Drop PROTO macro syntax and introduce alternative

* Feedback given by some external users was that the PROTO syntax was opaque and unintuitive. As such, drop that macro and introduce an alternative syntax. * Convert all to use 'cursor_advance' macro API Signed-off-by: Brenden Blanco <[email protected]>
heatseekr · Jul 2, 2015 · 6ec65e4 · 6ec65e4
1 parent 307fff0
commit 6ec65e4
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Showing 11 changed files with 170 additions and 135 deletions.
diff --git a/examples/tc_neighbor_sharing.c b/examples/tc_neighbor_sharing.c
@@ -19,14 +19,16 @@ int pass(struct __sk_buff *skb) {
 // returns: > 0 when an IP is known
 // = 0 when an IP is not known, or non-IP traffic
 int classify_wan(struct __sk_buff *skb) {
- BEGIN(ethernet);
- PROTO(ethernet) {
+ u8 *cursor = 0;
+ ethernet: {
+ struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet));
  switch (ethernet->type) {
- case 0x0800: goto ip;
+ case ETH_P_IP: goto ip;
+ default: goto EOP;
  }
- goto EOP;
  }
- PROTO(ip) {
+ ip: {
+ struct ip_t *ip = cursor_advance(cursor, sizeof(*ip));
  u32 dip = ip->dst;
  struct ipkey key = {.client_ip=dip};
  int *val = learned_ips.lookup(&key);
@@ -42,14 +44,16 @@ int classify_wan(struct __sk_buff *skb) {
 // Mark the inserted entry with a non-zero value to be used by the classify_wan
 // lookup.
 int classify_neighbor(struct __sk_buff *skb) {
- BEGIN(ethernet);
- PROTO(ethernet) {
+ u8 *cursor = 0;
+ ethernet: {
+ struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet));
  switch (ethernet->type) {
- case 0x0800: goto ip;
+ case ETH_P_IP: goto ip;
+ default: goto EOP;
  }
- goto EOP;
  }
- PROTO(ip) {
+ ip: {
+ struct ip_t *ip = cursor_advance(cursor, sizeof(*ip));
  u32 sip = ip->src;
  struct ipkey key = {.client_ip=sip};
  int val = 1;

diff --git a/examples/tunnel_monitor/monitor.c b/examples/tunnel_monitor/monitor.c
@@ -57,37 +57,43 @@ int handle_egress(struct __sk_buff *skb) {
 
 // parse the outer vxlan frame
 int handle_outer(struct __sk_buff *skb) {
- BEGIN(ethernet);
- PROTO(ethernet) {
- // filter bcast/mcast from the stats
- if (ethernet->dst & (1ull << 40))
- return 1;
- switch (ethernet->type) {
- case 0x0800: goto ip;
- }
- goto EOP;
- }
- PROTO(ip) {
- skb->cb[CB_SIP] = ip->src;
- skb->cb[CB_DIP] = ip->dst;
- switch (ip->nextp) {
- case 17: goto udp;
- }
- goto EOP;
+ u8 *skb_cursor = 0;
+
+ struct ethernet_t *ethernet = bpf_consume_skb(skb_cursor, sizeof(*ethernet));
+
+ // filter bcast/mcast from the stats
+ if (ethernet->dst & (1ull << 40))
+ goto finish;
+
+ switch (ethernet->type) {
+ case 0x0800: goto ip;
+ default: goto finish;
  }
- PROTO(udp) {
- switch (udp->dport) {
- case 4789: goto vxlan;
- }
- goto EOP;
+
+ip: ;
+ struct ip_t *ip = bpf_consume_skb(skb_cursor, sizeof(*ip));
+ skb->cb[CB_SIP] = ip->src;
+ skb->cb[CB_DIP] = ip->dst;
+
+ switch (ip->nextp) {
+ case 17: goto udp;
+ default: goto finish;
  }
- PROTO(vxlan) {
- skb->cb[CB_VNI] = vxlan->key;
- skb->cb[CB_OFFSET] = (u64)vxlan + sizeof(*vxlan);
- parser.call(skb, 2);
- goto EOP;
+
+udp: ;
+ struct udp_t *udp = bpf_consume_skb(skb_cursor, sizeof(*udp));
+ switch (udp->dport) {
+ case 4789: goto vxlan;
+ default: goto finish;
  }
-EOP:
+
+vxlan: ;
+ struct vxlan_t *vxlan = bpf_consume_skb(skb_cursor, sizeof(*vxlan));
+ skb->cb[CB_VNI] = vxlan->key;
+ skb->cb[CB_OFFSET] = (u64)vxlan + sizeof(*vxlan);
+ parser.call(skb, 2);
+
+finish:
  return 1;
 }
 
