Fix the interface alias code. Previously, I was expecting something

like

tun0: flags=blah
	10.0.0.1 -> 10.0.0.100
	10.0.0.2 -> 10.0.0.100
	10.0.0.3 -> 10.0.0.100

to DTRT, despite the SIOCAIFADDR for each new alias returning
-1 & EEXIST while adding the alias anyway.  In real life, once
we have the second alias with the same destination, nothing will
route any more !  Also, because I was ignoring EEXIST, the
dynamic IP assignment code was assigning duplicate addresses
('cos it was being lied to by iface_inAdd()).

Now we have

tun0: flags=blah
	10.0.0.1 -> 255.255.255.255
	10.0.0.2 -> 10.0.0.100
	10.0.0.3 -> 255.255.255.255

This works - stuff bound to 10.1 & 10.3 will be considered alive
by the kernel, and when they route back to the tun device, the
packets get aliased to 10.2 and go out to 10.100 (as with the
original plan).

We still see the EEXIST in SIOCAIFADDR, but ignore it when our
destination is 255.255.255.255, assuming that the alias *was*
actually added.

Additionally, ``iface add'' may now optionally be given only
the interface address.  The mask & destination default to
255.255.255.255.

4 files changed, 113 insertions, 29 deletions

diff --git a/usr.sbin/ppp/command.c b/usr.sbin/ppp/command.c
index a1b1789..f474aca 100644
--- a/usr.sbin/ppp/command.c
+++ b/usr.sbin/ppp/command.c
@@ -17,7 +17,7 @@
  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
- * $Id: command.c,v 1.168 1998/10/22 02:32:48 brian Exp $
+ * $Id: command.c,v 1.169 1998/10/24 01:08:45 brian Exp $
  *
  */
 #include <sys/types.h>
@@ -132,7 +132,7 @@
 #define NEG_DNS		50
 
 const char Version[] = "2.0";
-const char VersionDate[] = "$Date: 1998/10/22 02:32:48 $";
+const char VersionDate[] = "$Date: 1998/10/24 01:08:45 $";
 
 static int ShowCommand(struct cmdargs const *);
 static int TerminalCommand(struct cmdargs const *);
@@ -2321,21 +2321,27 @@ IfaceAddCommand(struct cmdargs const *arg)
   int bits, n, how;
   struct in_addr ifa, mask, brd;
 
-  if (arg->argc == arg->argn + 2) {
-    if (!ParseAddr(NULL, 1, arg->argv + arg->argn, &ifa, &mask, &bits))
-      return -1;
-    n = 1;
-  } else if (arg->argc == arg->argn + 3) {
+  if (arg->argc == arg->argn + 1) {
     if (!ParseAddr(NULL, 1, arg->argv + arg->argn, &ifa, NULL, NULL))
       return -1;
-    if (!ParseAddr(NULL, 1, arg->argv + arg->argn + 1, &mask, NULL, NULL))
+    mask.s_addr = brd.s_addr = INADDR_BROADCAST;
+  } else {
+    if (arg->argc == arg->argn + 2) {
+      if (!ParseAddr(NULL, 1, arg->argv + arg->argn, &ifa, &mask, &bits))
+        return -1;
+      n = 1;
+    } else if (arg->argc == arg->argn + 3) {
+      if (!ParseAddr(NULL, 1, arg->argv + arg->argn, &ifa, NULL, NULL))
+        return -1;
+      if (!ParseAddr(NULL, 1, arg->argv + arg->argn + 1, &mask, NULL, NULL))
+        return -1;
+      n = 2;
+    } else
       return -1;
-    n = 2;
-  } else
-    return -1;
 
-  if (!ParseAddr(NULL, 1, arg->argv + arg->argn + n, &brd, NULL, NULL))
-    return -1;
+    if (!ParseAddr(NULL, 1, arg->argv + arg->argn + n, &brd, NULL, NULL))
+      return -1;
+  }
 
   how = IFACE_ADD_LAST;
   if (arg->cmd->args)
diff --git a/usr.sbin/ppp/iface.c b/usr.sbin/ppp/iface.c
index c217690..bca10ee 100644
--- a/usr.sbin/ppp/iface.c
+++ b/usr.sbin/ppp/iface.c
@@ -23,7 +23,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id:$
+ *	$Id: iface.c,v 1.1 1998/10/22 02:32:49 brian Exp $
  */
 
