[lxc-devel] [PATCH] handle hashed command socket names

Serge Hallyn serge.hallyn at ubuntu.com
Mon Aug 25 13:39:14 UTC 2014


Quoting S.Çağlar Onur (caglar at 10ur.org):
> With the new hashed command socket names (e85898415c), it possible to have have something like below;
> 
> [caglar at qop:~/go/src/github.com/lxc/go-lxc(master)] cat /proc/net/unix | grep lxc
> 0000000000000000: 00000002 00000000 00010000 0001 01 53465 @lxc/d086e835c86f4b8d/command
> [...]
> 
> list_active_containers reads /proc/net/unix to find all running containers but this new format no longer includes the container name or its lxcpath.
> 
> This patch introduces two new commands (LXC_CMD_GET_NAME and LXC_CMD_GET_LXCPATH) and starts to use those in list_active_containers call.
> 
> Signed-off-by: S.Çağlar Onur <caglar at 10ur.org>

Thanks Çağlar.

Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>

(Except for one requested change below, can be done inline)

> ---
>  src/lxc/commands.c     | 118 ++++++++++++++++++++++++++++++++++++++++++-------
>  src/lxc/commands.h     |   4 ++
>  src/lxc/lxccontainer.c |  20 ++++++++-
>  3 files changed, 124 insertions(+), 18 deletions(-)
> 
> diff --git a/src/lxc/commands.c b/src/lxc/commands.c
> index f46efc5..f56aece 100644
> --- a/src/lxc/commands.c
> +++ b/src/lxc/commands.c
> @@ -75,13 +75,22 @@
>  lxc_log_define(lxc_commands, lxc);
>  
>  static int fill_sock_name(char *path, int len, const char *name,
> -			  const char *lxcpath)
> +			  const char *lxcpath, const char *hashed_sock_name)
>  {
>  	char *tmppath;
>  	size_t tmplen;
>  	uint64_t hash;
>  	int ret;
>  
> +	if (hashed_sock_name != NULL) {
> +		ret = snprintf(path, len, "lxc/%s/command", hashed_sock_name);
> +		if (ret < 0) {

	|| ret > len, for sanity since len is passed in.  I realize it shouldn't
	be possible, but neither should a mars orbiter crashing due to failure
	to convert units

> +			ERROR("Error writing to command sock path");
> +			return -1;
> +		}
> +		return 0;
> +	}
> +
>  	if (!lxcpath) {
>  		lxcpath = lxc_global_config_value("lxc.lxcpath");
>  		if (!lxcpath) {
> @@ -89,9 +98,8 @@ static int fill_sock_name(char *path, int len, const char *name,
>  			return -1;
>  		}
>  	}
> -		
> -	ret = snprintf(path, len, "%s/%s/command", lxcpath, name);
>  
> +	ret = snprintf(path, len, "%s/%s/command", lxcpath, name);
>  	if (ret < 0) {
>  		ERROR("Error writing to command sock path");
>  		return -1;
> @@ -108,7 +116,7 @@ static int fill_sock_name(char *path, int len, const char *name,
>  		return -1;
>  	}
>  	hash = fnv_64a_buf(tmppath, ret, FNV1A_64_INIT);
> -	ret = snprintf(path, len, "lxc/%016" PRIx64 "/cmd_sock", hash);
> +	ret = snprintf(path, len, "lxc/%016" PRIx64 "/command", hash);

I guess for any valid non-hashed case lxcpath will start with '/' so that
sufficient disambiguates the two cases, so this is fine.

