X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=networking%2Fifplugd.c;h=9bc1a075f51bcfeb201ddc4e29a791252e4d622f;hb=ed4393bdc7a4d3b1b59293a3393eb1d6953bac99;hp=ac6607c9155a6b9740a632cb592473a665f76927;hpb=f422a722bb7c0b39a086255380c87eb4ba7af45b;p=oweals%2Fbusybox.git

diff --git a/networking/ifplugd.c b/networking/ifplugd.c
index ac6607c91..9bc1a075f 100644
--- a/networking/ifplugd.c
+++ b/networking/ifplugd.c
@@ -1,18 +1,65 @@
 /* vi: set sw=4 ts=4: */
 /*
- * ifplugd for busybox
+ * ifplugd for busybox, based on ifplugd 0.28 (written by Lennart Poettering).
  *
  * Copyright (C) 2009 Maksym Kryzhanovskyy <xmaks@email.cz>
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
+//config:config IFPLUGD
+//config:	bool "ifplugd (9.9 kb)"
+//config:	default y
+//config:	select PLATFORM_LINUX
+//config:	help
+//config:	Network interface plug detection daemon.
+
+//applet:IF_IFPLUGD(APPLET(ifplugd, BB_DIR_USR_SBIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_IFPLUGD) += ifplugd.o
+
+//usage:#define ifplugd_trivial_usage
+//usage:       "[OPTIONS]"
+//usage:#define ifplugd_full_usage "\n\n"
+//usage:       "Network interface plug detection daemon\n"
+//usage:     "\n	-n		Don't daemonize"
+//usage:     "\n	-s		Don't log to syslog"
+//usage:     "\n	-i IFACE	Interface"
+//usage:     "\n	-f/-F		Treat link detection error as link down/link up"
+//usage:     "\n			(otherwise exit on error)"
+//usage:     "\n	-a		Don't up interface at each link probe"
+//usage:     "\n	-M		Monitor creation/destruction of interface"
+//usage:     "\n			(otherwise it must exist)"
+//usage:     "\n	-r PROG		Script to run"
+//usage:     "\n	-x ARG		Extra argument for script"
+//usage:     "\n	-I		Don't exit on nonzero exit code from script"
+//usage:     "\n	-p		Don't run \"up\" script on startup"
+//usage:     "\n	-q		Don't run \"down\" script on exit"
+//usage:     "\n	-l		Always run script on startup"
+//usage:     "\n	-t SECS		Poll time in seconds"
+//usage:     "\n	-u SECS		Delay before running script after link up"
+//usage:     "\n	-d SECS		Delay after link down"
+//usage:     "\n	-m MODE		API mode (mii, priv, ethtool, wlan, iff, auto)"
+//usage:     "\n	-k		Kill running daemon"
+
 #include "libbb.h"
 
 #include "fix_u32.h"
 #include <linux/if.h>
 #include <linux/mii.h>
 #include <linux/ethtool.h>
-#include <net/ethernet.h>
+#ifdef HAVE_NET_ETHERNET_H
+/* musl breakage:
+ * In file included from /usr/include/net/ethernet.h:10,
+ *                  from networking/ifplugd.c:41:
+ * /usr/include/netinet/if_ether.h:96: error: redefinition of 'struct ethhdr'
+ *
+ * Build succeeds without it on musl. Commented it out.
+ * If on your system you need it, consider removing <linux/ethtool.h>
+ * and copy-pasting its definitions here (<linux/ethtool.h> is what pulls in
+ * conflicting definition of struct ethhdr on musl).
+ */
+/* # include <net/ethernet.h> */
+#endif
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
 #include <linux/sockios.h>
@@ -21,8 +68,16 @@
 #define __user
 #include <linux/wireless.h>
 
+#ifndef ETH_ALEN
+# define ETH_ALEN  6
+#endif
+
 /*
-TODO: describe compat status here.
+From initial port to busybox, removed most of the redundancy by
+converting implementation of a polymorphic interface to the strict
+functional style. The main role is run a script when link state
+changed, other activities like audio signal or detailed reports
+are on the script itself.
 
