Look for and use gethostbyname() if we don't have getaddrinfo(). Fail to

configure if we can't find any name resolver (autotools only).

This puts back the gethostbyname()/gethostbyname2() code removed in
I3348179626e97daaddfbc89e3ed21e39915e3de4 and
If59ce8a038776eadd6cd1794ed0e2dad8bf8a22c but as a last-resort option (only
if we don't have a better or more modern name resolver).

As suggested/requested by Guy in https://code.wireshark.org/review/#/c/7423/

Change-Id: I706dbbd65135f47c67d3d8d88a61ad7273914c47
Reviewed-on: https://code.wireshark.org/review/7447
Petri-Dish: Jeff Morriss <jeff.morriss.ws@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Jeff Morriss <jeff.morriss.ws@gmail.com>

5 files changed, 129 insertions, 25 deletions

diff --git a/ConfigureChecks.cmake b/ConfigureChecks.cmake
index 50e312e04a..69ca619068 100644
--- a/ConfigureChecks.cmake
+++ b/ConfigureChecks.cmake
@@ -69,6 +69,8 @@ cmake_pop_check_state()
 #
 check_symbol_exists("floorl" "math.h"    HAVE_FLOORL)
 check_function_exists("getaddrinfo"      HAVE_GETADDRINFO)
+check_function_exists("gethostbyname"    HAVE_GETHOSTBYNAME)
+check_function_exists("gethostbyname2"   HAVE_GETHOSTBYNAME2)
 check_function_exists("getopt_long"      HAVE_GETOPT_LONG)
 if(HAVE_GETOPT_LONG)
     if(HAVE_GETOPT_H)
diff --git a/acinclude.m4 b/acinclude.m4
index 6db1b966eb..2d89e2278e 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -276,19 +276,46 @@ AC_DEFUN([AC_WIRESHARK_GETADDRINFO_LIB_CHECK],
     AC_CHECK_FUNCS(getaddrinfo, ,
 	AC_CHECK_LIB(nsl, getaddrinfo,
 		     [
-		         NSL_LIBS="-lnsl"
+			 NSL_LIBS="-lnsl"
 			 AC_DEFINE(HAVE_GETADDRINFO, 1, [Defined if we have getaddrinfo])
 		     ]))
     AC_SUBST(NSL_LIBS)
 ])
 
