Separate event state gathering from action dispatch in main epoll loop.

This is the first step towards using coroutines.

src/arp.c

@@ -62,52 +62,7 @@ int arp_probe_max = 2000;          // maximum delay until repeated probe (ms)
 #define RATE_LIMIT_INTERVAL 60000  // delay between successive attempts
 #define DEFEND_INTERVAL 10000      // minimum interval between defensive ARPs
 
-typedef enum {
-    AS_NONE = 0,        // Nothing to react to wrt ARP
-    AS_COLLISION_CHECK, // Checking to see if another host has our IP before
-                        // accepting a new lease.
-    AS_GW_CHECK,        // Seeing if the default GW still exists on the local
-                        // segment after the hardware link was lost.
-    AS_GW_QUERY,        // Finding the default GW MAC address.
-    AS_DEFENSE,         // Defending our IP address (RFC5227)
-    AS_MAX,
-} arp_state_t;
-
-typedef enum {
-    ASEND_COLLISION_CHECK,
-    ASEND_GW_PING,
-    ASEND_ANNOUNCE,
-    ASEND_MAX,
-} arp_send_t;
-
-struct arp_stats {
-    long long ts;
-    int count;
-};
-
-struct arp_data {
-    struct dhcpmsg dhcp_packet;   // Used only for AS_COLLISION_CHECK
-    struct arpMsg reply;
-    struct arp_stats send_stats[ASEND_MAX];
-    long long wake_ts[AS_MAX];
-    long long last_conflict_ts;   // TS of the last conflicting ARP seen.
-    long long arp_check_start_ts; // TS of when we started the
-                                  // AS_COLLISION_CHECK state.
-    size_t reply_offset;
-    arp_state_t state;
-    unsigned int total_conflicts; // Total number of address conflicts on
-                                  // the interface.  Never decreases.
-    int gw_check_initpings;       // Initial count of ASEND_GW_PING when
-                                  // AS_GW_CHECK was entered.
-    uint16_t probe_wait_time;     // Time to wait for a COLLISION_CHECK reply
-                                  // (in ms?).
-    bool using_bpf:1;             // Is a BPF installed on the ARP socket?
-    bool relentless_def:1;        // Don't give up defense no matter what.
-    bool router_replied:1;
-    bool server_replied:1;
-};
-
-static struct arp_data garp = {
+struct arp_data garp = {
     .state = AS_NONE,
     .wake_ts = { -1, -1, -1, -1, -1 },
     .send_stats = {{0,0},{0,0},{0,0}},
@@ -237,7 +192,7 @@ void arp_close_fd(struct client_state_t cs[static 1])
         garp.wake_ts[i] = -1;
 }
 
-static void arp_reopen_fd(struct client_state_t cs[static 1])
+void arp_reopen_fd(struct client_state_t cs[static 1])
 {
     arp_state_t prev_state = garp.state;
     arp_min_close_fd(cs);
@@ -406,7 +361,7 @@ static int arp_get_gw_hwaddr(struct client_state_t cs[static 1])
     return 0;
 }
 
-static void arp_failed(struct client_state_t cs[static 1])
+void arp_failed(struct client_state_t cs[static 1])
 {
     log_line("%s: arp: Offered address is in use.  Declining.",
              client_config.interface);
@@ -427,7 +382,7 @@ static void arp_failed(struct client_state_t cs[static 1])
                      0 : RATE_LIMIT_INTERVAL);
 }
 
-static void arp_gw_failed(struct client_state_t cs[static 1])
+void arp_gw_failed(struct client_state_t cs[static 1])
 {
     garp.wake_ts[AS_GW_CHECK] = -1;
     reinit_selecting(cs, 0);
@@ -794,31 +749,31 @@ static const arp_state_fn_t arp_states[] = {
     { arp_do_invalid, 0 }, // AS_MAX
 };
 