 One questionable point of the design is netlink usage:
 
@@ -62,20 +117,11 @@ enum {
 #endif
 };
 #if ENABLE_FEATURE_PIDFILE
-# define OPTION_STR "+ansfFi:r:It:u:d:m:pqlx:Mk"
+# define OPTION_STR "+ansfFi:r:It:+u:+d:+m:pqlx:Mk"
 #else
-# define OPTION_STR "+ansfFi:r:It:u:d:m:pqlx:M"
+# define OPTION_STR "+ansfFi:r:It:+u:+d:+m:pqlx:M"
 #endif
 
-enum { // api mode
-	API_AUTO	= 'a',
-	API_ETHTOOL	= 'e',
-	API_MII		= 'm',
-	API_PRIVATE	= 'p',
-	API_WLAN	= 'w',
-	API_IFF		= 'i',
-};
-
 enum { // interface status
 	IFSTATUS_ERR = -1,
 	IFSTATUS_DOWN = 0,
@@ -89,7 +135,9 @@ enum { // constant fds
 
 struct globals {
 	smallint iface_last_status;
+	smallint iface_prev_status;
 	smallint iface_exists;
+	smallint api_method_num;
 
 	/* Used in getopt32, must have sizeof == sizeof(int) */
 	unsigned poll_time;
@@ -100,9 +148,6 @@ struct globals {
 	const char *api_mode;
 	const char *script_name;
 	const char *extra_arg;
-
-	smallint (*detect_link_func)(void);
-	smallint (*cached_detect_link_func)(void);
 };
 #define G (*ptr_to_globals)
 #define INIT_G() do { \
@@ -117,106 +162,7 @@ struct globals {
 } while (0)
 
 
-static int run_script(const char *action)
-{
-	char *argv[5];
-	int r;
-
-	bb_error_msg("executing '%s %s %s'", G.script_name, G.iface, action);
-
-#if 1
-
-	argv[0] = (char*) G.script_name;
-	argv[1] = (char*) G.iface;
-	argv[2] = (char*) action;
-	argv[3] = (char*) G.extra_arg;
-	argv[4] = NULL;
-
-	/* r < 0 - can't exec, 0 <= r < 1000 - exited, >1000 - killed by sig (r-1000) */
-	r = wait4pid(spawn(argv));
-
-	bb_error_msg("exit code: %d", r);
-	return (option_mask32 & FLAG_IGNORE_RETVAL) ? 0 : r;
-
-#else /* insanity */
-
-	struct fd_pair pipe_pair;
-	char buf[256];
-	int i = 0;
-
-	xpiped_pair(pipe_pair);
-
-	pid = vfork();
-	if (pid < 0) {
-		bb_perror_msg("fork");
-		return -1;
-	}
-
-	/* child */
-	if (pid == 0) {
-		xmove_fd(pipe_pair.wr, 1);
-		xdup2(1, 2);
-		if (pipe_pair.rd > 2)
-			close(pipe_pair.rd);
-
-		// umask(0022); // Set up a sane umask
-
-		execlp(G.script_name, G.script_name, G.iface, action, G.extra_arg, NULL);
-		_exit(EXIT_FAILURE);
-	}
-
-	/* parent */
-	close(pipe_pair.wr);
-
-	while (1) {
-		if (bb_got_signal && bb_got_signal != SIGCHLD) {
-			bb_error_msg("killing child");
-			kill(pid, SIGTERM);
-			bb_got_signal = 0;
-			break;
-		}
-
-		r = read(pipe_pair.rd, &buf[i], 1);
-
-		if (buf[i] == '\n' || i == sizeof(buf)-2 || r != 1) {
-			if (r == 1 && buf[i] != '\n')
-				i++;
-
-			buf[i] = '\0';
-
-			if (i > 0)
-				bb_error_msg("client: %s", buf);
-
-			i = 0;
-		} else {
-			i++;
-		}
-
-		if (r != 1)
-			break;
-	}
-
-	close(pipe_pair.rd);
-
-	wait(&r);
-
-	if (!WIFEXITED(r) || WEXITSTATUS(r) != 0) {
-		bb_error_msg("program execution failed, return value is %i",
-			WEXITSTATUS(r));
-		return option_mask32 & FLAG_IGNORE_RETVAL ? 0 : WEXITSTATUS(r);
-	}
-	bb_error_msg("program executed successfully");
-	return 0;
-#endif
-}
-
-static int network_ioctl(int request, void* data, const char *errmsg)
-{
-	int r = ioctl(ioctl_fd, request, data);
-	if (r < 0 && errmsg)
-		bb_perror_msg(errmsg);
-	return r;
-}
+/* Utility routines */
 
 static void set_ifreq_to_ifname(struct ifreq *ifreq)
 {
@@ -224,96 +170,33 @@ static void set_ifreq_to_ifname(struct ifreq *ifreq)
 	strncpy_IFNAMSIZ(ifreq->ifr_name, G.iface);
 }
 
