[lxc-devel] [PATCH] Add get_interfaces to the API - v2
Stéphane Graber
stgraber at ubuntu.com
Mon Sep 16 19:04:45 UTC 2013
On Mon, Sep 16, 2013 at 02:54:44PM -0400, S.Çağlar Onur wrote:
> On Mon, Sep 16, 2013 at 2:39 PM, Stéphane Graber <stgraber at ubuntu.com>wrote:
>
> > On Mon, Sep 16, 2013 at 02:26:47PM -0400, S.Çağlar Onur wrote:
> > > get_ips accepts an interface name as a parameter but there was no
> > > way to get the interfaces names from the container. This patch
> > > introduces a new get_interfaces call to the API so that users
> > > can obtain the name of the interfaces.
> > >
> > > Signed-off-by: S.Çağlar Onur <caglar at 10ur.org>
> >
> > I think I'm fine with this version:
> >
> > One quick comment though, wouldn't we expect get_interfaces() to return
> > all the interfaces by default, including loopback, including those
> > without addresses and those that aren't standard packet based IP
> > interfaces?
> >
> > I still think we don't want to list loopback addresses in get_ips(), at
> > least by default, but I think I'd expect get_interfaces to return me all
> > the existing interfaces without filtering. Does that make sense?
>
>
> Guess so. I've no objection including loopback in get_interfaces. I
> excluded it thinking that there is no point returning it as get_ips will
> ignore it. What about something like below as a replacement to v2 (this
> version starts to use if_nameindex instead of getifaddrs)?
I'd rather not use if_nameindex unless someone re-implements a bionic
version of it under lxc/includes/ as I just confirmed it doesn't exist
on bionic and so commiting that change would break our Android builds (I
know bionic is a real pain).
It took me a couple of days to find an slightly adapt a reasonable
implementation of getifaddrs for bionic, so I'd like not to have to go
through that again (but don't mind it if someone else contributes a
bionic compatible implementation).
So just to clarify what I think should happen in a perfect worls :)
1) get_interfaces() would always return all the network interfaces
visible by the guest, so I'd expect those to match the entries from
ifconfig -a (or ip link show)
2) get_ips() should default to only listing global IP addresses, so by
default ignore the loopback device and only return scope-global for
IPv6 (its current behaviour)
3) If specifically passed interface="lo", then I'd expect get_ips to
return the loopback IP addresses (not currently the case, but
probably should be the case)
Does that make sense?
>
> +static char** lxcapi_get_interfaces(struct lxc_container *c)
> +{
> + int count = 0;
> + struct if_nameindex *if_ni = NULL, *i;
> + char **interfaces = NULL, **temp;
> + int old_netns = -1, new_netns = -1;
> +
> + if (!enter_to_ns(c, &old_netns, &new_netns))
> + goto out;
> +
> + if_ni = if_nameindex();
> + if (if_ni == NULL) {
> + SYSERROR("failed to get interfaces list");
> + goto out;
> + }
> +
> + for (i = if_ni; ! (i->if_index == 0 && i->if_name == NULL); i++) {
> + count += 1;
> + temp = realloc(interfaces, count * sizeof(*interfaces));
> + if (!temp) {
> + count -= 1;
> + goto out;
> + }
> + interfaces = temp;
> + interfaces[count - 1] = strdup(i->if_name);
> + }
> +
> +out:
> + if_freenameindex(if_ni);
> +
> + exit_from_ns(c, &old_netns, &new_netns);
> +
> + /* Append NULL to the array */
> + interfaces = (char **)lxc_append_null_to_array((void **)interfaces,
> count);
> +
> + return interfaces;
> +}
>
> And if we need get_ips to return ips then I guess we can always add a flag
> to get_ips as you suggested before?
