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.c

+/*
+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 <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <arpa/inet.h>
+#include <sys/un.h>
+
+#include "babeld.h"
+#include "util.h"
+#include "interface.h"
+#include "source.h"
+#include "neighbour.h"
+#include "kernel.h"
+#include "route.h"
+#include "xroute.h"
+#include "ctl.h"
+
+#define MEMCPY(y,x) (memcpy(y, x, sizeof y))
+
+const char *control_socket_path = "/var/run/babeld.socket";
+struct ctl *ctl_connection;
+
+static void
+ctl_close_connection(struct ctl *ctl)
+{
+    struct ctl **c = &ctl_connection;
+    while(*c != ctl)
+        c = &(*c)->next;
+    *c = ctl->next;
+
+    close(ctl->fd);
+    free(ctl->buffer_in.data);
+    free(ctl->buffer_out.data);
+    free(ctl);
+}
+
+static int
+ctl_resize_buffer(struct ctl_buffer *buffer, size_t n)
+{
+    if(buffer->size < n) {
+        char *new;
+        n = (n + 4095) & ~4095;
+        new = realloc(buffer->data, n);
+        if(!new) {
+            fprintf(stderr, "realloc(ctl_buffer)\n");
+            return -1;
+        }
+        buffer->data = new;
+        buffer->size = n;
+    }
+    return 0;
+}
+
+static int
+ctl_dump_interface(struct ctl_buffer *buffer, struct interface *ifp)
+{
+    size_t end = buffer->end + strlen(ifp->name) + 1 + 4;
+    if(ctl_resize_buffer(buffer, end))
+        return -1;
+    DO_HTONL(buffer->data + buffer->end, ifp->ifindex);
+    strcpy(buffer->data + buffer->end + 4, ifp->name);
+    buffer->end = end;
+    return 0;
+}
+
+static int
+ctl_dump_neighbour(struct ctl_buffer *buffer, struct neighbour *neigh)
+{
+    struct ctl_dump_neighbour *neigh_dump;
+    size_t end = buffer->end + sizeof *neigh_dump;
+    if(ctl_resize_buffer(buffer, end))
+        return -1;
+    neigh_dump = (void *)(buffer->data + buffer->end);
+    MEMCPY(neigh_dump->address, neigh->address);
+    neigh_dump->ifindex = htonl(neigh->ifp->ifindex);
+    neigh_dump->reach = htons(neigh->hello.reach);
+    neigh_dump->rxcost = htons(neighbour_rxcost(neigh));
+    neigh_dump->txcost = htons(neigh->txcost);
+    neigh_dump->rtt = htonl(neigh->rtt);
+    neigh_dump->rttcost = htonl(neighbour_rttcost(neigh));
+    neigh_dump->channel = htonl(neigh->ifp->channel);
+    neigh_dump->if_up = htons(if_up(neigh->ifp));
+    buffer->end = end;
+    return 0;
+}
+
+static int
+ctl_dump_route(struct ctl_buffer *buffer, struct babel_route *route)
+{
+    struct ctl_dump_route *route_dump;
+    size_t end = buffer->end + sizeof *route_dump;
+    if(ctl_resize_buffer(buffer, end))
+        return -1;
+    route_dump = (void *)(buffer->data + buffer->end);
+    MEMCPY(route_dump->prefix, route->src->prefix);
+    route_dump->plen = route->src->plen;
+    route_dump->metric = htons(route_metric(route));
+    route_dump->smoothed_metric = htons(route_smoothed_metric(route));
+    route_dump->refmetric = htons(route->refmetric);
+    MEMCPY(route_dump->id, route->src->id);
+    route_dump->seqno = htonl((int32_t)route->seqno);
+    route_dump->age = htonl((int32_t)(now.tv_sec - route->time));
+    route_dump->ifindex = htonl(route->neigh->ifp->ifindex);
+    MEMCPY(route_dump->neigh_address, route->neigh->address);
