Import routes installed by other software as HNAs

files/olsrd.conf.default.txt

@@ -110,6 +110,25 @@
 
 # RtProto 0
 
+# Announce host routes some other software put in the kernel as HNAs, so
+# addresses olsr has no other way of learning about become reachable from
+# the olsr side. The value is the route protocol identifying that software -
+# another routing daemon, a roaming or tunnel manager, anything that
+# installs routes under a protocol of its own. 0 (the default) disables it.
+# Only host routes are taken, so a default route or an aggregate can never
+# turn into an HNA.
+#
+# ImportPrefix, repeatable, bounds what may be announced. Without any, every
+# host route of that protocol is imported - including addresses off transfer
+# networks and management interfaces, so a whitelist is usually what you want.
+#
+# The example imports what protocol 42 installs within one address space:
+#
+# ImportProto 42
+# ImportPrefix 10.12.0.0/16
+
+# ImportProto 0
+
 # Specifies the routing Table olsr uses
 # RtTable is for host routes, RtTableDefault for the route to the default
 # internet gateway (2 in case of IPv6+NIIT) and RtTableTunnel is for

src/cfgparser/cfgfile_gen.c

@@ -480,6 +480,27 @@ void olsrd_write_cnf_autobuf_uncached(struct autobuf *out, struct olsrd_config *
         cnf->rt_proto == expected ? "# " : "",
         cnf->rt_proto == expected ? DEF_RTPROTO : cnf->rt_proto);
   }
+  abuf_appendf(out,
+    "\n"
+    "# Route protocol whose host routes are announced as HNAs, so hosts\n"
+    "# only another routing daemon knows about become reachable over olsr.\n"
+    "# 0 disables the import. ImportPrefix, repeatable, bounds what may be\n"
+    "# announced; without any, every host route of that protocol is taken\n"
+    "\n");
+  if (cnf->import_proto != DEF_IMPORTPROTO) {
+    struct ip_prefix_list *hna;
+
+    abuf_appendf(out, "ImportProto %u\n", cnf->import_proto);
+
+    for (hna = cnf->import_prefixes; hna != NULL; hna = hna->next) {
+      struct ipaddr_str addrbuf;
+      abuf_appendf(out, "ImportPrefix %s/%d\n",
+          olsr_ip_to_string(&addrbuf, &hna->net.prefix), hna->net.prefix_len);
+    }
+  } else {
+    abuf_appendf(out, "# ImportProto %u\n", DEF_IMPORTPROTO);
+  }
+
   abuf_appendf(out,
     "\n"
     "# Specifies the routing Table olsr uses\n"

src/cfgparser/olsrd_conf.c

@@ -1049,6 +1049,10 @@ olsrd_free_cnf(struct olsrd_config **cnfVariableAddress)
 
   ip_prefix_list_clear(&cnf->hna_entries);
 
+  ip_prefix_list_clear(&cnf->import_prefixes);
+
+  ip_prefix_list_clear(&cnf->import_prefixes);
+
   while (cnf->plugins) {
     struct plugin_entry *plugin = cnf->plugins;
     cnf->plugins = cnf->plugins->next;
@@ -1095,6 +1099,8 @@ set_default_cnf(struct olsrd_config *cnf, char * configuration_file)
   cnf->allow_no_interfaces = DEF_ALLOW_NO_INTS;
   cnf->tos = DEF_TOS;
   cnf->rt_proto = DEF_RTPROTO;
+  cnf->import_proto = DEF_IMPORTPROTO;
+  cnf->import_prefixes = NULL;
   cnf->rt_table = DEF_RT_AUTO;
   cnf->rt_table_default = DEF_RT_AUTO;
   cnf->rt_table_tunnel = DEF_RT_AUTO;

src/cfgparser/oparse.y

@@ -192,6 +192,8 @@ static int add_ipv6_addr(YYSTYPE ipaddr_arg, YYSTYPE prefixlen_arg)
 %token TOK_TOS
 %token TOK_OLSRPORT
 %token TOK_RTPROTO
+%token TOK_IMPORTPROTO
+%token TOK_IMPORTPREFIX
 %token TOK_RTTABLE
 %token TOK_RTTABLE_DEFAULT
 %token TOK_RTTABLE_TUNNEL
@@ -296,6 +298,8 @@ stmt:       idebug
           | atos
           | aolsrport
           | irtproto
+          | iimportproto
+          | iimportprefix
           | irttable
           | irttable_default
           | irttable_tunnel
@@ -1062,6 +1066,66 @@ aolsrport: TOK_OLSRPORT TOK_INTEGER
 }
 ;
 