-void handle_arp_response(struct client_state_t cs[static 1])
+void arp_packet_action(struct client_state_t cs[static 1])
+{
+    if (arp_states[garp.state].packet_fn)
+        arp_states[garp.state].packet_fn(cs);
+    arp_reply_clear();
+}
+
+int arp_packet_get(struct client_state_t cs[static 1])
 {
     ssize_t r = 0;
     if (garp.reply_offset < sizeof garp.reply) {
         r = safe_read(cs->arpFd, (char *)&garp.reply + garp.reply_offset,
                       sizeof garp.reply - garp.reply_offset);
+        if (r == 0)
+            return ARPR_CLOSED;
         if (r < 0) {
             log_error("%s: (%s) ARP response read failed: %s",
                       client_config.interface, __func__, strerror(errno));
-            switch (garp.state) {
-            case AS_COLLISION_CHECK: arp_failed(cs); break;
-            case AS_GW_CHECK: arp_gw_failed(cs); break;
-            default: arp_reopen_fd(cs); break;
-            }
-        } else
-            garp.reply_offset += (size_t)r;
-    }
-
-    if (r <= 0) {
-        handle_arp_timeout(cs, curms());
-        return;
+            return ARPR_ERROR;
+        }
+        garp.reply_offset += (size_t)r;
     }
 
     if (garp.reply_offset < ARP_MSG_SIZE)
-        return;
+        return ARPR_NONE;
 
     // Emulate the BPF filters if they are not in use.
     if (!garp.using_bpf &&
@@ -826,12 +781,9 @@ void handle_arp_response(struct client_state_t cs[static 1])
          (garp.state == AS_DEFENSE &&
           !arp_validate_bpf_defense(cs, &garp.reply)))) {
         arp_reply_clear();
-        return;
+        return ARPR_NONE;
     }
-
-    if (arp_states[garp.state].packet_fn)
-        arp_states[garp.state].packet_fn(cs);
-    arp_reply_clear();
+    return ARPR_PENDING;
 }
 
 // Perform retransmission if necessary.

src/arp.h

@@ -58,6 +58,53 @@ extern int arp_probe_num;
 extern int arp_probe_min;
 extern int arp_probe_max;
 
+typedef enum {
+    AS_NONE = 0,        // Nothing to react to wrt ARP
+    AS_COLLISION_CHECK, // Checking to see if another host has our IP before
+                        // accepting a new lease.
+    AS_GW_CHECK,        // Seeing if the default GW still exists on the local
+                        // segment after the hardware link was lost.
+    AS_GW_QUERY,        // Finding the default GW MAC address.
+    AS_DEFENSE,         // Defending our IP address (RFC5227)
+    AS_MAX,
+} arp_state_t;
+
+typedef enum {
+    ASEND_COLLISION_CHECK,
+    ASEND_GW_PING,
+    ASEND_ANNOUNCE,
+    ASEND_MAX,
+} arp_send_t;
+
+struct arp_stats {
+    long long ts;
+    int count;
+};
+
+struct arp_data {
+    struct dhcpmsg dhcp_packet;   // Used only for AS_COLLISION_CHECK
+    struct arpMsg reply;
+    struct arp_stats send_stats[ASEND_MAX];
+    long long wake_ts[AS_MAX];
+    long long last_conflict_ts;   // TS of the last conflicting ARP seen.
+    long long arp_check_start_ts; // TS of when we started the
+                                  // AS_COLLISION_CHECK state.
+    size_t reply_offset;
+    arp_state_t state;
+    unsigned int total_conflicts; // Total number of address conflicts on
+                                  // the interface.  Never decreases.
+    int gw_check_initpings;       // Initial count of ASEND_GW_PING when
+                                  // AS_GW_CHECK was entered.
+    uint16_t probe_wait_time;     // Time to wait for a COLLISION_CHECK reply
+                                  // (in ms?).
+    bool using_bpf:1;             // Is a BPF installed on the ARP socket?
+    bool relentless_def:1;        // Don't give up defense no matter what.
+    bool router_replied:1;
+    bool server_replied:1;
+};
+
+extern struct arp_data garp;
+
 void set_arp_relentless_def(bool v);
 void arp_reset_send_stats(void);
 void arp_close_fd(struct client_state_t cs[static 1]);
@@ -66,7 +113,19 @@ int arp_check(struct client_state_t cs[static 1],
 int arp_gw_check(struct client_state_t cs[static 1]);
 void arp_set_defense_mode(struct client_state_t cs[static 1]);
 void arp_success(struct client_state_t cs[static 1]);
-void handle_arp_response(struct client_state_t cs[static 1]);
+void arp_failed(struct client_state_t cs[static 1]);
+void arp_gw_failed(struct client_state_t cs[static 1]);
+void arp_reopen_fd(struct client_state_t cs[static 1]);
+
+enum {
+    ARPR_NONE = 0,
+    ARPR_ERROR,
+    ARPR_PENDING,
+    ARPR_CLOSED,
+};
+void arp_packet_action(struct client_state_t cs[static 1]);
+int arp_packet_get(struct client_state_t cs[static 1]);
+
 void handle_arp_timeout(struct client_state_t cs[static 1], long long nowts);
 long long arp_get_wake_ts(void);
 

