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coap_io.c: select outbound interface when responding to multicast requests

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coap_network_send() uses the address given by local_interface as
source address of outgoing IP packets. For responses to requests
that have been received via IP multicast, this address is a
multicast group and thus must not be set as source in the IP header.

As a workaround, this change clears the address and ifindex so that
the kernel selects a suitable outbound interface.
This commit is contained in:
Olaf Bergmann committed 2015-06-10 17:59:52 +02:00
1 parent d989bb174c
commit 91f37ae1a7
1 file changed
+22 -7
Download Patch File Download Diff File Expand all files Collapse all files
src/coap_io.c
+22 -7
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@@ -271,9 +271,17 @@ coap_network_send(struct coap_context_t *context UNUSED_PARAM,
memset(pktinfo, 0, sizeof(struct in6_pktinfo));
pktinfo->ipi6_ifindex = ep->ifindex;
memcpy(&pktinfo->ipi6_addr,
&local_interface->addr.addr.sin6.sin6_addr,
local_interface->addr.size);
if (coap_is_mcast(&local_interface->addr)) {
/* We cannot send with multicast address as source address
* and hence let the kernel pick the outgoing interface. */
pktinfo->ipi6_ifindex = 0;
memset(&pktinfo->ipi6_addr, 0, sizeof(pktinfo->ipi6_addr));
} else {
pktinfo->ipi6_ifindex = ep->ifindex;
memcpy(&pktinfo->ipi6_addr,
&local_interface->addr.addr.sin6.sin6_addr,
local_interface->addr.size);
}
break;
}
case AF_INET: {
@@ -291,10 +299,17 @@ coap_network_send(struct coap_context_t *context UNUSED_PARAM,
pktinfo = (struct in_pktinfo *)CMSG_DATA(cmsg);
memset(pktinfo, 0, sizeof(struct in_pktinfo));
pktinfo->ipi_ifindex = ep->ifindex;
memcpy(&pktinfo->ipi_spec_dst,
&local_interface->addr.addr.sin.sin_addr,
local_interface->addr.size);
if (coap_is_mcast(&local_interface->addr)) {
/* We cannot send with multicast address as source address
* and hence let the kernel pick the outgoing interface. */
pktinfo->ipi_ifindex = 0;
memset(&pktinfo->ipi_spec_dst, 0, sizeof(pktinfo->ipi_spec_dst));
} else {
pktinfo->ipi_ifindex = ep->ifindex;
memcpy(&pktinfo->ipi_spec_dst,
&local_interface->addr.addr.sin.sin_addr,
local_interface->addr.size);
}
break;
}
default: