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mavlink_main: fix broadcast computation

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The way the broadcast IP is currently fetched is by sending an ioctl()
request. The limitation of this is that the broadcast address may not
be set on the network interface (more specifically, it is usually not
set in docker containers). In those cases, it results in the broadcast
address becoming 0.0.0.0, which is not valid [1].

This fix uses the network IP and the netmask to compute the directed
broadcast address. This should be more reliable, as both of those are
always set on the network interface.

[1]: https://tools.ietf.org/html/rfc1122, section 3.2.1.3 (a)
This commit is contained in:
Jonas Vautherin
2018-01-21 14:58:04 +01:00
committed by Lorenz Meier
parent 463217a5f9
commit 38c949731f
2 changed files with 38 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/modules/mavlink/mavlink_main.cpp
+30 -24
View File
@@ -56,10 +56,6 @@
#include <termios.h>
#include <time.h>
#ifdef __PX4_POSIX
#include <net/if.h>
#endif
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
@@ -1121,7 +1117,6 @@ Mavlink::find_broadcast_address()
offset += sizeof(struct ifreq)
#endif
) {
// Point to next network interface in buffer.
cur_ifreq = (struct ifreq *) & (((uint8_t *)ifconf.ifc_req)[offset]);
@@ -1136,19 +1131,6 @@ Mavlink::find_broadcast_address()
continue;
}
struct ifreq bc_ifreq;
memset(&bc_ifreq, 0, sizeof(bc_ifreq));
strncpy(bc_ifreq.ifr_name, cur_ifreq->ifr_name, IF_NAMESIZE);
ret = ioctl(_socket_fd, SIOCGIFBRDADDR, &bc_ifreq);
if (ret != 0) {
PX4_DEBUG("getting broadcast address failed for %s", cur_ifreq->ifr_name);
continue;
}
struct in_addr &sin_addr = ((struct sockaddr_in *)&cur_ifreq->ifr_addr)->sin_addr;
// Accept network interfaces to local network only. This means it's an IP starting with:
@@ -1162,19 +1144,21 @@ Mavlink::find_broadcast_address()
}
if (!_broadcast_address_found) {
PX4_INFO("using network interface %s, IP: %s", cur_ifreq->ifr_name, inet_ntoa(sin_addr));
const struct in_addr netmask_addr = query_netmask_addr(_socket_fd, *cur_ifreq);
const struct in_addr broadcast_addr = compute_broadcast_addr(sin_addr, netmask_addr);
struct in_addr &bc_addr = ((struct sockaddr_in *)&bc_ifreq.ifr_broadaddr)->sin_addr;
PX4_INFO("with broadcast IP: %s", inet_ntoa(bc_addr));
PX4_INFO("using network interface %s, IP: %s", cur_ifreq->ifr_name, inet_ntoa(sin_addr));
PX4_INFO("with netmask: %s", inet_ntoa(netmask_addr));
PX4_INFO("and broadcast IP: %s", inet_ntoa(broadcast_addr));
_bcast_addr.sin_family = AF_INET;
_bcast_addr.sin_addr = bc_addr;
_bcast_addr.sin_addr = broadcast_addr;
_broadcast_address_found = true;
} else {
PX4_INFO("ignoring additional network interface %s, IP: %s",
cur_ifreq->ifr_name, inet_ntoa(sin_addr));
PX4_DEBUG("ignoring additional network interface %s, IP: %s",
cur_ifreq->ifr_name, inet_ntoa(sin_addr));
}
}
@@ -1201,6 +1185,28 @@ Mavlink::find_broadcast_address()
#endif
}
#ifdef __PX4_POSIX
const in_addr
Mavlink::query_netmask_addr(const int socket_fd, const ifreq &ifreq)
{
struct ifreq netmask_ifreq;
memset(&netmask_ifreq, 0, sizeof(netmask_ifreq));
strncpy(netmask_ifreq.ifr_name, ifreq.ifr_name, IF_NAMESIZE);
ioctl(socket_fd, SIOCGIFNETMASK, &netmask_ifreq);
return ((struct sockaddr_in *)&netmask_ifreq.ifr_addr)->sin_addr;
}
const in_addr
Mavlink::compute_broadcast_addr(const in_addr &host_addr, const in_addr &netmask_addr)
{
struct in_addr broadcast_addr;
broadcast_addr.s_addr = ~netmask_addr.s_addr | host_addr.s_addr;
return broadcast_addr;
}
#endif
void
Mavlink::init_udp()
{
src/modules/mavlink/mavlink_main.h
+8
View File
@@ -59,6 +59,10 @@
#include <systemlib/mavlink_log.h>
#include <drivers/device/ringbuffer.h>
#ifdef __PX4_POSIX
#include <net/if.h>
#endif
#include <uORB/uORB.h>
#include <uORB/topics/mission.h>
#include <uORB/topics/mission_result.h>
@@ -417,6 +421,10 @@ public:
int get_socket_fd() { return _socket_fd; };
#ifdef __PX4_POSIX
const in_addr query_netmask_addr(const int socket_fd, const ifreq &ifreq);
const in_addr compute_broadcast_addr(const in_addr &host_addr, const in_addr &netmask_addr);
struct sockaddr_in *get_client_source_address() { return &_src_addr; }
void set_client_source_initialized() { _src_addr_initialized = true; }