www.baidu.com";
struct ip_addr addr;
err_t err;
if ((err = netconn_gethostbyname((char*)(hname), &(addr))) == ERR_OK) {
printf("netconn_gethostbyname(%s)==", (char*)(hname));
ip_addr_debug_print(LWIP_DBG_ON, (&addr));
printf("\n");
} else {
printf("netconn_gethostbyname(%s)==%i\n", (char*)(hname), (int)(err));
}
And the output:
netconn_gethostbyname(www.baidu.com)==-9
So why the DNS can not work?
2010/11/18 Bei Guan <address@hidden>
Hi all,
I have used the function netconn_gethostbyname in my program. I have set the #define LWIP_DNS 1 in lwipopts.h and I also have include the "lwip/api.h" before my main function. When I compile my program, it came cross an error message: undefined reference to `netconn_gethostbyname'. But some other function can be used successfully, such as netconn_connect.
So anyone can give me advice. Thanks a lot!
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