>  	if (ret < 0 || ret >= len) {
>  		ERROR("Command socket name too long");
>  		return -1;
> @@ -127,6 +135,8 @@ static const char *lxc_cmd_str(lxc_cmd_t cmd)
>  		[LXC_CMD_GET_CLONE_FLAGS] = "get_clone_flags",
>  		[LXC_CMD_GET_CGROUP]      = "get_cgroup",
>  		[LXC_CMD_GET_CONFIG_ITEM] = "get_config_item",
> +		[LXC_CMD_GET_NAME]        = "get_name",
> +		[LXC_CMD_GET_LXCPATH]     = "get_lxcpath",
>  	};
>  
>  	if (cmd >= LXC_CMD_MAX)
> @@ -259,7 +269,7 @@ static int lxc_cmd_rsp_send(int fd, struct lxc_cmd_rsp *rsp)
>   * returned in the cmd response structure.
>   */
>  static int lxc_cmd(const char *name, struct lxc_cmd_rr *cmd, int *stopped,
> -		   const char *lxcpath)
> +		   const char *lxcpath, const char *hashed_sock_name)
>  {
>  	int sock, ret = -1;
>  	char path[sizeof(((struct sockaddr_un *)0)->sun_path)] = { 0 };
> @@ -270,7 +280,7 @@ static int lxc_cmd(const char *name, struct lxc_cmd_rr *cmd, int *stopped,
>  	*stopped = 0;
>  
>  	len = sizeof(path)-1;
> -	if (fill_sock_name(offset, len, name, lxcpath))
> +	if (fill_sock_name(offset, len, name, lxcpath, hashed_sock_name))
>  		return -1;
>  
>  	sock = lxc_abstract_unix_connect(path);
> @@ -329,7 +339,7 @@ int lxc_try_cmd(const char *name, const char *lxcpath)
>  		.req = { .cmd = LXC_CMD_GET_INIT_PID },
>  	};
>  
> -	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
> +	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
>  
>  	if (stopped)
>  		return 0;
> @@ -369,7 +379,7 @@ pid_t lxc_cmd_get_init_pid(const char *name, const char *lxcpath)
>  		.req = { .cmd = LXC_CMD_GET_INIT_PID },
>  	};
>  
> -	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
> +	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -399,7 +409,7 @@ int lxc_cmd_get_clone_flags(const char *name, const char *lxcpath)
>  		.req = { .cmd = LXC_CMD_GET_CLONE_FLAGS },
>  	};
>  
> -	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
> +	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -438,7 +448,7 @@ char *lxc_cmd_get_cgroup_path(const char *name, const char *lxcpath,
>  		},
>  	};
>  
> -	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
> +	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
>  	if (ret < 0)
>  		return NULL;
>  
> @@ -497,7 +507,7 @@ char *lxc_cmd_get_config_item(const char *name, const char *item,
>  		       },
>  	};
>  
> -	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
> +	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
>  	if (ret < 0)
>  		return NULL;
>  
> @@ -548,7 +558,7 @@ lxc_state_t lxc_cmd_get_state(const char *name, const char *lxcpath)
>  		.req = { .cmd = LXC_CMD_GET_STATE }
>  	};
>  
> -	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
> +	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
>  	if (ret < 0 && stopped)
>  		return STOPPED;
>  
> @@ -589,7 +599,7 @@ int lxc_cmd_stop(const char *name, const char *lxcpath)
>  		.req = { .cmd = LXC_CMD_STOP },
>  	};
>  
> -	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
> +	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
>  	if (ret < 0) {
>  		if (stopped) {
>  			INFO("'%s' is already stopped", name);
> @@ -650,7 +660,7 @@ int lxc_cmd_console_winch(const char *name, const char *lxcpath)
>  		.req = { .cmd = LXC_CMD_CONSOLE_WINCH },
>  	};
>  
> -	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
> +	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -685,7 +695,7 @@ int lxc_cmd_console(const char *name, int *ttynum, int *fd, const char *lxcpath)
>  		.req = { .cmd = LXC_CMD_CONSOLE, .data = INT_TO_PTR(*ttynum) },
>  	};
>  
> -	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
> +	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -744,7 +754,81 @@ out_close:
>  	return 1;
>  }
>  
> +/*
> + * lxc_cmd_get_name: Returns the name of the container
> + *
> + * @hashed_sock_name: hashed socket name
> + *
> + * Returns the name on success, NULL on failure.
> + */
> +char *lxc_cmd_get_name(const char *hashed_sock_name)
> +{
> +	int ret, stopped;
> +	struct lxc_cmd_rr cmd = {
> +		.req = { .cmd = LXC_CMD_GET_NAME},
> +	};
> +
> +	ret = lxc_cmd(NULL, &cmd, &stopped, NULL, hashed_sock_name);
> +	if (ret < 0) {
> +		return NULL;
> +	}
> +
> +	if (cmd.rsp.ret == 0)
> +		return cmd.rsp.data;
> +	return NULL;
> +}
> +
> +static int lxc_cmd_get_name_callback(int fd, struct lxc_cmd_req *req,
> +					    struct lxc_handler *handler)
> +{
> +	struct lxc_cmd_rsp rsp;
> +
> +	memset(&rsp, 0, sizeof(rsp));
> +
> +	rsp.data = handler->name;
> +	rsp.datalen = strlen(handler->name) + 1;
