Commit ee3b56f2 authored by Noah Watkins's avatar Noah Watkins Committed by Sage Weil
Browse files

ceph: use kernel DNS resolver 



Change ceph_parse_ips to take either names given as
IP addresses or standard hostnames (e.g. localhost).
The DNS lookup is done using the dns_resolver facility
similar to its use in AFS, NFS, and CIFS.

This patch defines CONFIG_CEPH_LIB_USE_DNS_RESOLVER
that controls if this feature is on or off.

Signed-off-by: default avatarNoah Watkins <noahwatkins@gmail.com>
Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent 49d9224c

net/ceph/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -27,3 +27,17 @@ config CEPH_LIB_PRETTYDEBUG 


	  If unsure, say N.



config CEPH_LIB_USE_DNS_RESOLVER

	bool "Use in-kernel support for DNS lookup"

	depends on CEPH_LIB

	select DNS_RESOLVER

	default n

	help

	  If you say Y here, hostnames (e.g. monitor addresses) will

	  be resolved using the CONFIG_DNS_RESOLVER facility.



	  For information on how to use CONFIG_DNS_RESOLVER consult

	  Documentation/networking/dns_resolver.txt



	  If unsure, say N.

net/ceph/messenger.c

+102 −12
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/string.h>

#include <linux/bio.h>

#include <linux/blkdev.h>

#include <linux/dns_resolver.h>

#include <net/tcp.h>



#include <linux/ceph/libceph.h>
@@ -1077,6 +1078,101 @@ static void addr_set_port(struct sockaddr_storage *ss, int p) 
	}

}



/*

 * Unlike other *_pton function semantics, zero indicates success.

 */

static int ceph_pton(const char *str, size_t len, struct sockaddr_storage *ss,

		char delim, const char **ipend)

{

	struct sockaddr_in *in4 = (void *)ss;

	struct sockaddr_in6 *in6 = (void *)ss;



	memset(ss, 0, sizeof(*ss));



	if (in4_pton(str, len, (u8 *)&in4->sin_addr.s_addr, delim, ipend)) {

		ss->ss_family = AF_INET;

		return 0;

	}



	if (in6_pton(str, len, (u8 *)&in6->sin6_addr.s6_addr, delim, ipend)) {

		ss->ss_family = AF_INET6;

		return 0;

	}



	return -EINVAL;

}



/*

 * Extract hostname string and resolve using kernel DNS facility.

 */

#ifdef CONFIG_CEPH_LIB_USE_DNS_RESOLVER

static int ceph_dns_resolve_name(const char *name, size_t namelen,

		struct sockaddr_storage *ss, char delim, const char **ipend)

{

	const char *end, *delim_p;

	char *colon_p, *ip_addr = NULL;

	int ip_len, ret;



	/*

	 * The end of the hostname occurs immediately preceding the delimiter or

	 * the port marker (':') where the delimiter takes precedence.

	 */

	delim_p = memchr(name, delim, namelen);

	colon_p = memchr(name, ':', namelen);



	if (delim_p && colon_p)

		end = delim_p < colon_p ? delim_p : colon_p;

	else if (!delim_p && colon_p)

		end = colon_p;

	else {

		end = delim_p;

		if (!end) /* case: hostname:/ */

			end = name + namelen;

	}



	if (end <= name)

		return -EINVAL;



	/* do dns_resolve upcall */

	ip_len = dns_query(NULL, name, end - name, NULL, &ip_addr, NULL);

	if (ip_len > 0)

		ret = ceph_pton(ip_addr, ip_len, ss, -1, NULL);

	else

		ret = -ESRCH;



	kfree(ip_addr);



	*ipend = end;



	pr_info("resolve '%.*s' (ret=%d): %s\n", (int)(end - name), name,

			ret, ret ? "failed" : ceph_pr_addr(ss));



	return ret;

}

#else

static inline int ceph_dns_resolve_name(const char *name, size_t namelen,

		struct sockaddr_storage *ss, char delim, const char **ipend)

{

	return -EINVAL;

}

#endif



/*

 * Parse a server name (IP or hostname). If a valid IP address is not found

 * then try to extract a hostname to resolve using userspace DNS upcall.

 */

static int ceph_parse_server_name(const char *name, size_t namelen,

			struct sockaddr_storage *ss, char delim, const char **ipend)

{

	int ret;



	ret = ceph_pton(name, namelen, ss, delim, ipend);

	if (ret)

		ret = ceph_dns_resolve_name(name, namelen, ss, delim, ipend);



	return ret;

}



/*

 * Parse an ip[:port] list into an addr array.  Use the default

 * monitor port if a port isn't specified.
@@ -1085,15 +1181,13 @@ int ceph_parse_ips(const char *c, const char *end, 
		   struct ceph_entity_addr *addr,

		   int max_count, int *count)

{

	int i;

	int i, ret = -EINVAL;

	const char *p = c;



	dout("parse_ips on '%.*s'\n", (int)(end-c), c);

	for (i = 0; i < max_count; i++) {

		const char *ipend;

		struct sockaddr_storage *ss = &addr[i].in_addr;

		struct sockaddr_in *in4 = (void *)ss;

		struct sockaddr_in6 *in6 = (void *)ss;

		int port;

		char delim = ',';
@@ -1102,15 +1196,11 @@ int ceph_parse_ips(const char *c, const char *end, 
			p++;

		}



		memset(ss, 0, sizeof(*ss));

		if (in4_pton(p, end - p, (u8 *)&in4->sin_addr.s_addr,

			     delim, &ipend))

			ss->ss_family = AF_INET;

		else if (in6_pton(p, end - p, (u8 *)&in6->sin6_addr.s6_addr,

				  delim, &ipend))

			ss->ss_family = AF_INET6;

		else

		ret = ceph_parse_server_name(p, end - p, ss, delim, &ipend);

		if (ret)

			goto bad;

		ret = -EINVAL;



		p = ipend;



		if (delim == ']') {
@@ -1155,7 +1245,7 @@ int ceph_parse_ips(const char *c, const char *end, 


bad:

	pr_err("parse_ips bad ip '%.*s'\n", (int)(end - c), c);

	return -EINVAL;

	return ret;

}

EXPORT_SYMBOL(ceph_parse_ips);

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