lua: add add_uint8, add_uint16 and add_uint32 functions

Give an example.
We should now have enough functions to add pretty much anything
easily to a DHCP message from lua.

Author: rsmarples

README.md

@@ -84,6 +84,7 @@ local dhcp_opts = {
 	['DNSSERVER'] = 6,
 	['HOSTNAME'] = 12,
 	['DNSDOMAIN'] = 15,
+	['MTU'] = 26,
 	['PARAMETERREQUESTLIST'] = 55,
 	['FQDN'] = 81,
 }
@@ -178,6 +179,9 @@ function lookup_addr(hostname, htype, chaddr)
 end
 
 -- dhcpsd will call this function to add options to a DHCP reply.
+-- The dhcp table adds the following functions:
+--     add_ip, add_string, add_uint32, add_uint16 and add_uint8
+--     set_bootp_file, set_bootp_sname
 -- Return non zero to stop other plugins applying options.
 function add_dhcp_options(hostname, htype, chaddr)
 	if has_parameter_request(dhcp_opts['SUBNETMASK']) then
@@ -190,6 +194,9 @@ function add_dhcp_options(hostname, htype, chaddr)
 		dhcp.add_ip(dhcp_opts['DNSSERVER'], '10.73.1.1, 10.73.1.2')
 	end
 
+    -- If the subnet needs a specific MTU for PPPoE, etc
+    -- dhcp.add_uint16(dhcp_opts['MTU'], 1480);
+
 	hostname = trim_domain(hostname)
 	if dhcp.get_option(dhcp_opts['HOSTNAME']) == 'netbsd' then
 		dhcp.set_bootp_file('/boot-netbsd.img')

src/dhcp.h

@@ -267,6 +267,16 @@ uint32_t dhcp_atof(const char *);
 		memcpy(*(p), (v), (l));        \
 		*(p) = *(p) + (l);             \
 	} while (0 /* CONSTCOND */)
+#define DHCP_PUT_U8(p, e, o, v)                                     \
+	do {                                                        \
+		DHCP_PUT_CHECK((p), (e), sizeof(uint8_t));          \
+		DHCP_PUT_BIN((p), (e), (o), &(v), sizeof(uint8_t)); \
+	} while (0 /* CONSTCOND */)
+#define DHCP_PUT_U16(p, e, o, v)                                     \
+	do {                                                         \
+		DHCP_PUT_CHECK((p), (e), sizeof(uint16_t));          \
+		DHCP_PUT_BIN((p), (e), (o), &(v), sizeof(uint16_t)); \
+	} while (0 /* CONSTCOND */)
 #define DHCP_PUT_U32(p, e, o, v)                                     \
 	do {                                                         \
 		DHCP_PUT_CHECK((p), (e), sizeof(uint32_t));          \

src/plugins/lua.c

@@ -457,7 +457,7 @@ lua_add_dhcp_ip(lua_State *L)
 	char *str;
 	int err;
 
-	if (optn < 1 || optn > 255) {
+	if (optn < 1 || optn > 254) {
 		logerrx("%s: option out of range: %lld", lua_name, optn);
 		return 0;
 	}
@@ -477,13 +477,68 @@ lua_add_dhcp_ip(lua_State *L)
 }
 
 static int
-lua_add_dhcp_u32(lua_State *L)
+lua_add_dhcp_uint8(lua_State *L)
 {
 	struct lua_ctx *l = &lua_ctx;
 	long long optn = luaL_checkinteger(L, 1);
 	long long data = luaL_checkinteger(L, 2);
+	uint8_t u8;
 
-	if (optn < 1 || optn > 255) {
+	if (optn < 1 || optn > 254) {
+		logerrx("%s: option out of range: %lld", lua_name, optn);
+		return 0;
+	}
+	if (data < 0 || data > UINT8_MAX) {
+		logerrx("%s: data out of range: %lld", lua_name, data);
+		return 0;
+	}
+
+	if (l->l_p == NULL || l->l_e == NULL) {
+		logerrx("%s: cannot add options", lua_name);
+		return 0;
+	}
+
+	u8 = (uint8_t)data;
+	DHCP_PUT_U8(&l->l_p, l->l_e, (uint8_t)optn, u8);
+	return 0;
+}
+
+static int
+lua_add_dhcp_uint16(lua_State *L)
+{
+	struct lua_ctx *l = &lua_ctx;
+	long long optn = luaL_checkinteger(L, 1);
+	long long data = luaL_checkinteger(L, 2);
+	uint16_t u16;
+
+	if (optn < 1 || optn > 254) {
+		logerrx("%s: option out of range: %lld", lua_name, optn);
+		return 0;
+	}
+	if (data < 0 || data > UINT16_MAX) {
+		logerrx("%s: data out of range: %lld", lua_name, data);
+		return 0;
+	}
+
+	if (l->l_p == NULL || l->l_e == NULL) {
+		logerrx("%s: cannot add options", lua_name);
+		return 0;
+	}
+
+	u16 = htons(data);
+	DHCP_PUT_U16(&l->l_p, l->l_e, (uint8_t)optn, u16);
+	return 0;
+}
+
+static int
+lua_add_dhcp_uint32(lua_State *L)
+{
+	struct lua_ctx *l = &lua_ctx;
+	long long optn = luaL_checkinteger(L, 1);
+	long long data = luaL_checkinteger(L, 2);
+	uint32_t u32;
+
+	if (optn < 1 || optn > 254) {
 		logerrx("%s: option out of range: %lld", lua_name, optn);
 		return 0;
 	}
@@ -497,7 +552,8 @@ lua_add_dhcp_u32(lua_State *L)
 		return 0;
 	}
 
-	DHCP_PUT_U32(&l->l_p, l->l_e, (uint8_t)optn, data);
+	u32 = htonl(data);
+	DHCP_PUT_U32(&l->l_p, l->l_e, (uint8_t)optn, u32);
 	return 0;
 }
 
@@ -508,7 +564,7 @@ lua_add_dhcp_string(lua_State *L)
 	long long optn = luaL_checkinteger(L, 1);
 	const char *data = luaL_checkstring(L, 2);
 
-	if (optn < 1 || optn > 255) {
+	if (optn < 1 || optn > 254) {
 		logerrx("%s: option out of range: %lld", lua_name, optn);
 		return 0;
 	}
@@ -719,7 +775,9 @@ lua_init(struct plugin *p)
 		{ "set_bootp_file", lua_set_bootp_file },
 		{ "get_option", lua_get_dhcp_option },
 		{ "add_ip", lua_add_dhcp_ip },
-		{ "add_u32", lua_add_dhcp_u32 },
+		{ "add_uint8", lua_add_dhcp_uint8 },
+		{ "add_uint16", lua_add_dhcp_uint16 },
+		{ "add_uint32", lua_add_dhcp_uint32 },
 		{ "add_string", lua_add_dhcp_string },
 		{ NULL, NULL },
 	};