Bugfixes

[pilsnerfrajz]

Bugfixes

This adds a fix for bugs related to alarm and a buffer size constant.

Alarm Bug

The addition of fingerprinting introduced a bug were an alarm was not reset which caused a segmentation fault.

sudo ./bin/disco 192.168.1.1 -p 1-100
[+] Host 192.168.1.1 is up!
[*] Scanning 100 port(s) on 192.168.1.1...
[1]    62647 segmentation fault  sudo ./bin/disco 192.168.1.1 -p 1-100

The bug was fixed by setting alarm(0) in arp.c.

Buffer Constant

The MAC address print buffer constant used the run-time function strlen instead of a compile-time operator like sizeof to calculate the size, creating a warning. Since the -Werror compiler flag is used, this throws an error.

make
src/main.c:198:9: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant]
  198 |         char m[MAC_PRINT_BUF_SIZE];
      |                ^~~~~~~~~~~~~~~~~~
src/main.c:18:29: note: expanded from macro 'MAC_PRINT_BUF_SIZE'
   18 | #define MAC_PRINT_BUF_SIZE (strlen("[+] MAC address: 00:xx:de:ad:be:ef") + 1)
      |                            ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
make: *** [main.o] Error 1

By changing the constant to #define MAC_PRINT_BUF_SIZE (sizeof("[+] MAC address: 00:xx:de:ad:be:ef\n")) the error is fixed.