src/coroutine.h

@@ -0,0 +1,181 @@
+/* coroutine.h
+ * 
+ * Coroutine mechanics, implemented on top of standard ANSI C. See
+ * http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html for
+ * a full discussion of the theory behind this.
+ * 
+ * To use these macros to define a coroutine, you need to write a
+ * function that looks something like this.
+ * 
+ * [Simple version using static variables (scr macros)]
+ * int ascending (void) {
+ *    static int i;
+ * 
+ *    scrBegin;
+ *    for (i=0; i<10; i++) {
+ *       scrReturn(i);
+ *    }
+ *    scrFinish(-1);
+ * }
+ * 
+ * [Re-entrant version using an explicit context structure (ccr macros)]
+ * int ascending (ccrContParam) {
+ *    ccrBeginContext;
+ *    int i;
+ *    ccrEndContext(foo);
+ *
+ *    ccrBegin(foo);
+ *    for (foo->i=0; foo->i<10; foo->i++) {
+ *       ccrReturn(foo->i);
+ *    }
+ *    ccrFinish(-1);
+ * }
+ * 
+ * In the static version, you need only surround the function body
+ * with `scrBegin' and `scrFinish', and then you can do `scrReturn'
+ * within the function and on the next call control will resume
+ * just after the scrReturn statement. Any local variables you need
+ * to be persistent across an `scrReturn' must be declared static.
+ * 
+ * In the re-entrant version, you need to declare your persistent
+ * variables between `ccrBeginContext' and `ccrEndContext'. These
+ * will be members of a structure whose name you specify in the
+ * parameter to `ccrEndContext'.
+ * 
+ * The re-entrant macros will malloc() the state structure on first
+ * call, and free() it when `ccrFinish' is reached. If you want to
+ * abort in the middle, you can use `ccrStop' to free the state
+ * structure immediately (equivalent to an explicit return() in a
+ * caller-type routine).
+ * 
+ * A coroutine returning void type may call `ccrReturnV',
+ * `ccrFinishV' and `ccrStopV', or `scrReturnV', to avoid having to
+ * specify an empty parameter to the ordinary return macros.
+ * 
+ * Ground rules:
+ *  - never put `ccrReturn' or `scrReturn' within an explicit `switch'.
+ *  - never put two `ccrReturn' or `scrReturn' statements on the same
+ *    source line.
+ * 
+ * The caller of a static coroutine calls it just as if it were an
+ * ordinary function:
+ * 
+ * void main(void) {
+ *    int i;
+ *    do {
+ *       i = ascending();
+ *       printf("got number %d\n", i);
+ *    } while (i != -1);
+ * }
+ * 
+ * The caller of a re-entrant coroutine must provide a context
+ * variable:
+ * 
+ * void main(void) {
+ *    ccrContext z = 0;
+ *    do {
+ *       printf("got number %d\n", ascending (&z));
+ *    } while (z);
+ * }
+ * 
+ * Note that the context variable is set back to zero when the
+ * coroutine terminates (by crStop, or by control reaching
+ * crFinish). This can make the re-entrant coroutines more useful
+ * than the static ones, because you can tell when they have
+ * finished.
+ * 
+ * If you need to dispose of a crContext when it is non-zero (that
+ * is, if you want to stop calling a coroutine without suffering a
+ * memory leak), the caller should call `ccrAbort(ctx)' where `ctx'
+ * is the context variable.
+ * 
+ * This mechanism could have been better implemented using GNU C
+ * and its ability to store pointers to labels, but sadly this is
+ * not part of the ANSI C standard and so the mechanism is done by
+ * case statements instead. That's why you can't put a crReturn()
+ * inside a switch() statement.
+ */
+
+/*
+ * coroutine.h is copyright 1995,2000 Simon Tatham.
+ * 
+ * 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 SIMON TATHAM 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.
+ * 
+ * $Id$
+ */
+
+#ifndef COROUTINE_H
+#define COROUTINE_H
+
+#include <stdlib.h>
+
+/*
+ * `scr' macros for static coroutines.
+ */
+
+#define scrBegin         static int scrLine = 0; switch(scrLine) { case 0:;
+#define scrFinish(z)     } return (z)
+#define scrFinishV       } return
+
+#define scrReturn(z)     \
+        do {\
+            scrLine=__LINE__;\
+            return (z); case __LINE__:;\
+        } while (0)
+#define scrReturnV       \
+        do {\
+            scrLine=__LINE__;\
+            return; case __LINE__:;\
+        } while (0)
+
+/*
+ * `ccr' macros for re-entrant coroutines.
+ */
+
+#define ccrContParam     void **ccrParam
+
+#define ccrBeginContext  struct ccrContextTag { int ccrLine
+#define ccrEndContext(x) } *x = (struct ccrContextTag *)*ccrParam
+
+#define ccrBegin(x)      if(!x) {x= *ccrParam=malloc(sizeof(*x)); x->ccrLine=0;}\
+                         if (x) switch(x->ccrLine) { case 0:;
+#define ccrFinish(z)     } free(*ccrParam); *ccrParam=0; return (z)
+#define ccrFinishV       } free(*ccrParam); *ccrParam=0; return
+
+#define ccrReturn(z)     \
+        do {\
+            ((struct ccrContextTag *)*ccrParam)->ccrLine=__LINE__;\
+            return (z); case __LINE__:;\
+        } while (0)
+#define ccrReturnV       \
+        do {\
+            ((struct ccrContextTag *)*ccrParam)->ccrLine=__LINE__;\
+            return; case __LINE__:;\
+        } while (0)
+
+#define ccrStop(z)       do{ free(*ccrParam); *ccrParam=0; return (z); }while(0)
+#define ccrStopV         do{ free(*ccrParam); *ccrParam=0; return; }while(0)
+
+#define ccrContext       void *
+#define ccrAbort(ctx)    do { free (ctx); ctx = 0; } while (0)
+
+#endif /* COROUTINE_H */

