Add libifc, a library implementing core functionality that exists in ifconfig(8) today.

libifc (pronounced lib-ifconfig) aims to be a light abstraction layer between
programs and the kernel APIs for managing the network configuration.
This should hopefully make programs easier to maintain, and reduce code
duplication.

Work will begin on making ifconfig(8) use this library in the near future.

This code is still evolving. The interface should not be considered stable until
it is announced as such.

Submitted By: Marie Helene Kvello-Aune <marieheleneka@gmail.com>
Reviewed By: kp
Differential Revision: https://reviews.freebsd.org/D7529

share/examples/libifc/Makefile

@@ -0,0 +1,9 @@
+# $FreeBSD$
+
+default:
+	$(CC) -Wall -fPIC -lifc -g -o example_setdescription setdescription.c
+	$(CC) -Wall -fPIC -lifc -g -o example_setmtu setmtu.c
+	$(CC) -Wall -fPIC -lifc -g -o example_ifdestroy ifdestroy.c
+	$(CC) -Wall -fPIC -lifc -g -o example_ifcreate ifcreate.c
+clean:
+	rm -f example_*

share/examples/libifc/ifcreate.c

@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2016, Marie Helene Kvello-Aune
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * thislist of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation and/or
+ * other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libifc.h>
+
+
+int main(int argc, char *argv[])
+{
+	if (argc != 2) {
+		errx(EINVAL, "Invalid number of arguments."
+		    " Only one argument is accepted, and it should be the name"
+		    " of the interface to be created.");
+	}
+
+	char *ifname, *ifactualname;
+
+	/* We have a static number of arguments. Therefore we can do it simple. */
+	ifname = strdup(argv[1]);
+
+	printf("Requested interface name: %s\n", ifname);
+
+	libifc_handle_t *lifh = libifc_open();
+	if (libifc_create_interface(lifh, ifname, &ifactualname) == 0) {
+		printf("Successfully created interface '%s'\n", ifactualname);
+		libifc_close(lifh);
+		lifh = NULL;
+		free(ifname);
+		free(ifactualname);
+		return (0);
+	} else {
+		switch (libifc_err_errtype(lifh)) {
+		case SOCKET:
+			warnx("couldn't create socket. This shouldn't happen.\n");
+			break;
+		case IOCTL:
+			if (libifc_err_ioctlreq(lifh) == SIOCIFCREATE2) {
+				warnx(
+					"Failed to create interface (SIOCIFCREATE2)\n");
+			}
+			break;
+		default:
+			warnx(
+				"This is a thorough example accommodating for temporary"
+				" 'not implemented yet' errors. That's likely what happened"
+				" now. If not, your guess is as good as mine. ;)"
+				" Error code: %d\n", libifc_err_errno(
+					lifh));
+			break;
+		}
+
+		libifc_close(lifh);
+		lifh = NULL;
+		free(ifname);
+		free(ifactualname);
+		return (-1);
+	}
+}

share/examples/libifc/ifdestroy.c

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2016, Marie Helene Kvello-Aune
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * thislist of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation and/or
+ * other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libifc.h>
+
+
+int main(int argc, char *argv[])
+{
+	if (argc != 2) {
+		errx(EINVAL, "Invalid number of arguments."
+		    " Only one argument is accepted, and it should be the name"
+		    " of the interface to be destroyed.");
+	}
+
+	char *ifname;
+
+	/* We have a static number of arguments. Therefore we can do it simple. */
+	ifname = strdup(argv[1]);
+
+	printf("Interface name: %s\n", ifname);
+
+	libifc_handle_t *lifh = libifc_open();
+	if (libifc_destroy_interface(lifh, ifname) == 0) {
+		printf("Successfully destroyed interface '%s'.", ifname);
+		libifc_close(lifh);
+		lifh = NULL;
+		free(ifname);
+		return (0);
+	} else {
+		switch (libifc_err_errtype(lifh)) {
+		case SOCKET:
+			warnx("couldn't create socket. This shouldn't happen.\n");
+			break;
+		case IOCTL:
+			if (libifc_err_ioctlreq(lifh) == SIOCIFDESTROY) {
+				warnx(
+					"Failed to destroy interface (SIOCIFDESTROY)\n");
+			}
+			break;
+		default:
+			warnx(
+				"Should basically never end up here in this example.\n");
+			break;
+		}
+
+		libifc_close(lifh);
+		lifh = NULL;
+		free(ifname);
+		return (-1);
+	}
+}

