New -R option to control babeld via a unix socket

To be pushed upstream.
Co-authored-by: Julien Muchembled <jm@nexedi.com>

Makefile

@@ -9,10 +9,10 @@ CFLAGS = $(CDEBUGFLAGS) $(DEFINES) $(EXTRA_DEFINES)
 LDLIBS = -lrt
 
 SRCS = babeld.c net.c kernel.c util.c interface.c source.c neighbour.c \
-       route.c xroute.c message.c resend.c configuration.c local.c
+       route.c xroute.c message.c resend.c configuration.c local.c ctl.c
 
 OBJS = babeld.o net.o kernel.o util.o interface.o source.o neighbour.o \
-       route.o xroute.o message.o resend.o configuration.o local.o
+       route.o xroute.o message.o resend.o configuration.o local.o ctl.o
 
 babeld: $(OBJS)
 	$(CC) $(CFLAGS) $(LDFLAGS) -o babeld $(OBJS) $(LDLIBS)

babeld.c

@@ -52,6 +52,7 @@ THE SOFTWARE.
 #include "resend.h"
 #include "configuration.h"
 #include "local.h"
+#include "ctl.h"
 
 struct timeval now;
 
@@ -106,6 +107,7 @@ main(int argc, char **argv)
     void *vrc;
     unsigned int seed;
     struct interface *ifp;
+    int ctl_sockfd;
 
     gettime(&now);
 
@@ -123,7 +125,7 @@ main(int argc, char **argv)
     change_smoothing_half_life(4);
 
     while(1) {
-        opt = getopt(argc, argv, "m:p:h:H:i:k:A:sruS:d:g:lwz:M:t:T:c:C:DL:I:F");
+        opt = getopt(argc, argv, "m:p:h:H:i:k:A:sruS:d:g:lwz:M:t:T:c:C:DL:I:R:F");
         if(opt < 0)
             break;
 
@@ -258,6 +260,9 @@ main(int argc, char **argv)
         case 'I':
             pidfile = optarg;
             break;
+        case 'R':
+            control_socket_path = optarg;
+            break;
         case 'F':
             setup = 1;
             break;
@@ -501,6 +506,12 @@ main(int argc, char **argv)
     }
 #endif
 
+    ctl_sockfd = init_control_socket();
+    if(ctl_sockfd < 0) {
+        perror("Couldn't create control socket");
+        goto fail;
+    }
+
     init_signals();
     rc = resize_receive_buffer(1500);
     if(rc < 0)
@@ -552,7 +563,8 @@ main(int argc, char **argv)
 
     while(1) {
         struct timeval tv;
-        fd_set readfds;
+        fd_set readfds, writefds;
+        struct ctl *ctl, *ctl_next;
 
         gettime(&now);
 
@@ -572,6 +584,7 @@ main(int argc, char **argv)
         }
         timeval_min(&tv, &unicast_flush_timeout);
         FD_ZERO(&readfds);
+        FD_ZERO(&writefds);
         if(timeval_compare(&tv, &now) > 0) {
             int maxfd = 0;
             timeval_minus(&tv, &tv, &now);
@@ -593,7 +606,16 @@ main(int argc, char **argv)
                 maxfd = MAX(maxfd, local_sockets[i]);
             }
 #endif
-            rc = select(maxfd + 1, &readfds, NULL, NULL, &tv);
+            FD_SET(ctl_sockfd, &readfds);
+            maxfd = MAX(maxfd, ctl_sockfd);
+            for(ctl = ctl_connection; ctl; ctl = ctl->next) {
+                if(ctl->write < ctl->buffer_out.end)
+                    FD_SET(ctl->fd, &writefds);
+                else
+                    FD_SET(ctl->fd, &readfds);
+                maxfd = MAX(maxfd, ctl->fd);
+            }
+            rc = select(maxfd + 1, &readfds, &writefds, NULL, &tv);
             if(rc < 0) {
                 if(errno != EINTR) {
                     perror("select");
@@ -657,7 +679,16 @@ main(int argc, char **argv)
             i++;
         }
 #endif
-
+        if(FD_ISSET(ctl_sockfd, &readfds)) {
+            accept_ctl_connection(ctl_sockfd);
+        }
+        for(ctl = ctl_connection; ctl; ctl = ctl_next) {
+            ctl_next = ctl->next;
+            if (FD_ISSET(ctl->fd, &writefds))
+                ctl_write(ctl);
+            if (FD_ISSET(ctl->fd, &readfds))
+                ctl_read(ctl);
+        }
         if(reopening) {
             kernel_dump_time = now.tv_sec;
             check_neighbours_timeout = now;
@@ -819,7 +850,7 @@ main(int argc, char **argv)
             "                "
             "[-F] [-t table] [-T table] [-c file] [-C statement]\n"
             "                "
-            "[-d level] [-D] [-L logfile] [-I pidfile]\n"
+            "[-d level] [-D] [-L logfile] [-I pidfile] [-R control-socket]\n"
             "                "
             "[id] interface...\n",
             argv[0]);

ctl.h

+/*
+Copyright (c) 2014 Nexedi SA
+
+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 <stdint.h>
+
+/* Soft limit to protect against misbehaviour,
+ * but feel free to increase it if needed. */
+#define CTL_MAX_SIZE 65536
+
+#define CTL_VERSION 1
+
+#define CTL_MSG_DUMP       1
+
+#define CTL_DUMP_NONE      0
+#define CTL_DUMP_INSTALLED 1
+#define CTL_DUMP_FEASIBLE  2
+#define CTL_DUMP_ALL       3
+
+struct ctl_buffer {
+    char *data;
+    size_t size;
+    size_t end;
+};
+
+struct ctl_dump_neighbour {
+    uint8_t address[16];
+    uint32_t ifindex;
+    uint16_t reach;
+    uint16_t rxcost;
+    uint16_t txcost;
+    uint16_t rtt;
+    uint16_t rttcost;
+    int32_t channel;
+    uint16_t if_up;
+} __attribute__((packed));
+
+
+struct ctl_dump_route {
+    uint8_t prefix[16];
+    uint8_t plen;
+    uint16_t metric;
+    uint16_t smoothed_metric;
+    uint16_t refmetric;
+    uint8_t id[8];
+    int32_t seqno;
+    int32_t age;
+    uint32_t ifindex;
+    uint8_t neigh_address[16];
+    uint8_t nexthop[16];
+    uint8_t installed:1;
+    uint8_t feasible:1;
+} __attribute__((packed));
+
+struct ctl_dump_xroute {
+    uint8_t prefix[16];
+    uint8_t plen;
+    uint16_t metric;
+} __attribute__((packed));
+
+
+struct ctl {
+    struct ctl *next;
+    int fd;
+    struct ctl_buffer buffer_out;
+    struct ctl_buffer buffer_in;
+    size_t write;
+    int initialized:1;
+};
+
+extern const char *control_socket_path;
+extern struct ctl *ctl_connection;
+
+int init_control_socket();
+void accept_ctl_connection(int fd);
+void ctl_read(struct ctl *ctl);
+void ctl_write(struct ctl *ctl);