src/dhcp.c

@@ -380,13 +380,14 @@ static int validate_dhcp_packet(struct client_state_t cs[static 1],
     return 1;
 }
 
-void handle_packet(struct client_state_t cs[static 1])
+int dhcp_packet_get(struct client_state_t cs[static 1],
+                    struct dhcpmsg packet[static 1],
+                    uint8_t msgtype[static 1],
+                    uint32_t srcaddr[static 1])
 {
     if (cs->listenFd < 0)
-        return;
-    struct dhcpmsg packet;
-    uint32_t srcaddr;
-    ssize_t r = get_raw_packet(cs, &packet, &srcaddr);
+        return -1;
+    ssize_t r = get_raw_packet(cs, packet, srcaddr);
     if (r < 0) {
         // Not a transient issue handled by packet collection functions.
         if (r != -2) {
@@ -395,12 +396,11 @@ void handle_packet(struct client_state_t cs[static 1])
             stop_dhcp_listen(cs);
             start_dhcp_listen(cs);
         }
-        return;
+        return -1;
     }
-    uint8_t msgtype;
-    if (!validate_dhcp_packet(cs, (size_t)r, &packet, &msgtype))
-        return;
-    packet_action(cs, &packet, msgtype, srcaddr);
+    if (!validate_dhcp_packet(cs, (size_t)r, packet, msgtype))
+        return -1;
+    return 0;
 }
 
 // Initialize a DHCP client packet that will be sent to a server

src/dhcp.h

@@ -83,7 +83,10 @@ struct udp_dhcp_packet {
 
 void start_dhcp_listen(struct client_state_t cs[static 1]);
 void stop_dhcp_listen(struct client_state_t cs[static 1]);
-void handle_packet(struct client_state_t cs[static 1]);
+int dhcp_packet_get(struct client_state_t cs[static 1],
+                    struct dhcpmsg packet[static 1],
+                    uint8_t msgtype[static 1],
+                    uint32_t srcaddr[static 1]);
 ssize_t send_discover(struct client_state_t cs[static 1]);
 ssize_t send_selecting(struct client_state_t cs[static 1]);
 ssize_t send_renew(struct client_state_t cs[static 1]);

src/ndhc.c

@@ -182,7 +182,13 @@ static void setup_signals_ndhc(void)
     epoll_add(cs.epollFd, cs.signalFd);
 }
 