 #
+# AC_WIRESHARK_GETHOSTBY_LIB_CHECK
+#
+# Checks whether we need "-lnsl" to get "gethostby*()", which we use
+# in "resolv.c".
+#
+# Adapted from stuff in the AC_PATH_XTRA macro in "acspecific.m4" in
+# GNU Autoconf 2.13; the comment came from there.
+# Done by Guy Harris <guy@alum.mit.edu> on 2000-01-14.
+#
+AC_DEFUN([AC_WIRESHARK_GETHOSTBY_LIB_CHECK],
+[
+    # msh@cis.ufl.edu says -lnsl (and -lsocket) are needed for his 386/AT,
+    # to get the SysV transport functions.
+    # chad@anasazi.com says the Pyramid MIS-ES running DC/OSx (SVR4)
+    # needs -lnsl.
+    # The nsl library prevents programs from opening the X display
+    # on Irix 5.2, according to dickey@clark.net.
+    AC_CHECK_FUNCS(gethostbyname, ,
+	AC_CHECK_LIB(nsl, gethostbyname,
+		     [
+			NSL_LIBS="-lnsl"
+			AC_DEFINE(HAVE_GETHOSTBYNAME, 1, [Defined if we have gethostbyname])
+		     ]))
+    AC_SUBST(NSL_LIBS)
+])
+
+#
 # AC_WIRESHARK_SOCKET_LIB_CHECK
 #
 # Checks whether we need "-lsocket" to get "socket()", which is used
-# by libpcap on some platforms - and, in effect, "getaddrinfo()" on
-# most if not all platforms (so that it can use NIS or DNS or...
-# to look up host names).
+# by libpcap on some platforms - and, in effect, "gethostbyname()" or
+# "getaddrinfo()" on most if not all platforms (so that it can use NIS or
+# DNS or... to look up host names).
 #
 # Adapted from stuff in the AC_PATH_XTRA macro in "acspecific.m4" in
 # GNU Autoconf 2.13; the comment came from there.
@@ -1105,8 +1132,8 @@ AC_DEFUN([AC_WIRESHARK_ADNS_CHECK],
 		AC_CHECK_LIB(adns, adns_init,
 		  [
 		    ADNS_LIBS=-ladns
-	    	AC_DEFINE(HAVE_GNU_ADNS, 1, [Define to use GNU ADNS library])
-		have_good_adns=yes
+		    AC_DEFINE(HAVE_GNU_ADNS, 1, [Define to use GNU ADNS library])
+		    have_good_adns=yes
 		  ],, $SOCKET_LIBS $NSL_LIBS
 		)
 	else
@@ -1136,8 +1163,8 @@ AC_DEFUN([AC_WIRESHARK_LIBCAP_CHECK],
 		AC_CHECK_LIB(cap, cap_set_flag,
 		  [
 		    LIBCAP_LIBS=-lcap
-	    	AC_DEFINE(HAVE_LIBCAP, 1, [Define to use the libcap library])
-		have_good_libcap=yes
+		    AC_DEFINE(HAVE_LIBCAP, 1, [Define to use the libcap library])
+		    have_good_libcap=yes
 		  ],,
 		)
 	else
diff --git a/cmakeconfig.h.in b/cmakeconfig.h.in
index 2887c27c80..0ad3fb521a 100644
--- a/cmakeconfig.h.in
+++ b/cmakeconfig.h.in
@@ -70,6 +70,12 @@
 /* Define to 1 if you have the `getaddrinfo' function. */
 #cmakedefine HAVE_GETADDRINFO 1
 
+/* Define to 1 if you have the `gethostbyname' function. */
+#cmakedefine HAVE_GETHOSTBYNAME 1
+
+/* Define to 1 if you have the `gethostbyname2' function. */
+#cmakedefine HAVE_GETHOSTBYNAME2 1
+
 /* Define to 1 if you have the getopt_long function. */
 #cmakedefine HAVE_GETOPT_LONG 1
 
diff --git a/configure.ac b/configure.ac
index 6fe5adf103..ab37da80a4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2187,10 +2187,6 @@ AC_SUBST(randpkt_man)
 
 AC_SUBST(wiresharkfilter_man)
 
-dnl Checks for "getaddrinfo()" - and "-lnsl", if we need it to get
-dnl "getaddrinfo()".
-AC_WIRESHARK_GETADDRINFO_LIB_CHECK
-
 dnl Checks for "connect()", used as a proxy for "socket()" - and
 dnl "-lsocket", if we need it to get "connect()".
 AC_WIRESHARK_SOCKET_LIB_CHECK
@@ -2685,7 +2681,7 @@ AC_MSG_CHECKING(whether to use the c-ares library if available)
 
 AC_ARG_WITH(c-ares,
   AC_HELP_STRING( [--with-c-ares@<:@=DIR@:>@],
-                  [use c-ares (located in directory DIR, if supplied) - supersedes --with-adns @<:@default=yes, if present@:>@]),
+		  [use c-ares (located in directory DIR, if supplied) - supersedes --with-adns @<:@default=yes, if present@:>@]),
 [
 if   test "x$withval" = "xno";  then
 	want_c_ares=no
@@ -2710,7 +2706,7 @@ AC_MSG_CHECKING(whether to use the GNU ADNS library if available)
 
