[SOLVED] freebsd: SIOCSIFADDR returns EINVAL

smaclennan · 01-02-2020, 07:53 PM

I am trying to set the IP address of an interface. The interface is virtual (vtnet0) if that matters.

The SIOCGIFADDR ioctl works, but I can't get the set to work. Here is the code fragment:

Code:

static int set_ip(const char *ifname, const char *ip, unsigned mask, int down)
{
	int s = socket(AF_INET, SOCK_DGRAM, 0);
	if (s == -1) {
		perror("set_ip socket");
		return -1;
	}

	struct ifreq req;
	memset(&req, 0, sizeof(req));

	strlcpy(req.ifr_name, ifname, IF_NAMESIZE);

	struct sockaddr_in *in = (struct sockaddr_in *)&req.ifr_addr;
#ifndef __linux__
	in->sin_len = sizeof(struct sockaddr_in);
#endif
	in->sin_family = AF_INET;
	if (ip)
		in->sin_addr.s_addr = inet_addr(ip);

	errno = 0;
	if (ioctl(s, SIOCSIFADDR, &req)) {
		perror("SIOCSIFADDR");
		goto failed;
	}

Is this not the correct way to set the IP on FreeBSD?

cynwulf · 01-03-2020, 02:47 AM

Refer to ifconfig(8).

You need a ifconfig_<interface> stanza in rc.conf(8) to bring up the interface on boot.

smaclennan · 01-03-2020, 07:09 PM

Ok, I solved it. You can't use SIOCSIFADDR, or SIOCIFNETMASK, you must use SIOCAIFADDR (note the A) which takes an ifaliasreq struct. You still use SIOCSIFFLAGS though.