-static void signal_dispatch(void)
+enum {
+    SIGNAL_NONE = 0,
+    SIGNAL_RENEW,
+    SIGNAL_RELEASE
+};
+
+static int signal_dispatch(void)
 {
     struct signalfd_siginfo si;
     memset(&si, 0, sizeof si);
@@ -190,24 +196,22 @@ static void signal_dispatch(void)
     if (r < 0) {
         log_error("%s: ndhc: error reading from signalfd: %s",
                   client_config.interface, strerror(errno));
-        return;
+        return SIGNAL_NONE;
     }
     if ((size_t)r < sizeof si) {
         log_error("%s: ndhc: short read from signalfd: %zd < %zu",
                   client_config.interface, r, sizeof si);
-        return;
+        return SIGNAL_NONE;
     }
     switch (si.ssi_signo) {
-        case SIGUSR1: force_renew_action(&cs); break;
-        case SIGUSR2: force_release_action(&cs); break;
+        case SIGUSR1: return SIGNAL_RENEW;
+        case SIGUSR2: return SIGNAL_RELEASE;
         case SIGCHLD:
             suicide("ndhc-master: Subprocess terminated unexpectedly.  Exiting.");
-            break;
         case SIGTERM:
             log_line("Received SIGTERM.  Exiting gracefully.");
             exit(EXIT_SUCCESS);
-            break;
-        default: break;
+        default: return SIGNAL_NONE;
     }
 }
 
@@ -261,6 +265,7 @@ static void fail_if_state_dir_dne(void)
 #define NDHC_NUM_EP_FDS 7
 static void do_ndhc_work(void)
 {
+    struct dhcpmsg dhcp_packet;
     struct epoll_event events[NDHC_NUM_EP_FDS];
     long long nowts;
     int timeout;
@@ -284,27 +289,53 @@ static void do_ndhc_work(void)
     goto jumpstart;
 
     for (;;) {
-        int r = epoll_wait(cs.epollFd, events, NDHC_NUM_EP_FDS, timeout);
-        if (r < 0) {
+        int maxi = epoll_wait(cs.epollFd, events, NDHC_NUM_EP_FDS, timeout);
+        if (maxi < 0) {
             if (errno == EINTR)
                 continue;
             else
                 suicide("epoll_wait failed");
         }
-        for (int i = 0; i < r; ++i) {
+        for (int i = 0; i < maxi; ++i) {
             int fd = events[i].data.fd;
             if (fd == cs.signalFd) {
-                if (events[i].events & EPOLLIN)
-                    signal_dispatch();
+                if (!(events[i].events & EPOLLIN))
+                    return;
+                int sigv = signal_dispatch();
+                if (sigv == SIGNAL_RENEW)
+                    force_renew_action(&cs);
+                else if (sigv == SIGNAL_RELEASE)
+                    force_release_action(&cs);
             } else if (fd == cs.listenFd) {
-                if (events[i].events & EPOLLIN)
-                    handle_packet(&cs);
+                if (!(events[i].events & EPOLLIN))
+                    return;
+                uint32_t srcaddr;
+                uint8_t msgtype;
+                int r = dhcp_packet_get(&cs, &dhcp_packet, &msgtype, &srcaddr);
+                if (!r)
+                    packet_action(&cs, &dhcp_packet, msgtype, srcaddr);
             } else if (fd == cs.arpFd) {
-                if (events[i].events & EPOLLIN)
-                    handle_arp_response(&cs);
+                if (!(events[i].events & EPOLLIN))
+                    return;
+                int r = arp_packet_get(&cs);
+                if (r == ARPR_PENDING) {
+                    arp_packet_action(&cs);
+                } else if (r == ARPR_ERROR) {
+                    if (garp.state == AS_COLLISION_CHECK)
+                        arp_failed(&cs);
+                    else if (garp.state == AS_GW_CHECK)
+                        arp_gw_failed(&cs);
+                    else
+                        arp_reopen_fd(&cs);
+                    handle_arp_timeout(&cs, curms());
+                } else if (r == ARPR_CLOSED)
+                    handle_arp_timeout(&cs, curms());
             } else if (fd == cs.nlFd) {
-                if (events[i].events & EPOLLIN)
-                    handle_nl_message(&cs);
+                if (!(events[i].events & EPOLLIN))
+                    return;
+                int nl_event = nl_event_get(&cs);
+                if (nl_event != IFS_NONE)
+                    nl_event_react(&cs, nl_event);
             } else if (fd == ifchStream[0]) {
                 if (events[i].events & (EPOLLHUP|EPOLLERR|EPOLLRDHUP))
                     exit(EXIT_FAILURE);
@@ -312,8 +343,30 @@ static void do_ndhc_work(void)
                 if (events[i].events & (EPOLLHUP|EPOLLERR|EPOLLRDHUP))
                     exit(EXIT_FAILURE);
             } else if (fd == cs.rfkillFd && client_config.enable_rfkill) {
-                if (events[i].events & EPOLLIN)
-                    handle_rfkill_notice(&cs, client_config.rfkillIdx);
+                if (!(events[i].events & EPOLLIN))
+                    return;
+                int rfk = rfkill_get(&cs, 1, client_config.rfkillIdx);
+                if (rfk == RFK_ENABLED) {
+                    cs.rfkill_set = 1;
+                    if (cs.ifsPrevState == IFS_UP) {
+                        log_line("rfkill: radio now blocked; bringing interface down");
+                        cs.ifsPrevState = IFS_DOWN;
+                        ifnocarrier_action(&cs);
+                    } else
+                        log_line("rfkill: radio now blocked, but interface isn't up");
+                } else if (rfk == RFK_DISABLED) {
+                    cs.rfkill_set = 0;
+                    if (cs.ifsPrevState == IFS_DOWN) {
+                        log_line("rfkill: radio now unblocked; bringing interface up");
+                        cs.ifsPrevState = IFS_UP;
+                        ifup_action(&cs);
+                    } else {
+                        if (cs.ifsPrevState == IFS_SHUT)
+                            log_line("rfkill: radio now unblocked, but interface was shut down by user");
+                        else
+                            log_line("rfkill: radio now unblocked, but interface is removed");
+                    }
+                }
             } else
                 suicide("epoll_wait: unknown fd");
         }
@@ -461,7 +514,6 @@ void background(void)
 
