[lxc-devel] [PATCH] Add get_interfaces to the API - v2

Stéphane Graber stgraber at ubuntu.com
Mon Sep 16 18:39:34 UTC 2013


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?

> ---
>  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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-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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