> +	rsp.ret = 0;
> +
> +	return lxc_cmd_rsp_send(fd, &rsp);
> +}
> +
> +/*
> + * lxc_cmd_get_lxcpath: Returns the lxcpath of the container
> + *
> + * @hashed_sock_name: hashed socket name
> + *
> + * Returns the lxcpath on success, NULL on failure.
> + */
> +char *lxc_cmd_get_lxcpath(const char *hashed_sock_name)
> +{
> +	int ret, stopped;
> +	struct lxc_cmd_rr cmd = {
> +		.req = { .cmd = LXC_CMD_GET_LXCPATH},
> +	};
>  
> +	ret = lxc_cmd(NULL, &cmd, &stopped, NULL, hashed_sock_name);
> +	if (ret < 0) {
> +		return NULL;
> +	}
> +
> +	if (cmd.rsp.ret == 0)
> +		return cmd.rsp.data;
> +	return NULL;
> +}
> +
> +static int lxc_cmd_get_lxcpath_callback(int fd, struct lxc_cmd_req *req,
> +					struct lxc_handler *handler)
> +{
> +	struct lxc_cmd_rsp rsp;
> +
> +	memset(&rsp, 0, sizeof(rsp));
> +
> +	rsp.data = (char *)handler->lxcpath;
> +	rsp.datalen = strlen(handler->lxcpath) + 1;
> +	rsp.ret = 0;
> +
> +	return lxc_cmd_rsp_send(fd, &rsp);
> +}
>  
>  static int lxc_cmd_process(int fd, struct lxc_cmd_req *req,
>  			   struct lxc_handler *handler)
> @@ -760,6 +844,8 @@ static int lxc_cmd_process(int fd, struct lxc_cmd_req *req,
>  		[LXC_CMD_GET_CLONE_FLAGS] = lxc_cmd_get_clone_flags_callback,
>  		[LXC_CMD_GET_CGROUP]      = lxc_cmd_get_cgroup_callback,
>  		[LXC_CMD_GET_CONFIG_ITEM] = lxc_cmd_get_config_item_callback,
> +		[LXC_CMD_GET_NAME]        = lxc_cmd_get_name_callback,
> +		[LXC_CMD_GET_LXCPATH]     = lxc_cmd_get_lxcpath_callback,
>  	};
>  
>  	if (req->cmd >= LXC_CMD_MAX) {
> @@ -887,7 +973,7 @@ int lxc_cmd_init(const char *name, struct lxc_handler *handler,
>  	int len;
>  
>  	len = sizeof(path)-1;
> -	if (fill_sock_name(offset, len, name, lxcpath))
> +	if (fill_sock_name(offset, len, name, lxcpath, NULL))
>  		return -1;
>  
>  	fd = lxc_abstract_unix_open(path, SOCK_STREAM, 0);
> diff --git a/src/lxc/commands.h b/src/lxc/commands.h
> index 9efe2ad..e11a139 100644
> --- a/src/lxc/commands.h
> +++ b/src/lxc/commands.h
> @@ -41,6 +41,8 @@ typedef enum {
>  	LXC_CMD_GET_CLONE_FLAGS,
>  	LXC_CMD_GET_CGROUP,
>  	LXC_CMD_GET_CONFIG_ITEM,
> +	LXC_CMD_GET_NAME,
> +	LXC_CMD_GET_LXCPATH,
>  	LXC_CMD_MAX,
>  } lxc_cmd_t;
>  
> @@ -77,6 +79,8 @@ extern char *lxc_cmd_get_cgroup_path(const char *name, const char *lxcpath,
>  			const char *subsystem);
>  extern int lxc_cmd_get_clone_flags(const char *name, const char *lxcpath);
>  extern char *lxc_cmd_get_config_item(const char *name, const char *item, const char *lxcpath);
> +extern char *lxc_cmd_get_name(const char *hashed_sock);
> +extern char *lxc_cmd_get_lxcpath(const char *hashed_sock);
>  extern pid_t lxc_cmd_get_init_pid(const char *name, const char *lxcpath);
>  extern lxc_state_t lxc_cmd_get_state(const char *name, const char *lxcpath);
>  extern int lxc_cmd_stop(const char *name, const char *lxcpath);
> diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> index 172e667..9c34120 100644
> --- a/src/lxc/lxccontainer.c
> +++ b/src/lxc/lxccontainer.c
> @@ -3751,6 +3751,7 @@ int list_active_containers(const char *lxcpath, char ***nret,
>  	char **ct_name = NULL;
>  	size_t len = 0;
>  	struct lxc_container *c;
> +	bool is_hashed;
>  
>  	if (!lxcpath)
>  		lxcpath = lxc_global_config_value("lxc.lxcpath");
> @@ -3766,6 +3767,7 @@ int list_active_containers(const char *lxcpath, char ***nret,
>  		return -1;
>  
>  	while (getline(&line, &len, f) != -1) {
> +
>  		char *p = strrchr(line, ' '), *p2;
>  		if (!p)
>  			continue;
> @@ -3773,9 +3775,17 @@ int list_active_containers(const char *lxcpath, char ***nret,
>  		if (*p != 0x40)
>  			continue;
>  		p++;
> -		if (strncmp(p, lxcpath, lxcpath_len) != 0)
> +
> +		is_hashed = false;
> +		if (strncmp(p, lxcpath, lxcpath_len) == 0) {
> +			p += lxcpath_len;
> +		} else if (strncmp(p, "lxc/", 4) == 0) {
> +			p += 4;
> +			is_hashed = true;
> +		} else {
>  			continue;
> -		p += lxcpath_len;
> +		}
> +
>  		while (*p == '/')
>  			p++;
>  
> @@ -3785,6 +3795,12 @@ int list_active_containers(const char *lxcpath, char ***nret,
>  			continue;
>  		*p2 = '\0';
>  
> +		if (is_hashed) {
> +			if (strncmp(lxcpath, lxc_cmd_get_lxcpath(p), lxcpath_len) != 0)
> +				continue;
> +			p = lxc_cmd_get_name(p);
> +		}
> +
>  		if (array_contains(&ct_name, p, ct_name_cnt))
>  			continue;
>  
> -- 
> 1.9.1
> 
> _______________________________________________
> lxc-devel mailing list
> lxc-devel at lists.linuxcontainers.org
> http://lists.linuxcontainers.org/listinfo/lxc-devel


More information about the lxc-devel mailing list