It is useless and time-consuming to call get_original_dst() when the proxy
is not in transparent mode :

10:30:12.784822 accept(3, {sa_family=AF_INET, sin_port=htons(32788), sin_addr=inet_addr("10.0.3.2")}, [16]) = 5 <0.000026>
10:30:12.784933 fcntl64(5, F_SETFL, O_RDONLY|O_NONBLOCK) = 0 <0.000008>
10:30:12.784980 setsockopt(5, SOL_TCP, TCP_NODELAY, [1], 4) = 0 <0.000010>
10:30:12.785035 getsockopt(5, SOL_IP, 0x50 /* IP_??? */, 0xb0c93478, 0xb0c93460) = -1 ENOPROTOOPT (Protocol not available) <0.000015>
10:30:12.785107 getsockname(5, {sa_family=AF_INET, sin_port=htons(8000), sin_addr=inet_addr("10.0.3.1")}, [16]) = 0 <0.000011>
10:30:12.785207 write(2, "accepting from 0x806e9c8 => 1 co"..., 60) = 60 <0.000016>


--- hapoxy-1.1.32/haproxy.c	Sun Oct  9 11:32:39 2005
+++ ./haproxy.c	Sun Oct  9 11:54:25 2005
@@ -1592,7 +1592,7 @@
 /* some prototypes */
 static int maintain_proxies(void);
 
-/* this either returns the sockname or the original destination address. Code
+/* This either returns the sockname or the original destination address. Code
  * inspired from Patrick Schaaf's example of nf_getsockname() implementation.
  */
 static int get_original_dst(int fd, struct sockaddr_in *sa, socklen_t *salen) {
@@ -1723,7 +1723,8 @@
 	struct sockaddr_in sockname;
 	socklen_t namelen = sizeof(sockname);
 
-	if (get_original_dst(s->cli_fd, (struct sockaddr_in *)&sockname, &namelen) == -1)
+	if (!(s->proxy->options & PR_O_TRANSP) ||
+	    get_original_dst(s->cli_fd, (struct sockaddr_in *)&sockname, &namelen) == -1)
 	    getsockname(s->cli_fd, (struct sockaddr *)&sockname, &namelen);
 	s->srv_addr.sin_port = htons(ntohs(s->srv_addr.sin_port) + ntohs(sockname.sin_port));
     }
@@ -2499,7 +2500,8 @@
 	    socklen_t namelen = sizeof(sockname);
 	    unsigned char *pn, *sn;
 
-	    if (get_original_dst(cfd, (struct sockaddr_in *)&sockname, &namelen) == -1)
+	    if (!(s->proxy->options & PR_O_TRANSP) ||
+		get_original_dst(cfd, (struct sockaddr_in *)&sockname, &namelen) == -1)
 		getsockname(cfd, (struct sockaddr *)&sockname, &namelen);
 	    sn = (unsigned char *)&sockname.sin_addr;
 	    pn = (unsigned char *)&s->cli_addr.sin_addr;
@@ -2523,7 +2525,8 @@
 	    unsigned char *pn, *sn;
 	    int len;
 
-	    if (get_original_dst(cfd, (struct sockaddr_in *)&sockname, &namelen) == -1)
+	    if (!(s->proxy->options & PR_O_TRANSP) ||
+		get_original_dst(cfd, (struct sockaddr_in *)&sockname, &namelen) == -1)
 		getsockname(cfd, (struct sockaddr *)&sockname, &namelen);
 	    sn = (unsigned char *)&sockname.sin_addr;
 	    pn = (unsigned char *)&s->cli_addr.sin_addr;