>
> > ---
> > > src/lxc/lxccontainer.c | 117
> > ++++++++++++++++++++++++++++++++++---------------
> > > src/lxc/lxccontainer.h | 1 +
> > > src/lxc/utils.c | 22 +++++++++-
> > > src/lxc/utils.h | 1 +
> > > 4 files changed, 105 insertions(+), 36 deletions(-)
> > >
> > > diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> > > index 79237df..6aa59fc 100644
> > > --- a/src/lxc/lxccontainer.c
> > > +++ b/src/lxc/lxccontainer.c
> > > @@ -1179,23 +1179,26 @@ static bool lxcapi_clear_config_item(struct
> > lxc_container *c, const char *key)
> > > return ret == 0;
> > > }
> > >
> > > -char** lxcapi_get_ips(struct lxc_container *c, char* interface, char*
> > family, int scope)
> > > -{
> > > - int count = 0;
> > > - struct ifaddrs *interfaceArray = NULL, *tempIfAddr = NULL;
> > > - char addressOutputBuffer[INET6_ADDRSTRLEN];
> > > - void *tempAddrPtr = NULL;
> > > - char **addresses = NULL, **temp;
> > > - char *address = NULL;
> > > +static inline void exit_from_ns(struct lxc_container *c, int
> > *old_netns, int *new_netns) {
> > > + /* Switch back to original netns */
> > > + if (*old_netns >= 0 && setns(*old_netns, CLONE_NEWNET))
> > > + SYSERROR("failed to setns");
> > > + if (*new_netns >= 0)
> > > + close(*new_netns);
> > > + if (*old_netns >= 0)
> > > + close(*old_netns);
> > > +}
> > > +
> > > +static inline bool enter_to_ns(struct lxc_container *c, int *old_netns,
> > int *new_netns) {
> > > + int ret = 0;
> > > char new_netns_path[MAXPATHLEN];
> > > - int old_netns = -1, new_netns = -1, ret = 0;
> > >
> > > if (!c->is_running(c))
> > > goto out;
> > >
> > > /* Save reference to old netns */
> > > - old_netns = open("/proc/self/ns/net", O_RDONLY);
> > > - if (old_netns < 0) {
> > > + *old_netns = open("/proc/self/ns/net", O_RDONLY);
> > > + if (*old_netns < 0) {
> > > SYSERROR("failed to open /proc/self/ns/net");
> > > goto out;
> > > }
> > > @@ -1205,16 +1208,78 @@ char** lxcapi_get_ips(struct lxc_container *c,
> > char* interface, char* family, in
> > > if (ret < 0 || ret >= MAXPATHLEN)
> > > goto out;
> > >
> > > - new_netns = open(new_netns_path, O_RDONLY);
> > > - if (new_netns < 0) {
> > > + *new_netns = open(new_netns_path, O_RDONLY);
> > > + if (*new_netns < 0) {
> > > SYSERROR("failed to open %s", new_netns_path);
> > > goto out;
> > > }
> > >
> > > - if (setns(new_netns, CLONE_NEWNET)) {
> > > + if (setns(*new_netns, CLONE_NEWNET)) {
> > > SYSERROR("failed to setns");
> > > goto out;
> > > }
> > > + return true;
> > > +out:
> > > + exit_from_ns(c, old_netns, new_netns);
> > > + return false;
> > > +}
> > > +
> > > +static char** lxcapi_get_interfaces(struct lxc_container *c)
> > > +{
> > > + int count = 0;
> > > + struct ifaddrs *interfaceArray = NULL, *tempIfAddr = NULL;
> > > + char **interfaces = NULL, **temp;
> > > + int old_netns = -1, new_netns = -1;
> > > +
> > > + if (!enter_to_ns(c, &old_netns, &new_netns))
> > > + goto out;
> > > +
> > > + /* Grab the list of interfaces */
> > > + if (getifaddrs(&interfaceArray)) {
> > > + SYSERROR("failed to get interfaces list");
> > > + goto out;
> > > + }
> > > +
> > > + /* Iterate through the interfaces */
> > > + for (tempIfAddr = interfaceArray; tempIfAddr != NULL; tempIfAddr =
> > tempIfAddr->ifa_next) {
> > > + /* filter out loopback interface */
> > > + if(tempIfAddr->ifa_addr == NULL ||
> > tempIfAddr->ifa_addr->sa_family != AF_PACKET || strcmp("lo",
> > tempIfAddr->ifa_name) == 0)
> > > + continue;
> > > +
> > > + count += 1;
> > > + temp = realloc(interfaces, count * sizeof(*interfaces));
> > > + if (!temp) {
> > > + count -= 1;
> > > + goto out;
> > > + }
> > > + interfaces = temp;
> > > + interfaces[count - 1] = strdup(tempIfAddr->ifa_name);
> > > + }
> > > +
> > > +out:
> > > + if(interfaceArray)
> > > + freeifaddrs(interfaceArray);
> > > +
> > > + exit_from_ns(c, &old_netns, &new_netns);
> > > +
> > > + /* Append NULL to the array */
> > > + interfaces = (char **)lxc_append_null_to_array((void
> > **)interfaces, count);
> > > +
> > > + return interfaces;
> > > +}
> > > +
> > > +static char** lxcapi_get_ips(struct lxc_container *c, char* interface,
> > char* family, int scope)
> > > +{
> > > + int count = 0;
> > > + struct ifaddrs *interfaceArray = NULL, *tempIfAddr = NULL;
> > > + char addressOutputBuffer[INET6_ADDRSTRLEN];
> > > + void *tempAddrPtr = NULL;
> > > + char **addresses = NULL, **temp;
> > > + char *address = NULL;
> > > + int old_netns = -1, new_netns = -1;
> > > +
> > > + if (!enter_to_ns(c, &old_netns, &new_netns))
> > > + goto out;
> > >
> > > /* Grab the list of interfaces */