@@ -100,19 +106,19 @@ int handle_inner(struct __sk_buff *skb) {
  .outer_sip = skb->cb[CB_SIP],
  .outer_dip = skb->cb[CB_DIP]
  };
- BEGIN_OFFSET(ethernet, skb->cb[CB_OFFSET]);
- PROTO(ethernet) {
- switch (ethernet->type) {
- case 0x0800: goto ip;
- }
- goto EOP;
- }
- PROTO(ip) {
- key.inner_sip = ip->src;
- key.inner_dip = ip->dst;
- goto EOP;
+ u8 *skb_cursor = (u8 *)(u64)skb->cb[CB_OFFSET];
+
+ struct ethernet_t *ethernet = bpf_consume_skb(skb_cursor, sizeof(*ethernet));
+ switch (ethernet->type) {
+ case 0x0800: goto ip;
+ default: goto finish;
  }
-EOP:
+ip: ;
+ struct ip_t *ip = bpf_consume_skb(skb_cursor, sizeof(*ip));
+ key.inner_sip = ip->src;
+ key.inner_dip = ip->dst;
+
+finish:
  // consistent ordering
  if (key.outer_dip < key.outer_sip)
  swap_ipkey(&key);

diff --git a/examples/vlan_learning.c b/examples/vlan_learning.c
@@ -16,8 +16,9 @@ BPF_TABLE("hash", int, struct ifindex_leaf_t, egress, 4096);
 BPF_TABLE("hash", u64, struct ifindex_leaf_t, ingress, 4096);
 
 int handle_phys2virt(struct __sk_buff *skb) {
- BEGIN(ethernet);
- PROTO(ethernet) {
+ u8 *cursor = 0;
+ ethernet: {
+ struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet));
  u64 src_mac = ethernet->src;
  struct ifindex_leaf_t *leaf = ingress.lookup(&src_mac);
  if (leaf) {
@@ -33,13 +34,13 @@ int handle_phys2virt(struct __sk_buff *skb) {
  bpf_clone_redirect(skb, leaf->out_ifindex, 0);
  }
  }
-EOP:
  return 1;
 }
 
 int handle_virt2phys(struct __sk_buff *skb) {
- BEGIN(ethernet);
- PROTO(ethernet) {
+ u8 *cursor = 0;
+ ethernet: {
+ struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet));
  int src_ifindex = skb->ifindex;
  struct ifindex_leaf_t *leaf = egress.lookup(&src_ifindex);
  if (leaf) {
@@ -48,6 +49,5 @@ int handle_virt2phys(struct __sk_buff *skb) {
  bpf_clone_redirect(skb, leaf->out_ifindex, 0);
  }
  }
-EOP:
  return 1;
 }
diff --git a/src/cc/b_frontend_action.cc b/src/cc/b_frontend_action.cc
@@ -381,6 +381,18 @@ bool BTypeVisitor::VisitVarDecl(VarDecl *Decl) {
  return false;
  }
  tables_[Decl->getName()] = std::move(table);
+ } else if (const PointerType *P = Decl->getType()->getAs<PointerType>()) {
+ // if var is a pointer to a packet type, clone the annotation into the var
+ // decl so that the packet dext/dins rewriter can catch it
+ if (const RecordType *RT = P->getPointeeType()->getAs<RecordType>()) {
+ if (const RecordDecl *RD = RT->getDecl()->getDefinition()) {
+ if (DeprecatedAttr *DA = RD->getAttr<DeprecatedAttr>()) {
+ if (DA->getMessage() == "packet") {
+ Decl->addAttr(DA->clone(C));
+ }
+ }
+ }
+ }
  }
  return true;
 }

diff --git a/src/cc/export/helpers.h b/src/cc/export/helpers.h
@@ -42,18 +42,8 @@ __attribute__((section("maps/" _table_type))) \
 struct _name##_table_t _name
 
 // packet parsing state machine helpers
-#define BEGIN(next) \
- u64 _parse_cursor = 0; \
- goto next
-#define BEGIN_OFFSET(next, _base_offset) \
- u64 _parse_cursor = (_base_offset); \
- goto next
-
-#define PROTO(name) \
- goto EOP; \
-name: ; \
- struct name##_t *name __attribute__((deprecated("packet"))) = (void *)_parse_cursor; \
- _parse_cursor += sizeof(*name);
+#define cursor_advance(_cursor, _len) \
+ ({ void *_tmp = _cursor; _cursor += _len; _tmp; })
 
 char _license[4] SEC("license") = "GPL";
 

diff --git a/src/cc/export/proto.h b/src/cc/export/proto.h
@@ -14,18 +14,22 @@
  * limitations under the License.
  */
 
