net-analyzer/openbsd-netcat-1.195-r1: fix build for musl and Darwin

Package-Manager: Portage-3.0.18, Repoman-3.0.2
Signed-off-by: Fabian Groffen <grobian@gentoo.org>

5 files changed, 557 insertions, 44 deletions

diff --git a/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.105-musl-b64_ntop.patch b/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.105-musl-b64_ntop.patch
new file mode 100644
index 000000000000..a9603b38bc03
--- /dev/null
+++ b/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.105-musl-b64_ntop.patch
@@ -0,0 +1,349 @@
+diff -Naur netcat-openbsd-1.105.orig/Makefile netcat-openbsd-1.105/Makefile
+--- netcat-openbsd-1.105.orig/Makefile	2017-06-18 09:01:44.293852659 -0700
++++ netcat-openbsd-1.105/Makefile	2017-06-18 09:04:35.566687655 -0700
+@@ -1,7 +1,7 @@
+ #       $OpenBSD: Makefile,v 1.6 2001/09/02 18:45:41 jakob Exp $
+ 
+ PROG=	nc
+-SRCS=	netcat.c atomicio.c socks.c
++SRCS=	netcat.c atomicio.c socks.c compat/base64.c
+ 
+ LIBS=  `pkg-config --libs libbsd` -lresolv
+ OBJS=  $(SRCS:.c=.o)
+diff -Naur netcat-openbsd-1.105.orig/compat/base64.c netcat-openbsd-1.105/compat/base64.c
+--- netcat-openbsd-1.105.orig/compat/base64.c	1969-12-31 16:00:00.000000000 -0800
++++ netcat-openbsd-1.105/compat/base64.c	2017-06-18 09:01:31.288700637 -0700
+@@ -0,0 +1,315 @@
++/*	$OpenBSD: base64.c,v 1.8 2015/01/16 16:48:51 deraadt Exp $	*/
++
++/*
++ * Copyright (c) 1996 by Internet Software Consortium.
++ *
++ * Permission to use, copy, modify, and distribute this software for any
++ * purpose with or without fee is hereby granted, provided that the above
++ * copyright notice and this permission notice appear in all copies.
++ *
++ * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
++ * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
++ * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
++ * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
++ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
++ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
++ * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
++ * SOFTWARE.
++ */
++
++/*
++ * Portions Copyright (c) 1995 by International Business Machines, Inc.
++ *
++ * International Business Machines, Inc. (hereinafter called IBM) grants
++ * permission under its copyrights to use, copy, modify, and distribute this
++ * Software with or without fee, provided that the above copyright notice and
++ * all paragraphs of this notice appear in all copies, and that the name of IBM
++ * not be used in connection with the marketing of any product incorporating
++ * the Software or modifications thereof, without specific, written prior
++ * permission.
++ *
++ * To the extent it has a right to do so, IBM grants an immunity from suit
++ * under its patents, if any, for the use, sale or manufacture of products to
++ * the extent that such products are used for performing Domain Name System
++ * dynamic updates in TCP/IP networks by means of the Software.  No immunity is
++ * granted for any product per se or for any other function of any product.
++ *
++ * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
++ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
++ * PARTICULAR PURPOSE.  IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
++ * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
++ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
++ * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
++ */
++
++#include <sys/types.h>
++#include <sys/socket.h>
++#include <netinet/in.h>
++#include <arpa/inet.h>
++#include <arpa/nameser.h>
++
++#include <ctype.h>
++#include <resolv.h>
++#include <stdio.h>
++
++#include <stdlib.h>
++#include <string.h>
++
++static const char Base64[] =
++	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
++static const char Pad64 = '=';
++
++/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
++   The following encoding technique is taken from RFC 1521 by Borenstein
++   and Freed.  It is reproduced here in a slightly edited form for
++   convenience.
++
++   A 65-character subset of US-ASCII is used, enabling 6 bits to be
++   represented per printable character. (The extra 65th character, "=",
++   is used to signify a special processing function.)
++
++   The encoding process represents 24-bit groups of input bits as output
++   strings of 4 encoded characters. Proceeding from left to right, a
++   24-bit input group is formed by concatenating 3 8-bit input groups.
