acl: Avoid undefined behaviour due to 32-bit shift.

[paraslash.git] / acl.c

diff --git a/acl.c b/acl.c
index 10f56bf1bd90fd62e1bb129140365fbed3c2e136..75fdc55b12842890136afec74e70125f81b6318c 100644 (file)
--- a/acl.c
+++ b/acl.c
@@ -31,10 +31,12 @@ struct access_info {
 /**
  * Return true if addr_1 matches addr_2 in the first `netmask' bits.
  */
-static int v4_addr_match(uint32_t addr_1, uint32_t addr_2, uint8_t netmask)
+static bool v4_addr_match(uint32_t addr_1, uint32_t addr_2, uint8_t netmask)
 {
        uint32_t mask = ~0U;
 
+       if (netmask == 0) /* avoid 32-bit shift, which is undefined in C. */
+               return true;
        if (netmask < 32)
                mask <<= (32 - netmask);
        return (htonl(addr_1) & mask) == (htonl(addr_2) & mask);