 AC_ARG_WITH(adns,
   AC_HELP_STRING( [--with-adns@<:@=DIR@:>@],
-                  [use GNU ADNS (located in directory DIR, if supplied) @<:@default=yes, if present@:>@]),
+		  [use GNU ADNS (located in directory DIR, if supplied) @<:@default=yes, if present@:>@]),
 [
 if   test "x$withval" = "xno";  then
 	want_adns=no
@@ -2729,6 +2725,31 @@ else
 fi
 AC_SUBST(ADNS_LIBS)
 
+if test "x$have_good_c_ares" != "xyes" -a "x$have_good_adns" != "xyes"; then
+	# We don't have an asynchronous name resolver, look for a synchronous one
+
+	dnl Checks for "getaddrinfo()" - and "-lnsl", if we need it to get
+	dnl "getaddrinfo()".
+	AC_WIRESHARK_GETADDRINFO_LIB_CHECK
+
+	if test "x$ac_cv_func_getaddrinfo" != "xyes" ; then
+		# We don't have the modern name resolver, try older stuff
+
+		dnl Checks for "gethostbyname()" - and "-lnsl", if we need it to get
+		dnl "gethostbyname()".
+		AC_WIRESHARK_GETHOSTBY_LIB_CHECK
+
+		if test "x$ac_cv_func_gethostbyname" != "xyes" ; then
+			# Hopefully this never actually happens.
+			# The code works even without name resolvers but we
+			# alert the user to this unusual condition.
+			AC_MSG_ERROR(Couldn't find any name resolvers!)
+		fi
+
+		AC_CHECK_FUNCS(gethostbyname2)
+	fi
+fi
+
 dnl GEOIP Check
 GEOIP_LIBS=''
 AC_MSG_CHECKING(whether to use the GeoIP IP address mapping library if available)
diff --git a/epan/addr_resolv.c b/epan/addr_resolv.c
index 9002ad7940..11c37c9ce5 100644
--- a/epan/addr_resolv.c
+++ b/epan/addr_resolv.c
@@ -889,7 +889,7 @@ try_resolv:
             fill_dummy_ip4(addr, tp);
             return tp;
         }
-#elif defined(HAVE_GETADDRINFO)
+
         /*
          * The Windows "gethostbyaddr()" insists on translating 0.0.0.0 to
          * the name of the host on which it's running; to work around that
@@ -899,6 +899,7 @@ try_resolv:
          * Presumably getaddrinfo() behaves the same way.  Anyway, we should
          * never get to this code on Windows since those builds include c-ares.
          */
+#elif defined(HAVE_GETADDRINFO)
         if (addr != 0) {
             struct sockaddr_in sin;
 
@@ -911,6 +912,17 @@ try_resolv:
                 return tp;
             }
         }
+#elif defined(HAVE_GETHOSTBYNAME)
+        if (addr != 0) {
+            struct hostent *hostp;
+
+            hostp = gethostbyaddr((const char *)&addr, 4, AF_INET);
+
+            if (hostp != NULL && hostp->h_name[0] != '\0') {
+                g_strlcpy(tp->name, hostp->h_name, MAXNAMELEN);
+                return tp;
+            }
+        }
 #endif
 
         /* unknown host or DNS timeout */
@@ -943,6 +955,8 @@ host_lookup6(const struct e_in6_addr *addr, gboolean *found)
     async_dns_queue_msg_t *caqm;
 #elif defined(HAVE_GETADDRINFO)
     struct sockaddr_in6 sin6;
+#elif defined(HAVE_GETHOSTBYNAME)
+    struct hostent *hostp;
 #endif
 #endif /* INET6 */
 
