Add simple IPv4 only ifconfig() function from Finit

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Makefile

@@ -56,7 +56,7 @@ endif
 DISTFILES   = README LICENSE
 HEADERS     = lite.h
 OBJS       := chomp.o copyfile.o dir.o fexist.o fisdir.o fmode.o fsendfile.o
-OBJS       += makepath.o pidfile.o pidfilefn.o rsync.o
+OBJS       += ifconfig.o makepath.o pidfile.o pidfilefn.o rsync.o
 OBJS       += strlcpy.o strlcat.o strtonum.o tempfile.o
 DEPS       := $(OBJS:.o=.d)
 JUNK        = *~ *.bak *.map .*.d *.d DEADJOE semantic.cache *.gdb *.elf core core.*

README.md

@@ -86,6 +86,11 @@ Generic Functions
   `dst` is allowed to be `NULL` to be able to read and discard `len`
   bytes from `src`.
 
+- `ifconfig(ifname, addr, mask, up)`
+
+  Basic ifconfig like operations on an interface.  Only supports IPv4
+  adresses.  Note that mask is not CIDR notation.
+
 - `makepath(dir)`
 
   Create all components of the specified directory.

ifconfig.c

@@ -0,0 +1,92 @@
+/* Fastinit (finit) ifconfig() implementation.
+ *
+ * Copyright (c) 2008 Claudio Matsuoka <http://helllabs.org/finit/>
+ * Copyright (C) 2009-2014  Joachim Nilsson <joachim.nilsson@westermo.se>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+extern size_t strlcpy(char *dst, const char *src, size_t siz);
+
+/**
+ * ifconfig - Basic ifconfig like operations on an interface
+ * @ifname: Name of interface to operate on
+ * @addr:   If @up then set this optional IPv4 address
+ * @mask:   If @up and @addr, and @addr is not INADDR_ANY, then set netmask
+ * @up:     Control %IFF_UP flag on interface
+ *
+ * Returns:
+ * POSIX OK(0) on success, or non-zero on error.
+ */
+int ifconfig(char *ifname, char *addr, char *mask, int up)
+{
+	int sd, ret = -1;
+	struct ifreq ifr;
+	struct sockaddr_in *sin = (struct sockaddr_in *)&ifr.ifr_addr;
+
+	if ((sd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0)
+		return -1;
+
+	memset(&ifr, 0, sizeof (ifr));
+	strlcpy(ifr.ifr_name, ifname, IFNAMSIZ);
+	ifr.ifr_addr.sa_family = AF_INET;
+
+	if (up) {
+		if (addr) {
+			if (inet_pton(AF_INET, addr, &sin->sin_addr) == 1)
+				ret = ioctl(sd, SIOCSIFADDR, &ifr);
+		}
+
+		/* Non-zero IP address */
+		if (mask && strcmp(addr, "0.0.0.0")) {
+			if (inet_pton(AF_INET, mask, &sin->sin_addr) == -1)
+				ret = ioctl(sd, SIOCSIFNETMASK, &ifr);
+		}
+	}
+
+	if (!ioctl(sd, SIOCGIFFLAGS, &ifr)) {
+		if (up)
+			ifr.ifr_flags |=  IFF_UP;
+		else
+			ifr.ifr_flags &= ~IFF_UP;
+
+		ret = ioctl(sd, SIOCSIFFLAGS, &ifr);
+	}
+
+	close(sd);
+
+	return ret;
+}
+
+/**
+ * Local Variables:
+ *  version-control: t
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */

lite.h

@@ -45,6 +45,8 @@ int     movefile   (char *src, char *dst);
 int     fcopyfile  (FILE *src, FILE *dst);
 size_t  fsendfile  (FILE *src, FILE *dst, size_t len);
 
+int     ifconfig   (char *ifname, char *addr, char *mask, int up);
+
 int     mkpath     (char *dir, mode_t mode);
 int     makepath   (char *dir);