 static void wait_for_rfkill()
 {
-    cs.rfkill_set = 1;
     struct epoll_event events[2];
     cs.rfkillFd = rfkill_open(&client_config.enable_rfkill);
     if (cs.rfkillFd < 0)
@@ -480,13 +532,20 @@ static void wait_for_rfkill()
         }
         for (int i = 0; i < r; ++i) {
             int fd = events[i].data.fd;
-            if (fd == cs.rfkillFd) {
-                if (events[i].events & EPOLLIN) {
-                    if (!rfkill_wait_for_end(&cs))
-                        goto rfkill_gone;
-                }
-            } else
+            if (fd != cs.rfkillFd)
                 suicide("epoll_wait: unknown fd");
+            if (events[i].events & EPOLLIN) {
+                int rfk = rfkill_get(&cs, 0, 0);
+                if (rfk == RFK_DISABLED) {
+                    switch (perform_ifup()) {
+                    case 1: case 0: goto rfkill_gone;
+                    case -3:
+                        log_line("rfkill: radio immediately blocked again; spurious?");
+                        break;
+                    default: suicide("failed to set the interface to up state");
+                    }
+                }
+            }
         }
     }
 rfkill_gone:

src/netlink.c

@@ -43,67 +43,81 @@
 #include "nl.h"
 #include "state.h"
 
-static void nl_process_msgs(const struct nlmsghdr *nlh, void *data)
+int nl_event_react(struct client_state_t cs[static 1], int state)
 {
-    struct ifinfomsg *ifm = NLMSG_DATA(nlh);
-    struct client_state_t *cs = data;
+    if (state == cs->ifsPrevState)
+        return -1;
 
     // If the rfkill switch is set, a lot of netlink state change
     // commands will fail outright, so just ignore events until
     // it is gone.
     if (cs->rfkill_set)
-        return;
+        return -1;
 
