Buffer overflow in nprintf()

[nezza]

nprintf does not check bounds of its buffer.

Example code:

char *testbuf = calloc(1, sizeof(char) * 1000001);
memset(testbuf, 'A', 1000000);
printf("Testbuf len: %ld\n", strlen(testbuf));
nprintf(client, testbuf);

[MagicalTux]

nprintf() now uses vsnprintf() and will reallocate its buffer if not large enough.