+iimportproto: TOK_IMPORTPROTO TOK_INTEGER
+{
+  PARSER_DEBUG_PRINTF("ImportProto: %d\n", $2->integer);
+  olsr_cnf->import_proto = $2->integer;
+  free($2);
+}
+;
+
+iimportprefix: TOK_IMPORTPREFIX TOK_IPV4_ADDR TOK_SLASH TOK_INTEGER
+{
+  union olsr_ip_addr ipaddr;
+
+  if (olsr_cnf->ip_version == AF_INET6) {
+    fprintf(stderr, "IPv4 addresses can only be used if \"IpVersion\" == 4, skipping ImportPrefix.\n");
+    olsr_startup_sleep(3);
+  } else {
+    PARSER_DEBUG_PRINTF("ImportPrefix: %s/%d\n", $2->string, $4->integer);
+
+    if (inet_pton(AF_INET, $2->string, &ipaddr.v4) <= 0) {
+      fprintf(stderr, "iimportprefix: Failed converting IP address %s\n", $2->string);
+      YYABORT;
+    }
+    if ($4->integer > olsr_cnf->maxplen) {
+      fprintf(stderr, "iimportprefix: Prefix len %u > %d is not allowed!\n", $4->integer, olsr_cnf->maxplen);
+      YYABORT;
+    }
+
+    ip_prefix_list_add(&olsr_cnf->import_prefixes, &ipaddr, $4->integer);
+  }
+  free($2->string);
+  free($2);
+  free($4);
+}
+        |     TOK_IMPORTPREFIX TOK_IPV6_ADDR TOK_SLASH TOK_INTEGER
+{
+  union olsr_ip_addr ipaddr;
+
+  if (olsr_cnf->ip_version == AF_INET) {
+    fprintf(stderr, "IPv6 addresses can only be used if \"IpVersion\" == 6, skipping ImportPrefix.\n");
+    olsr_startup_sleep(3);
+  } else {
+    PARSER_DEBUG_PRINTF("ImportPrefix: %s/%d\n", $2->string, $4->integer);
+
+    if (inet_pton(AF_INET6, $2->string, &ipaddr.v6) <= 0) {
+      fprintf(stderr, "iimportprefix: Failed converting IP address %s\n", $2->string);
+      YYABORT;
+    }
+    if ($4->integer > olsr_cnf->maxplen) {
+      fprintf(stderr, "iimportprefix: Prefix len %u > %d is not allowed!\n", $4->integer, olsr_cnf->maxplen);
+      YYABORT;
+    }
+
+    ip_prefix_list_add(&olsr_cnf->import_prefixes, &ipaddr, $4->integer);
+  }
+  free($2->string);
+  free($2);
+  free($4);
+}
+;
+
 irtproto: TOK_RTPROTO TOK_INTEGER
 {
   PARSER_DEBUG_PRINTF("RtProto: %d\n", $2->integer);

src/cfgparser/oscan.lex

@@ -354,6 +354,16 @@ IPV6ADDR {IPV6PAT1}|{IPV6PAT2}|{IPV6PAT3}|{IPV6PAT4}|{IPV6PAT5}|{IPV6PAT6}|{IPV6
   return TOK_OLSRPORT;
 }
 
+"ImportProto" {
+  yylval = NULL;
+  return TOK_IMPORTPROTO;
+}
+
+"ImportPrefix" {
+  yylval = NULL;
+  return TOK_IMPORTPREFIX;
+}
+
 "RtProto" {
   olsrd_config_checksum_add(yytext, yyleng);
   yylval = NULL;

src/linux/kernel_routes_nl.c

@@ -50,6 +50,8 @@
 #include "log.h"
 #include "net_os.h"
 #include "ifnet.h"
+#include "olsr.h"
+#include "route_import.h"
 
 #include <assert.h>
 #include <linux/types.h>
@@ -166,34 +168,59 @@ static void rtnetlink_read(int sock, void *data __attribute__ ((unused)), unsign
     .msg_flags = 0,
   };
 
-  char buffer[4096];
+  /* route messages carry more attributes than a link message and can
+   * outgrow a fixed buffer; size each one from a peek first */
+  int bufsize = 4096;
+  char *buffer = olsr_malloc(bufsize, "netlink receive buffer");
   struct nlmsghdr *nlh = (struct nlmsghdr *)ARM_NOWARN_ALIGN(buffer);
   int ret;
 
   iov.iov_base = (void *) buffer;
-  iov.iov_len = sizeof(buffer);
+  iov.iov_len = bufsize;
+
+  while ((ret = recvmsg(sock, &msg, MSG_DONTWAIT | MSG_TRUNC | MSG_PEEK)) >= 0) {
+    if (ret > bufsize) {
+      free(buffer);
+      buffer = olsr_malloc(ret, "netlink receive buffer expansion");
+      bufsize = ret;
+
+      iov.iov_base = (void *) buffer;
+      iov.iov_len = bufsize;
+      nlh = (struct nlmsghdr *)ARM_NOWARN_ALIGN(buffer);
+    }
+
+    ret = recvmsg(sock, &msg, MSG_DONTWAIT);
+    if (ret < 0) {
+      goto end;
+    }
 