++   These 24 bits are then treated as 4 concatenated 6-bit groups, each
++   of which is translated into a single digit in the base64 alphabet.
++
++   Each 6-bit group is used as an index into an array of 64 printable
++   characters. The character referenced by the index is placed in the
++   output string.
++
++                         Table 1: The Base64 Alphabet
++
++      Value Encoding  Value Encoding  Value Encoding  Value Encoding
++          0 A            17 R            34 i            51 z
++          1 B            18 S            35 j            52 0
++          2 C            19 T            36 k            53 1
++          3 D            20 U            37 l            54 2
++          4 E            21 V            38 m            55 3
++          5 F            22 W            39 n            56 4
++          6 G            23 X            40 o            57 5
++          7 H            24 Y            41 p            58 6
++          8 I            25 Z            42 q            59 7
++          9 J            26 a            43 r            60 8
++         10 K            27 b            44 s            61 9
++         11 L            28 c            45 t            62 +
++         12 M            29 d            46 u            63 /
++         13 N            30 e            47 v
++         14 O            31 f            48 w         (pad) =
++         15 P            32 g            49 x
++         16 Q            33 h            50 y
++
++   Special processing is performed if fewer than 24 bits are available
++   at the end of the data being encoded.  A full encoding quantum is
++   always completed at the end of a quantity.  When fewer than 24 input
++   bits are available in an input group, zero bits are added (on the
++   right) to form an integral number of 6-bit groups.  Padding at the
++   end of the data is performed using the '=' character.
++
++   Since all base64 input is an integral number of octets, only the
++         -------------------------------------------------                       
++   following cases can arise:
++   
++       (1) the final quantum of encoding input is an integral
++           multiple of 24 bits; here, the final unit of encoded
++	   output will be an integral multiple of 4 characters
++	   with no "=" padding,
++       (2) the final quantum of encoding input is exactly 8 bits;
++           here, the final unit of encoded output will be two
++	   characters followed by two "=" padding characters, or
++       (3) the final quantum of encoding input is exactly 16 bits;
++           here, the final unit of encoded output will be three
++	   characters followed by one "=" padding character.
++   */
++
++int
++b64_ntop(src, srclength, target, targsize)
++	u_char const *src;
++	size_t srclength;
++	char *target;
++	size_t targsize;
++{
++	size_t datalength = 0;
++	u_char input[3];
++	u_char output[4];
++	int i;
++
++	while (2 < srclength) {
++		input[0] = *src++;
++		input[1] = *src++;
++		input[2] = *src++;
++		srclength -= 3;
++
++		output[0] = input[0] >> 2;
++		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
++		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
++		output[3] = input[2] & 0x3f;
++
++		if (datalength + 4 > targsize)
++			return (-1);
++		target[datalength++] = Base64[output[0]];
++		target[datalength++] = Base64[output[1]];
++		target[datalength++] = Base64[output[2]];
++		target[datalength++] = Base64[output[3]];
++	}
++    
++	/* Now we worry about padding. */
++	if (0 != srclength) {
++		/* Get what's left. */
++		input[0] = input[1] = input[2] = '\0';
++		for (i = 0; i < srclength; i++)
++			input[i] = *src++;
++	
++		output[0] = input[0] >> 2;
++		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
++		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
++
++		if (datalength + 4 > targsize)
++			return (-1);
++		target[datalength++] = Base64[output[0]];
++		target[datalength++] = Base64[output[1]];
++		if (srclength == 1)
++			target[datalength++] = Pad64;
++		else
++			target[datalength++] = Base64[output[2]];
++		target[datalength++] = Pad64;
++	}
++	if (datalength >= targsize)
++		return (-1);
++	target[datalength] = '\0';	/* Returned value doesn't count \0. */
++	return (datalength);
++}
++
++/* skips all whitespace anywhere.
++   converts characters, four at a time, starting at (or after)
++   src from base - 64 numbers into three 8 bit bytes in the target area.
++   it returns the number of data bytes stored at the target, or -1 on error.
