if sockaddr_storage is available, use it, even if IPv6 support is disabled

Support for using sockaddr_storage was originally added to support IPv6,
and only used if IPv6 support was enabled.  Two decades later, support
for sockaddr_storage is ubiquitous and can simplify our code paths,
so use the modern interface whenever we can now.

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Part-of: <https://gitlab.freedesktop.org/xorg/lib/libxtrans/-/merge_requests/28>

3 files changed, 29 insertions, 47 deletions

diff --git a/Xtrans.h b/Xtrans.h
index 8796b7e..8cf0daf 100644
--- a/Xtrans.h
+++ b/Xtrans.h
@@ -131,7 +131,13 @@ static const char *__xtransname = "_XTrans";
  * This structure needs to be independent of the socket/TLI interface used.
  */
 
-#if defined(IPv6) && defined(AF_INET6)
+/* Temporary workaround for consumers whose configure scripts were
+   generated with pre-1.6 versions of xtrans.m4 */
+#if defined(IPv6) && !defined(HAVE_STRUCT_SOCKADDR_STORAGE)
+#define HAVE_STRUCT_SOCKADDR_STORAGE
+#endif
+
+#ifdef HAVE_STRUCT_SOCKADDR_STORAGE
 typedef struct sockaddr_storage Xtransaddr;
 #else
 #define XTRANS_MAX_ADDR_LEN	128	/* large enough to hold sun_path */
diff --git a/Xtranssock.c b/Xtranssock.c
index 69c20cd..b2692e5 100644
--- a/Xtranssock.c
+++ b/Xtranssock.c
@@ -296,24 +296,16 @@ static int
 TRANS(SocketINETGetAddr) (XtransConnInfo ciptr)
 
 {
-#ifdef IPv6
-    struct sockaddr_storage socknamev6;
+#ifdef HAVE_STRUCT_SOCKADDR_STORAGE
+    struct sockaddr_storage sockname;
 #else
-    struct sockaddr_in socknamev4;
+    struct sockaddr_in sockname;
 #endif
-    void *socknamePtr;
-    SOCKLEN_T namelen;
+    void *socknamePtr = &sockname;
+    SOCKLEN_T namelen = sizeof(sockname);
 
     prmsg (3,"SocketINETGetAddr(%p)\n", (void *) ciptr);
 
-#ifdef IPv6
-    namelen = sizeof(socknamev6);
-    socknamePtr = &socknamev6;
-#else
-    namelen = sizeof(socknamev4);
-    socknamePtr = &socknamev4;
-#endif
-
     bzero(socknamePtr, namelen);
 
     if (getsockname (ciptr->fd,(struct sockaddr *) socknamePtr,
@@ -338,11 +330,7 @@ TRANS(SocketINETGetAddr) (XtransConnInfo ciptr)
         return -1;
     }
 
-#ifdef IPv6
     ciptr->family = ((struct sockaddr *)socknamePtr)->sa_family;
-#else
-    ciptr->family = socknamev4.sin_family;
-#endif
     ciptr->addrlen = namelen;
     memcpy (ciptr->addr, socknamePtr, ciptr->addrlen);
 
@@ -359,25 +347,13 @@ static int
 TRANS(SocketINETGetPeerAddr) (XtransConnInfo ciptr)
 
 {
-#ifdef IPv6
-    struct sockaddr_storage socknamev6;
-#endif
-    struct sockaddr_in 	socknamev4;
-    void *socknamePtr;
-    SOCKLEN_T namelen;
-
-#ifdef IPv6
-    if (ciptr->family == AF_INET6)
-    {
-	namelen = sizeof(socknamev6);
-	socknamePtr = &socknamev6;
-    }
-    else
+#ifdef HAVE_STRUCT_SOCKADDR_STORAGE
+    struct sockaddr_storage sockname;
+#else
+    struct sockaddr_in 	sockname;
 #endif
-    {
-	namelen = sizeof(socknamev4);
-	socknamePtr = &socknamev4;
-    }
+    void *socknamePtr = &sockname;
+    SOCKLEN_T namelen = sizeof(sockname);
 
     bzero(socknamePtr, namelen);
 
@@ -863,7 +839,7 @@ TRANS(SocketINETCreateListener) (XtransConnInfo ciptr, const char *port,
                                  unsigned int flags)
 
 {
-#ifdef IPv6
+#ifdef HAVE_STRUCT_SOCKADDR_STORAGE
     struct sockaddr_storage sockname;
 #else
     struct sockaddr_in	    sockname;
@@ -937,7 +913,6 @@ TRANS(SocketINETCreateListener) (XtransConnInfo ciptr, const char *port,
 	sport = 0;
 
     bzero(&sockname, sizeof(sockname));
-#ifdef IPv6
     if (Sockettrans2devtab[ciptr->index].family == AF_INET) {
 	namelen = sizeof (struct sockaddr_in);
 #ifdef BSD44SOCKETS
@@ -947,6 +922,7 @@ TRANS(SocketINETCreateListener) (XtransConnInfo ciptr, const char *port,
 	((struct sockaddr_in *)&sockname)->sin_port = htons(sport);
 	((struct sockaddr_in *)&sockname)->sin_addr.s_addr = htonl(INADDR_ANY);
     } else {
+#ifdef IPv6
 	namelen = sizeof (struct sockaddr_in6);
 #ifdef SIN6_LEN
 	((struct sockaddr_in6 *)&sockname)->sin6_len = sizeof(sockname);
@@ -954,15 +930,13 @@ TRANS(SocketINETCreateListener) (XtransConnInfo ciptr, const char *port,
 	((struct sockaddr_in6 *)&sockname)->sin6_family = AF_INET6;
 	((struct sockaddr_in6 *)&sockname)->sin6_port = htons(sport);
 	((struct sockaddr_in6 *)&sockname)->sin6_addr = in6addr_any;
-    }
 #else
-#ifdef BSD44SOCKETS
-    sockname.sin_len = sizeof (sockname);
-#endif
-    sockname.sin_family = AF_INET;
-    sockname.sin_port = htons (sport);
-    sockname.sin_addr.s_addr = htonl (INADDR_ANY);
+        prmsg (1,
+               "SocketINETCreateListener: unsupported address family %d\n",
+               Sockettrans2devtab[ciptr->index].family);
+        return TRANS_CREATE_LISTENER_FAILED;
 #endif
+    }
 
     if ((status = TRANS(SocketCreateListener) (ciptr,
 	(struct sockaddr *) &sockname, namelen, flags)) < 0)
diff --git a/xtrans.m4 b/xtrans.m4
index fbb6527..f145f42 100644
--- a/xtrans.m4
+++ b/xtrans.m4
@@ -55,9 +55,11 @@ AC_DEFUN([XTRANS_TCP_FLAGS],[
  ])
 
  # POSIX.1g changed the type of pointer passed to getsockname/getpeername/etc.
- AC_CHECK_TYPES([socklen_t], [], [], [
+ # and added a type defined to be large enough to hold any sockaddr format.
+ AC_CHECK_TYPES([socklen_t, struct sockaddr_storage], [], [], [
 AC_INCLUDES_DEFAULT
-#include <sys/socket.h>])
+#include <sys/socket.h>
+ ])
 
  # XPG4v2/UNIX95 added msg_control - check to see if we need to define
  # _XOPEN_SOURCE to get it (such as on Solaris)