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mavlink: adapt network detection for Mac, use heap

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It seems that Mac does not support the ioctl to check how big the ifconf
buffer needs to be. Therefore we just have to make a guess.
Alos, instead of allocating the variable size array on the stack, it's
probably safer to use the heap.
This commit is contained in:
Julian Oes
2016-04-08 09:41:10 +02:00
parent 20cd5f3e76
commit ae2c28677d
1 changed files with 29 additions and 24 deletions
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55
src/modules/mavlink/mavlink_main.cpp
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@@ -998,35 +998,47 @@ Mavlink::init_udp()
}
_src_addr.sin_port = htons(_remote_port);
// Find out the required size of the buffer first.
// We can get the number by providing NULL to ifc_req.
struct ifconf ifconf;
int ret;
#if defined(__APPLE__) && defined(__MACH__)
// On Mac, we can't determine the required buffer
// size in advance, so we just use what tends to work.
ifconf.ifc_len = 1024;
#else
// On Linux, we can determine the required size of the
// buffer first by providing NULL to ifc_req.
ifconf.ifc_req = NULL;
ifconf.ifc_len = 0;
int ret = ioctl(_socket_fd, SIOCGIFCONF, &ifconf);
ret = ioctl(_socket_fd, SIOCGIFCONF, &ifconf);
if (ret != 0) {
PX4_WARN("getting required buffer size failed");
return;
}
#endif
PX4_DEBUG("need to allocate %d bytes", ifconf.ifc_len);
// Allocate buffer as long as needed.
uint8_t ifreqs_buf[ifconf.ifc_len];
memset(ifreqs_buf, 0, ifconf.ifc_len);
ifconf.ifc_req = (struct ifreq *)ifreqs_buf;
// Allocate buffer.
ifconf.ifc_req = (struct ifreq *)(new uint8_t[ifconf.ifc_len]);
if (ifconf.ifc_req == nullptr) {
PX4_ERR("Could not allocate ifconf buffer");
return;
}
memset(ifconf.ifc_req, 0, ifconf.ifc_len);
ret = ioctl(_socket_fd, SIOCGIFCONF, &ifconf);
if (ret != 0) {
PX4_WARN("getting network config failed");
PX4_ERR("getting network config failed");
delete[] ifconf.ifc_req;
return;
}
size_t offset = 0;
// Later used to point to next network interface in buffer.
struct ifreq *cur_ifreq = (struct ifreq *)&ifreqs_buf[offset];
struct ifreq *cur_ifreq = (struct ifreq *)&(((uint8_t *)ifconf.ifc_req)[offset]);
// The ugly `for` construct is used because it allows to use
// `continue` and `break`.
@@ -1038,8 +1050,7 @@ Mavlink::init_udp()
// sizeof sockaddr or ifr_addr.sa_len.
offset += IF_NAMESIZE
+ (sizeof(struct sockaddr) > cur_ifreq->ifr_addr.sa_len ?
sizeof(struct sockaddr) :
cur_ifreq->ifr_addr.sa_len)
sizeof(struct sockaddr) : cur_ifreq->ifr_addr.sa_len)
#else
// On Linux, it's much easier to traverse the buffer, every entry
// has the constant length.
@@ -1048,14 +1059,7 @@ Mavlink::init_udp()
) {
// Point to next network interface in buffer.
cur_ifreq = (struct ifreq *)&ifreqs_buf[offset];
#if defined(__APPLE__) && defined(__MACH__)
if (cur_ifreq->ifr_addr.sa_len == 0) {
// The current entry seems zero, we're probably through.
break;
}
#endif
cur_ifreq = (struct ifreq *)&(((uint8_t *)ifconf.ifc_req)[offset]);
PX4_DEBUG("looking at %s", cur_ifreq->ifr_name);
@@ -1073,7 +1077,7 @@ Mavlink::init_udp()
strncpy(bc_ifreq.ifr_name, cur_ifreq->ifr_name, IF_NAMESIZE);
ret = ioctl(_socket_fd, SIOCGIFBRDADDR, &bc_ifreq);
if (ret != 0) {
PX4_INFO("getting broadcast address failed for %s", cur_ifreq->ifr_name);
PX4_DEBUG("getting broadcast address failed for %s", cur_ifreq->ifr_name);
continue;
}
@@ -1105,13 +1109,14 @@ Mavlink::init_udp()
}
}
if (!_broadcast_address_found) {
PX4_WARN("no broadcasting address found");
return;
}
if (_broadcast_address_found) {
_bcast_addr.sin_port = htons(_remote_port);
} else {
PX4_WARN("no broadcasting address found");
}
delete[] ifconf.ifc_req;
#endif
}