@@ -991,14 +1005,22 @@ try_resolv:
             return tp;
         }
 #elif defined(HAVE_GETADDRINFO)
-            memset(&sin6, 0, sizeof(sin6));
-            sin6.sin6_family      = AF_INET6;
-            memcpy(sin6.sin6_addr.s6_addr, addr, sizeof(*addr));
-            if (getnameinfo((struct sockaddr *)&sin6, sizeof(sin6),
-                            tp->name, sizeof(tp->name),
-                            NULL, 0, NI_NAMEREQD) == 0) {
-                return tp;
-            }
+        memset(&sin6, 0, sizeof(sin6));
+        sin6.sin6_family      = AF_INET6;
+        memcpy(sin6.sin6_addr.s6_addr, addr, sizeof(*addr));
+        if (getnameinfo((struct sockaddr *)&sin6, sizeof(sin6),
+                        tp->name, sizeof(tp->name),
+                        NULL, 0, NI_NAMEREQD) == 0) {
+            return tp;
+        }
+#elif defined(HAVE_GETHOSTBYNAME)
+        /* Quick hack to avoid DNS/YP timeout */
+        hostp = gethostbyaddr((const char *)addr, sizeof(*addr), AF_INET6);
+
+        if (hostp != NULL && hostp->h_name[0] != '\0') {
+            g_strlcpy(tp->name, hostp->h_name, MAXNAMELEN);
+            return tp;
+        }
 #endif
 #endif /* INET6 */
     }
@@ -3249,6 +3271,8 @@ get_host_ipaddr(const char *host, guint32 *addrp)
     async_hostent_t ahe;
 #elif defined(HAVE_GETADDRINFO)
     struct addrinfo hint, *result = NULL;
+#elif defined(HAVE_GETHOSTBYNAME)
+    struct hostent *hp;
 #endif
 
     /*
@@ -3315,6 +3339,18 @@ get_host_ipaddr(const char *host, guint32 *addrp)
                 return ret_val;
             }
         }
+#elif defined(HAVE_GETHOSTBYNAME)
+        hp = gethostbyname(host);
+        if (hp == NULL) {
+            /* No. */
+            return FALSE;
+            /* Apparently, some versions of gethostbyaddr can
+             * return IPv6 addresses. */
+         } else if (hp->h_length <= (int) sizeof (struct in_addr)) {
+             memcpy(&ipaddr, hp->h_addr, hp->h_length);
+         } else {
+             return FALSE;
+         }
 #endif
     } else {
         /* Does the string really contain dotted-quad IP?
@@ -3346,6 +3382,8 @@ get_host_ipaddr6(const char *host, struct e_in6_addr *addrp)
     async_hostent_t ahe;
 #elif defined(HAVE_GETADDRINFO)
     struct addrinfo hint, *result = NULL;
+#elif defined(HAVE_GETHOSTBYNAME2)
+    struct hostent *hp;
 #endif /* HAVE_C_ARES */
 
     if (str_to_ip6(host, addrp))
@@ -3408,6 +3446,12 @@ get_host_ipaddr6(const char *host, struct e_in6_addr *addrp)
             return ret_val;
         }
     }
+#elif defined(HAVE_GETHOSTBYNAME2)
+    hp = gethostbyname2(host, AF_INET6);
+    if (hp != NULL && hp->h_length == sizeof(struct e_in6_addr)) {
+        memcpy(addrp, hp->h_addr, hp->h_length);
+        return TRUE;
+    }
 #endif
 
     return FALSE;
@@ -3418,8 +3462,9 @@ get_host_ipaddr6(const char *host, struct e_in6_addr *addrp)
  * Return "ip6" if it is IPv6, "ip" otherwise (including the case
  * that we don't know)
  */
-const char* host_ip_af(const char *host
-#ifndef HAVE_GETADDRINFO
+const char *
+host_ip_af(const char *host
+#if !defined(HAVE_GETADDRINFO) || !defined(HAVE_GETHOSTBYNAME2)
         _U_
 #endif
         )
@@ -3435,6 +3480,9 @@ const char* host_ip_af(const char *host
         }
         freeaddrinfo(result);
     }
+#elif defined(HAVE_GETHOSTBYNAME2)
+    struct hostent *h;
+    return (h = gethostbyname2(host, AF_INET6)) && h->h_addrtype == AF_INET6 ? "ip6" : "ip";
 #endif
     return af;
 }