README: add some useful links for leak checks

without -Werror=implicit-function-declaration our test for GNU-style
getservbyname_r silently succeeds on NetBSD 10
(because the function exists, so the testcase links successfully).

however NetBSD's version has a completely different signature which
leads to crashes at runtime:

    Program terminated with signal SIGSEGV, Segmentation fault.
    #0  0x0000f1707faa2b78 in free () from /usr/lib/libc.so.12
    [Current thread is 1 (process 25072)]
    (gdb) backtrace
    #0  0x0000f1707faa2b78 in free () from /usr/lib/libc.so.12
    #1  0x0000f1707fac58b0 in _servent_open () from /usr/lib/libc.so.12
    #2  0x0000f1707fac5a60 in setservent_r () from /usr/lib/libc.so.12
    #3  0x0000f1707fac4490 in getservbyname_r () from /usr/lib/libc.so.12
    #4  0x0000f17080235788 in mygetservbyname_r (name=0xf1707f847ab0 "80", proto=0x0, result_buf=0xffffffe29738, buf=0xffffffe29338 "", buflen=1024, result=0xffffffe29758) at src/core.c:917
    #5  0x0000f17080235aa8 in proxy_getaddrinfo (node=0xf1707f847ba0 "4get.nadeko.net", service=0xf1707f847ab0 "80", hints=0xffffffe29978, res=0xffffffe29968) at src/core.c:1004
    #6  0x0000f17080238a94 in getaddrinfo (node=0xf1707f847ba0 "4get.nadeko.net", service=0xf1707f847ab0 "80", hints=0xffffffe29978, res=0xffffffe29968) at src/libproxychains.c:795

netbsd's signature is:
struct servent *
getservbyname_r(const char *name, const char *proto, struct servent *sp,
    struct servent_data *sd)

and basically the first thing it does is to free existing members of the
sd struct, which obviously crashes when the thing passed as 4th argument
isn't actually that kind of struct.

README

@@ -263,6 +263,15 @@ Known Problems:
   there are unconfirmed reports that it works as root though.
   musl libc is unaffected from the bug.
 
+Useful links
+------------
+the following sites may prove useful to check for leaks:
+https://ipfighter.com/
+https://browserleaks.com/webrtc
+https://dnsleaktest.com
+http://check.torproject.org - tor specific
+http://ifconfig.me - can be used via curl
+http://ifconfig.io/
 
 Community:
 ----------

configure

@@ -182,6 +182,7 @@ ishaiku() {
 check_compile 'whether C compiler works' '' 'int main() {return 0;}' || fail 'error: install a C compiler and library'
 check_compile 'whether libc headers are complete' '' '#include <netdb.h>\nint main() {return 0;}' || fail 'error: necessary libc headers are not installed'
 check_compile 'whether C compiler understands -Wno-unknown-pragmas' '-Wno-unknown-pragmas' 'int main() {return 0;}'
+check_compile 'whether C compiler understands -Werror=implicit-function-declaration' '-Werror=implicit-function-declaration' 'int main() {return 0;}'
 
 if ! check_compile 'whether getnameinfo() servlen argument is POSIX compliant (socklen_t)' "-DGN_NODELEN_T=socklen_t -DGN_SERVLEN_T=socklen_t -DGN_FLAGS_T=int" \
 '#define _GNU_SOURCE\n#include <netdb.h>\nint getnameinfo(const struct sockaddr *, socklen_t, char *, socklen_t, char *, socklen_t, int);int main() {\nreturn 0;}' ; then
@@ -220,6 +221,7 @@ check_define __APPLE__ && {
 	fi
 }
 check_define __FreeBSD__ && bsd_detected=true
+check_define __NetBSD__ && bsd_detected=true
 check_define __OpenBSD__ && {
 bsd_detected=true
 echo "CFLAGS+=-DIS_OPENBSD">>config.mak
@@ -249,7 +251,7 @@ check_link "whether we can use -Wl,--no-as-needed" "-Wl,--no-as-needed" \
 LD_SONAME_FLAG=
 printf "checking what's the option to use in linker to set library name ... "
 for o in --soname -h -soname -install_name; do
-	check_link_silent "-shared -Wl,$o,libconftest.so" "void test_func(int a) {}" && LD_SONAME_FLAG=$o && break
+	check_link_silent "-shared -Wl,$o,libconftest.so" "void test_func(void) {}" && LD_SONAME_FLAG=$o && break
 done
 if [ -z "$LD_SONAME_FLAG" ]; then
 	printf '\ncannot find an option to set library name\n'

src/daemon/daemon.c

@@ -5,6 +5,7 @@
 
 */
 
+#undef _GNU_SOURCE
 #define _GNU_SOURCE
 #include <unistd.h>
 #define _POSIX_C_SOURCE 200809L

src/libproxychains.c

@@ -241,7 +241,7 @@ static int proxy_from_string(const char *proxystring,
 		ul = p-u;
 		p++;
 		pl = at-p;
-		if(proxytype == RS_PT_SOCKS5 && (ul > 255 || pl > 255))
+		if(ul > 255 || pl > 255)
 			return 0;
 		memcpy(user_buf, u, ul);
 		user_buf[ul]=0;
@@ -767,7 +767,7 @@ HOOKFUNC(int, connect, int sock, const struct sockaddr *addr, unsigned int len)
 }
 
 #ifdef IS_SOLARIS
-HOOKFUNC(int, __xnet_connect, int sock, const struct sockaddr *addr, unsigned int len)
+HOOKFUNC(int, __xnet_connect, int sock, const struct sockaddr *addr, unsigned int len) {
 	return connect(sock, addr, len);
 }
 #endif

src/proxychains.conf

@@ -79,12 +79,12 @@ proxy_dns
 # we use the reserved 224.x.x.x range by default,
 # if the proxified app does a DNS request, we will return an IP from that range.
 # on further accesses to this ip we will send the saved DNS name to the proxy.
-# in case some control-freak app checks the returned ip, and denies to
+# in case some control-freak app checks the returned ip, and denies to 
 # connect, you can use another subnet, e.g. 10.x.x.x or 127.x.x.x.
 # of course you should make sure that the proxified app does not need
-# *real* access to this subnet.
+# *real* access to this subnet. 
 # i.e. dont use the same subnet then in the localnet section
-#remote_dns_subnet 127
+#remote_dns_subnet 127 
 #remote_dns_subnet 10
 remote_dns_subnet 224
 
@@ -109,7 +109,7 @@ tcp_connect_time_out 8000
 
 ## RFC6890 Loopback address range
 ## if you enable this, you have to make sure remote_dns_subnet is not 127
-## you'll need to enable it if you want to use an application that
+## you'll need to enable it if you want to use an application that 
 ## connects to localhost.
 # localnet 127.0.0.0/255.0.0.0
 # localnet ::1/128
@@ -147,8 +147,8 @@ tcp_connect_time_out 8000
 #            	socks5	192.168.67.78	1080	lamer	secret
 #		http	192.168.89.3	8080	justu	hidden
 #	 	socks4	192.168.1.49	1080
-#	        http	192.168.39.93	8080
-#
+#	        http	192.168.39.93	8080	
+#		
 #
 #       proxy types: http, socks4, socks5, raw
 #         * raw: The traffic is simply forwarded to the proxy without modification.
@@ -159,3 +159,4 @@ tcp_connect_time_out 8000
 # meanwile
 # defaults set to "tor"
 socks4 	127.0.0.1 9050
+