How to get an IP address from network interfaces

[dangbinghoo]

On Thursday, 21 April 2022 at 07:20:30 UTC, dangbinghoo wrote:
> On Thursday, 21 April 2022 at 07:04:18 UTC, Alexander Zhirov 
> wrote:
>> I want to get the IP address of the network interface. There 
>> is both a wireless interface and a wired one. Is it possible, 
>> knowing the name of the network interface, to get its IP 
>> address?
>
> ```d
> 	import core.sys.posix.sys.ioctl;
> 	import core.sys.posix.arpa.inet;
> 	
> 	import core.stdc.string;
> 	import core.stdc.stdio;
> 	import core.stdc.errno;
> 	import core.sys.posix.stdio;
> 	import core.sys.posix.unistd;
> 	
> 	string ip;
>
> 	
> 	int get(string if_name)
> 	{
> 		int s = socket(AF_INET, SOCK_DGRAM, 0);
> 		if (s < 0) {
> 			fprintf(stderr, "Create socket failed!errno=%d", errno);
> 			return -1;
> 		}
> 	
> 		ifreq ifr;
> 		uint nIP, nNetmask, nBroadIP;
>
> 		strcpy(ifr.ifr_name.ptr, std.string.toStringz(if_name));
> 		try {
> 			if (ioctl(s, SIOCGIFHWADDR, &ifr) < 0) {
> 				return -2;
> 			}
> 		}
> 		catch (Exception e) {
> 			writeln("Error operation on netif " ~ if_name);
> 			return -2;
> 		}
> 		memcpy(macaddr.ptr, cast(char *)ifr.ifr_hwaddr.sa_data.ptr, 
> 6);
> 	
> 		if (ioctl(s, SIOCGIFADDR, &ifr) < 0) {
> 			nIP = 0;
> 		}
> 		else {
> 			nIP = *cast(uint*)(&ifr.ifr_broadaddr.sa_data[2]);
> 			ip = fromStringz(inet_ntoa(*cast(in_addr*)&nIP)).idup;
> 		}
>        }
>
> ```

PS:

     ```d
     //handle binding to net/if.h
     struct ifmap
     {
         c_ulong mem_start;
         c_ulong mem_end;
         ushort base_addr;
         ubyte irq;
         ubyte dma;
         ubyte port;
         /* 3 bytes spare */
     }

     struct ifreq {
     	private union ifr_ifrn_ {
     		char[IFNAMSIZ] ifrn_name; /* if name, e.g. "en0" */	
     	}
     	ifr_ifrn_ ifr_ifrn;

     	private union ifr_ifru_ {
     		sockaddr ifru_addr;
     		sockaddr ifru_dstaddr;
     		sockaddr ifru_broadaddr;
     		sockaddr ifru_netmask;
     		sockaddr ifru_hwaddr;
     		short	ifru_flags;
     		int	ifru_ivalue;
     		int	ifru_mtu;
     		ifmap ifru_map;
     		byte[IFNAMSIZ] ifru_slave;	/* Just fits the size */
     		byte[IFNAMSIZ] ifru_newname;
     		byte * ifru_data;
     	}
     	ifr_ifru_ ifr_ifru;

     	// NOTE: alias will not work : alias ifr_ifrn.ifrn_name	    
ifr_name;
     	@property ref ifr_name() { return ifr_ifrn.ifrn_name; } /* 
interface name */
     	@property ref ifr_hwaddr() { return ifr_ifru.ifru_hwaddr; } 
/* MAC address */
     	@property ref ifr_addr() { return ifr_ifru.ifru_addr; } /* 
address */
     	@property ref ifr_dstaddr() { return ifr_ifru.ifru_dstaddr; 
} /* other end of p-p lnk */
     	@property ref ifr_broadaddr() { return 
ifr_ifru.ifru_broadaddr; } /* broadcast address	*/
     	@property ref ifr_netmask() { return  ifr_ifru.ifru_netmask; 
} /* interface net mask */
     	@property ref ifr_flags() { return ifr_ifru.ifru_flags; } /* 
flags	*/
     	@property ref ifr_metric() { return ifr_ifru.ifru_ivalue; } 
/* metric */
     	@property ref ifr_mtu() { return ifr_ifru.ifru_mtu; } /* mtu 
*/
     	@property ref ifr_map() { return ifr_ifru.ifru_map; } /* 
device map */
     	@property ref ifr_slave() { return ifr_ifru.ifru_slave; } /* 
slave device */
     	@property ref ifr_data() { return ifr_ifru.ifru_data; } /* 
for use by interface */
     	@property ref ifr_ifindex() { return ifr_ifru.ifru_ivalue; } 
/* interface index */
     	@property ref ifr_bandwidth() { return ifr_ifru.ifru_ivalue; 
} /* link bandwidth */
     	@property ref ifr_qlen() { return ifr_ifru.ifru_ivalue; } /* 
queue length */
     	@property ref ifr_newname() { return ifr_ifru.ifru_newname; 
} /* New name */
     }

```