-static const char *strstatus(int status)
-{
-	if (status == IFSTATUS_ERR)
-		return "error";
-	return "down\0up" + (status * 5);
-}
-
-static void up_iface(void)
+static int network_ioctl(int request, void* data, const char *errmsg)
 {
-	struct ifreq ifrequest;
-
-	if (!G.iface_exists)
-		return;
-
-	set_ifreq_to_ifname(&ifrequest);
-	if (network_ioctl(SIOCGIFFLAGS, &ifrequest, "can't get interface flags") < 0) {
-		G.iface_exists = 0;
-		return;
-	}
-
-	if (!(ifrequest.ifr_flags & IFF_UP)) {
-		ifrequest.ifr_flags |= IFF_UP;
-		/* Let user know we mess up with interface */
-		bb_error_msg("upping interface");
-		if (network_ioctl(SIOCSIFFLAGS, &ifrequest, "can't set interface flags") < 0)
-			xfunc_die();
-	}
-
-#if 0 /* why do we mess with IP addr? It's not our business */
-	if (network_ioctl(SIOCGIFADDR, &ifrequest, "can't get interface address") < 0) {
-	} else if (ifrequest.ifr_addr.sa_family != AF_INET) {
-		bb_perror_msg("the interface is not IP-based");
-	} else {
-		((struct sockaddr_in*)(&ifrequest.ifr_addr))->sin_addr.s_addr = INADDR_ANY;
-		network_ioctl(SIOCSIFADDR, &ifrequest, "can't set interface address");
-	}
-	network_ioctl(SIOCGIFFLAGS, &ifrequest, "can't get interface flags");
-#endif
+	int r = ioctl(ioctl_fd, request, data);
+	if (r < 0 && errmsg)
+		bb_perror_msg("%s failed", errmsg);
+	return r;
 }
 
-static void maybe_up_new_iface(void)
-{
-	if (!(option_mask32 & FLAG_NO_AUTO))
-		up_iface();
-
-#if 0 /* bloat */
-	struct ifreq ifrequest;
-	struct ethtool_drvinfo driver_info;
-
-	set_ifreq_to_ifname(&ifrequest);
-	driver_info.cmd = ETHTOOL_GDRVINFO;
-	ifrequest.ifr_data = &driver_info;
-	if (network_ioctl(SIOCETHTOOL, &ifrequest, NULL) == 0) {
-		char buf[sizeof("/xx:xx:xx:xx:xx:xx")];
-
-		/* Get MAC */
-		buf[0] = '\0';
-		set_ifreq_to_ifname(&ifrequest);
-		if (network_ioctl(SIOCGIFHWADDR, &ifrequest, NULL) == 0) {
-			sprintf(buf, "/%02X:%02X:%02X:%02X:%02X:%02X",
-				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[0]),
-				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[1]),
-				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[2]),
-				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[3]),
-				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[4]),
-				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[5]));
-		}
-
-		bb_error_msg("using interface %s%s with driver<%s> (version: %s)",
-			G.iface, buf, driver_info.driver, driver_info.version);
-	}
-#endif
-
-	G.cached_detect_link_func = NULL;
-}
+/* Link detection routines and table */
 
 static smallint detect_link_mii(void)
 {
-	struct ifreq ifreq;
-	struct mii_ioctl_data *mii = (void *)&ifreq.ifr_data;
+	/* char buffer instead of bona-fide struct avoids aliasing warning */
+	char buf[sizeof(struct ifreq)];
+	struct ifreq *const ifreq = (void *)buf;
 
-	set_ifreq_to_ifname(&ifreq);
+	struct mii_ioctl_data *mii = (void *)&ifreq->ifr_data;
+
+	set_ifreq_to_ifname(ifreq);
 
-	if (network_ioctl(SIOCGMIIPHY, &ifreq, "SIOCGMIIPHY failed") < 0) {
+	if (network_ioctl(SIOCGMIIPHY, ifreq, "SIOCGMIIPHY") < 0) {
 		return IFSTATUS_ERR;
 	}
 
 	mii->reg_num = 1;
 
-	if (network_ioctl(SIOCGMIIREG, &ifreq, "SIOCGMIIREG failed") < 0) {
+	if (network_ioctl(SIOCGMIIREG, ifreq, "SIOCGMIIREG") < 0) {
 		return IFSTATUS_ERR;
 	}
 
