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udp: add core-level multicast support for IPv6

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So far, the UDP core module implemented only IPv4 multicast support.
This patch extends the module with the features necessary for socket
layers on top to implement IPv6 multicast support as well:

o If a UDP PCB is bound to an IPv6 multicast address, a unicast source
  address is selected and used to send the packet instead, as is
  required (and was the case for IPv4 multicast already).

o Unlike IPv4's IP_MULTICAST_IF socket option, which takes a source
  IPv4 address, the IPV6_MULTICAST_IF socket option (from RFC 3493)
  takes an interface identifier to denote the interface to use for
  outgoing multicast-destined packets. A new pair of UDP PCB API
  calls, udp_[gs]et_multicast_netif_index(), are added to support
  this. The new definition "NETIF_NO_INDEX" may be used to indicate
  that lwIP should pick an interface instead.

  IPv4 socket implementations may now also choose to map the given
  source address to an interface index immediately and use the new
  facility instead of the old udp_[gs]et_multicast_netif_addr() one.
  A side effect of limiting the old facility to IPv4 is that for dual-
  stack configurations with multicast support, the UDP PCB size is
  reduced by (up to) 16 bytes.

o For configurations that enable loopback interface support, the IPv6
  code now also supports multicast loopback (IPV6_MULTICAST_LOOP).

o The LWIP_MULTICAST_TX_OPTIONS opt.h setting now covers both IPv4
  and IPv6, and as such is no longer strictly linked to IGMP. It is
  therefore placed in its own lwIP options subgroup in opt.h.

The IPV6_MULTICAST_HOPS socket option can already be implemented using
the existing IP_MULTICAST_TTL support, and thus requires no additional
changes. Overall, this patch should not break any existing code.
This commit is contained in:
David van Moolenbroek
2017-02-06 14:12:37 +00:00
committed by Dirk Ziegelmeier
parent 4a9db56f4c
commit ab8119360e
7 changed files with 90 additions and 41 deletions
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5
src/core/init.c
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@@ -96,7 +96,7 @@ PACK_STRUCT_END
#error "If you want to use DHCP, you have to define LWIP_UDP=1 in your lwipopts.h"
#endif
#if (!LWIP_UDP && LWIP_MULTICAST_TX_OPTIONS)
#error "If you want to use IGMP/LWIP_MULTICAST_TX_OPTIONS, you have to define LWIP_UDP=1 in your lwipopts.h"
#error "If you want to use LWIP_MULTICAST_TX_OPTIONS, you have to define LWIP_UDP=1 in your lwipopts.h"
#endif
#if (!LWIP_UDP && LWIP_DNS)
#error "If you want to use DNS, you have to define LWIP_UDP=1 in your lwipopts.h"
@@ -123,9 +123,6 @@ PACK_STRUCT_END
#if (LWIP_IGMP && !LWIP_IPV4)
#error "IGMP needs LWIP_IPV4 enabled in your lwipopts.h"
#endif
#if (LWIP_MULTICAST_TX_OPTIONS && !LWIP_IPV4)
#error "LWIP_MULTICAST_TX_OPTIONS needs LWIP_IPV4 enabled in your lwipopts.h"
#endif
#if ((LWIP_NETCONN || LWIP_SOCKET) && (MEMP_NUM_TCPIP_MSG_API<=0))
#error "If you want to use Sequential API, you have to define MEMP_NUM_TCPIP_MSG_API>=1 in your lwipopts.h"
#endif