New -X option to control babeld via a unix socket

TODO: documentation

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

Makefile

@@ -11,11 +11,11 @@ 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 \
-       hmac.c rfc6234/sha224-256.c BLAKE2/ref/blake2s-ref.c
+       ctl.c hmac.c rfc6234/sha224-256.c BLAKE2/ref/blake2s-ref.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 \
-       hmac.o rfc6234/sha224-256.o BLAKE2/ref/blake2s-ref.o
+       ctl.o hmac.o rfc6234/sha224-256.o BLAKE2/ref/blake2s-ref.o
 
 babeld: $(OBJS)
 	$(CC) $(CFLAGS) $(LDFLAGS) -o babeld $(OBJS) $(LDLIBS)

babeld.c

@@ -53,6 +53,7 @@ THE SOFTWARE.
 #include "configuration.h"
 #include "local.h"
 #include "version.h"
+#include "ctl.h"
 
 struct timeval now;
 
@@ -136,6 +137,7 @@ main(int argc, char **argv)
     void *vrc;
     unsigned int seed;
     struct interface *ifp;
+    int ctl_sockfd;
 
     gettime(&now);
 
@@ -157,7 +159,7 @@ main(int argc, char **argv)
 
     while(1) {
         opt = getopt(argc, argv,
-                     "m:p:h:H:i:k:A:srS:d:g:G:lwz:M:t:T:c:C:DL:I:V");
+                     "m:p:h:H:i:k:A:srS:d:g:G:lwz:M:t:T:c:C:DL:I:X:V");
         if(opt < 0)
             break;
 
@@ -302,6 +304,9 @@ main(int argc, char **argv)
             fprintf(stderr, "%s\n", BABELD_VERSION);
             exit(0);
             break;
+        case 'X':
+            control_socket_path = optarg;
+            break;
         default:
             goto usage;
         }
@@ -521,6 +526,12 @@ main(int argc, char **argv)
         }
     }
 
+    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)
@@ -574,8 +585,9 @@ main(int argc, char **argv)
 
     while(1) {
         struct timeval tv;
-        fd_set readfds;
         struct neighbour *neigh;
+        fd_set readfds, writefds;
+        struct ctl *ctl, *ctl_next;
 
         gettime(&now);
 
@@ -597,6 +609,7 @@ main(int argc, char **argv)
             timeval_min(&tv, &neigh->buf.timeout);
         }
         FD_ZERO(&readfds);
+        FD_ZERO(&writefds);
         if(timeval_compare(&tv, &now) > 0) {
             int maxfd = 0;
             timeval_minus(&tv, &tv, &now);
@@ -616,7 +629,16 @@ main(int argc, char **argv)
                 FD_SET(local_sockets[i].fd, &readfds);
                 maxfd = MAX(maxfd, local_sockets[i].fd);
             }
-            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");
@@ -684,6 +706,16 @@ main(int argc, char **argv)
             i++;
         }
 
+        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;
@@ -851,7 +883,7 @@ main(int argc, char **argv)
             "               "
             "[-t table] [-T table] [-c file] [-C statement]\n"
             "               "
-            "[-d level] [-D] [-L logfile] [-I pidfile]\n"
+            "[-d level] [-D] [-L logfile] [-I pidfile] [-X control-socket]\n"
             "               "
             "interface...\n",
             BABELD_VERSION);

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_INTERFACE  (1 << 0)
+#define CTL_DUMP_NEIGHBOUR  (1 << 1)
+#define CTL_DUMP_XROUTE     (1 << 2)
+#define CTL_DUMP_ROUTE(x)   (x >> 3 & 3)
+#define CTL_DUMP_ROUTE_NONE      0
+#define CTL_DUMP_ROUTE_INSTALLED 1
+#define CTL_DUMP_ROUTE_FEASIBLE  2
+#define CTL_DUMP_ROUTE_ALL       3
+
+#define CTL_ROUTE_INSTALLED (1 << 0)
+#define CTL_ROUTE_FEASIBLE  (1 << 1)
+
+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 flags;
+} __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;
+    unsigned 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);