@@ -322,18 +205,21 @@ static smallint detect_link_mii(void)
 
 static smallint detect_link_priv(void)
 {
-	struct ifreq ifreq;
-	struct mii_ioctl_data *mii = (void *)&ifreq.ifr_data;
+	/* char buffer instead of bona-fide struct avoids aliasing warning */
+	char buf[sizeof(struct ifreq)];
+	struct ifreq *const ifreq = (void *)buf;
 
-	set_ifreq_to_ifname(&ifreq);
+	struct mii_ioctl_data *mii = (void *)&ifreq->ifr_data;
 
-	if (network_ioctl(SIOCDEVPRIVATE, &ifreq, "SIOCDEVPRIVATE failed") < 0) {
+	set_ifreq_to_ifname(ifreq);
+
+	if (network_ioctl(SIOCDEVPRIVATE, ifreq, "SIOCDEVPRIVATE") < 0) {
 		return IFSTATUS_ERR;
 	}
 
 	mii->reg_num = 1;
 
-	if (network_ioctl(SIOCDEVPRIVATE+1, &ifreq, "SIOCDEVPRIVATE+1 failed") < 0) {
+	if (network_ioctl(SIOCDEVPRIVATE+1, ifreq, "SIOCDEVPRIVATE+1") < 0) {
 		return IFSTATUS_ERR;
 	}
 
@@ -350,7 +236,7 @@ static smallint detect_link_ethtool(void)
 	edata.cmd = ETHTOOL_GLINK;
 	ifreq.ifr_data = (void*) &edata;
 
-	if (network_ioctl(SIOCETHTOOL, &ifreq, "ETHTOOL_GLINK failed") < 0) {
+	if (network_ioctl(SIOCETHTOOL, &ifreq, "ETHTOOL_GLINK") < 0) {
 		return IFSTATUS_ERR;
 	}
 
@@ -363,7 +249,7 @@ static smallint detect_link_iff(void)
 
 	set_ifreq_to_ifname(&ifreq);
 
-	if (network_ioctl(SIOCGIFFLAGS, &ifreq, "SIOCGIFFLAGS failed") < 0) {
+	if (network_ioctl(SIOCGIFFLAGS, &ifreq, "SIOCGIFFLAGS") < 0) {
 		return IFSTATUS_ERR;
 	}
 
@@ -381,20 +267,21 @@ static smallint detect_link_iff(void)
 
 static smallint detect_link_wlan(void)
 {
+	int i;
 	struct iwreq iwrequest;
 	uint8_t mac[ETH_ALEN];
 
-	memset(&iwrequest, 0, sizeof(struct iwreq));
+	memset(&iwrequest, 0, sizeof(iwrequest));
 	strncpy_IFNAMSIZ(iwrequest.ifr_ifrn.ifrn_name, G.iface);
 
-	if (network_ioctl(SIOCGIWAP, &iwrequest, "SIOCGIWAP failed") < 0) {
+	if (network_ioctl(SIOCGIWAP, &iwrequest, "SIOCGIWAP") < 0) {
 		return IFSTATUS_ERR;
 	}
 
-	memcpy(mac, &(iwrequest.u.ap_addr.sa_data), ETH_ALEN);
+	memcpy(mac, &iwrequest.u.ap_addr.sa_data, ETH_ALEN);
 
 	if (mac[0] == 0xFF || mac[0] == 0x44 || mac[0] == 0x00) {
-		for (int i = 1; i < ETH_ALEN; ++i) {
+		for (i = 1; i < ETH_ALEN; ++i) {
 			if (mac[i] != mac[0])
 				return IFSTATUS_UP;
 		}
@@ -404,61 +291,135 @@ static smallint detect_link_wlan(void)
 	return IFSTATUS_UP;
 }
 
-static smallint detect_link_auto(void)
+enum { // api mode
+	API_ETHTOOL, // 'e'
+	API_MII,     // 'm'
+	API_PRIVATE, // 'p'
+	API_WLAN,    // 'w'
+	API_IFF,     // 'i'
+	API_AUTO,    // 'a'
+};
+
+static const char api_modes[] ALIGN1 = "empwia";
+
+static const struct {
+	const char *name;
+	smallint (*func)(void);
+} method_table[] = {
+	{ "SIOCETHTOOL"       , &detect_link_ethtool },
+	{ "SIOCGMIIPHY"       , &detect_link_mii     },
+	{ "SIOCDEVPRIVATE"    , &detect_link_priv    },
+	{ "wireless extension", &detect_link_wlan    },
+	{ "IFF_RUNNING"       , &detect_link_iff     },
+};
+
+static const char *strstatus(int status)
 {
-	const char *method;
-	smallint iface_status;
-	smallint sv_logmode;
-
-	if (G.cached_detect_link_func) {
-		iface_status = G.cached_detect_link_func();
-		if (iface_status != IFSTATUS_ERR)
-			return iface_status;
-	}
+	if (status == IFSTATUS_ERR)
+		return "error";
+	return "down\0up" + (status * 5);
+}
 
