Improved IPv6 netmask parsing
The subnet mask parsing in toV6CIDR only worked for very well behaved
subnet strings. This became apparent after the BMC received a DHCP
assigned IPv6 address with an Address Prefix equal to /128. Any
netmask values trailing the final ":" character were ignored. In
addition it assumed all subnet entries would be submitted in shorthand
form.
The changes here handle mask values supplied following the final ":"
character. It also does more sanity checking on the incoming subnet
string.
Tested:
Supplied the function with the following test patterns, and confirmed
the function returns accurate address prefix values.
ffff:ffff::
ffff:ffff:ffff::
ffff:ffff:fc00::
ffff:0:0:0:0:0:0:0
ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffc
ffff:0fff::
ffff:fgff::
ffff:0:0:6:0:0:0:0
::
:
abcd:efgh:ijkl:mnop:pqrs:tuvw:xyz:abcd
ffff:0:0:0:0:0:0
Change-Id: Ib2c73fe07a6a3f1c7a5f0e8f231dfef21badb3af
Signed-off-by: Johnathan Mantey <johnathanx.mantey@intel.com>
diff --git a/util.cpp b/util.cpp
index e517f06..eb3bf5f 100644
--- a/util.cpp
+++ b/util.cpp
@@ -37,59 +37,40 @@
uint8_t toV6Cidr(const std::string& subnetMask)
{
- uint8_t pos = 0;
- uint8_t prevPos = 0;
- uint8_t cidr = 0;
- uint16_t buff{};
- do
+ struct in6_addr subnet;
+ int ret = inet_pton(AF_INET6, subnetMask.c_str(), &subnet);
+ if (ret != 1)
{
- // subnet mask look like ffff:ffff::
- // or ffff:c000::
- pos = subnetMask.find(":", prevPos);
- if (pos == std::string::npos)
- {
- break;
- }
+ log<level::ERR>("Invalid Mask",
+ entry("SUBNETMASK=%s", subnetMask.c_str()));
+ return 0;
+ }
- auto str = subnetMask.substr(prevPos, (pos - prevPos));
- prevPos = pos + 1;
-
- // String length is 0
- if (!str.length())
- {
- return cidr;
- }
- // converts it into number.
- if (sscanf(str.c_str(), "%hx", &buff) <= 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;
}
+ trailingZeroes = __builtin_ctz(subnet.s6_addr32[lv]);
+ zeroesFound |= trailingZeroes;
- // convert the number into bitset
- // and check for how many ones are there.
- // if we don't have all the ones then make
- // sure that all the ones should be left justify.
-
- if (__builtin_popcount(buff) != 16)
+ if (bitsSet + trailingZeroes != 32)
{
- if (((sizeof(buff) * 8) - (__builtin_ctz(buff))) !=
- __builtin_popcount(buff))
- {
- log<level::ERR>("Invalid Mask",
- entry("SUBNETMASK=%s", subnetMask.c_str()));
-
- return 0;
- }
- cidr += __builtin_popcount(buff);
- return cidr;
+ // There are '1' bits interspersed with '0' bits
+ log<level::ERR>("Invalid Mask",
+ entry("SUBNETMASK=%s", subnetMask.c_str()));
+ return 0;
}
-
- cidr += 16;
- } while (1);
-
+ cidr += bitsSet;
+ }
return cidr;
}
} // anonymous namespace