> > > if (getifaddrs(&interfaceArray)) {
> > > @@ -1243,7 +1308,6 @@ char** lxcapi_get_ips(struct lxc_container *c,
> > char* interface, char* family, in
> > > continue;
> > > else if (!interface && strcmp("lo", tempIfAddr->ifa_name)
> > == 0)
> > > continue;
> > > -
> > > address = (char
> > *)inet_ntop(tempIfAddr->ifa_addr->sa_family,
> > > tempAddrPtr,
> > > addressOutputBuffer,
> > > @@ -1265,28 +1329,10 @@ out:
> > > if(interfaceArray)
> > > freeifaddrs(interfaceArray);
> > >
> > > - /* Switch back to original netns */
> > > - if (old_netns >= 0 && setns(old_netns, CLONE_NEWNET))
> > > - SYSERROR("failed to setns");
> > > - if (new_netns >= 0)
> > > - close(new_netns);
> > > - if (old_netns >= 0)
> > > - close(old_netns);
> > > + exit_from_ns(c, &old_netns, &new_netns);
> > >
> > > /* Append NULL to the array */
> > > - if (count) {
> > > - count++;
> > > - temp = realloc(addresses, count * sizeof(*addresses));
> > > - if (!temp) {
> > > - int i;
> > > - for (i = 0; i < count-1; i++)
> > > - free(addresses[i]);
> > > - free(addresses);
> > > - return NULL;
> > > - }
> > > - addresses = temp;
> > > - addresses[count - 1] = NULL;
> > > - }
> > > + addresses = (char **)lxc_append_null_to_array((void **)addresses,
> > count);
> > >
> > > return addresses;
> > > }
> > > @@ -2576,6 +2622,7 @@ struct lxc_container *lxc_container_new(const char
> > *name, const char *configpath
> > > c->get_config_path = lxcapi_get_config_path;
> > > c->set_config_path = lxcapi_set_config_path;
> > > c->clone = lxcapi_clone;
> > > + c->get_interfaces = lxcapi_get_interfaces;
> > > c->get_ips = lxcapi_get_ips;
> > > c->attach = lxcapi_attach;
> > > c->attach_run_wait = lxcapi_attach_run_wait;
> > > diff --git a/src/lxc/lxccontainer.h b/src/lxc/lxccontainer.h
> > > index f9ae43b..f17d975 100644
> > > --- a/src/lxc/lxccontainer.h
> > > +++ b/src/lxc/lxccontainer.h
> > > @@ -90,6 +90,7 @@ struct lxc_container {
> > > * the length which was our would be printed. */
> > > int (*get_config_item)(struct lxc_container *c, const char *key,
> > char *retv, int inlen);
> > > int (*get_keys)(struct lxc_container *c, const char *key, char
> > *retv, int inlen);
> > > + char** (*get_interfaces)(struct lxc_container *c);
> > > char** (*get_ips)(struct lxc_container *c, char* interface, char*
> > family, int scope);
> > > /*
> > > * get_cgroup_item returns the number of bytes read, or an error
> > (<0).
> > > diff --git a/src/lxc/utils.c b/src/lxc/utils.c
> > > index 78b234d..924cc19 100644
> > > --- a/src/lxc/utils.c
> > > +++ b/src/lxc/utils.c
> > > @@ -852,7 +852,7 @@ int lxc_write_to_file(const char *filename, const
> > void* buf, size_t count, bool
> > > return -1;
> > > ret = lxc_write_nointr(fd, buf, count);
> > > if (ret < 0)
> > > - goto out_error;
> > > + goto out_error;
> > > if ((size_t)ret != count)
> > > goto out_error;
> > > if (add_newline) {
> > > @@ -899,3 +899,23 @@ int lxc_read_from_file(const char *filename, void*
> > buf, size_t count)
> > > errno = saved_errno;
> > > return ret;
> > > }
> > > +
> > > +void **lxc_append_null_to_array(void **array, size_t count)
> > > +{
> > > + void **temp;
> > > +
> > > + /* Append NULL to the array */
> > > + if (count) {
> > > + temp = realloc(array, (count + 1) * sizeof(*array));
> > > + if (!temp) {
> > > + int i;
> > > + for (i = 0; i < count; i++)
> > > + free(array[i]);
> > > + free(array);
> > > + return NULL;
> > > + }
> > > + array = temp;
> > > + array[count] = NULL;
> > > + }
> > > + return array;
> > > +}
> > > diff --git a/src/lxc/utils.h b/src/lxc/utils.h
> > > index ba7cfb3..55f98fa 100644
> > > --- a/src/lxc/utils.h
> > > +++ b/src/lxc/utils.h
> > > @@ -236,4 +236,5 @@ extern void lxc_free_array(void **array, lxc_free_fn
> > element_free_fn);
> > > extern size_t lxc_array_len(void **array);
> > > extern void **lxc_dup_array(void **array, lxc_dup_fn element_dup_fn,
> > lxc_free_fn element_free_fn);
> > >
> > > +extern void **lxc_append_null_to_array(void **array, size_t count);
> > > #endif
> > > --
> > > 1.8.1.2
> > >
> > >
> > >
> > ------------------------------------------------------------------------------
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> > > _______________________________________________
> > > Lxc-devel mailing list
> > > Lxc-devel at lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/lxc-devel
> >
> > --
> > Stéphane Graber
> > Ubuntu developer
> > http://www.ubuntu.com
> >
>
>
>
> --
> S.Çağlar Onur <caglar at 10ur.org>
--
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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