luci-lib-ip: support scoped IPv6 addresses

Ref: https://github.com/openwrt/luci/issues/3380
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

libs/luci-lib-ip/src/ip.c

@@ -62,6 +62,7 @@ typedef struct {
 		struct ether_addr mac;
 		uint8_t u8[16];
 	} addr;
+	uint32_t scope;
 	uint16_t family;
 	int16_t bits;
 } cidr_t;
@@ -177,7 +178,7 @@ static bool parse_mask(int family, const char *mask, int16_t *bits)
 
 static bool parse_cidr(const char *dest, cidr_t *pp)
 {
-	char *p, buf[INET6_ADDRSTRLEN * 2 + 2];
+	char *p, *s, buf[INET6_ADDRSTRLEN * 2 + 2];
 
 	strncpy(buf, dest, sizeof(buf) - 1);
 
@@ -186,6 +187,11 @@ static bool parse_cidr(const char *dest, cidr_t *pp)
 	if (p)
 		*p++ = 0;
 
+	s = strchr(buf, '%');
+
+	if (s)
+		*s++ = 0;
+
 	if (inet_pton(AF_INET, buf, &pp->addr.v4))
 		pp->family = AF_INET;
 	else if (inet_pton(AF_INET6, buf, &pp->addr.v6))
@@ -195,6 +201,22 @@ static bool parse_cidr(const char *dest, cidr_t *pp)
 	else
 		return false;
 
+	if (s)
+	{
+		if (pp->family != AF_INET6)
+			return false;
+
+		if (!(pp->addr.v6.s6_addr[0] == 0xFE &&
+		      pp->addr.v6.s6_addr[1] >= 0x80 &&
+		      pp->addr.v6.s6_addr[2] <= 0xBF))
+			return false;
+
+		pp->scope = if_nametoindex(s);
+
+		if (pp->scope == 0)
+			return false;
+	}
+
 	if (p)
 	{
 		if (!parse_mask(pp->family, p, &pp->bits))
@@ -210,7 +232,7 @@ static bool parse_cidr(const char *dest, cidr_t *pp)
 
 static int format_cidr(lua_State *L, cidr_t *p)
 {
-	char buf[INET6_ADDRSTRLEN];
+	char *s, buf[INET6_ADDRSTRLEN + 1 + IF_NAMESIZE + 4];
 
 	if (p->family == AF_PACKET)
 	{
@@ -229,13 +251,19 @@ static int format_cidr(lua_State *L, cidr_t *p)
 	}
 	else
 	{
+		inet_ntop(p->family, &p->addr.v6, buf, sizeof(buf));
+
+		s = buf + strlen(buf);
+
+		if (p->scope != 0 && if_indextoname(p->scope, s + 1) != NULL) {
+			*s++ = '%';
+			s += strlen(s);
+		}
+
 		if (p->bits < AF_BITS(p->family))
-			lua_pushfstring(L, "%s/%d",
+			s += sprintf(s, "/%d", p->bits);
-			                inet_ntop(p->family, &p->addr.v6, buf, sizeof(buf)),
+
-			                p->bits);
+		lua_pushstring(L, buf);
-		else
-			lua_pushstring(L,
-			               inet_ntop(p->family, &p->addr.v6, buf, sizeof(buf)));
 	}
 
 	return 1;
@@ -765,6 +793,25 @@ static int cidr_mapped4(lua_State *L)
 	return 1;
 }
 
+static int cidr_unscoped(lua_State *L)
+{
+	cidr_t *p1 = L_checkcidr(L, 1, NULL);
+	cidr_t *p2;
+
+	if (p1->family != AF_INET6)
+		return 0;
+
+	if (!(p2 = lua_newuserdata(L, sizeof(*p2))))
+		return 0;
+
+	*p2 = *p1;
+	p2->scope = 0;
+
+	luaL_getmetatable(L, LUCI_IP_CIDR);
+	lua_setmetatable(L, -2);
+	return 1;
+}
+
 static int cidr_tolinklocal(lua_State *L)
 {
 	cidr_t *p1 = L_checkcidr(L, 1, NULL);
@@ -1601,6 +1648,7 @@ static const luaL_reg ip_cidr_methods[] = {
 	{ "mask",			cidr_mask         },
 	{ "broadcast",		cidr_broadcast    },
 	{ "mapped4",		cidr_mapped4      },
+	{ "unscoped",		cidr_unscoped     },
 	{ "tomac",			cidr_tomac        },
 	{ "tolinklocal",	cidr_tolinklocal  },
 	{ "contains",		cidr_contains     },