+    MEMCPY(route_dump->nexthop, route->nexthop);
+    route_dump->flags = (route->installed ? CTL_ROUTE_INSTALLED : 0)
+                      | (route_feasible(route) ? CTL_ROUTE_FEASIBLE : 0);
+    buffer->end = end;
+    return 0;
+}
+
+static int
+ctl_dump_xroute(struct ctl_buffer *buffer, struct xroute *xroute)
+{
+    struct ctl_dump_xroute *xroute_dump;
+    size_t end = buffer->end + sizeof *xroute_dump;
+    if(ctl_resize_buffer(buffer, end))
+        return -1;
+    xroute_dump = (void *)(buffer->data + buffer->end);
+    MEMCPY(xroute_dump->prefix, xroute->prefix);
+    xroute_dump->plen = xroute->plen;
+    xroute_dump->metric = htons(xroute->metric);
+    buffer->end = end;
+    return 0;
+}
+
+static int
+ctl_dump(struct ctl_buffer *buffer, void *packet, size_t length)
+{
+    size_t count_offset, header_offset;
+    unsigned count;
+    uint8_t flags = *(uint8_t*)packet;
+    uint8_t flags_routes = CTL_DUMP_ROUTE(flags);
+
+    header_offset = buffer->end;
+    buffer->end += 6;
+#define START_ARRAY (count_offset = buffer->end += 2, count = 0)
+#define END_ARRAY do { \
+        if(!count && ctl_resize_buffer(buffer, count_offset)) \
+            return -1;                                        \
+        DO_HTONS(buffer->data + count_offset - 2, count);     \
+    } while(0)
+
+    START_ARRAY;
+    if(flags & CTL_DUMP_INTERFACE) {
+        struct interface *ifp;
+        FOR_ALL_INTERFACES(ifp) {
+            /* Apparently we get some garbage interfaces from command line. */
+            if(!ifp->ifindex)
+                continue;
+            if(ctl_dump_interface(buffer, ifp) ||
+               !(uint16_t)++count /* make sure we don't overflow */)
+                return -1;
+        }
+    }
+    END_ARRAY;
+
+    START_ARRAY;
+    if(flags & CTL_DUMP_NEIGHBOUR) {
+        struct neighbour *neigh;
+        FOR_ALL_NEIGHBOURS(neigh)
+            if(ctl_dump_neighbour(buffer, neigh) || !(uint16_t)++count)
+                return -1;
+    }
+    END_ARRAY;
+
+    START_ARRAY;
+    if(flags & CTL_DUMP_XROUTE) {
+        struct xroute_stream *xroutes;
+        struct xroute *xroute;
+        xroutes = xroute_stream();
+        if(!xroutes)
+            return -1;
+        while((xroute = xroute_stream_next(xroutes)) &&
+              !ctl_dump_xroute(buffer, xroute) &&
+              (uint16_t)++count);
+        xroute_stream_done(xroutes);
+        if(xroute)
+            return -1;
+    }
+    END_ARRAY;
+
+    START_ARRAY;
+    if(flags_routes != CTL_DUMP_ROUTE_NONE) {
+        struct babel_route *route;
+        struct route_stream *routes;
+        routes = route_stream(flags_routes == CTL_DUMP_ROUTE_INSTALLED);
+        if(!routes)
+            return -1;
+        while((route = route_stream_next(routes)) &&
+              ((flags_routes == CTL_DUMP_ROUTE_FEASIBLE && !route_feasible(route))
+               || !ctl_dump_route(buffer, route)) &&
+              (uint16_t)++count);
+        route_stream_done(routes);
+        if(route)
+            return -1;
+    }
+    END_ARRAY;
+
+#undef START_ARRAY
+#undef END_ARRAY
+    DO_HTONS(buffer->data + header_offset, CTL_MSG_DUMP);
+    DO_HTONL(buffer->data + header_offset + 2, buffer->end - header_offset - 6);
+    return 0;
+}
+
+static void
