Wireguard: Refactor tunnel encaps decoding

3 files changed, 200 insertions, 1 deletions

diff --git a/lib/Makefile b/lib/Makefile
index 5c78b2a9..300ccc85 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -1,4 +1,4 @@
-src := bitmap.c bitops.c checksum.c event.c flowspec.c idm.c ip.c lists.c mac.c md5.c mempool.c net.c patmatch.c printf.c resource.c sha1.c sha256.c sha512.c slab.c slists.c strtoul.c tbf.c timer.c xmalloc.c
+src := bitmap.c bitops.c checksum.c event.c flowspec.c idm.c ip.c lists.c mac.c md5.c mempool.c net.c patmatch.c printf.c resource.c sha1.c sha256.c sha512.c slab.c slists.c strtoul.c tbf.c timer.c xmalloc.c tunnel_encaps.c
 obj := $(src-o-files)
 $(all-daemon)
 
diff --git a/lib/tunnel_encaps.c b/lib/tunnel_encaps.c
new file mode 100644
index 00000000..43fcdbcb
--- /dev/null
+++ b/lib/tunnel_encaps.c
@@ -0,0 +1,180 @@
+#include "lib/tunnel_encaps.h"
+
+static
+int decode_wireguard(const void *p, size_t sub_tlv_len, wg_key *pubkey, u16 *flags)
+{
+  if (sub_tlv_len != sizeof(wg_key)) {
+    log(L_TRACE "WG: wireguard len error %d", sub_tlv_len);
+    return -1;
+  }
+
+  memcpy(pubkey, p, sizeof(wg_key));
+  *flags |= FLAG_BGP_TUNNEL_ENCAP_A_SUB_TLV_ENCAP;
+  return 0;
+}
+
+static
+int decode_color(const void *p, size_t sub_tlv_len, u32 *color, u16 *flags)
+{
+  if (sub_tlv_len != 8) {
+    log(L_TRACE "WG: color len error %d", sub_tlv_len);
+    return -1;
+  }
+
+  if (get_u16(p) != 0x030b) {
+    log(L_TRACE "WG: color error %04x", get_u16(p));
+    return -1;
+  }
+
+  *color = get_u32(p+2);
+  *flags |= FLAG_BGP_TUNNEL_ENCAP_A_SUB_TLV_COLOR;
+  return 0;
+}
+
+static
+int decode_udp_dest_port(const void *p, size_t sub_tlv_len, u16 *udp_dest_port, u16 *flags)
+{
+  if (sub_tlv_len != 2) {
+    log(L_TRACE "WG: udp dest port len error %d", sub_tlv_len);
+    return -1;
+  }
+
+  *udp_dest_port = get_u16(p);
+  *flags |= FLAG_BGP_TUNNEL_ENCAP_A_SUB_TLV_UDP_DEST_PORT;
+  return 0;
+}
+
+static
+int decode_tunnel_ep(const void *p, size_t sub_tlv_len, u32 *as4, ip_addr *tunnel_ep, u16 *flags)
+{
+  if (sub_tlv_len < 6) {
+    log(L_TRACE "WG: tunnel ep len error");
+    return -1;
+  }
+
+  *as4 = get_u32(p);
+  u16 af = get_u16(p + 4);
+  switch (af) {
+  case NET_IP4:
+    if (sub_tlv_len != 10) {
+      log(L_TRACE "WG: IPv4 len error %d", sub_tlv_len);
+      return -1;
+    }
+    *tunnel_ep = ipa_from_ip4(get_ip4(p + 6));
+    *flags |= FLAG_BGP_TUNNEL_ENCAP_A_SUB_TLV_TUNNEL_EP;
+    return 0;
+  case NET_IP6:
+    if (sub_tlv_len != 22) {
+      log(L_TRACE "WG: IPv6 len error %d", sub_tlv_len);
+      return -1;
+    }
+    *tunnel_ep = ipa_from_ip6(get_ip6(p + 6));
+    *flags |= FLAG_BGP_TUNNEL_ENCAP_A_SUB_TLV_TUNNEL_EP;
+    return 0;
+  default:
+    log(L_TRACE "WG: Address family error %d", af);
+    return -1;
+  }
+}
+
+static
+int decode_sub_tlv(const u8 *p, size_t len, wg_key *pubkey,
+		   u32 *tunnel_ep_as, ip_addr *tunnel_ep_addr,
+		   u32 *color, u16 *udp_dest_port, u16 *flags)
+{
+  if (len < 3) {
+    log(L_TRACE "WG: sub_tlv len error %d", len);
+    return -1;
+  }
+
+  const u8 *first = p;
+  const u8 *last = p + len;
+  int type = get_u8(p++);
+  u16 sub_tlv_len = 0;
+
+  log(L_TRACE "WG: sub tlv type %d", type);
