Tried to clean up multicast handling. Now we don't try to guess

multicast abilities depending on definedness of symbols and use hard-wired
system-dependent configuration defines instead.

Please test whereever you can.

2 files changed, 119 insertions, 0 deletions

diff --git a/sysdep/linux/Modules b/sysdep/linux/Modules
index 4a99916..1b867d8 100644
--- a/sysdep/linux/Modules
+++ b/sysdep/linux/Modules
@@ -2,3 +2,4 @@
 krt-scan.c
 krt-scan.h
 #endif
+sysio.h
diff --git a/sysdep/linux/sysio.h b/sysdep/linux/sysio.h
new file mode 100644
index 0000000..bef8a61
--- /dev/null
+++ b/sysdep/linux/sysio.h
@@ -0,0 +1,118 @@
+/*
+ *	BIRD Internet Routing Daemon -- Linux Multicasting and Network Includes
+ *
+ *	(c) 1998--1999 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifdef IPV6
+#include <linux/in6.h>			/* FIXMEv6: glibc variant? */
+
+#else
+
+/*
+ *  Multicasting in Linux systems is a real mess. Not only different kernels
+ *  have different interfaces, but also different libc's export it in different
+ *  ways. Horrible.
+ */
+
+static inline char *sysio_mcast_setup(sock *s)
+{
+  int zero = 0;
+
+  if (ipa_nonzero(s->daddr))
+    {
+      if (
+#ifdef IP_DEFAULT_MULTICAST_TTL
+	  s->ttl != IP_DEFAULT_MULTICAST_TTL &&
+#endif
+	  setsockopt(s->fd, SOL_IP, IP_MULTICAST_TTL, &s->ttl, sizeof(s->ttl)) < 0)
+	return "IP_MULTICAST_TTL";
+      if (
+#ifdef IP_DEFAULT_MULTICAST_LOOP
+	  IP_DEFAULT_MULTICAST_LOOP &&
+#endif
+	  setsockopt(s->fd, SOL_IP, IP_MULTICAST_LOOP, &zero, sizeof(zero)) < 0)
+	return "IP_MULTICAST_LOOP";
+    }
+  return NULL;
+}
+
+#ifdef CONFIG_LINUX_MC_MREQN
+/*
+ *  2.1 and newer kernels use struct mreqn which passes ifindex, so no
+ *  problems with unnumbered devices.
+ */
+
+#ifndef HAVE_STRUCT_IP_MREQN
+/* Several versions of glibc don't define this structure, so we have to do it ourselves */
+struct ip_mreqn
+{
+	struct in_addr	imr_multiaddr;		/* IP multicast address of group */
+	struct in_addr	imr_address;		/* local IP address of interface */
+	int		imr_ifindex;		/* Interface index */
+};
+#endif
+
+static inline char *sysio_mcast_join(sock *s)
+{
+  struct ip_mreqn mreq;
+  char *err;
+
+  if (err = sysio_mcast_setup(s))
+    return err;
+  mreq.imr_ifindex = s->iface->index;
+  set_inaddr(&mreq.imr_address, s->iface->addr->ip);
+  set_inaddr(&mreq.imr_multiaddr, s->daddr);
+  /* This defines where should we send _outgoing_ multicasts */
+  if (setsockopt(s->fd, SOL_IP, IP_MULTICAST_IF, &mreq, sizeof(mreq)) < 0)
+    return "IP_MULTICAST_IF";
+  /* And this one sets interface for _receiving_ multicasts from */
+  if (ipa_nonzero(s->saddr) && setsockopt(s->fd, SOL_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
+    return "IP_ADD_MEMBERSHIP";
+  return NULL;
+}
+#endif
+
+#if defined(CONFIG_LINUX_MC_MREQ) || defined(CONFIG_LINUX_MC_MREQ_BIND)
+/*
+ *  Older kernels support only struct mreq which matches interfaces by their
+ *  addresses and thus fails on unnumbered devices. On newer 2.0 kernels
+ *  we can use SO_BINDTODEVICE to circumvent this problem.
+ */
+
+#include <net/if.h>
+
+static inline char *sysio_mcast_join(sock *s)
+{
+  struct in_addr mreq;
+  struct ip_mreq mreq_add;
+  char *err;
+
+  if (err = sysio_mcast_setup(s))
+    return err;
+  set_inaddr(&mreq, s->iface->addr->ip);
+#ifdef CONFIG_LINUX_MC_MREQ_BIND
+  {
+    struct ifreq ifr;
+    strcpy(ifr.ifr_name, s->iface->name);
+    if (setsockopt(s->fd, SOL_SOCKET, SO_BINDTODEVICE, &ifr, sizeof(ifr)) < 0)
+      return "SO_BINDTODEVICE";
+    mreq_add.imr_interface.s_addr = INADDR_ANY;
+  }
+#else
+  mreq_add.imr_interface = mreq;
+#endif
+  set_inaddr(&mreq_add.imr_multiaddr, s->daddr);
+  /* This defines where should we send _outgoing_ multicasts */
+  if (setsockopt(s->fd, SOL_IP, IP_MULTICAST_IF, &mreq, sizeof(mreq)) < 0)
+    return "IP_MULTICAST_IF";
+  /* And this one sets interface for _receiving_ multicasts from */
+  if (ipa_nonzero(s->saddr) && setsockopt(s->fd, SOL_IP, IP_ADD_MEMBERSHIP, &mreq_add, sizeof(mreq_add)) < 0)
+    return "IP_ADD_MEMBERSHIP";
+  return NULL;
+}
+#endif
+
+#endif