-	sv_logmode = logmode;
-	logmode = LOGMODE_NONE;
-
-	iface_status = detect_link_ethtool();
-	if (iface_status != IFSTATUS_ERR) {
-		G.cached_detect_link_func = detect_link_ethtool;
-		method = "SIOCETHTOOL";
- found_method:
-		logmode = sv_logmode;
-		bb_error_msg("using %s detection mode", method);
-		return iface_status;
-	}
+static int run_script(const char *action)
+{
+	char *env_PREVIOUS, *env_CURRENT;
+	char *argv[5];
+	int r;
 
-	iface_status = detect_link_mii();
-	if (iface_status != IFSTATUS_ERR) {
-		G.cached_detect_link_func = detect_link_mii;
-		method = "SIOCGMIIPHY";
-		goto found_method;
-	}
+	bb_error_msg("executing '%s %s %s'", G.script_name, G.iface, action);
 
-	iface_status = detect_link_priv();
-	if (iface_status != IFSTATUS_ERR) {
-		G.cached_detect_link_func = detect_link_priv;
-		method = "SIOCDEVPRIVATE";
-		goto found_method;
+	argv[0] = (char*) G.script_name;
+	argv[1] = (char*) G.iface;
+	argv[2] = (char*) action;
+	argv[3] = (char*) G.extra_arg;
+	argv[4] = NULL;
+
+	env_PREVIOUS = xasprintf("%s=%s", IFPLUGD_ENV_PREVIOUS, strstatus(G.iface_prev_status));
+	putenv(env_PREVIOUS);
+	env_CURRENT = xasprintf("%s=%s", IFPLUGD_ENV_CURRENT, strstatus(G.iface_last_status));
+	putenv(env_CURRENT);
+
+	/* r < 0 - can't exec, 0 <= r < 0x180 - exited, >=0x180 - killed by sig (r-0x180) */
+	r = spawn_and_wait(argv);
+
+	bb_unsetenv_and_free(env_PREVIOUS);
+	bb_unsetenv_and_free(env_CURRENT);
+
+	bb_error_msg("exit code: %d", r & 0xff);
+	return (option_mask32 & FLAG_IGNORE_RETVAL) ? 0 : r;
+}
+
+static void up_iface(void)
+{
+	struct ifreq ifrequest;
+
+	if (!G.iface_exists)
+		return;
+
+	set_ifreq_to_ifname(&ifrequest);
+	if (network_ioctl(SIOCGIFFLAGS, &ifrequest, "getting interface flags") < 0) {
+		G.iface_exists = 0;
+		return;
 	}
 
-	iface_status = detect_link_wlan();
-	if (iface_status != IFSTATUS_ERR) {
-		G.cached_detect_link_func = detect_link_wlan;
-		method = "wireless extension";
-		goto found_method;
+	if (!(ifrequest.ifr_flags & IFF_UP)) {
+		ifrequest.ifr_flags |= IFF_UP;
+		/* Let user know we mess up with interface */
+		bb_error_msg("upping interface");
+		if (network_ioctl(SIOCSIFFLAGS, &ifrequest, "setting interface flags") < 0) {
+			if (errno != ENODEV)
+				xfunc_die();
+			G.iface_exists = 0;
+			return;
+		}
 	}
 