+  if (type >= 0 && type <= 127) {
+    sub_tlv_len = get_u8(p);
+    p++;
+  } else if (type >= 128 && type <= 255) {
+    sub_tlv_len = get_u16(p);
+    p += 2;
+  } else {
+    log(L_TRACE "WG: sub_tlv type error %d", type);
+    return -1;
+  }
+
+  log(L_TRACE "WG: sub tlv len %d", sub_tlv_len);
+  if (p + sub_tlv_len > last) {
+    log(L_TRACE "WG: sub_tlv value len error %d", sub_tlv_len);
+    return -1;
+  }
+
+  int res = 0;
+
+  switch (type) {
+  case BGP_TUNNEL_ENCAP_A_SUB_TLV_ENCAP:
+    res = decode_wireguard(p, sub_tlv_len, pubkey, flags);
+    break;
+  case BGP_TUNNEL_ENCAP_A_SUB_TLV_TUNNEL_EP:
+    res = decode_tunnel_ep(p, sub_tlv_len, tunnel_ep_as, tunnel_ep_addr, flags);
+    break;
+  case BGP_TUNNEL_ENCAP_A_SUB_TLV_COLOR:
+    res = decode_color(p, sub_tlv_len, color, flags);
+    break;
+  case BGP_TUNNEL_ENCAP_A_SUB_TLV_UDP_DEST_PORT:
+    res = decode_udp_dest_port(p, sub_tlv_len, udp_dest_port, flags);
+    break;
+  default:
+    /* Skip unsupported sub-TLV. */
+    res = 0;
+    break;
+  }
+
+  if (res < 0)
+    return res;
+
+  return p - first + sub_tlv_len;
+}
+
+int decode_tunnel_encap(const eattr *e, u16 wg_tunnel_type, wg_key *pubkey, u32 *as4, ip_addr *tunnel_ep, u32 *color, u16 *udp_port, u16 *flags)
+{
+  const u8 *p = e->u.ptr->data;
+  int len = e->u.ptr->length;
+
+  if (len < 4) {
+    log(L_TRACE "WG: tunnel_encap len error %d", len);
+    return -1;
+  }
+
+  u16 tunnel_type = get_u16(p);
+
+  log(L_DEBUG "WG: tunnel type %d", tunnel_type);
+
+  if (tunnel_type != wg_tunnel_type) {
+    log(L_TRACE "WG: tunnel type error %d", tunnel_type);
+    return -1;
+  }
+
+  u16 value_length = get_u16(p + 2);
+
+  log(L_TRACE "WG: tunnel encap value len %d", value_length);
+
+  if (len < value_length + 4) {
+    log(L_TRACE "WG: tunnel encap len error %d", value_length);
+    return -1;
+  }
+
+  for (const u8 *cur = p + 4; cur < p + 4 + value_length;) {
+    int res = decode_sub_tlv(cur, value_length, pubkey, as4, tunnel_ep, color, udp_port, flags);
+
+    if (res < 0) {
+      log(L_TRACE "WG: decode error %d", res);
+      return res;
+    }
+
+    cur += res;
+  }
+
+  return 0;
+}
diff --git a/lib/tunnel_encaps.h b/lib/tunnel_encaps.h
new file mode 100644
index 00000000..6c85a883
--- /dev/null
+++ b/lib/tunnel_encaps.h
@@ -0,0 +1,19 @@
+#ifndef _BIRD_TUNNEL_ENCAPS_
+#define _BIRD_TUNNEL_ENCAPS_
+
+#include "nest/route.h"
+#include "sysdep/linux/wireguard.h"
+
+#define BGP_TUNNEL_ENCAP_A_SUB_TLV_ENCAP         1
+#define BGP_TUNNEL_ENCAP_A_SUB_TLV_COLOR         4
+#define BGP_TUNNEL_ENCAP_A_SUB_TLV_TUNNEL_EP     6
+#define BGP_TUNNEL_ENCAP_A_SUB_TLV_UDP_DEST_PORT 8
+
+#define FLAG_BGP_TUNNEL_ENCAP_A_SUB_TLV_ENCAP         (1<<BGP_TUNNEL_ENCAP_A_SUB_TLV_ENCAP)
+#define FLAG_BGP_TUNNEL_ENCAP_A_SUB_TLV_COLOR         (1<<BGP_TUNNEL_ENCAP_A_SUB_TLV_COLOR)
+#define FLAG_BGP_TUNNEL_ENCAP_A_SUB_TLV_TUNNEL_EP     (1<<BGP_TUNNEL_ENCAP_A_SUB_TLV_TUNNEL_EP)
+#define FLAG_BGP_TUNNEL_ENCAP_A_SUB_TLV_UDP_DEST_PORT (1<<BGP_TUNNEL_ENCAP_A_SUB_TLV_UDP_DEST_PORT)
+
+int decode_tunnel_encap(const eattr *e, u16 wg_tunnel_type, wg_key *pubkey, u32 *as4, ip_addr *tunnel_ep, u32 *color, u16 *udp_port, u16 *flags);
+
+#endif	/* _BIRD_TUNNEL_ENCAPS_ */