+/*
+ * Data types corresponding to multi-byte integral values within data
+ * structures. These are defined as arrays of octets, so that they're
+ * not aligned on their "natural" boundaries, and so that you *must*
+ * use the EXTRACT_ macros to extract them (which you should be doing
+ * *anyway*, so as not to assume a particular byte order or alignment
+ * in your code).
+ *
+ * We even want EXTRACT_U_1 used for 8-bit integral values, so we
+ * define nd_uint8_t and nd_int8_t as arrays as well.
+ */
+typedef unsigned char nd_uint8_t[1];
+typedef unsigned char nd_uint16_t[2];
+typedef unsigned char nd_uint24_t[3];
+typedef unsigned char nd_uint32_t[4];
+typedef unsigned char nd_uint40_t[5];
+typedef unsigned char nd_uint48_t[6];
+typedef unsigned char nd_uint56_t[7];
+typedef unsigned char nd_uint64_t[8];
+
+typedef signed char nd_int8_t[1];
+
+/*
+ * Use this for IPv4 addresses and netmasks.
+ *
+ * It's defined as an array of octets, so that it's not guaranteed to
+ * be aligned on its "natural" boundary (in some packet formats, it
+ * *isn't* so aligned), and it's defined as a structure in the hopes
+ * that this makes it harder to naively use EXTRACT_BE_U_4() to extract
+ * the value - in many cases you just want to use UNALIGNED_MEMCPY() to
+ * copy its value, so that it remains in network byte order.
+ *
+ * (Among other things, we don't want somebody thinking "IPv4 addresses,
+ * they're in network byte order, so we want EXTRACT_BE_U_4(), right?"
+ * and then handing the result to system APIs that expect network-order
+ * IPv4 addresses, such as inet_ntop(), on their little-endian PCs, getting
+ * the wrong behavior, and concluding "oh, it must be in *little*-endian
+ * order" and "fixing" it to use EXTRACT_LE_U_4(). Yes, people do this;
+ * that's why Wireshark has tvb_get_ipv4(), to extract an IPv4 address from
+ * a packet data buffer; it was introduced in reaction to somebody who
+ * *had* done that.)
+ */
+typedef struct {
+ unsigned char bytes[4];
+} nd_ipv4;
+
+/*
+ * Use this for IPv6 addresses and netmasks.
+ */
+typedef struct {
+ unsigned char bytes[16];
+} nd_ipv6;
+
+/*
+ * Use this for MAC addresses.
+ */
+#define MAC_ADDR_LEN 6 /* length of MAC addresses */
+typedef unsigned char nd_mac_addr[MAC_ADDR_LEN];
+
+/*
+ * Use this for blobs of bytes; make them arrays of nd_byte.
+ */
+typedef unsigned char nd_byte;
+
projects / tcpdump / blobdiff