share/examples/libifc/setdescription.c

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2016, Marie Helene Kvello-Aune
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * thislist of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation and/or
+ * other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libifc.h>
+
+
+int main(int argc, char *argv[])
+{
+	if (argc != 3) {
+		errx(EINVAL, "Invalid number of arguments."
+		    " First argument should be interface name, second argument"
+		    " should be the description to set.");
+	}
+
+	char *ifname, *ifdescr, *curdescr;
+	/* We have a static number of arguments. Therefore we can do it simple. */
+	ifname = strdup(argv[1]);
+	ifdescr = strdup(argv[2]);
+	curdescr = NULL;
+
+	printf("Interface name: %s\n", ifname);
+
+	libifc_handle_t *lifh = libifc_open();
+	if (libifc_get_description(lifh, ifname, &curdescr) == 0) {
+		printf("Old description: %s\n", curdescr);
+	}
+
+	printf("New description: %s\n\n", ifdescr);
+
+	if (libifc_set_description(lifh, ifname, ifdescr) == 0) {
+		printf("New description successfully set.\n");
+	} else {
+		switch (libifc_err_errtype(lifh)) {
+		case SOCKET:
+			err(libifc_err_errno(lifh), "Socket error");
+			break;
+		case IOCTL:
+			err(libifc_err_errno(
+				    lifh), "IOCTL(%lu) error",
+			    libifc_err_ioctlreq(lifh));
+			break;
+		case OTHER:
+			err(libifc_err_errno(lifh), "Other error");
+			break;
+		}
+	}
+
+	free(ifname);
+	free(ifdescr);
+	free(curdescr);
+	ifname = NULL;
+	ifdescr = NULL;
+	curdescr = NULL;
+
+	libifc_close(lifh);
+	return (0);
+}

share/examples/libifc/setmtu.c

@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2016, Marie Helene Kvello-Aune
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * thislist of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation and/or
+ * other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libifc.h>
+
+
+int main(int argc, char *argv[])
+{
+	if (argc != 3) {
+		errx(EINVAL, "Invalid number of arguments."
+		    " First argument should be interface name, second argument"
+		    " should be the MTU to set.");
+	}
+
+	char *ifname, *ptr;
+	int mtu;
+
+	/* We have a static number of arguments. Therefore we can do it simple. */
+	ifname = strdup(argv[1]);
+	mtu = (int)strtol(argv[2], &ptr, 10);
+
+	printf("Interface name: %s\n", ifname);
+	printf("New MTU: %d", mtu);
+
+	libifc_handle_t *lifh = libifc_open();
+	if (libifc_set_mtu(lifh, ifname, mtu) == 0) {
+		printf("Successfully changed MTU of %s to %d\n", ifname, mtu);
+		libifc_close(lifh);
+		lifh = NULL;
+		free(ifname);
+		return (0);
+	} else {
+		switch (libifc_err_errtype(lifh)) {
+		case SOCKET:
+			warnx("couldn't create socket. This shouldn't happen.\n");
+			break;
+		case IOCTL:
+			if (libifc_err_ioctlreq(lifh) == SIOCSIFMTU) {
+				warnx("Failed to set MTU (SIOCSIFMTU)\n");
+			} else {
+				warnx(
+					"Failed to set MTU due to error in unexpected ioctl() call %lu. Error code: %i.\n",
+					libifc_err_ioctlreq(lifh),
+					libifc_err_errno(lifh));
+			}
+			break;
+		default:
+			warnx(
+				"Should basically never end up here in this example.\n");
+			break;
+		}
+
+		libifc_close(lifh);
+		lifh = NULL;
+		free(ifname);
+		return (-1);
+	}
+}