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?

On Thursday, 21 April 2022 at 07:04:18 UTC, Alexander Zhirov wrote:

	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;
		}
       }

On Thursday, 21 April 2022 at 07:20:30 UTC, dangbinghoo wrote:

	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 */
}

On Thursday, 21 April 2022 at 07:20:30 UTC, dangbinghoo wrote:

	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;
		}
       }

Gives a lot of errors when compiling

app.d(19): Error: function `std.stdio.makeGlobal!"core.stdc.stdio.stderr".makeGlobal` at /usr/include/dlang/dmd/std/stdio.d(5198) conflicts with variable `core.stdc.stdio.stderr` at /usr/include/dlang/dmd/core/stdc/stdio.d(927)
app.d(19): Error: function `core.stdc.stdio.fprintf(shared(_IO_FILE)* stream, scope const(char*) format, scope const ...)` is not callable using argument types `(void, string, int)`
app.d(19):        cannot pass argument `makeGlobal(StdFileHandle _iob)()` of type `void` to parameter `shared(_IO_FILE)* stream`
app.d(23): Error: undefined identifier `ifreq`
app.d(26): Error: undefined identifier `string` in package `std`
app.d(39): Error: undefined identifier `macaddr`
app.d(48): Error: undefined identifier `fromStringz`

On Thursday, 21 April 2022 at 07:38:04 UTC, Alexander Zhirov wrote:

	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;
		}
       }

app.d(19): Error: function `std.stdio.makeGlobal!"core.stdc.stdio.stderr".makeGlobal` at /usr/include/dlang/dmd/std/stdio.d(5198) conflicts with variable `core.stdc.stdio.stderr` at /usr/include/dlang/dmd/core/stdc/stdio.d(927)
app.d(19): Error: function `core.stdc.stdio.fprintf(shared(_IO_FILE)* stream, scope const(char*) format, scope const ...)` is not callable using argument types `(void, string, int)`
app.d(19):        cannot pass argument `makeGlobal(StdFileHandle _iob)()` of type `void` to parameter `shared(_IO_FILE)* stream`
app.d(23): Error: undefined identifier `ifreq`
app.d(26): Error: undefined identifier `string` in package `std`
app.d(39): Error: undefined identifier `macaddr`
app.d(48): Error: undefined identifier `fromStringz`

```d
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 */
}

On Friday, 22 April 2022 at 05:28:52 UTC, dangbinghoo wrote:

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

it's actually POSIX C API binding for D. you should get similar code in C when searching StackOverflow.

the only thing to do this is just to look at /usr/include/dlang for POSIX API already complete binding from the official. if something is missing, you just do-it-yourself in your code.

On Thursday, 21 April 2022 at 07:20:30 UTC, dangbinghoo wrote:

It really makes me sad when I see this. D has some native networking API but unfortunately you have go to the OS API to have this basic functionality. D should really expand its own API so that we don't have to use OS APIs.