++ */
++
++int
++b64_pton(src, target, targsize)
++	char const *src;
++	u_char *target;
++	size_t targsize;
++{
++	int tarindex, state, ch;
++	u_char nextbyte;
++	char *pos;
++
++	state = 0;
++	tarindex = 0;
++
++	while ((ch = (unsigned char)*src++) != '\0') {
++		if (isspace(ch))	/* Skip whitespace anywhere. */
++			continue;
++
++		if (ch == Pad64)
++			break;
++
++		pos = strchr(Base64, ch);
++		if (pos == 0) 		/* A non-base64 character. */
++			return (-1);
++
++		switch (state) {
++		case 0:
++			if (target) {
++				if (tarindex >= targsize)
++					return (-1);
++				target[tarindex] = (pos - Base64) << 2;
++			}
++			state = 1;
++			break;
++		case 1:
++			if (target) {
++				if (tarindex >= targsize)
++					return (-1);
++				target[tarindex]   |=  (pos - Base64) >> 4;
++				nextbyte = ((pos - Base64) & 0x0f) << 4;
++				if (tarindex + 1 < targsize)
++					target[tarindex+1] = nextbyte;
++				else if (nextbyte)
++					return (-1);
++			}
++			tarindex++;
++			state = 2;
++			break;
++		case 2:
++			if (target) {
++				if (tarindex >= targsize)
++					return (-1);
++				target[tarindex]   |=  (pos - Base64) >> 2;
++				nextbyte = ((pos - Base64) & 0x03) << 6;
++				if (tarindex + 1 < targsize)
++					target[tarindex+1] = nextbyte;
++				else if (nextbyte)
++					return (-1);
++			}
++			tarindex++;
++			state = 3;
++			break;
++		case 3:
++			if (target) {
++				if (tarindex >= targsize)
++					return (-1);
++				target[tarindex] |= (pos - Base64);
++			}
++			tarindex++;
++			state = 0;
++			break;
++		}
++	}
++
++	/*
++	 * We are done decoding Base-64 chars.  Let's see if we ended
++	 * on a byte boundary, and/or with erroneous trailing characters.
++	 */
++
++	if (ch == Pad64) {			/* We got a pad char. */
++		ch = (unsigned char)*src++;	/* Skip it, get next. */
++		switch (state) {
++		case 0:		/* Invalid = in first position */
++		case 1:		/* Invalid = in second position */
++			return (-1);
++
++		case 2:		/* Valid, means one byte of info */
++			/* Skip any number of spaces. */
++			for (; ch != '\0'; ch = (unsigned char)*src++)
++				if (!isspace(ch))
++					break;
++			/* Make sure there is another trailing = sign. */
++			if (ch != Pad64)
++				return (-1);
++			ch = (unsigned char)*src++;		/* Skip the = */
++			/* Fall through to "single trailing =" case. */
++			/* FALLTHROUGH */
++
++		case 3:		/* Valid, means two bytes of info */
++			/*
++			 * We know this char is an =.  Is there anything but
++			 * whitespace after it?
++			 */
++			for (; ch != '\0'; ch = (unsigned char)*src++)
++				if (!isspace(ch))
++					return (-1);
++
++			/*
++			 * Now make sure for cases 2 and 3 that the "extra"
++			 * bits that slopped past the last full byte were
++			 * zeros.  If we don't check them, they become a
++			 * subliminal channel.
++			 */
++			if (target && tarindex < targsize &&
++			    target[tarindex] != 0)
++				return (-1);
++		}
++	} else {
++		/*
++		 * We ended by seeing the end of the string.  Make sure we
++		 * have no partial bytes lying around.
