xdp-tailcall: add DNS XDP program

add DNS XDP program as tail called program

Signed-off-by: Vincent Li <[email protected]>

xdp-tailcall/Makefile

@@ -2,7 +2,7 @@
 
 XDP_TARGETS := xdp_tailcall.bpf
 BPF_SKEL_TARGETS := $(XDP_TARGETS)
-USER_TARGETS := xdp_sni xdp_sni_log
+USER_TARGETS := xdp_tailcall_sni xdp_tailcall_sni_log xdp_tailcall_dns xdp_tailcall_dns_log
 
 LIB_DIR = ../lib
 

xdp-tailcall/xdp_dns.h

@@ -0,0 +1,91 @@
+#define DNS_PORT        53
+#define RR_TYPE_OPT     41
+
+#define FRAME_SIZE   1000000000
+
+/*
+ *  Store the DNS header
+ */
+struct dnshdr {
+        __u16 id;
+        union {
+                struct {
+                        __u8  rd     : 1;
+                        __u8  tc     : 1;
+                        __u8  aa     : 1;
+                        __u8  opcode : 4;
+                        __u8  qr     : 1;
+
+                        __u8  rcode  : 4;
+                        __u8  cd     : 1;
+                        __u8  ad     : 1;
+                        __u8  z      : 1;
+                        __u8  ra     : 1;
+                }        as_bits_and_pieces;
+                __u16 as_value;
+        } flags;
+        __u16 qdcount;
+        __u16 ancount;
+        __u16 nscount;
+        __u16 arcount;
+};
+
+struct dns_qrr {
+        __u16 qtype;
+        __u16 qclass;
+};
+
+struct dns_rr {
+        __u16 type;
+        __u16 class;
+        __u32 ttl;
+        __u16 rdata_len;
+} __attribute__((packed));
+
+struct option {
+        __u16 code;
+        __u16 len;
+        __u8  data[];
+} __attribute__((packed));
+
+/*
+ *  Recalculate the checksum
+ */
+static __always_inline
+void update_checksum(__u16 *csum, __u16 old_val, __u16 new_val)
+{
+        __u32 new_csum_value;
+        __u32 new_csum_comp;
+        __u32 undo;
+
+        undo = ~((__u32)*csum) + ~((__u32)old_val);
+        new_csum_value = undo + (undo < ~((__u32)old_val)) + (__u32)new_val;
+        new_csum_comp = new_csum_value + (new_csum_value < ((__u32)new_val));
+        new_csum_comp = (new_csum_comp & 0xFFFF) + (new_csum_comp >> 16);
+        new_csum_comp = (new_csum_comp & 0xFFFF) + (new_csum_comp >> 16);
+        *csum = (__u16)~new_csum_comp;
+}
+
+
+//TCP
+
+#define NSEC_PER_SEC 1000000000L
+
+#define ETH_ALEN 6
+#define ETH_P_IP 0x0800
+#define ETH_P_IPV6 0x86DD
+
+#define IP_DF 0x4000
+#define IP_MF 0x2000
+#define IP_OFFSET 0x1fff
+
+#define swap(a, b) \
+        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
+
+#define __get_unaligned_t(type, ptr) ({                                         \
+        const struct { type x; } __attribute__((__packed__)) *__pptr = (typeof(__pptr))(ptr); \
+        __pptr->x;                                                              \
+})
+
+#define get_unaligned(ptr) __get_unaligned_t(typeof(*(ptr)), (ptr))
+