-  while ((ret = recvmsg(sock, &msg, MSG_DONTWAIT)) >= 0) {
     /*check message*/
     len = nlh->nlmsg_len;
     plen = len - sizeof(nlh);
     if (len > ret || plen < 0) {
       OLSR_PRINTF(1,"Malformed netlink message: "
              "len=%d left=%d plen=%d\n",
               len, ret, plen);
-      return;
+      goto end;
     }
 
     OLSR_PRINTF(3, "Netlink message received: type 0x%x\n", nlh->nlmsg_type);
     if ((nlh->nlmsg_type == RTM_NEWLINK) || ( nlh->nlmsg_type == RTM_DELLINK)) {
       /* handle ifup/ifdown */
       netlink_process_link(nlh);
     }
+
+    if ((nlh->nlmsg_type == RTM_NEWROUTE) || (nlh->nlmsg_type == RTM_DELROUTE)) {
+      /* another daemon's route came or went - see ImportProto */
+      process_import_nlh(nlh, nlh->nlmsg_type == RTM_DELROUTE);
+    }
   }
 
   if (errno != EAGAIN) {
     OLSR_PRINTF(1,"netlink listen error %u - %s\n",errno,strerror(errno));
   }
+end:
+  free(buffer);
 }
 
 static void

src/main.c

@@ -86,6 +86,7 @@
 #include <linux/types.h>
 #include <linux/rtnetlink.h>
 #include "kernel_routes.h"
+#include "route_import.h"
 
 #endif /* __linux__ */
 
@@ -560,6 +561,9 @@ int main(int argc, char *argv[]) {
 
   /* create a socket for netlink calls */
 #ifdef __linux__
+  {
+  int rtnetlink_groups = RTMGRP_LINK;
+
   olsr_cnf->rtnl_s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
   if (olsr_cnf->rtnl_s < 0) {
     char buf2[1024];
@@ -571,11 +575,18 @@ int main(int argc, char *argv[]) {
     olsr_syslog(OLSR_LOG_INFO, "rtnetlink could not be set to nonblocking");
   }
 
-  if ((olsr_cnf->rt_monitor_socket = rtnetlink_register_socket(RTMGRP_LINK)) < 0) {
+  /* only ask the kernel for route changes when something wants them: a
+   * busy table would otherwise wake olsrd on every neighbour's update */
+  if (olsr_cnf->import_proto != 0) {
+    rtnetlink_groups |= (olsr_cnf->ip_version == AF_INET) ? RTMGRP_IPV4_ROUTE : RTMGRP_IPV6_ROUTE;
+  }
+
+  if ((olsr_cnf->rt_monitor_socket = rtnetlink_register_socket(rtnetlink_groups)) < 0) {
     char buf2[1024];
     snprintf(buf2, sizeof(buf2), "rtmonitor socket: %s", strerror(errno));
     olsr_exit(buf2, EXIT_FAILURE);
   }
+  }
 #endif /* __linux__ */
 
   /* create routing socket */
@@ -773,6 +784,9 @@ int main(int argc, char *argv[]) {
 
   olsr_shutdown_registered = true;
 
+  /* seed the HNA list from what is already in the routing table */
+  route_import_init();
+
   /* Starting scheduler */
   olsr_scheduler();
 

src/olsr_cfg.h

@@ -81,6 +81,7 @@
 #define DEF_CLEAR_SCREEN     true
 #define DEF_OLSRPORT         698
 #define DEF_RTPROTO          0 /* 0 means OS-specific default */
+#define DEF_IMPORTPROTO      0 /* 0 disables the route import */
 #define DEF_RT_NONE          -1
 #define DEF_RT_AUTO          0
 
@@ -303,6 +304,10 @@ struct olsrd_config {
   struct hyst_param hysteresis_param;
   struct plugin_entry *plugins;
   struct ip_prefix_list *hna_entries;
+  /* route protocol whose host routes become HNAs, 0 to disable */
+  uint8_t import_proto;
+  /* optional whitelist bounding what import_proto may announce */
+  struct ip_prefix_list *import_prefixes;
   struct ip_prefix_list *ipc_nets;
   struct if_config_options *interface_defaults;
   struct olsr_if *interfaces;
@@ -417,6 +422,8 @@ extern "C" {
 
   int ip_prefix_list_remove(struct ip_prefix_list **, const union olsr_ip_addr *, uint8_t);
 
+  void ip_prefix_list_clear(struct ip_prefix_list **list);
+
   struct ip_prefix_list *ip_prefix_list_find(struct ip_prefix_list *, const union olsr_ip_addr *net, uint8_t prefix_len);
 
 /*