+ctl_work(struct ctl *ctl)
+{
+    struct ctl_buffer *buffer_in = &ctl->buffer_in;
+    uint16_t type;
+    uint32_t length;
+    size_t packet_size;
+    while((packet_size = sizeof type + sizeof length) <= buffer_in->end) {
+        void *p = buffer_in->data;
+        int ret = -1;
+        DO_NTOHS(type, p); p += sizeof type;
+        DO_NTOHL(length, p); p += sizeof length;
+        packet_size += length;
+        if(packet_size <= buffer_in->end)
+            switch(type) {
+            case CTL_MSG_DUMP:
+                ret = ctl_dump(&ctl->buffer_out, p, length);
+                break;
+            }
+        else if(length < CTL_MAX_SIZE)
+            return;
+        if(ret)
+            return ctl_close_connection(ctl);
+        else
+            memmove(buffer_in->data, p + length,
+                    buffer_in->end -= packet_size);
+    }
+}
+
+static void
+unlink_control_socket()
+{
+    unlink(control_socket_path);
+}
+
+int
+init_control_socket()
+{
+    struct sockaddr_un sa_un;
+    struct stat stat;
+    int fd;
+
+    if(strlen(control_socket_path) >= sizeof sa_un.sun_path)
+        return -1;
+    if(!lstat(control_socket_path, &stat)) {
+        if(!S_ISSOCK(stat.st_mode))
+            return -1;
+        unlink(control_socket_path);
+    }
+    if((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
+        return -1;
+    sa_un.sun_family = AF_UNIX;
+    strcpy(sa_un.sun_path, control_socket_path);
+    if(bind(fd, (struct sockaddr *)&sa_un, sizeof sa_un) < 0) {
+        close(fd);
+        return -1;
+    }
+    atexit(unlink_control_socket);
+    listen(fd, 5);
+    return fd;
+}
+
+void
+accept_ctl_connection(int fd)
+{
+    struct ctl *ctl;
+    fd = accept(fd, NULL, NULL);
+    if(fd < 0)
+        return;
+    ctl = calloc(1, sizeof *ctl);
+    if(!ctl) {
+        close(fd);
+        return;
+    }
+    ctl->fd = fd;
+    ctl->next = ctl_connection;
+    ctl_connection = ctl;
+}
+
+void
+ctl_read(struct ctl *ctl)
+{
+    struct ctl_buffer *buffer = &ctl->buffer_in;
+    size_t end = buffer->end;
+    size_t read_n = buffer->size - end;
+    if(read_n || (ctl_resize_buffer(buffer, buffer->size + 1),
+                  read_n = buffer->size - end)) {
+        ssize_t n = recv(ctl->fd, buffer->data + buffer->end, read_n, 0);
+        if(n > 0) {
+            buffer->end = end + n;
+            if(!ctl->initialized) {
+                if(buffer->end &&
+                  (ctl->initialized = *(uint8_t*)buffer->data == CTL_VERSION))
+                    memmove(buffer->data, buffer->data + 1, --buffer->end);
+                else
+                    return ctl_close_connection(ctl);
+            }
+            return ctl_work(ctl);
+        }
+        if(n && errno == EINTR)
+            return;
+    }
+    ctl_close_connection(ctl);
+}
+
+void
+ctl_write(struct ctl *ctl)
+{
+    struct ctl_buffer *buffer = &ctl->buffer_out;
+    ssize_t n;
+    n = send(ctl->fd, buffer->data + ctl->write, buffer->end - ctl->write, 0);
+    if(n > 0) {
+        ctl->write += n;
+        if(ctl->write == buffer->end)
+            ctl->write = buffer->end = 0;
+    } else if(!n || errno != EINTR)
+        ctl_close_connection(ctl);
+}

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);