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mavlink: look up broadcast address, don't guess it

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This commit is contained in:
Julian Oes
2016-03-29 17:35:28 +02:00
committed by Lorenz Meier
parent a7e9bc8ba5
commit 56585082ec
1 changed files with 15 additions and 19 deletions
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34
src/modules/mavlink/mavlink_main.cpp
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@@ -1016,6 +1016,16 @@ Mavlink::init_udp()
continue;
}
struct ifreq bc_ifreq;
memset(&bc_ifreq, 0, sizeof(bc_ifreq));
strncpy(bc_ifreq.ifr_name, ifreqs[i].ifr_name, IF_NAMESIZE);
ret = ioctl(_socket_fd, SIOCGIFBRDADDR, &bc_ifreq);
if (ret != 0) {
PX4_WARN("getting broadcast address failed");
return;
}
struct in_addr &sin_addr = ((struct sockaddr_in *)&ifreqs[i].ifr_addr)->sin_addr;
// Accept network interfaces to local network only. This means it's an IP starting with:
@@ -1023,33 +1033,19 @@ Mavlink::init_udp()
// Also see https://tools.ietf.org/html/rfc1918#section-3
uint8_t first_byte = sin_addr.s_addr & 0xFF;
int32_t subnet_mask = 0x0;
if (first_byte == 192) {
// /24
subnet_mask = 0xFFFFFF;
} else if (first_byte != 172) {
// /16
subnet_mask = 0xFFFF;
} else if (first_byte != 10) {
// /8
subnet_mask = 0xFF;
} else {
// Ignore anything else.
if (first_byte != 192 && first_byte != 172 && first_byte != 10) {
continue;
}
if (!network_interface_found) {
PX4_INFO("using network interface %s, IP: %s", ifreqs[i].ifr_name, inet_ntoa(sin_addr));
_bcast_addr.sin_family = AF_INET;
struct in_addr &bc_addr = ((struct sockaddr_in *)&bc_ifreq.ifr_broadaddr)->sin_addr;
PX4_INFO("with broadcast IP: %s", inet_ntoa(bc_addr));
// Assemble the broadcast address. This should be done using the default gateway IP
// instead of the IP. However, for most cases, this should work.
_bcast_addr.sin_addr.s_addr = (~subnet_mask) | sin_addr.s_addr;
PX4_INFO("broadcast address should be: %s", inet_ntoa(_bcast_addr.sin_addr));
_bcast_addr.sin_family = AF_INET;
_bcast_addr.sin_addr = bc_addr;
network_interface_found = true;
} else {