-	iface_status = detect_link_iff();
-	if (iface_status != IFSTATUS_ERR) {
-		G.cached_detect_link_func = detect_link_iff;
-		method = "IFF_RUNNING";
-		goto found_method;
+#if 0 /* why do we mess with IP addr? It's not our business */
+	if (network_ioctl(SIOCGIFADDR, &ifrequest, "can't get interface address") < 0) {
+	} else if (ifrequest.ifr_addr.sa_family != AF_INET) {
+		bb_perror_msg("the interface is not IP-based");
+	} else {
+		((struct sockaddr_in*)(&ifrequest.ifr_addr))->sin_addr.s_addr = INADDR_ANY;
+		network_ioctl(SIOCSIFADDR, &ifrequest, "can't set interface address");
 	}
+	network_ioctl(SIOCGIFFLAGS, &ifrequest, "can't get interface flags");
+#endif
+}
+
+static void maybe_up_new_iface(void)
+{
+	if (!(option_mask32 & FLAG_NO_AUTO))
+		up_iface();
+
+#if 0 /* bloat */
+	struct ifreq ifrequest;
+	struct ethtool_drvinfo driver_info;
+
+	set_ifreq_to_ifname(&ifrequest);
+	driver_info.cmd = ETHTOOL_GDRVINFO;
+	ifrequest.ifr_data = &driver_info;
+	if (network_ioctl(SIOCETHTOOL, &ifrequest, NULL) == 0) {
+		char buf[sizeof("/xx:xx:xx:xx:xx:xx")];
+
+		/* Get MAC */
+		buf[0] = '\0';
+		set_ifreq_to_ifname(&ifrequest);
+		if (network_ioctl(SIOCGIFHWADDR, &ifrequest, NULL) == 0) {
+			sprintf(buf, "/%02X:%02X:%02X:%02X:%02X:%02X",
+				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[0]),
+				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[1]),
+				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[2]),
+				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[3]),
+				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[4]),
+				(uint8_t)(ifrequest.ifr_hwaddr.sa_data[5]));
+		}
 
-	logmode = sv_logmode;
-	return iface_status; /* IFSTATUS_ERR */
+		bb_error_msg("using interface %s%s with driver<%s> (version: %s)",
+			G.iface, buf, driver_info.driver, driver_info.version);
+	}
+#endif
+	if (G.api_mode[0] == 'a')
+		G.api_method_num = API_AUTO;
 }
 
 static smallint detect_link(void)
@@ -475,24 +436,36 @@ static smallint detect_link(void)
 	if (!(option_mask32 & FLAG_NO_AUTO))
 		up_iface();
 
-	status = G.detect_link_func();
+	if (G.api_method_num == API_AUTO) {
+		int i;
+		smallint sv_logmode;
+
+		sv_logmode = logmode;
+		for (i = 0; i < ARRAY_SIZE(method_table); i++) {
+			logmode = LOGMODE_NONE;
+			status = method_table[i].func();
+			logmode = sv_logmode;
+			if (status != IFSTATUS_ERR) {
+				G.api_method_num = i;
+				bb_error_msg("using %s detection mode", method_table[i].name);
+				break;
+			}
+		}
+	} else {
+		status = method_table[G.api_method_num].func();
+	}
+
 	if (status == IFSTATUS_ERR) {
 		if (option_mask32 & FLAG_IGNORE_FAIL)
 			status = IFSTATUS_DOWN;
-		if (option_mask32 & FLAG_IGNORE_FAIL_POSITIVE)
+		else if (option_mask32 & FLAG_IGNORE_FAIL_POSITIVE)
 			status = IFSTATUS_UP;
-	}
-
-	if (status == IFSTATUS_ERR
-	 && G.detect_link_func == detect_link_auto
-	) {
-		bb_error_msg("failed to detect link status");
+		else if (G.api_mode[0] == 'a')
+			bb_error_msg("can't detect link status");
 	}
 
 	if (status != G.iface_last_status) {
-//TODO: is it safe to repeatedly do this?
-		setenv(IFPLUGD_ENV_PREVIOUS, strstatus(G.iface_last_status), 1);
-		setenv(IFPLUGD_ENV_CURRENT, strstatus(status), 1);
+		G.iface_prev_status = G.iface_last_status;
 		G.iface_last_status = status;
 	}
 
@@ -501,57 +474,56 @@ static smallint detect_link(void)
 
 static NOINLINE int check_existence_through_netlink(void)
 {
-	char replybuf[1024];
+	int iface_len;
+	/* Buffer was 1K, but on linux-3.9.9 it was reported to be too small.
+	 * netlink.h: "limit to 8K to avoid MSG_TRUNC when PAGE_SIZE is very large".
+	 * Note: on error returns (-1) we exit, no need to free replybuf.
+	 */
+	enum { BUF_SIZE = 8 * 1024 };
+	char *replybuf = xmalloc(BUF_SIZE);
 
+	iface_len = strlen(G.iface);
 	while (1) {
 		struct nlmsghdr *mhdr;
 		ssize_t bytes;
 