++		 */
++		if (state != 0)
++			return (-1);
++	}
++
++	return (tarindex);
++}
+diff -Naur netcat-openbsd-1.105.orig/compat/base64.h netcat-openbsd-1.105/compat/base64.h
+--- netcat-openbsd-1.105.orig/compat/base64.h	1969-12-31 16:00:00.000000000 -0800
++++ netcat-openbsd-1.105/compat/base64.h	2017-06-18 09:09:02.057554167 -0700
+@@ -0,0 +1,3 @@
++#include <sys/types.h>
++int b64_ntop(u_char const* src, size_t srclength, char *target, size_t targsize);
++int b64_pton(char const* src, u_char *target, size_t targsize);
+diff -Naur netcat-openbsd-1.105.orig/socks.c netcat-openbsd-1.105/socks.c
+--- netcat-openbsd-1.105.orig/socks.c	2017-06-18 09:01:44.293852659 -0700
++++ netcat-openbsd-1.105/socks.c	2017-06-18 09:09:21.105757665 -0700
+@@ -40,6 +40,7 @@
+ #include <resolv.h>
+ #include <bsd/readpassphrase.h>
+ #include "atomicio.h"
++#include "compat/base64.h"
+ 
+ #define SOCKS_PORT	"1080"
+ #define HTTP_PROXY_PORT	"3128"
diff --git a/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.190-darwin.patch b/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.190-darwin.patch
index a8453c09067c..72a3fe8ed9f5 100644
--- a/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.190-darwin.patch
+++ b/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.190-darwin.patch
@@ -34,50 +34,6 @@ index a0fb51b..bbb5dd1 100644
  
  #include "atomicio.h"
  
-@@ -240,6 +243,43 @@ static int connect_with_timeout(int fd, const struct sockaddr *sa,
- 
- static void quit();
- 
-+static char* strtonumerrs[] = {
-+	"too large",
-+	"too small",
-+	"invalid"
-+};
-+
-+static long long
-+strtonum(
-+		const char *nptr,
-+		long long minval,
-+		long long maxval,
-+		const char **errstr)
-+{
-+	long long val;
-+
-+	while (*nptr != '\0' && isspace(*nptr))
-+		nptr++;
-+	if (*nptr == '\0') {
-+		if (errstr != NULL)
-+			*errstr = strtonumerrs[2];
-+		return 0;
-+	}
-+	val = atoll(nptr);
-+	if (val < minval) {
-+		if (errstr != NULL)
-+			*errstr = strtonumerrs[1];
-+		return 0;
-+	}
-+	if (val > maxval) {
-+		if (errstr != NULL)
-+			*errstr = strtonumerrs[0];
-+		return 0;
-+	}
-+	*errstr = NULL;
-+	return val;
-+}
-+
- int
- main(int argc, char *argv[])
- {
 @@ -814,9 +814,8 @@
  # endif
  			} else {
diff --git a/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.190-darwin13.patch b/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.190-darwin13.patch
new file mode 100644
index 000000000000..5a643a2945f3
--- /dev/null
+++ b/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.190-darwin13.patch
@@ -0,0 +1,50 @@
+strtonum isn't available on <Darwin-10.15
+
+diff --git a/netcat.c b/netcat.c
+index a0fb51b..bbb5dd1 100644
+--- a/netcat.c
++++ b/netcat.c
+@@ -240,6 +243,43 @@ static int connect_with_timeout(int fd, const struct sockaddr *sa,
+ 
+ static void quit();
+ 
++static char* strtonumerrs[] = {
++	"too large",
++	"too small",
++	"invalid"
++};
++
++static long long
++strtonum(
++		const char *nptr,
++		long long minval,
++		long long maxval,
++		const char **errstr)
++{
++	long long val;
++
++	while (*nptr != '\0' && isspace(*nptr))
++		nptr++;
++	if (*nptr == '\0') {
++		if (errstr != NULL)
++			*errstr = strtonumerrs[2];
++		return 0;
++	}
++	val = atoll(nptr);
++	if (val < minval) {
++		if (errstr != NULL)
++			*errstr = strtonumerrs[1];
++		return 0;
++	}
++	if (val > maxval) {
++		if (errstr != NULL)
++			*errstr = strtonumerrs[0];
++		return 0;
++	}
++	*errstr = NULL;
++	return val;
++}
++
+ int
+ main(int argc, char *argv[])
+ {