-    switch(nlh->nlmsg_type) {
-        case RTM_NEWLINK:
-            if (ifm->ifi_index != client_config.ifindex)
-                break;
-            // IFF_UP corresponds to ifconfig down or ifconfig up.
-            if (ifm->ifi_flags & IFF_UP) {
-                // IFF_RUNNING is the hardware carrier.
-                if (ifm->ifi_flags & IFF_RUNNING) {
-                    if (cs->ifsPrevState != IFS_UP) {
-                        cs->ifsPrevState = IFS_UP;
-                        ifup_action(cs);
-                    }
-                } else if (cs->ifsPrevState != IFS_DOWN) {
-                    // Interface configured, but no hardware carrier.
-                    cs->ifsPrevState = IFS_DOWN;
-                    ifnocarrier_action(cs);
-                }
-            } else if (cs->ifsPrevState != IFS_SHUT) {
-                // User shut down the interface.
-                cs->ifsPrevState = IFS_SHUT;
-                ifdown_action(cs);
-            }
-            break;
-        case RTM_DELLINK:
-            if (ifm->ifi_index != client_config.ifindex)
-                break;
-            if (cs->ifsPrevState != IFS_REMOVED) {
-                cs->ifsPrevState = IFS_REMOVED;
-                log_line("Interface removed.  Exiting.");
-                exit(EXIT_SUCCESS);
-            }
-            break;
-        default:
-            break;
+    switch (state) {
+    case IFS_UP:
+        cs->ifsPrevState = IFS_UP;
+        ifup_action(cs);
+        break;
+    case IFS_DOWN:
+        // Interface configured, but no hardware carrier.
+        cs->ifsPrevState = IFS_DOWN;
+        ifnocarrier_action(cs);
+        break;
+    case IFS_SHUT:
+        // User shut down the interface.
+        cs->ifsPrevState = IFS_SHUT;
+        ifdown_action(cs);
+        break;
+    case IFS_REMOVED:
+        cs->ifsPrevState = IFS_REMOVED;
+        log_line("Interface removed.  Exiting.");
+        exit(EXIT_SUCCESS);
+        break;
+    default: break;
     }
+    return 0;
 }
 
-void handle_nl_message(struct client_state_t cs[static 1])
+static int nl_process_msgs_return;
+static void nl_process_msgs(const struct nlmsghdr *nlh, void *data)
+{
+    (void)data;
+    struct ifinfomsg *ifm = NLMSG_DATA(nlh);
+
+    if (ifm->ifi_index != client_config.ifindex)
+        return;
+
+    if (nlh->nlmsg_type == RTM_NEWLINK) {
+        // IFF_UP corresponds to ifconfig down or ifconfig up.
+        // IFF_RUNNING is the hardware carrier.
+        if (ifm->ifi_flags & IFF_UP) {
+            if (ifm->ifi_flags & IFF_RUNNING)
+                nl_process_msgs_return = IFS_UP;
+            else
+                nl_process_msgs_return = IFS_DOWN;
+        } else {
+            nl_process_msgs_return = IFS_SHUT;
+        }
+    } else if (nlh->nlmsg_type == RTM_DELLINK)
+        nl_process_msgs_return = IFS_REMOVED;
+}
+
+int nl_event_get(struct client_state_t cs[static 1])
 {
     char nlbuf[8192];
     ssize_t ret;
     assert(cs->nlFd != -1);
+    nl_process_msgs_return = IFS_NONE;
     do {
         ret = nl_recv_buf(cs->nlFd, nlbuf, sizeof nlbuf);
         if (ret < 0)
             break;
-        if (nl_foreach_nlmsg(nlbuf, ret, 0, cs->nlPortId, nl_process_msgs, cs)
+        if (nl_foreach_nlmsg(nlbuf, ret, 0, cs->nlPortId, nl_process_msgs, 0)
             < 0)
             break;
     } while (ret > 0);
+    return nl_process_msgs_return;
 }
 
 static int get_if_index_and_mac(const struct nlmsghdr *nlh,

src/netlink.h

@@ -40,7 +40,8 @@ enum {
     IFS_REMOVED
 };
 
-void handle_nl_message(struct client_state_t cs[static 1]);
+int nl_event_react(struct client_state_t cs[static 1], int state);
+int nl_event_get(struct client_state_t cs[static 1]);
 int nl_getifdata(void);
 
 #endif /* NK_NETLINK_H_ */

src/rfkill.c

@@ -26,7 +26,6 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <stdbool.h>
 #include <string.h>
 #include <errno.h>
 #include <sys/types.h>
@@ -36,8 +35,6 @@
 #include "nk/log.h"
 #include "nk/io.h"
 #include "ndhc.h"
-#include "netlink.h"
-#include "ifset.h"
 #include "rfkill.h"
 
 int rfkill_open(char enable_rfkill[static 1])
@@ -53,90 +50,31 @@ int rfkill_open(char enable_rfkill[static 1])
     return r;
 }
 
