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[pkgsrc/trunk]: pkgsrc/net/libfetch/files Fix strict aliasing issue which GCC...



details:   https://anonhg.NetBSD.org/pkgsrc/rev/5fb30e86ac7f
branches:  trunk
changeset: 562818:5fb30e86ac7f
user:      tnn <tnn%pkgsrc.org@localhost>
date:      Thu Aug 06 14:02:38 2009 +0000

description:
Fix strict aliasing issue which GCC 4.4 complained about.

While we know that "struct sockaddr_storage" has been engineered to alias
to all the sockaddr structs, the compiler does not know about this.
Thus, code like this may be unsafe to use:

struct sockaddr_storage ss;
struct sockaddr_in *sin = &ss;
sin->sin_port = 0; /* dereferencing here breaks ISO C aliasing rules */

A workaround is to wrap the struct in a union, e.g:
union anonymous {
  struct sockaddr_storage ss;
  struct sockaddr_in sin;
} u;
u.sin.sin_port = 0;
--
Approved by: joerg

diffstat:

 net/libfetch/files/ftp.c |  81 +++++++++++++++++++++++------------------------
 1 files changed, 40 insertions(+), 41 deletions(-)

diffs (188 lines):

diff -r c33fb77510e2 -r 5fb30e86ac7f net/libfetch/files/ftp.c
--- a/net/libfetch/files/ftp.c  Thu Aug 06 13:54:03 2009 +0000
+++ b/net/libfetch/files/ftp.c  Thu Aug 06 14:02:38 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ftp.c,v 1.27 2009/02/22 19:11:48 joerg Exp $   */
+/*     $NetBSD: ftp.c,v 1.28 2009/08/06 14:02:38 tnn Exp $     */
 /*-
  * Copyright (c) 1998-2004 Dag-Erling Coïdan Smørgrav
  * Copyright (c) 2008, 2009 Joerg Sonnenberger <joerg%NetBSD.org@localhost>
@@ -620,9 +620,12 @@
 ftp_transfer(conn_t *conn, const char *oper, const char *file, const char *op_arg,
     int mode, off_t offset, const char *flags)
 {
-       struct sockaddr_storage sa;
-       struct sockaddr_in6 *sin6;
-       struct sockaddr_in *sin4;
+       union anonymous {
+               struct sockaddr_storage ss;
+               struct sockaddr sa;
+               struct sockaddr_in6 sin6;
+               struct sockaddr_in sin4;
+       } u;
        const char *bindaddr;
        const char *filename;
        int filenamelen, type;
@@ -650,16 +653,16 @@
                goto ouch;
 
        /* find our own address, bind, and listen */
-       l = sizeof(sa);
-       if (getsockname(conn->sd, (struct sockaddr *)&sa, &l) == -1)
+       l = sizeof(u.ss);
+       if (getsockname(conn->sd, &u.sa, &l) == -1)
                goto sysouch;
-       if (sa.ss_family == AF_INET6)
-               unmappedaddr((struct sockaddr_in6 *)&sa, &l);
+       if (u.ss.ss_family == AF_INET6)
+               unmappedaddr(&u.sin6, &l);
 
 retry_mode:
 
        /* open data socket */
-       if ((sd = socket(sa.ss_family, SOCK_STREAM, IPPROTO_TCP)) == -1) {
+       if ((sd = socket(u.ss.ss_family, SOCK_STREAM, IPPROTO_TCP)) == -1) {
                fetch_syserr();
                return (NULL);
        }
@@ -673,7 +676,7 @@
                /* send PASV command */
                if (verbose)
                        fetch_info("setting passive mode");
-               switch (sa.ss_family) {
+               switch (u.ss.ss_family) {
                case AF_INET:
                        if ((e = ftp_cmd(conn, "PASV")) != FTP_PASSIVE_MODE)
                                goto ouch;
@@ -746,28 +749,26 @@
                                goto sysouch;
 
                /* construct sockaddr for data socket */
-               l = sizeof(sa);
-               if (getpeername(conn->sd, (struct sockaddr *)&sa, &l) == -1)
+               l = sizeof(u.ss);
+               if (getpeername(conn->sd, &u.sa, &l) == -1)
                        goto sysouch;
-               if (sa.ss_family == AF_INET6)
-                       unmappedaddr((struct sockaddr_in6 *)&sa, &l);
-               switch (sa.ss_family) {
+               if (u.ss.ss_family == AF_INET6)
+                       unmappedaddr(&u.sin6, &l);
+               switch (u.ss.ss_family) {
                case AF_INET6:
-                       sin6 = (struct sockaddr_in6 *)&sa;
                        if (e == FTP_EPASSIVE_MODE)
-                               sin6->sin6_port = htons(port);
+                               u.sin6.sin6_port = htons(port);
                        else {
-                               memcpy(&sin6->sin6_addr, addr + 2, 16);
-                               memcpy(&sin6->sin6_port, addr + 19, 2);
+                               memcpy(&u.sin6.sin6_addr, addr + 2, 16);
+                               memcpy(&u.sin6.sin6_port, addr + 19, 2);
                        }
                        break;
                case AF_INET:
-                       sin4 = (struct sockaddr_in *)&sa;
                        if (e == FTP_EPASSIVE_MODE)
-                               sin4->sin_port = htons(port);
+                               u.sin4.sin_port = htons(port);
                        else {
-                               memcpy(&sin4->sin_addr, addr, 4);
-                               memcpy(&sin4->sin_port, addr + 4, 2);
+                               memcpy(&u.sin4.sin_addr, addr, 4);
+                               memcpy(&u.sin4.sin_port, addr + 4, 2);
                        }
                        break;
                default:
@@ -780,9 +781,9 @@
                        fetch_info("opening data connection");
                bindaddr = getenv("FETCH_BIND_ADDRESS");
                if (bindaddr != NULL && *bindaddr != '\0' &&
-                   fetch_bind(sd, sa.ss_family, bindaddr) != 0)
+                   fetch_bind(sd, u.ss.ss_family, bindaddr) != 0)
                        goto sysouch;
-               if (connect(sd, (struct sockaddr *)&sa, l) == -1)
+               if (connect(sd, &u.sa, l) == -1)
                        goto sysouch;
 
