Allow compilation on Darwin, reverting parts of Linux/Debian patch

Signed-off-by: Fabian Groffen <grobian@gentoo.org>

--- a/netcat.c	2023-09-26 15:04:51.169658537 +0200
+++ b/netcat.c	2023-09-26 15:07:00.270929256 +0200
@@ -50,13 +50,18 @@
 # include <bsd/readpassphrase.h>
 #endif
 
+#ifndef IPTOS_LOWCOST
+# define IPTOS_LOWCOST 0x02
+#endif
 #ifndef IPTOS_LOWDELAY
 # define IPTOS_LOWDELAY 0x10
 # define IPTOS_THROUGHPUT 0x08
 # define IPTOS_RELIABILITY 0x04
-# define IPTOS_LOWCOST 0x02
 # define IPTOS_MINCOST IPTOS_LOWCOST
 #endif /* IPTOS_LOWDELAY */
+#ifndef SOCK_CLOEXEC
+# define SOCK_CLOEXEC 0
+#endif
 
 # ifndef IPTOS_DSCP_AF11
 # define	IPTOS_DSCP_AF11		0x28
@@ -108,8 +113,9 @@
 # include <tls.h>
 #endif
 #include <unistd.h>
-#include <bsd/stdlib.h>
-#include <bsd/string.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
 
 #include "atomicio.h"
 
@@ -814,9 +820,8 @@
 				int connfd;
 
 				len = sizeof(cliaddr);
-				connfd = accept4(s, (struct sockaddr *)&cliaddr,
-				    &len, SOCK_NONBLOCK);
-				if (connfd == -1) {
+				connfd = accept(s, (struct sockaddr *)&cliaddr, &len);
+				if (connfd == -1 || fcntl(connfd, F_SETFL, O_NONBLOCK) == -1) {
 					/* For now, all errnos are fatal */
 					err(1, "accept");
 				}
@@ -1069,6 +1074,8 @@
 		} else
 			err(1, "poll failed");
 	}
+	if (fcntl(s, F_SETFD, FD_CLOEXEC) == -1)
+		return -1;
 
 	return ret;
 }
@@ -1218,9 +1225,13 @@
 		    port, gai_strerror(error));
 
 	for (res = res0; res; res = res->ai_next) {
-		if ((s = socket(res->ai_family, res->ai_socktype |
-		    SOCK_NONBLOCK, res->ai_protocol)) == -1)
+		if ((s = socket(res->ai_family, res->ai_socktype,
+		    res->ai_protocol)) == -1)
 			continue;
+		if (fcntl(s, F_SETFL, O_NONBLOCK) == -1) {
+			close(s);
+			continue;
+		}
 
 		/* Bind to a local port or source address if specified. */
 		if (sflag || pflag) {
--- a/socks.c	2023-09-26 15:04:51.085185645 +0200
+++ b/socks.c	2023-09-26 15:07:30.947097100 +0200
@@ -38,7 +38,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <resolv.h>
-#include <bsd/readpassphrase.h>
+#include <readpassphrase.h>
 #include "atomicio.h"
 
 #define SOCKS_PORT	"1080"
@@ -53,6 +53,8 @@
 #define SOCKS_DOMAIN	3
 #define SOCKS_IPV6	4
 
+#define explicit_bzero(S,L) bzero(S,L)
+
 int	remote_connect(const char *, const char *, struct addrinfo, char *);
 int	socks_connect(const char *, const char *, struct addrinfo,
 	    const char *, const char *, struct addrinfo, int,