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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: Noah Watkins <noahwatkins@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Noah Watkins 2011-09-23 11:48:42 -07:00 committed by Sage Weil
parent 49d9224c04
commit ee3b56f265
2 changed files with 116 additions and 12 deletions
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14
net/ceph/Kconfig
View File

@ -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.

114
net/ceph/messenger.c
View File

@ -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);