Glynn Clements wrote:
>Glover George wrote:
>
>
>>Hi, I'm working on a little module here and was wondering what the BEST
>>way to get an interface's current ip address by using it's name (i.e.,
>>eth0) is. I was trying one way using sockets and it just doesn't seem
>>to reliably give it to me every time. I was using these two functions
>>below, but I it would return NULL some of the time from
>>IPCon_GetIpAddrByStr sometimes, so I'm not sure. I need a way to be
>>able to reliably obtain this ip at any give time (due to dhcp, etc). Any
>>pointers? TIA.
>>
>>struct in_addr * IPCon::IPCon_GetIpAddr(void)
>>{
>> struct ifreq ifr;
>> struct sockaddr_in *saddr;
>> int fd;
>> fd = get_sockfd();
>> if (fd >= 0 )
>> {
>> strcpy(ifr.ifr_name, m_ifname);
>> ifr.ifr_addr.sa_family = AF_INET;
>> if (ioctl(fd, SIOCGIFADDR, &ifr) == 0)
>> {
>> saddr = (sockaddr_in *)&ifr.ifr_addr;
>> return &saddr->sin_addr;
>>
>>
>
>You are returning a pointer to data which is on the stack, and which
>ceases to be valid once you've returned from the function.
>
>You should either have the caller supply the buffer, e.g.
>
> bool IPCon::IPCon_GetIpAddr(struct in_addr *result)
>
>or allocate the memory dynamically, with malloc() or new.
>
Is it possible to get this information but for an IPv6 address (the
question I asked a few days ago)?
-- FiX
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