-		bytes = recv(netlink_fd, &replybuf, sizeof(replybuf), MSG_DONTWAIT);
+		bytes = recv(netlink_fd, replybuf, BUF_SIZE, MSG_DONTWAIT);
 		if (bytes < 0) {
 			if (errno == EAGAIN)
-				return G.iface_exists;
+				goto ret;
 			if (errno == EINTR)
 				continue;
-
 			bb_perror_msg("netlink: recv");
 			return -1;
 		}
 
 		mhdr = (struct nlmsghdr*)replybuf;
 		while (bytes > 0) {
-			if (!NLMSG_OK(mhdr, bytes)
-			 || bytes < sizeof(struct nlmsghdr)
-			 || bytes < mhdr->nlmsg_len
-			) {
+			if (!NLMSG_OK(mhdr, bytes)) {
 				bb_error_msg("netlink packet too small or truncated");
 				return -1;
 			}
 
 			if (mhdr->nlmsg_type == RTM_NEWLINK || mhdr->nlmsg_type == RTM_DELLINK) {
 				struct rtattr *attr;
-				struct ifinfomsg *imsg;
 				int attr_len;
 
-				imsg = NLMSG_DATA(mhdr);
-
 				if (mhdr->nlmsg_len < NLMSG_LENGTH(sizeof(struct ifinfomsg))) {
 					bb_error_msg("netlink packet too small or truncated");
 					return -1;
 				}
 
-				attr = (struct rtattr*)((char*)imsg + NLMSG_ALIGN(sizeof(struct ifinfomsg)));
-				attr_len = NLMSG_PAYLOAD(mhdr, sizeof(struct ifinfomsg));
+				attr = IFLA_RTA(NLMSG_DATA(mhdr));
+				attr_len = IFLA_PAYLOAD(mhdr);
 
 				while (RTA_OK(attr, attr_len)) {
 					if (attr->rta_type == IFLA_IFNAME) {
-						char ifname[IFNAMSIZ + 1];
 						int len = RTA_PAYLOAD(attr);
-
 						if (len > IFNAMSIZ)
 							len = IFNAMSIZ;
-						memcpy(ifname, RTA_DATA(attr), len);
-						if (strcmp(G.iface, ifname) == 0) {
+						if (iface_len <= len
+						 && strncmp(G.iface, RTA_DATA(attr), len) == 0
+						) {
 							G.iface_exists = (mhdr->nlmsg_type == RTM_NEWLINK);
 						}
 					}
@@ -563,26 +535,11 @@ static NOINLINE int check_existence_through_netlink(void)
 		}
 	}
 
+ ret:
+	free(replybuf);
 	return G.iface_exists;
 }
 
-static NOINLINE int netlink_open(void)
-{
-	int fd;
-	struct sockaddr_nl addr;
-
-	fd = xsocket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
-
-	memset(&addr, 0, sizeof(addr));
-	addr.nl_family = AF_NETLINK;
-	addr.nl_groups = RTMGRP_LINK;
-	addr.nl_pid = getpid();
-
-	xbind(fd, (struct sockaddr*)&addr, sizeof(addr));
-
-	return fd;
-}
-
 #if ENABLE_FEATURE_PIDFILE
 static NOINLINE pid_t read_pid(const char *filename)
 {
@@ -607,6 +564,7 @@ int ifplugd_main(int argc UNUSED_PARAM, char **argv)
 	const char *iface_status_str;
 	struct pollfd netlink_pollfd[1];
 	unsigned opts;
+	const char *api_mode_found;
 #if ENABLE_FEATURE_PIDFILE
 	char *pidfile_name;
 	pid_t pid_from_pidfile;
@@ -614,7 +572,6 @@ int ifplugd_main(int argc UNUSED_PARAM, char **argv)
 
 	INIT_G();
 
-	opt_complementary = "t+:u+:d+";
 	opts = getopt32(argv, OPTION_STR,
 		&G.iface, &G.script_name, &G.poll_time, &G.delay_up,
 		&G.delay_down, &G.api_mode, &G.extra_arg);
@@ -623,12 +580,13 @@ int ifplugd_main(int argc UNUSED_PARAM, char **argv)
 	applet_name = xasprintf("ifplugd(%s)", G.iface);
 
 #if ENABLE_FEATURE_PIDFILE
-	pidfile_name = xasprintf(_PATH_VARRUN"ifplugd.%s.pid", G.iface);
+	pidfile_name = xasprintf(CONFIG_PID_FILE_PATH "/ifplugd.%s.pid", G.iface);
 	pid_from_pidfile = read_pid(pidfile_name);
 
 	if (opts & FLAG_KILL) {
 		if (pid_from_pidfile > 0)
-			kill(pid_from_pidfile, SIGQUIT);
+			/* Upstream tool use SIGINT for -k */
+			kill(pid_from_pidfile, SIGINT);
 		return EXIT_SUCCESS;
 	}
 
