util: Collapse toCidr functions
This collapses the v4/v6 Cidr conversion function into a single routine.
It also removes multi-instruction instrinsics like popcnt, and instead
only uses ctz / clz when needed.
Change-Id: I3fecec9b050617d2556488a5d0c007df860a080b
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/util.cpp b/util.cpp
index 25d2838..bf6bf7f 100644
--- a/util.cpp
+++ b/util.cpp
@@ -35,90 +35,43 @@
using namespace sdbusplus::xyz::openbmc_project::Common::Error;
namespace fs = std::filesystem;
-uint8_t toV6Cidr(const std::string& subnetMask)
-{
- struct in6_addr subnet;
- int ret = inet_pton(AF_INET6, subnetMask.c_str(), &subnet);
- if (ret != 1)
- {
- log<level::ERR>("Invalid Mask",
- entry("SUBNETMASK=%s", subnetMask.c_str()));
- return 0;
- }
-
- uint8_t cidr = 0;
- bool zeroesFound = false;
- int bitsSet, trailingZeroes;
- for (int lv = 0; lv < 4; lv++)
- {
- subnet.s6_addr32[lv] = be32toh(subnet.s6_addr32[lv]);
- bitsSet = __builtin_popcount(subnet.s6_addr32[lv]);
- if (zeroesFound && bitsSet)
- {
- log<level::ERR>("Invalid Mask",
- entry("SUBNETMASK=%s", subnetMask.c_str()));
- return 0;
- }
-
- // The __builtin_ctz function returns -1 when the value is 0 on arm.
- // GCC's doc specifies that:
- // If x is 0, the result is undefined.
- // https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gcc/Other-Builtins.html
- // So we could not rely on the undefined behavior.
- // Handling the 0 case specifically fixes the issue.
- if (subnet.s6_addr32[lv] == 0)
- {
- trailingZeroes = 32;
- }
- else
- {
- trailingZeroes = __builtin_ctz(subnet.s6_addr32[lv]);
- }
- zeroesFound |= trailingZeroes;
-
- if (bitsSet + trailingZeroes != 32)
- {
- // There are '1' bits interspersed with '0' bits
- log<level::ERR>("Invalid Mask",
- entry("SUBNETMASK=%s", subnetMask.c_str()));
- return 0;
- }
- cidr += bitsSet;
- }
- return cidr;
-}
} // anonymous namespace
uint8_t toCidr(int addressFamily, const std::string& subnetMask)
{
- if (addressFamily == AF_INET6)
- {
- return toV6Cidr(subnetMask);
- }
-
- uint32_t buff;
-
- auto rc = inet_pton(addressFamily, subnetMask.c_str(), &buff);
- if (rc <= 0)
+ uint32_t subnet[sizeof(in6_addr) / sizeof(uint32_t)];
+ if (inet_pton(addressFamily, subnetMask.c_str(), &subnet) != 1)
{
log<level::ERR>("inet_pton failed:",
entry("SUBNETMASK=%s", subnetMask.c_str()));
return 0;
}
- buff = be32toh(buff);
- // total no of bits - total no of leading zero == total no of ones
- if (((sizeof(buff) * 8) - (__builtin_ctz(buff))) ==
- __builtin_popcount(buff))
+ static_assert(sizeof(in6_addr) % sizeof(uint32_t) == 0);
+ static_assert(sizeof(in_addr) % sizeof(uint32_t) == 0);
+ auto i = (addressFamily == AF_INET ? sizeof(in_addr) : sizeof(in6_addr)) /
+ sizeof(uint32_t);
+ while (i > 0)
{
- return __builtin_popcount(buff);
+ if (subnet[--i] != 0)
+ {
+ auto v = be32toh(subnet[i]);
+ static_assert(sizeof(unsigned) == sizeof(uint32_t));
+ auto trailing = __builtin_ctz(v);
+ auto ret = (i + 1) * 32 - trailing;
+ bool valid = ~v == 0 || 32 == trailing + __builtin_clz(~v);
+ while (i > 0 && (valid = (~subnet[--i] == 0) && valid))
+ ;
+ if (!valid)
+ {
+ log<level::ERR>("Invalid netmask",
+ entry("SUBNETMASK=%s", subnetMask.c_str()));
+ return 0;
+ }
+ return ret;
+ }
}
- else
- {
- log<level::ERR>("Invalid Mask",
- entry("SUBNETMASK=%s", subnetMask.c_str()));
- return 0;
- }
+ return 0;
}
std::string toMask(int addressFamily, uint8_t prefix)