diff --git a/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.195-darwin.patch b/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.195-darwin.patch
new file mode 100644
index 000000000000..489eceedf6c0
--- /dev/null
+++ b/net-analyzer/openbsd-netcat/files/openbsd-netcat-1.195-darwin.patch
@@ -0,0 +1,96 @@
+Allow compilation on Darwin
+
+diff --git a/netcat.c b/netcat.c
+index a0fb51b..bbb5dd1 100644
+--- a/netcat.c
++++ b/netcat.c
+@@ -51,11 +51,16 @@
+ # 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
+ 
+@@ -108,8 +110,9 @@
+ # 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 +814,8 @@
+ # endif
+ 			} else {
+ 				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");
+ 				}
+@@ -1100,6 +1099,8 @@
+ 			return -1;
+ 		}
+ 	}
++	if (fcntl(s, F_SETFD, FD_CLOEXEC) == -1)
++		return -1;
+ 
+ 	memset(&s_un, 0, sizeof(struct sockaddr_un));
+ 	s_un.sun_family = AF_UNIX;
+@@ -1174,9 +1175,13 @@
+ 		    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)) < 0)
++		if ((s = socket(res->ai_family, res->ai_socktype,
++		    res->ai_protocol)) < 0)
++			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) {
+diff --git a/socks.c b/socks.c
+index 9068f39..68b68e3 100644
+--- a/socks.c
++++ b/socks.c
+@@ -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"
+--- a/socks.c
++++ b/socks.c
+@@ -53,5 +53,7 @@
+ #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);
+ int	socks_connect(const char *, const char *, struct addrinfo,
diff --git a/net-analyzer/openbsd-netcat/openbsd-netcat-1.195-r1.ebuild b/net-analyzer/openbsd-netcat/openbsd-netcat-1.195-r1.ebuild
new file mode 100644
index 000000000000..6fd1b2b6f906
--- /dev/null
+++ b/net-analyzer/openbsd-netcat/openbsd-netcat-1.195-r1.ebuild
@@ -0,0 +1,62 @@
+# Copyright 1999-2021 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=7
+
+inherit toolchain-funcs
+
+DESCRIPTION="The OpenBSD network swiss army knife"
+HOMEPAGE="https://cvsweb.openbsd.org/src/usr.bin/nc/
+	https://salsa.debian.org/debian/netcat-openbsd"
+SRC_URI="http://http.debian.net/debian/pool/main/n/netcat-openbsd/netcat-openbsd_${PV}.orig.tar.gz
+	http://http.debian.net/debian/pool/main/n/netcat-openbsd/netcat-openbsd_${PV}-2.debian.tar.xz"
+LICENSE="BSD"
+SLOT="0"
+IUSE="elibc_Darwin"
+
+KEYWORDS="~amd64 ~arm64 ~ppc64 ~x86 ~amd64-linux ~x64-macos"
+
+BDEPEND="virtual/pkgconfig"
+RDEPEND="!elibc_Darwin? ( dev-libs/libbsd )
+	!net-analyzer/netcat
+	!net-analyzer/netcat6
+"
+
+S=${WORKDIR}/netcat-openbsd-${PV}
+
+src_prepare() {
+	for i_patch in $(<"${WORKDIR}"/debian/patches/series); do
+		eapply "${WORKDIR}"/debian/patches/"${i_patch}"
+	done
+	if [[ ${CHOST} == *-darwin* ]] ; then
+		# this undoes some of the Debian/Linux changes
+		eapply "${FILESDIR}"/${PN}-1.195-darwin.patch
+		if [[ ${CHOST##*-darwin} -lt 19 ]] ; then
+			eapply "${FILESDIR}"/${PN}-1.190-darwin13.patch
+		fi
+	fi
+	if use elibc_musl ; then
+		eapply "${FILESDIR}"/${PN}-1.105-musl-b64_ntop.patch
+	fi
+	default
+}
+
+src_compile() {
+	emake CC=$(tc-getCC) CFLAGS="${CFLAGS}" LDFLAGS="${LDFLAGS}"
+}
+
+src_install() {
+	dobin nc
+	doman nc.1
+	cd "${WORKDIR}"/debian || die
+	newdoc netcat-openbsd.README.Debian README
+	dodoc -r examples
+}
+
+pkg_postinst() {
+	if [[ ${KERNEL} = "linux" ]]; then
+		ewarn "SO_REUSEPORT is introduced in linux 3.9. If your running kernel is older"
+		ewarn "and kernel header is newer, nc will not listen correctly. Matching the header"
+		ewarn "to the running kernel will do. See bug #490246 for details."
+	fi
+}