@@ -636,35 +594,26 @@ int ifplugd_main(int argc UNUSED_PARAM, char **argv)
 		bb_error_msg_and_die("daemon already running");
 #endif
 
-	switch (G.api_mode[0]) {
-	case API_AUTO:
-		G.detect_link_func = detect_link_auto;
-		break;
-	case API_ETHTOOL:
-		G.detect_link_func = detect_link_ethtool;
-		break;
-	case API_MII:
-		G.detect_link_func = detect_link_mii;
-		break;
-	case API_PRIVATE:
-		G.detect_link_func = detect_link_priv;
-		break;
-	case API_WLAN:
-		G.detect_link_func = detect_link_wlan;
-		break;
-	case API_IFF:
-		G.detect_link_func = detect_link_iff;
-		break;
-	default:
+	api_mode_found = strchr(api_modes, G.api_mode[0]);
+	if (!api_mode_found)
 		bb_error_msg_and_die("unknown API mode '%s'", G.api_mode);
-	}
+	G.api_method_num = api_mode_found - api_modes;
 
 	if (!(opts & FLAG_NO_DAEMON))
 		bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
 
 	xmove_fd(xsocket(AF_INET, SOCK_DGRAM, 0), ioctl_fd);
 	if (opts & FLAG_MONITOR) {
-		xmove_fd(netlink_open(), netlink_fd);
+		struct sockaddr_nl addr;
+		int fd = xsocket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
+
+		memset(&addr, 0, sizeof(addr));
+		addr.nl_family = AF_NETLINK;
+		addr.nl_groups = RTMGRP_LINK;
+		addr.nl_pid = getpid();
+
+		xbind(fd, (struct sockaddr*)&addr, sizeof(addr));
+		xmove_fd(fd, netlink_fd);
 	}
 
 	write_pidfile(pidfile_name);
@@ -726,7 +675,6 @@ int ifplugd_main(int argc UNUSED_PARAM, char **argv)
 	delay_time = 0;
 	while (1) {
 		int iface_status_old;
-		int iface_exists_old;
 
 		switch (bb_got_signal) {
 		case SIGINT:
@@ -752,12 +700,12 @@ int ifplugd_main(int argc UNUSED_PARAM, char **argv)
 			goto exiting;
 		}
 
-		iface_status_old = iface_status;
-		iface_exists_old = G.iface_exists;
-
 		if ((opts & FLAG_MONITOR)
 		 && (netlink_pollfd[0].revents & POLLIN)
 		) {
+			int iface_exists_old;
+
+			iface_exists_old = G.iface_exists;
 			G.iface_exists = check_existence_through_netlink();
 			if (G.iface_exists < 0) /* error */
 				goto exiting;
@@ -770,6 +718,7 @@ int ifplugd_main(int argc UNUSED_PARAM, char **argv)
 		}
 
 		/* note: if !G.iface_exists, returns DOWN */
+		iface_status_old = iface_status;
 		iface_status = detect_link();
 		if (iface_status == IFSTATUS_ERR) {
 			if (!(opts & FLAG_MONITOR))
@@ -783,7 +732,7 @@ int ifplugd_main(int argc UNUSED_PARAM, char **argv)
 
 			if (delay_time) {
 				/* link restored its old status before
-				 * we run script. don't run the script: */
+				 * we ran script. don't run the script: */
 				delay_time = 0;
 			} else {
 				delay_time = monotonic_sec();
@@ -791,15 +740,19 @@ int ifplugd_main(int argc UNUSED_PARAM, char **argv)
 					delay_time += G.delay_up;
 				if (iface_status == IFSTATUS_DOWN)
 					delay_time += G.delay_down;
-				if (delay_time == 0)
-					delay_time++;
+#if 0  /* if you are back in 1970... */
+				if (delay_time == 0) {
+					sleep(1);
+					delay_time = 1;
+				}
+#endif
 			}
 		}
 
 		if (delay_time && (int)(monotonic_sec() - delay_time) >= 0) {
-			delay_time = 0;
 			if (run_script(iface_status_str) != 0)
 				goto exiting;
+			delay_time = 0;
 		}
 	} /* while (1) */