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Date: Fri, 23 Sep 2011 11:48:42 -0700
From: Noah Watkins <noahwatkins@...il.com>
To: Sage Weil <sage@...dream.net>
Cc: ceph-devel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] 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@...il.com>
---
net/ceph/Kconfig | 14 ++++++
net/ceph/messenger.c | 114 ++++++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 116 insertions(+), 12 deletions(-)
diff --git a/net/ceph/Kconfig b/net/ceph/Kconfig
index be683f2..cc04dd6 100644
--- a/net/ceph/Kconfig
+++ b/net/ceph/Kconfig
@@ -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.
+
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index c340e2e..947a6f3 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -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>
@@ -1078,6 +1079,101 @@ 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);
--
1.7.6.1
--
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