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Fix for GitHub issue #37: remember *nix device names.

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This commit is contained in:
Adam Ierymenko 2014-02-11 14:21:59 -08:00
commit 3f912eb4ad
4 changed files with 65 additions and 21 deletions
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47
node/EthernetTap.cpp
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@ -234,6 +234,7 @@ EthernetTap::EthernetTap(
_fd(0)
{
char procpath[128];
struct stat sbuf;
Mutex::Lock _l(__tapCreateLock); // create only one tap at a time, globally
if (mtu > 4096)
@ -246,13 +247,19 @@ EthernetTap::EthernetTap(
struct ifreq ifr;
memset(&ifr,0,sizeof(ifr));
{ // pick an unused device name
// Try to recall our last device name, or pick an unused one if that fails.
bool recalledDevice = false;
if ((tag)&&(tag[0])) {
Utils::scopy(ifr.ifr_name,sizeof(ifr.ifr_name),tag);
Utils::snprintf(procpath,sizeof(procpath),"/proc/sys/net/ipv4/conf/%s",ifr.fr_name);
recalledDevice = (stat(procpath,&sbuf) != 0);
}
if (!recalledDevice) {
int devno = 0;
struct stat sbuf;
do {
Utils::snprintf(ifr.ifr_name,sizeof(ifr.ifr_name),"zt%d",devno++);
Utils::snprintf(procpath,sizeof(procpath),"/proc/sys/net/ipv4/conf/%s",ifr.ifr_name);
} while (stat(procpath,&sbuf) == 0);
} while (stat(procpath,&sbuf) == 0); // try zt#++ until we find one that does not exist
}
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
@ -359,17 +366,33 @@ EthernetTap::EthernetTap(
if (stat("/dev/zt0",&stattmp))
throw std::runtime_error("/dev/zt# tap devices do not exist and unable to load kernel extension");
// Open the first available device (ones in use will fail with resource busy)
for(int i=0;i<256;++i) {
Utils::snprintf(devpath,sizeof(devpath),"/dev/zt%d",i);
if (stat(devpath,&stattmp))
throw std::runtime_error("no more TAP devices available");
_fd = ::open(devpath,O_RDWR);
if (_fd > 0) {
Utils::snprintf(_dev,sizeof(_dev),"zt%d",i);
break;
// Try to reopen the last device we had, if we had one and it's still unused.
bool recalledDevice = false;
if ((tag)&&(tag[0])) {
Utils::snprintf(devpath,sizeof(devpath),"/dev/%s",tag);
if (stat(devpath,&stattmp) == 0) {
_fd = ::open(devpath,O_RDWR);
if (_fd > 0) {
Utils::scopy(_dev,sizeof(_dev),tag);
recalledDevice = true;
}
}
}
// Open the first unused tap device if we didn't recall a previous one.
if (!recalledDevice) {
for(int i=0;i<256;++i) {
Utils::snprintf(devpath,sizeof(devpath),"/dev/zt%d",i);
if (stat(devpath,&stattmp))
throw std::runtime_error("no more TAP devices available");
_fd = ::open(devpath,O_RDWR);
if (_fd > 0) {
Utils::snprintf(_dev,sizeof(_dev),"zt%d",i);
break;
}
}
}
if (_fd <= 0)
throw std::runtime_error("unable to open TAP device or no more devices available");