luci-lib-ip: add functions to deal with IPv6 mapped IPv6

 * Add luci.ip.cidr.is6mapped4() to test whether an IPv6 CIDR is a mapped IPv4 one
 * Add luci.ip.cidr.mapped4() to derive IPv4 from mapped CIDR
 * Remove mapped IPv4 workaround from constructor as it breaks genuine addrs like ::ffff:0

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

diff --git a/libs/luci-lib-ip/src/ip.c b/libs/luci-lib-ip/src/ip.c
index 595ac8c..b91966c 100644 (file)
--- a/libs/luci-lib-ip/src/ip.c
+++ b/libs/luci-lib-ip/src/ip.c
@@ -126,27 +126,23 @@ static bool parse_mask(int family, const char *mask, int *bits)
 
 static bool parse_cidr(const char *dest, cidr_t *pp)
 {
-       char *p, *a, buf[INET6_ADDRSTRLEN * 2 + 2];
+       char *p, buf[INET6_ADDRSTRLEN * 2 + 2];
        uint8_t bitlen = 0;
 
        strncpy(buf, dest, sizeof(buf) - 1);
 
-       a = buf;
        p = strchr(buf, '/');
 
        if (p)
                *p++ = 0;
 
-       if (!strncasecmp(buf, "::ffff:", 7))
-               a += 7;
-
-       if (inet_pton(AF_INET, a, &pp->addr.v4))
+       if (inet_pton(AF_INET, buf, &pp->addr.v4))
        {
                bitlen = 32;
                pp->family = AF_INET;
                pp->len = sizeof(struct in_addr);
        }
-       else if (inet_pton(AF_INET6, a, &pp->addr.v6))
+       else if (inet_pton(AF_INET6, buf, &pp->addr.v6))
        {
                bitlen = 128;
                pp->family = AF_INET6;
@@ -383,6 +379,31 @@ static int cidr_is4linklocal(lua_State *L)
        return 1;
 }
 
+static bool _is_mapped4(cidr_t *p)
+{
+       return (p->family == AF_INET6 &&
+               p->addr.v6.s6_addr[0] == 0 &&
+               p->addr.v6.s6_addr[1] == 0 &&
+               p->addr.v6.s6_addr[2] == 0 &&
+               p->addr.v6.s6_addr[3] == 0 &&
+               p->addr.v6.s6_addr[4] == 0 &&
+               p->addr.v6.s6_addr[5] == 0 &&
+               p->addr.v6.s6_addr[6] == 0 &&
+               p->addr.v6.s6_addr[7] == 0 &&
+               p->addr.v6.s6_addr[8] == 0 &&
+               p->addr.v6.s6_addr[9] == 0 &&
+               p->addr.v6.s6_addr[10] == 0xFF &&
+               p->addr.v6.s6_addr[11] == 0xFF);
+}
+
+static int cidr_is6mapped4(lua_State *L)
+{
+       cidr_t *p = L_checkcidr(L, 1, NULL);
+
+       lua_pushboolean(L, _is_mapped4(p));
+       return 1;
+}
+
 static int cidr_is6(lua_State *L)
 {
        cidr_t *p = L_checkcidr(L, 1, NULL);
@@ -550,6 +571,26 @@ static int cidr_broadcast(lua_State *L)
        return 1;
 }
 
+static int cidr_mapped4(lua_State *L)
+{
+       cidr_t *p1 = L_checkcidr(L, 1, NULL);
+       cidr_t *p2;
+
+       if (!_is_mapped4(p1))
+               return 0;
+
+       if (!(p2 = lua_newuserdata(L, sizeof(*p2))))
+               return 0;
+
+       p2->family = AF_INET;
+       p2->bits = (p1->bits > 32) ? 32 : p1->bits;
+       memcpy(&p2->addr.v4, p1->addr.v6.s6_addr + 12, sizeof(p2->addr.v4));
+
+       luaL_getmetatable(L, LUCI_IP_CIDR);
+       lua_setmetatable(L, -2);
+       return 1;
+}
+
 static int cidr_contains(lua_State *L)
 {
        cidr_t *p1 = L_checkcidr(L, 1, NULL);
@@ -1309,6 +1350,7 @@ static const luaL_reg ip_cidr_methods[] = {
        { "is4linklocal",       cidr_is4linklocal },
        { "is6",                        cidr_is6          },
        { "is6linklocal",       cidr_is6linklocal },
+       { "is6mapped4",         cidr_is6mapped4   },
        { "lower",                      cidr_lower        },
        { "higher",                     cidr_higher       },
        { "equal",                      cidr_equal        },
@@ -1317,6 +1359,7 @@ static const luaL_reg ip_cidr_methods[] = {
        { "host",                       cidr_host         },
        { "mask",                       cidr_mask         },
        { "broadcast",          cidr_broadcast    },
+       { "mapped4",            cidr_mapped4      },
        { "contains",       cidr_contains     },
        { "add",                        cidr_add          },
        { "sub",                        cidr_sub          },