-static int rfkill_check(struct client_state_t cs[static 1],
-                        int (*rfenable)(struct client_state_t[static 1]),
-                        int (*rfdisable)(struct client_state_t[static 1]),
-                        bool check_idx, uint32_t rfkidx)
+// check_idx: Does rfkidx have any meaning?
+// rfkidx: Pay attention only to this radio kill switch number.
+int rfkill_get(struct client_state_t cs[static 1],
+               int check_idx, uint32_t rfkidx)
 {
     struct rfkill_event event;
     ssize_t len = safe_read(cs->rfkillFd, (char *)&event, sizeof event);
     if (len < 0) {
         log_error("rfkill: safe_read failed: %s", strerror(errno));
-        return -1;
+        return RFK_FAIL;
     }
     if (len != RFKILL_EVENT_SIZE_V1) {
         log_error("rfkill: event has unexpected size: %d", len);
-        return -1;
+        return RFK_FAIL;
     }
     log_line("rfkill: idx[%u] type[%u] op[%u] soft[%u] hard[%u]",
              event.idx, event.type, event.op, event.soft, event.hard);
     if (check_idx && event.idx != rfkidx)
-        return 0;
+        return RFK_NONE;
     if (event.op != RFKILL_OP_CHANGE && event.op != RFKILL_OP_CHANGE_ALL)
-        return 0;
+        return RFK_NONE;
     if (event.soft || event.hard) {
-        return rfenable(cs);
+        return RFK_ENABLED;
     } else {
-        return rfdisable(cs);
+        return RFK_DISABLED;
     }
 }
 
-static int handle_rfkill_notice_enable(struct client_state_t cs[static 1])
-{
-    cs->rfkill_set = 1;
-    if (cs->ifsPrevState == IFS_UP) {
-        log_line("rfkill: radio now blocked; bringing interface down");
-        cs->ifsPrevState = IFS_DOWN;
-        ifnocarrier_action(cs);
-    } else
-        log_line("rfkill: radio now blocked, but interface isn't up");
-    return 0;
-}
-
-static int handle_rfkill_notice_disable(struct client_state_t cs[static 1])
-{
-    cs->rfkill_set = 0;
-    if (cs->ifsPrevState == IFS_DOWN) {
-        log_line("rfkill: radio now unblocked; bringing interface up");
-        cs->ifsPrevState = IFS_UP;
-        ifup_action(cs);
-    } else {
-        if (cs->ifsPrevState == IFS_SHUT)
-            log_line("rfkill: radio now unblocked, but interface was shut down by user");
-        else
-            log_line("rfkill: radio now unblocked, but interface is removed");
-    }
-    return 0;
-}
-
-static int rfkill_wait_for_end_enable(struct client_state_t cs[static 1])
-{
-    (void)cs;
-    return -1;
-}
-
-static int rfkill_wait_for_end_disable(struct client_state_t cs[static 1])
-{
-    switch (perform_ifup()) {
-    case 1: case 0:
-        cs->rfkill_set = 0;
-        return 0;
-    case -3:
-        log_line("rfkill: radio immediately blocked again; spurious?");
-        return -1;
-    default: suicide("failed to set the interface to up state");
-    }
-}
-
-int handle_rfkill_notice(struct client_state_t cs[static 1], uint32_t rfkidx)
-{
-    return rfkill_check(cs, handle_rfkill_notice_enable,
-                        handle_rfkill_notice_disable, true, rfkidx);
-}
-
-int rfkill_wait_for_end(struct client_state_t cs[static 1])
-{
-    return rfkill_check(cs, rfkill_wait_for_end_enable,
-                        rfkill_wait_for_end_disable, false, 0);
-}
-

src/rfkill.h

@@ -28,9 +28,16 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
+enum {
+    RFK_NONE = 0,
+    RFK_FAIL,
+    RFK_ENABLED,
+    RFK_DISABLED,
+};
+
 int rfkill_open(char enable_rfkill[static 1]);
-int handle_rfkill_notice(struct client_state_t cs[static 1], uint32_t rfkidx);
-int rfkill_wait_for_end(struct client_state_t cs[static 1]);
+int rfkill_get(struct client_state_t cs[static 1],
+               int check_idx, uint32_t rfkidx);
 
 #endif