[LXC] Add functions to manage veth device pairs

This gives us the ability to create a veth pair so that we can move one
into the network namespace of an LXC container.
This commit is contained in:
Dan Smith 2008-06-26 16:07:48 +00:00
parent 99ded85f45
commit e59eb52fad
3 changed files with 244 additions and 0 deletions

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@ -64,6 +64,7 @@ CLIENT_SOURCES = \
lxc_driver.c lxc_driver.h \
lxc_conf.c lxc_conf.h \
lxc_container.c lxc_container.h \
veth.c veth.h \
nodeinfo.h nodeinfo.c \
util.c util.h

219
src/veth.c Normal file
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@ -0,0 +1,219 @@
/*
* veth.c: Tools for managing veth pairs
*
* Copyright IBM Corp. 2008
*
* See COPYING.LIB for the License of this software
*
* Authors:
* David L. Leskovec <dlesko at linux.vnet.ibm.com>
*/
#include <config.h>
#include <string.h>
#include "veth.h"
#include "internal.h"
#include "memory.h"
#include "util.h"
#define DEBUG(fmt,...) VIR_DEBUG(__FILE__, fmt, __VA_ARGS__)
#define DEBUG0(msg) VIR_DEBUG(__FILE__, "%s", msg)
/* Functions */
/**
* getFreeVethName:
* @veth: name for veth device (NULL to find first open)
* @maxLen: max length of veth name
* @startDev: device number to start at (x in vethx)
*
* Looks in /sys/class/net/ to find the first available veth device
* name.
*
* Returns 0 on success or -1 in case of error
*/
static int getFreeVethName(char *veth, int maxLen, int startDev)
{
int rc = -1;
int devNum = startDev;
char path[PATH_MAX];
do {
snprintf(path, PATH_MAX, "/sys/class/net/veth%d/", devNum);
++devNum;
} while (virFileExists(path));
snprintf(veth, maxLen, "veth%d", devNum);
rc = devNum;
return rc;
}
/**
* vethCreate:
* @veth1: name for one end of veth pair
* @veth1MaxLen: max length of veth1 name
* @veth2: name for one end of veth pair
* @veth2MaxLen: max length of veth1 name
*
* Creates a veth device pair using the ip command:
* ip link add veth1 type veth peer name veth2
* NOTE: If veth1 and veth2 names are not specified, ip will auto assign
* names. There seems to be two problems here -
* 1) There doesn't seem to be a way to determine the names of the
* devices that it creates. They show up in ip link show and
* under /sys/class/net/ however there is no guarantee that they
* are the devices that this process just created.
* 2) Once one of the veth devices is moved to another namespace, it
* is no longer visible in the parent namespace. This seems to
* confuse the name assignment causing it to fail with File exists.
* Because of these issues, this function currently forces the caller
* to fully specify the veth device names.
*
* Returns 0 on success or -1 in case of error
*/
int vethCreate(char* veth1, int veth1MaxLen,
char* veth2, int veth2MaxLen)
{
int rc = -1;
const char *argv[] = {
"ip", "link", "add", veth1, "type", "veth", "peer", "name", veth2, NULL
};
int cmdResult;
int vethDev = 0;
if ((NULL == veth1) || (NULL == veth2)) {
goto error_out;
}
DEBUG("veth1: %s veth2: %s", veth1, veth2);
if (1 > strlen(veth1)) {
vethDev = getFreeVethName(veth1, veth1MaxLen, 0);
++vethDev;
DEBUG("assigned veth1: %s", veth1);
}
if (1 > strlen(veth2)) {
vethDev = getFreeVethName(veth2, veth2MaxLen, vethDev);
DEBUG("assigned veth2: %s", veth2);
}
rc = virRun(NULL, (char**)argv, &cmdResult);
if (0 == rc) {
rc = cmdResult;
}
error_out:
return rc;
}
/**
* vethDelete:
* @veth: name for one end of veth pair
*
* This will delete both veth devices in a pair. Only one end needs to
* be specified. The ip command will identify and delete the other veth
* device as well.
* ip link del veth
*
* Returns 0 on success or -1 in case of error
*/
int vethDelete(const char *veth)
{
int rc = -1;
const char *argv[] = {"ip", "link", "del", veth, NULL};
int cmdResult;
if (NULL == veth) {
goto error_out;
}
DEBUG("veth: %s", veth);
rc = virRun(NULL, (char**)argv, &cmdResult);
if (0 == rc) {
rc = cmdResult;
}
error_out:
return rc;
}
/**
* vethInterfaceUpOrDown:
* @veth: name of veth device
* @upOrDown: 0 => down, 1 => up
*
* Enables a veth device using the ifconfig command. A NULL inetAddress
* will cause it to be left off the command line.
*
* Returns 0 on success or -1 in case of error
*/
int vethInterfaceUpOrDown(const char* veth, int upOrDown)
{
int rc = -1;
const char *argv[] = {"ifconfig", veth, NULL, NULL};
int cmdResult;
if (NULL == veth) {
goto error_out;
}
if (0 == upOrDown)
argv[2] = "down";
else
argv[2] = "up";
rc = virRun(NULL, (char**)argv, &cmdResult);
if (0 == rc) {
rc = cmdResult;
}
error_out:
return rc;
}
/**
* moveInterfaceToNetNs:
* @interface: name of device
* @pidInNs: PID of process in target net namespace
*
* Moves the given device into the target net namespace specified by the given
* pid using this command:
* ip link set interface netns pidInNs
*
* Returns 0 on success or -1 in case of error
*/
int moveInterfaceToNetNs(const char* interface, int pidInNs)
{
int rc;
/* offset of the pid field in the following args */
char *pid = NULL;
const char *argv[] = {
"ip", "link", "set", interface, "netns", NULL, NULL
};
int cmdResult;
int len;
if (NULL == interface) {
goto error_out;
}
if (asprintf(&pid, "%d", pidInNs) == -1)
goto error_out;
argv[5] = pid;
rc = virRun(NULL, (char**)argv, &cmdResult);
if (0 == rc)
rc = cmdResult;
error_out:
VIR_FREE(pid);
return rc;
}

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src/veth.h Normal file
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/*
* veth.h: Interface to tools for managing veth pairs
*
* Copyright IBM Corp. 2008
*
* See COPYING.LIB for the License of this software
*
* Authors:
* David L. Leskovec <dlesko at linux.vnet.ibm.com>
*/
#ifndef VETH_H
#define VETH_H
#include <config.h>
/* Function declarations */
int vethCreate(char* veth1, int veth1MaxLen, char* veth2,
int veth2MaxLen);
int vethDelete(const char* veth);
int vethInterfaceUpOrDown(const char* veth, int upOrDown);
int moveInterfaceToNetNs(const char *interface, int pidInNs);
#endif /* VETH_H */