From 305dad8388ea27b4d1bf1202e90ad6947ae0ab26 Mon Sep 17 00:00:00 2001
From: Pavan Balaji <balaji@anl.gov>
Date: Thu, 21 Jan 2016 17:01:42 -0600
Subject: [PATCH] hydra: improve localhost detection.
Be more forgiving for systems that do not resolve "localhost" or
equivalent names very well (e.g., they are not added to /etc/hosts).
Try them out, and if nothing works, fallback to "is not local" mode.
Thanks to Orion Poplawski <orion@cora.nwra.com> for the suggestion.
---
src/pm/hydra/utils/sock/sock.c | 89 +++++++++++++++++++++++-------------------
1 file changed, 48 insertions(+), 41 deletions(-)
diff --git a/src/pm/hydra/utils/sock/sock.c b/src/pm/hydra/utils/sock/sock.c
index 86b25077aac2..dc56c767f544 100644
--- a/src/pm/hydra/utils/sock/sock.c
+++ b/src/pm/hydra/utils/sock/sock.c
@@ -492,7 +492,7 @@ HYD_status HYDU_sock_get_iface_ip(char *iface, char **ip)
HYD_status HYDU_sock_is_local(char *host, int *is_local)
{
struct hostent *ht;
- char *host_ip = NULL, *local_ip = NULL, *lhost_ip = NULL;
+ char *host_ip = NULL, *lhost_ip = NULL;
char lhost[MAX_HOSTNAME_LEN];
struct sockaddr_in sa;
struct ifaddrs *ifaddr, *ifa;
@@ -516,54 +516,63 @@ HYD_status HYDU_sock_is_local(char *host, int *is_local)
/* STEP 1: If "host" matches the local host name, return */
if (gethostname(lhost, MAX_HOSTNAME_LEN) < 0) {
- HYDU_ERR_SETANDJUMP(status, HYD_INTERNAL_ERROR, "gethostname returned an error\n");
+ /* We can't figure out what my localhost name is. *sigh*. We
+ * could return an error here, but we will just punt it to the
+ * upper layer saying that we don't know if it is local. We
+ * cannot try steps 2 and 3 either, since we don't have our
+ * local hostname. */
+ goto fn_exit;
}
else if (!strcmp(lhost, host)) {
*is_local = 1;
goto fn_exit;
}
+ else {
+ /* we have our local hostname, but that does not match the
+ * provided hostname. Let's try to get our remote IP address
+ * first. If we can't get that, we can give up. */
+ /* If we are unable to resolve the remote host name, it need
+ * not be an error. It could mean that the user is using an
+ * alias for the hostname (e.g., an ssh config alias) */
+ if ((ht = gethostbyname(host)) == NULL)
+ goto fn_exit;
+ memset((char *) &sa, 0, sizeof(struct sockaddr_in));
+ memcpy(&sa.sin_addr, ht->h_addr_list[0], ht->h_length);
- /* STEP 2: If the IP address associated with "host" and the IP address local
- * host resolves to match, return */
-
- if ((ht = gethostbyname(lhost)) == NULL) {
- HYDU_ERR_SETANDJUMP(status, HYD_INTERNAL_ERROR, "gethostbyname error on %s: %s\n",
- lhost, hstrerror(h_errno));
+ /* Find the IP address of the host */
+ host_ip = HYDU_strdup((char *) inet_ntop(AF_INET, (const void *) &sa.sin_addr, buf,
+ MAX_HOSTNAME_LEN));
+ HYDU_ASSERT(host_ip, status);
}
- memset((char *) &sa, 0, sizeof(struct sockaddr_in));
- memcpy(&sa.sin_addr, ht->h_addr_list[0], ht->h_length);
-
- /* Find the IP address of the host */
- lhost_ip = HYDU_strdup((char *) inet_ntop(AF_INET, (const void *) &sa.sin_addr, buf,
- MAX_HOSTNAME_LEN));
- HYDU_ASSERT(lhost_ip, status);
+ /* OK, if we are here, we got the remote IP. We have two ways of
+ * getting the local IP: gethostbyname or getifaddrs. We'll try
+ * both. */
- /* If we are unable to resolve the remote host name, it need not be an
- * error. It could mean that the user is using an alias for the hostname
- * (e.g., an ssh config alias) */
- if ((ht = gethostbyname(host)) == NULL)
- goto fn_exit;
+ /* STEP 2: Let's try the gethostbyname model */
- memset((char *) &sa, 0, sizeof(struct sockaddr_in));
- memcpy(&sa.sin_addr, ht->h_addr_list[0], ht->h_length);
+ if ((ht = gethostbyname(lhost))) {
+ memset((char *) &sa, 0, sizeof(struct sockaddr_in));
+ memcpy(&sa.sin_addr, ht->h_addr_list[0], ht->h_length);
- /* Find the IP address of the host */
- host_ip = HYDU_strdup((char *) inet_ntop(AF_INET, (const void *) &sa.sin_addr, buf,
- MAX_HOSTNAME_LEN));
- HYDU_ASSERT(host_ip, status);
+ /* Find the IP address of the host */
+ lhost_ip = HYDU_strdup((char *) inet_ntop(AF_INET, (const void *) &sa.sin_addr, buf,
+ MAX_HOSTNAME_LEN));
+ HYDU_ASSERT(lhost_ip, status);
- /* See if the IP address of the hostname we got matches the IP address
- * to which the local host resolves */
- if (!strcmp(lhost_ip, host_ip)) {
- *is_local = 1;
- goto fn_exit;
+ /* See if the IP address of the hostname we got matches the IP
+ * address to which the local host resolves */
+ if (!strcmp(lhost_ip, host_ip)) {
+ *is_local = 1;
+ goto fn_exit;
+ }
}
+ /* Either gethostbyname didn't resolve or we didn't find a match.
+ * Either way, let's try the getifaddr model. */
- /* STEP 3: Find all local IP addresses and try to match the host IP
- * with it. */
+ /* STEP 3: Let's try the getifaddr model */
if (getifaddrs(&ifaddr) == -1)
HYDU_ERR_SETANDJUMP(status, HYD_INTERNAL_ERROR, "getifaddrs failed\n");
@@ -573,21 +582,21 @@ HYD_status HYDU_sock_is_local(char *host, int *is_local)
if (ifa->ifa_addr && ifa->ifa_addr->sa_family == AF_INET) {
struct sockaddr_in *sa_ptr = (struct sockaddr_in *) ifa->ifa_addr;
- local_ip = HYDU_strdup((char *)
+ lhost_ip = HYDU_strdup((char *)
inet_ntop(AF_INET, (const void *) &(sa_ptr->sin_addr), buf,
MAX_HOSTNAME_LEN));
- HYDU_ASSERT(local_ip, status);
+ HYDU_ASSERT(lhost_ip, status);
- /* STEP 3: For each local IP address, see if it matches the "host"
+ /* For each local IP address, see if it matches the "host"
* IP address */
- if (!strcmp(host_ip, local_ip)) {
+ if (!strcmp(host_ip, lhost_ip)) {
*is_local = 1;
freeifaddrs(ifaddr);
goto fn_exit;
}
- HYDU_FREE(local_ip);
- local_ip = NULL;
+ HYDU_FREE(lhost_ip);
+ lhost_ip = NULL;
}
}
@@ -596,8 +605,6 @@ HYD_status HYDU_sock_is_local(char *host, int *is_local)
fn_exit:
if (host_ip)
HYDU_FREE(host_ip);
- if (local_ip)
- HYDU_FREE(local_ip);
if (lhost_ip)
HYDU_FREE(lhost_ip);
return status;
--
1.9.1