 #include <sys/types.h>
@@ -232,6 +232,7 @@ iface_addr_Zap(const char *name, struct iface_addr *addr)
     me->sin_len = peer->sin_len = sizeof(struct sockaddr_in);
     me->sin_addr = addr->ifa;
     peer->sin_addr = addr->brd;
+    log_Printf(LogDEBUG, "Delete %s\n", inet_ntoa(addr->ifa));
     if (ID0ioctl(s, SIOCDIFADDR, &ifra) < 0)
       log_Printf(LogWARN, "iface_addr_Zap: ioctl(SIOCDIFADDR, %s): %s\n",
                  inet_ntoa(addr->ifa), strerror(errno));
@@ -256,7 +257,7 @@ int
 iface_inAdd(struct iface *iface, struct in_addr ifa, struct in_addr mask,
             struct in_addr brd, int how)
 {
-  int slot, s;
+  int slot, s, chg;
   struct ifaliasreq ifra;
   struct sockaddr_in *me, *peer, *msk;
   struct iface_addr *addr;
@@ -284,27 +285,76 @@ iface_inAdd(struct iface *iface, struct in_addr ifa, struct in_addr mask,
     return 0;
   }
 
+  /*
+   * We've gotta be careful here.  If we try to add an address with the
+   * same destination as an existing interface, nothing will work.
+   * Instead, we tweak all previous address entries that match the
+   * to-be-added destination to 255.255.255.255 (w/ a similar netmask).
+   * There *may* be more than one - if the user has ``iface add''ed
+   * stuff previously.
+   */
+  for (chg = 0; chg < iface->in_addrs; chg++) {
+    if ((iface->in_addr[chg].brd.s_addr == brd.s_addr &&
+         brd.s_addr != INADDR_BROADCAST) || chg == slot) {
+      memset(&ifra, '\0', sizeof ifra);
+      strncpy(ifra.ifra_name, iface->name, sizeof ifra.ifra_name - 1);
+      me = (struct sockaddr_in *)&ifra.ifra_addr;
+      msk = (struct sockaddr_in *)&ifra.ifra_mask;
+      peer = (struct sockaddr_in *)&ifra.ifra_broadaddr;
+      me->sin_family = msk->sin_family = peer->sin_family = AF_INET;
+      me->sin_len = msk->sin_len = peer->sin_len = sizeof(struct sockaddr_in);
+      me->sin_addr = iface->in_addr[chg].ifa;
+      msk->sin_addr = iface->in_addr[chg].mask;
+      peer->sin_addr = iface->in_addr[chg].brd;
+      log_Printf(LogDEBUG, "Delete %s\n", inet_ntoa(me->sin_addr));
+      ID0ioctl(s, SIOCDIFADDR, &ifra);	/* Don't care if it fails... */
+      if (chg != slot) {
+        peer->sin_addr.s_addr = iface->in_addr[chg].brd.s_addr =
+          msk->sin_addr.s_addr = iface->in_addr[chg].mask.s_addr =
+            INADDR_BROADCAST;
+        iface->in_addr[chg].bits = 32;
+        log_Printf(LogDEBUG, "Add %s -> 255.255.255.255\n",
+                   inet_ntoa(me->sin_addr));
+        if (ID0ioctl(s, SIOCAIFADDR, &ifra) < 0 && errno != EEXIST) {
+          /* Oops - that's bad(ish) news !  We've lost an alias ! */
+          log_Printf(LogERROR, "iface_inAdd: ioctl(SIOCAIFADDR): %s: %s\n",
+               inet_ntoa(me->sin_addr), strerror(errno));
+          iface->in_addrs--;
+          bcopy(iface->in_addr + chg + 1, iface->in_addr + chg,
+                (iface->in_addrs - chg) * sizeof iface->in_addr[0]);
+          if (slot > chg)
+            slot--;
+          chg--;
+        }
+      }
+    }
+  }
+
   memset(&ifra, '\0', sizeof ifra);
   strncpy(ifra.ifra_name, iface->name, sizeof ifra.ifra_name - 1);
-
   me = (struct sockaddr_in *)&ifra.ifra_addr;
   msk = (struct sockaddr_in *)&ifra.ifra_mask;
   peer = (struct sockaddr_in *)&ifra.ifra_broadaddr;
-
   me->sin_family = msk->sin_family = peer->sin_family = AF_INET;
   me->sin_len = msk->sin_len = peer->sin_len = sizeof(struct sockaddr_in);
-
   me->sin_addr = ifa;
   msk->sin_addr = mask;
   peer->sin_addr = brd;
 
