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Another possible workaround for what seems to be a Linux bug in some newer kernels.

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This commit is contained in:
Adam Ierymenko 2020-11-11 14:42:56 -05:00
parent d735a1d04c
commit 2d489a8679
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GPG Key ID: C8877CF2D7A5D7F3
1 changed files with 31 additions and 30 deletions
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61
osdep/LinuxEthernetTap.cpp
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@ -166,31 +166,39 @@ LinuxEthernetTap::LinuxEthernetTap(
throw std::runtime_error("unable to configure TUN/TAP device for TAP operation");
}
_dev = ifr.ifr_name;
::ioctl(_fd,TUNSETPERSIST,0); // valgrind may generate a false alarm here
int sock = socket(AF_INET,SOCK_DGRAM,0);
const int sock = socket(AF_INET,SOCK_DGRAM,0);
if (sock <= 0) {
::close(_fd);
throw std::runtime_error("unable to open netlink socket");
}
if (fcntl(_fd,F_SETFL,fcntl(_fd,F_GETFL) & ~O_NONBLOCK) == -1) {
::close(_fd);
throw std::runtime_error("unable to set flags on file descriptor for TAP device");
}
_dev = ifr.ifr_name;
if (ioctl(sock,SIOCGIFFLAGS,(void *)&ifr) < 0) {
::close(_fd);
::close(sock);
throw std::runtime_error("unable to get TAP interface flags");
}
ifr.ifr_flags |= IFF_UP;
if (ioctl(sock,SIOCSIFFLAGS,(void *)&ifr) < 0) {
::close(_fd);
::close(sock);
throw std::runtime_error("unable to set TAP interface flags");
// Set/check loop is a workaround for a weird likely kernel bug in which
// the interface doesn't come up right away when set to up. This causes
// settings like the MAC address to not "take."
for(;;) {
if (ioctl(sock,SIOCGIFFLAGS,(void *)&ifr) < 0) {
::close(_fd);
::close(sock);
throw std::runtime_error("unable to get TAP interface flags");
}
ifr.ifr_flags |= IFF_UP;
if (ioctl(sock,SIOCSIFFLAGS,(void *)&ifr) < 0) {
::close(_fd);
::close(sock);
throw std::runtime_error("unable to bring up TAP interface");
}
if (ioctl(sock,SIOCGIFFLAGS,(void *)&ifr) < 0) {
::close(_fd);
::close(sock);
throw std::runtime_error("unable to get TAP interface flags");
}
usleep(1000);
if ((ifr.ifr_flags & IFF_UP) != 0)
break;
}
ifr.ifr_ifru.ifru_hwaddr.sa_family = ARPHRD_ETHER;
@ -201,6 +209,7 @@ LinuxEthernetTap::LinuxEthernetTap(
throw std::runtime_error("unable to configure TAP hardware (MAC) address");
return;
}
ifr.ifr_ifru.ifru_mtu = (int)mtu;
if (ioctl(sock,SIOCSIFMTU,(void *)&ifr) < 0) {
::close(_fd);
@ -208,6 +217,11 @@ LinuxEthernetTap::LinuxEthernetTap(
throw std::runtime_error("unable to configure TAP MTU");
}
if (fcntl(_fd,F_SETFL,fcntl(_fd,F_GETFL) & ~O_NONBLOCK) == -1) {
::close(_fd);
throw std::runtime_error("unable to set flags on file descriptor for TAP device");
}
::close(sock);
// Set close-on-exec so that devices cannot persist if we fork/exec for update
@ -215,19 +229,6 @@ LinuxEthernetTap::LinuxEthernetTap(
(void)::pipe(_shutdownSignalPipe);
/*
globalDeviceMap[nwids] = _dev;
devmapf = fopen((_homePath + ZT_PATH_SEPARATOR_S + "devicemap").c_str(),"w");
if (devmapf) {
gdmEntry = globalDeviceMap.begin();
while (gdmEntry != globalDeviceMap.end()) {
fprintf(devmapf,"%s=%s\n",gdmEntry->first.c_str(),gdmEntry->second.c_str());
++gdmEntry;
}
fclose(devmapf);
}
*/
_thread = Thread::start(this);
}