                /* make the server initiate the transfer */
@@ -806,9 +807,9 @@
                char *ap;
                char hname[INET6_ADDRSTRLEN];
 
-               switch (sa.ss_family) {
+               switch (u.ss.ss_family) {
                case AF_INET6:
-                       ((struct sockaddr_in6 *)&sa)->sin6_port = 0;
+                       u.sin6.sin6_port = 0;
 #ifdef IPV6_PORTRANGE
                        arg = low ? IPV6_PORTRANGE_DEFAULT : IPV6_PORTRANGE_HIGH;
                        if (setsockopt(sd, IPPROTO_IPV6, IPV6_PORTRANGE,
@@ -817,7 +818,7 @@
 #endif
                        break;
                case AF_INET:
-                       ((struct sockaddr_in *)&sa)->sin_port = 0;
+                       u.sin4.sin_port = 0;
 #ifdef IP_PORTRANGE
                        arg = low ? IP_PORTRANGE_DEFAULT : IP_PORTRANGE_HIGH;
                        if (setsockopt(sd, IPPROTO_IP, IP_PORTRANGE,
@@ -828,19 +829,18 @@
                }
                if (verbose)
                        fetch_info("binding data socket");
-               if (bind(sd, (struct sockaddr *)&sa, l) == -1)
+               if (bind(sd, &u.sa, l) == -1)
                        goto sysouch;
                if (listen(sd, 1) == -1)
                        goto sysouch;
 
                /* find what port we're on and tell the server */
-               if (getsockname(sd, (struct sockaddr *)&sa, &l) == -1)
+               if (getsockname(sd, &u.sa, &l) == -1)
                        goto sysouch;
-               switch (sa.ss_family) {
+               switch (u.ss.ss_family) {
                case AF_INET:
-                       sin4 = (struct sockaddr_in *)&sa;
-                       a = ntohl(sin4->sin_addr.s_addr);
-                       p = ntohs(sin4->sin_port);
+                       a = ntohl(u.sin4.sin_addr.s_addr);
+                       p = ntohs(u.sin4.sin_port);
                        e = ftp_cmd(conn, "PORT %d,%d,%d,%d,%d,%d",
                            (a >> 24) & 0xff, (a >> 16) & 0xff,
                            (a >> 8) & 0xff, a & 0xff,
@@ -849,18 +849,17 @@
                case AF_INET6:
 #define UC(b)  (((int)b)&0xff)
                        e = -1;
-                       sin6 = (struct sockaddr_in6 *)&sa;
-                       sin6->sin6_scope_id = 0;
-                       if (getnameinfo((struct sockaddr *)&sa, l,
+                       u.sin6.sin6_scope_id = 0;
+                       if (getnameinfo(&u.sa, l,
                                hname, sizeof(hname),
                                NULL, 0, NI_NUMERICHOST) == 0) {
                                e = ftp_cmd(conn, "EPRT |%d|%s|%d|", 2, hname,
-                                   htons(sin6->sin6_port));
+                                   htons(u.sin6.sin6_port));
                                if (e == -1)
                                        goto ouch;
                        }
                        if (e != FTP_OK) {
-                               ap = (char *)&sin6->sin6_addr;
+                               ap = (char *)&u.sin6.sin6_addr;
                                e = ftp_cmd(conn,
                                    "LPRT %d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d",
                                    6, 16,
@@ -869,8 +868,8 @@
                                    UC(ap[8]), UC(ap[9]), UC(ap[10]), UC(ap[11]),
                                    UC(ap[12]), UC(ap[13]), UC(ap[14]), UC(ap[15]),
                                    2,
-                                   (ntohs(sin6->sin6_port) >> 8) & 0xff,
-                                   ntohs(sin6->sin6_port)        & 0xff);
+                                   (ntohs(u.sin6.sin6_port) >> 8) & 0xff,
+                                   ntohs(u.sin6.sin6_port)        & 0xff);
                        }
                        break;
                default:



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