-  /*
-   * Note: EEXIST is sometimes returned, despite the route actually being
-   *       added !
-   */
-  if (ID0ioctl(s, SIOCAIFADDR, &ifra) < 0 && errno != EEXIST) {
-    log_Printf(LogERROR, "iface_inAdd: ioctl(SIOCAIFADDR): %s\n",
-               strerror(errno));
+  if (log_IsKept(LogDEBUG)) {
+    char buf[16];
+
+    strncpy(buf, inet_ntoa(brd), sizeof buf-1);
+    buf[sizeof buf - 1] = '\0';
+    log_Printf(LogDEBUG, "Add %s -> %s\n", inet_ntoa(ifa), buf);
+  }
+
+  /* An EEXIST failure w/ brd == INADDR_BROADCAST is ok (and works!) */
+  if (ID0ioctl(s, SIOCAIFADDR, &ifra) < 0 &&
+      (brd.s_addr != INADDR_BROADCAST || errno != EEXIST)) {
+    log_Printf(LogERROR, "iface_inAdd: ioctl(SIOCAIFADDR): %s: %s\n",
+               inet_ntoa(ifa), strerror(errno));
+    ID0ioctl(s, SIOCDIFADDR, &ifra);	/* EEXIST ? */
     close(s);
     return 0;
   }
diff --git a/usr.sbin/ppp/ppp.8 b/usr.sbin/ppp/ppp.8
index de37467..80e1832 100644
--- a/usr.sbin/ppp/ppp.8
+++ b/usr.sbin/ppp/ppp.8
@@ -1,4 +1,4 @@
-.\" $Id: ppp.8,v 1.126 1998/09/18 23:28:10 brian Exp $
+.\" $Id: ppp.8,v 1.127 1998/10/22 02:32:49 brian Exp $
 .Dd 20 September 1995
 .Os FreeBSD
 .Dt PPP 8
@@ -2488,7 +2488,7 @@ This command is used to control the interface used by
 .Ar Command
 may be one of the following:
 .Bl -tag -width XX
-.It iface add[!] Ar addr[/bits| mask] peer
+.It iface add[!] Ar addr[[/bits| mask] peer]
 Add the given
 .Ar addr mask peer
 combination to the interface.  Instead of specifying
@@ -2500,6 +2500,20 @@ If the given address already exists, the command fails unless the
 .Dq \&!
 is used - in which case the previous interface address entry is overwritten
 with the new one, allowing a change of netmask or peer address.
+.Pp
+If only
+.Ar addr
+is specified,
+.Ar bits
+defaults to
+.Dq 32
+and
+.Ar peer
+defaults to
+.Dq 255.255.255.255 .
+This address (the broadcast address) is the only duplicate peer address that
+.Nm
+allows.
 .It iface clear
 If this command is used while
 .Nm
diff --git a/usr.sbin/ppp/ppp.8.m4 b/usr.sbin/ppp/ppp.8.m4
index de37467..80e1832 100644
--- a/usr.sbin/ppp/ppp.8.m4
+++ b/usr.sbin/ppp/ppp.8.m4
@@ -1,4 +1,4 @@
-.\" $Id: ppp.8,v 1.126 1998/09/18 23:28:10 brian Exp $
+.\" $Id: ppp.8,v 1.127 1998/10/22 02:32:49 brian Exp $
 .Dd 20 September 1995
 .Os FreeBSD
 .Dt PPP 8
@@ -2488,7 +2488,7 @@ This command is used to control the interface used by
 .Ar Command
 may be one of the following:
 .Bl -tag -width XX
-.It iface add[!] Ar addr[/bits| mask] peer
+.It iface add[!] Ar addr[[/bits| mask] peer]
 Add the given
 .Ar addr mask peer
 combination to the interface.  Instead of specifying
@@ -2500,6 +2500,20 @@ If the given address already exists, the command fails unless the
 .Dq \&!
 is used - in which case the previous interface address entry is overwritten
 with the new one, allowing a change of netmask or peer address.
+.Pp
+If only
+.Ar addr
+is specified,
+.Ar bits
+defaults to
+.Dq 32
+and
+.Ar peer
+defaults to
+.Dq 255.255.255.255 .
+This address (the broadcast address) is the only duplicate peer address that
+.Nm
+allows.
 .It iface clear
 If this command is used while
 .Nm