libs/luci-lib-ip/src/ip.luadoc

@@ -837,6 +837,23 @@ instances which are not a mapped address, it will return nothing in this case.
 print(addr:mapped4()) -- "172.16.19.1"`
 ]]
 
+---[[
+Derive unscoped IPv6 address of CIDR instance.
+
+Construct a copy of the given IPv6 CIDR instance and drop the associated
+address scope information.
+
+This function has no effect on IPv4 instances or MAC address instances,
+it will return nothing in this case.
+
+@class function
+@sort 19
+@name cidr.unscoped
+@return Return a new CIDR instance representing the unscoped IPv6 address.
+@usage `local addr = luci.ip.new("fe80::1234%eth0")
+print(addr:unscoped()) -- "fe80::1234"`
+]]
+
 ---[[
 Derive MAC address of IPv6 link local CIDR instance.
 
@@ -848,7 +865,7 @@ instances which are not a link local address, it will return nothing in this
 case.
 
 @class function
-@sort 19
+@sort 20
 @name cidr.tomac
 @return Return a new CIDR instance representing the MAC address if this
   instance is an IPv6 link local address, else return nothing.
@@ -866,7 +883,7 @@ This function has no effect on IPv4 instances or IPv6 instances, it will return
 nothing in this case.
 
 @class function
-@sort 20
+@sort 21
 @name cidr.tolinklocal
 @return Return a new CIDR instance representing the IPv6 link local address.
 @usage `local mac = luci.ip.new("64:66:B3:47:E1:B9")
@@ -877,7 +894,7 @@ print(mac:tolinklocal()) -- "fe80::6666:b3ff:fe47:e1b9"`
 Test whether CIDR contains given range.
 
 @class function
-@sort 21
+@sort 22
 @name cidr.contains
 @param addr A `luci.ip.cidr` instance or a string convertible by
 	`luci.ip.new()` to test.
@@ -902,7 +919,7 @@ Add given amount to CIDR instance. If the result would overflow the maximum
 address space, the result is set to the highest possible address.
 
 @class function
-@sort 22
+@sort 23
 @name cidr.add
 @param amount A numeric value between 0 and 0xFFFFFFFF, a
 	`luci.ip.cidr` instance or a string convertible by
@@ -951,7 +968,7 @@ Subtract given amount from CIDR instance. If the result would under, the lowest
 possible address is returned.
 
 @class function
-@sort 23
+@sort 24
 @name cidr.sub
 @param amount A numeric value between 0 and 0xFFFFFFFF, a
 	`luci.ip.cidr` instance or a string convertible by
@@ -999,7 +1016,7 @@ print(mac)                     -- "00:00:00:00:00:00"`
 Calculate the lowest possible host address within this CIDR instance.
 
 @class function
-@sort 24
+@sort 25
 @name cidr.minhost
 @return Returns a new CIDR instance representing the lowest host address
 	within this range.
@@ -1017,7 +1034,7 @@ print(mac:minhost())   -- "00:14:22:01:00:01"`
 Calculate the highest possible host address within this CIDR instance.
 
 @class function
-@sort 25
+@sort 26
 @name cidr.maxhost
 @return Returns a new CIDR instance representing the highest host address
 	within this range.
@@ -1042,7 +1059,7 @@ It is usually not required to call this function directly as CIDR objects
 define it as __tostring function in the associated metatable.
 
 @class function
-@sort 26
+@sort 27
 @name cidr.string
 @return Returns a string representing the range or address of this CIDR instance
 ]]