Clean up linux shellcode Makefile

Now you can "make single_bind_tcp_shell", or the like, and build one
payload instead of the kludgy embedded shell script that always builds
all of them.

Need to do the same with BSD.

external/source/shellcode/linux/ia32/Makefile

@@ -1,17 +1,43 @@
-ASM=nasm
 STAGERS=stager_sock_bind stager_sock_bind_udp stager_sock_bind_icmp \
         stager_egghunt stager_sock_find stager_sock_reverse \
         stager_sock_reverse_icmp stager_sock_reverse_udp \
-		  stager_sock_reverse_udp_dns
+				stager_sock_reverse_udp_dns
 STAGES=stage_tcp_shell stage_udp_shell
 SINGLE=single_adduser single_bind_tcp_shell single_find_tcp_shell \
        single_reverse_tcp_shell single_reverse_udp_shell single_exec
+
 OBJS=${STAGERS} ${STAGES} ${SINGLE}
 
-include ../../Makefile.incl
+.SUFFIXES:
+.SUFFIXES: .asm .hex .disasm .o
+
+# Tell Make not to delete these intermediate files
+.PRECIOUS: %.hex %.disasm
+
+all: $(SINGLE) $(STAGES) $(STAGERS)
+
+%.o: %.asm %.bin %.hex %.disasm
+	@nasm -o $@ -f elf $<
+
+%.bin: %.asm
+	@nasm -o $@ -f bin $<
+
+# Replace 00 with \x00.  Put quotes at beginning and end of line.  Put plus at
+# end of all lines but the last.  This ends up outputting an escaped string
+# suitable for use in a Ruby script.
+%.hex: %.bin
+	@xxd -c 16 -ps $< | \
+		sed -e 's/\([0123456789abcdef][0123456789abcdef]\)/\\x\1/g' \
+		-e 's/^/"/;s/$$/"/;$$ b;s/$$/+/;' > $@
+
+%.disasm: %.bin
+	@ndisasm -b 32 $< > $@
+
+$(SINGLE) $(STAGES) $(STAGERS): %: %.o
+	@echo "Building $@... (`wc -c $(<:.o=.bin)|awk '{print $$1}'` bytes)"
+	@ld -i -m elf_i386 $< -o $@
+	@chmod +x $@
 
-all: 
-	@for i in ${OBJS}; ${BUILDASM}; done
 
 clean:
-	rm -f *.o *.hex ${OBJS} *.disasm
+	rm -f *.bin *.tmp *.o *.hex ${OBJS} *.disasm