From: Topi Miettinen Date: Sat, 2 Jul 2022 14:15:42 +0000 (+0300) Subject: basic: generate netmasks for IPv6 and generic IP family addresses X-Git-Tag: v252-rc1~297^2~3 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3f36b9ed477ce3b003d03e3dcca7376fbdcee1a4;p=thirdparty%2Fsystemd.git basic: generate netmasks for IPv6 and generic IP family addresses Added functions to generate netmasks for IPv6 and generic IP family addresses. --- diff --git a/src/basic/in-addr-util.c b/src/basic/in-addr-util.c index fe356c6d15c..cefe3f7661b 100644 --- a/src/basic/in-addr-util.c +++ b/src/basic/in-addr-util.c @@ -586,6 +586,7 @@ unsigned char in4_addr_netmask_to_prefixlen(const struct in_addr *addr) { return 32U - u32ctz(be32toh(addr->s_addr)); } +/* Calculate an IPv4 netmask from prefix length, for example /8 -> 255.0.0.0. */ struct in_addr* in4_addr_prefixlen_to_netmask(struct in_addr *addr, unsigned char prefixlen) { assert(addr); assert(prefixlen <= 32); @@ -599,6 +600,47 @@ struct in_addr* in4_addr_prefixlen_to_netmask(struct in_addr *addr, unsigned cha return addr; } +/* Calculate an IPv6 netmask from prefix length, for example /16 -> ffff::. */ +struct in6_addr* in6_addr_prefixlen_to_netmask(struct in6_addr *addr, unsigned char prefixlen) { + assert(addr); + assert(prefixlen <= 128); + + for (unsigned i = 0; i < 16; i++) { + uint8_t mask; + + if (prefixlen >= 8) { + mask = 0xFF; + prefixlen -= 8; + } else if (prefixlen > 0) { + mask = 0xFF << (8 - prefixlen); + prefixlen = 0; + } else { + assert(prefixlen == 0); + mask = 0; + } + + addr->s6_addr[i] = mask; + } + + return addr; +} + +/* Calculate an IPv4 or IPv6 netmask from prefix length, for example /8 -> 255.0.0.0 or /16 -> ffff::. */ +int in_addr_prefixlen_to_netmask(int family, union in_addr_union *addr, unsigned char prefixlen) { + assert(addr); + + switch (family) { + case AF_INET: + in4_addr_prefixlen_to_netmask(&addr->in, prefixlen); + return 0; + case AF_INET6: + in6_addr_prefixlen_to_netmask(&addr->in6, prefixlen); + return 0; + default: + return -EAFNOSUPPORT; + } +} + int in4_addr_default_prefixlen(const struct in_addr *addr, unsigned char *prefixlen) { uint8_t msb_octet = *(uint8_t*) addr; diff --git a/src/basic/in-addr-util.h b/src/basic/in-addr-util.h index fbc60436c79..19fa35f1d28 100644 --- a/src/basic/in-addr-util.h +++ b/src/basic/in-addr-util.h @@ -138,6 +138,8 @@ int in_addr_from_string_auto(const char *s, int *ret_family, union in_addr_union unsigned char in4_addr_netmask_to_prefixlen(const struct in_addr *addr); struct in_addr* in4_addr_prefixlen_to_netmask(struct in_addr *addr, unsigned char prefixlen); +struct in6_addr* in6_addr_prefixlen_to_netmask(struct in6_addr *addr, unsigned char prefixlen); +int in_addr_prefixlen_to_netmask(int family, union in_addr_union *addr, unsigned char prefixlen); int in4_addr_default_prefixlen(const struct in_addr *addr, unsigned char *prefixlen); int in4_addr_default_subnet_mask(const struct in_addr *addr, struct in_addr *mask); int in4_addr_mask(struct in_addr *addr, unsigned char prefixlen); diff --git a/src/test/test-in-addr-util.c b/src/test/test-in-addr-util.c index f5dcad65d54..31d767e41d4 100644 --- a/src/test/test-in-addr-util.c +++ b/src/test/test-in-addr-util.c @@ -364,4 +364,56 @@ TEST(in_addr_to_string) { test_in_addr_to_string_one(AF_INET6, "fe80::"); } +TEST(in_addr_prefixlen_to_netmask) { + union in_addr_union addr; + static const char *const ipv4_netmasks[] = { + "0.0.0.0", "128.0.0.0", "192.0.0.0", "224.0.0.0", "240.0.0.0", + "248.0.0.0", "252.0.0.0", "254.0.0.0", "255.0.0.0", + "255.128.0.0", "255.192.0.0", "255.224.0.0", "255.240.0.0", + "255.248.0.0", "255.252.0.0", "255.254.0.0", "255.255.0.0", + "255.255.128.0", "255.255.192.0", "255.255.224.0", "255.255.240.0", + "255.255.248.0", "255.255.252.0", "255.255.254.0", "255.255.255.0", + "255.255.255.128", "255.255.255.192", "255.255.255.224", "255.255.255.240", + "255.255.255.248", "255.255.255.252", "255.255.255.254", "255.255.255.255", + }; + + static const char *const ipv6_netmasks[] = { + [0] = "::", + [1] = "8000::", + [2] = "c000::", + [7] = "fe00::", + [8] = "ff00::", + [9] = "ff80::", + [16] = "ffff::", + [17] = "ffff:8000::", + [32] = "ffff:ffff::", + [33] = "ffff:ffff:8000::", + [64] = "ffff:ffff:ffff:ffff::", + [65] = "ffff:ffff:ffff:ffff:8000::", + [96] = "ffff:ffff:ffff:ffff:ffff:ffff::", + [97] = "ffff:ffff:ffff:ffff:ffff:ffff:8000:0", + [127] = "ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe", + [128] = "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff" + }; + + for (unsigned char prefixlen = 0; prefixlen <= 32; prefixlen++) { + _cleanup_free_ char *result = NULL; + + assert_se(in_addr_prefixlen_to_netmask(AF_INET, &addr, prefixlen) >= 0); + assert_se(in_addr_to_string(AF_INET, &addr, &result) >= 0); + printf("test_in_addr_prefixlen_to_netmask: %s == %s\n", ipv4_netmasks[prefixlen], result); + assert_se(streq(ipv4_netmasks[prefixlen], result)); + } + + for (unsigned char prefixlen = 0; prefixlen <= 128; prefixlen++) { + _cleanup_free_ char *result = NULL; + + assert_se(in_addr_prefixlen_to_netmask(AF_INET6, &addr, prefixlen) >= 0); + assert_se(in_addr_to_string(AF_INET6, &addr, &result) >= 0); + printf("test_in_addr_prefixlen_to_netmask: %s\n", result); + if (ipv6_netmasks[prefixlen]) + assert_se(streq(ipv6_netmasks[prefixlen], result)); + } +} + DEFINE_TEST_MAIN(LOG_DEBUG);