Avoid DNS reverse resolution for server names (take 3)

[nfs-utils.git] / utils / gssd / gssd_proc.c

diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
index 22800885e2be12ce9fdc68386c63025fde68ca21..af1844c2d38490e1ccb5c21e2aa45cd34cca376e 100644 (file)
--- a/utils/gssd/gssd_proc.c
+++ b/utils/gssd/gssd_proc.c
@@ -67,6 +67,7 @@
 #include <errno.h>
 #include <gssapi/gssapi.h>
 #include <netdb.h>
+#include <ctype.h>
 
 #include "gssd.h"
 #include "err_util.h"
@@ -107,6 +108,9 @@ struct pollfd * pollarray;
 
 unsigned long pollsize;  /* the size of pollaray (in pollfd's) */
 
+/* Avoid DNS reverse lookups on server names */
+int avoid_dns = 1;
+
 /*
  * convert a presentation address string to a sockaddr_storage struct. Returns
  * true on success or false on failure.
@@ -165,12 +169,31 @@ addrstr_to_sockaddr(struct sockaddr *sa, const char *node, const char *port)
  * convert a sockaddr to a hostname
  */
 static char *
-sockaddr_to_hostname(const struct sockaddr *sa, const char *addr)
+get_servername(const char *name, const struct sockaddr *sa, const char *addr)
 {
        socklen_t               addrlen;
        int                     err;
        char                    *hostname;
        char                    hbuf[NI_MAXHOST];
+       unsigned char           buf[sizeof(struct in6_addr)];
+       int                     servername = 0;
+
+       if (avoid_dns) {
+               /*
+                * Determine if this is a server name, or an IP address.
+                * If it is an IP address, do the DNS lookup otherwise
+                * skip the DNS lookup.
+                */
+               servername = 0;
+               if (strchr(name, '.') && inet_pton(AF_INET, name, buf) == 1)
+                       servername = 1; /* IPv4 */
+               else if (strchr(name, ':') && inet_pton(AF_INET6, name, buf) == 1)
+                       servername = 1; /* or IPv6 */
+
+               if (servername) {
+                       return strdup(name);
+               }
+       }
 
        switch (sa->sa_family) {
        case AF_INET:
@@ -208,7 +231,7 @@ read_service_info(char *info_file_name, char **servicename, char **servername,
                  struct sockaddr *addr) {
 #define INFOBUFLEN 256
        char            buf[INFOBUFLEN + 1];
-       static char     dummy[128];
+       static char     server[128];
        int             nbytes;
        static char     service[128];
        static char     address[128];
@@ -236,7 +259,7 @@ read_service_info(char *info_file_name, char **servicename, char **servername,
                   "service: %127s %15s version %15s\n"
                   "address: %127s\n"
                   "protocol: %15s\n",
-                  dummy,
+                  server,
                   service, program, version,
                   address,
                   protoname);
@@ -258,7 +281,7 @@ read_service_info(char *info_file_name, char **servicename, char **servername,
        if (!addrstr_to_sockaddr(addr, address, port))
                goto fail;
 
-       *servername = sockaddr_to_hostname(addr, address);
+       *servername = get_servername(server, addr, address);
        if (*servername == NULL)
                goto fail;