diff options
Diffstat (limited to 'src/c/urweb.c')
-rw-r--r-- | src/c/urweb.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/src/c/urweb.c b/src/c/urweb.c index 238b27e2..4d2de1dd 100644 --- a/src/c/urweb.c +++ b/src/c/urweb.c @@ -3455,6 +3455,23 @@ uw_Basis_string uw_Basis_makeSigString(uw_context ctx, uw_Basis_string sig) { return r; } +/* This bit of crafty code is intended to prevent GCC from performing + * optimizations that would enable timing attacks. See: + * http://www.impredicative.com/pipermail/ur/2011-July/000659.html + */ +int uw_streq(uw_Basis_string s1, uw_Basis_string s2) { + int i, x = 0, len1 = strlen(s1); + + if (len1 != strlen(s2)) return 0; + + for (i = 0; i < len1; ++i) { + __asm__ __volatile__ (""); + x |= s1[i] ^ s2[i]; + } + + return x == 0; +} + uw_Basis_string uw_Basis_sigString(uw_context ctx, uw_unit u) { return ctx->app->cookie_sig(ctx); } |