+#include <uapi/linux/if_ether.h>
+
+#define BPF_PACKET_HEADER __attribute__((packed)) __attribute__((deprecated("packet")))
+
 struct ethernet_t {
  unsigned long long dst:48;
  unsigned long long src:48;
  unsigned int type:16;
-} __attribute__((packed));
+} BPF_PACKET_HEADER;
 
 struct dot1q_t {
  unsigned short pri:3;
  unsigned short cfi:1;
  unsigned short vlanid:12;
  unsigned short type;
-} __attribute__((packed));
+} BPF_PACKET_HEADER;
 
 struct arp_t {
  unsigned short htype;
@@ -37,7 +41,7 @@ struct arp_t {
  unsigned long long spa:32;
  unsigned long long tha:48;
  unsigned int tpa;
-} __attribute__((packed));
+} BPF_PACKET_HEADER;
 
 struct ip_t {
  unsigned char ver:4; // byte 0
@@ -54,14 +58,14 @@ struct ip_t {
  unsigned short hchecksum;
  unsigned int src; // byte 12
  unsigned int dst; // byte 16
-} __attribute__((packed));
+} BPF_PACKET_HEADER;
 
 struct udp_t {
  unsigned short sport;
  unsigned short dport;
  unsigned short length;
  unsigned short crc;
-} __attribute__((packed));
+} BPF_PACKET_HEADER;
 
 struct tcp_t {
  unsigned short src_port; // byte 0
@@ -81,7 +85,7 @@ struct tcp_t {
  unsigned short rcv_wnd;
  unsigned short cksum; // byte 16
  unsigned short urg_ptr;
-} __attribute__((packed));
+} BPF_PACKET_HEADER;
 
 struct vxlan_t {
  unsigned int rsv1:4;
@@ -90,4 +94,4 @@ struct vxlan_t {
  unsigned int rsv3:24;
  unsigned int key:24;
  unsigned int rsv4:8;
-} __attribute__((packed));
+} BPF_PACKET_HEADER;
diff --git a/tests/cc/test_brb.c b/tests/cc/test_brb.c
@@ -106,6 +106,7 @@ int pem(struct __sk_buff *skb) {
 
 static int br_common(struct __sk_buff *skb, int which_br) __attribute__((always_inline));
 static int br_common(struct __sk_buff *skb, int which_br) {
+ u8 *cursor = 0;
  bpf_metadata_t meta = {};
  u16 proto;
  u16 arpop;
@@ -126,8 +127,8 @@ static int br_common(struct __sk_buff *skb, int which_br) {
  meta.rx_port_id = skb->cb[1];
  }
 
- BEGIN(ethernet);
- PROTO(ethernet) {
+ struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet));
+ {
  dmac.addr = ethernet->dst;
  if (meta.prog_id != 0) {
  /* send to the router */
@@ -152,22 +153,24 @@ static int br_common(struct __sk_buff *skb, int which_br) {
  }
 
  switch (ethernet->type) {
- case 0x0800: goto ip;
- case 0x0806: goto arp;
- case 0x8100: goto dot1q;
+ case ETH_P_IP: goto ip;
+ case ETH_P_ARP: goto arp;
+ case ETH_P_8021Q: goto dot1q;
+ default: goto EOP;
  }
- goto EOP;
  }
 
- PROTO(dot1q) {
+ dot1q: {
+ struct dot1q_t *dot1q = cursor_advance(cursor, sizeof(*dot1q));
  switch(dot1q->type) {
- case 0x0806: goto arp;
- case 0x0800: goto ip;
+ case ETH_P_IP: goto ip;
+ case ETH_P_ARP: goto arp;
+ default: goto EOP;
  }
- goto EOP;
  }
 
- PROTO(arp) {
+ arp: {
+ struct arp_t *arp = cursor_advance(cursor, sizeof(*arp));
  /* mac learning */
  arpop = arp->oper;
  if (arpop == 2) {
@@ -180,7 +183,7 @@ static int br_common(struct __sk_buff *skb, int which_br) {
  __u32 ifindex = *rtrif_p;
  eth_addr_t smac;
 
- smac.addr = ethernet->src;
+ smac.addr = ethernet->src;
  if (which_br == 1)
  br1_mac_ifindex.update(&smac, &ifindex);
  else
@@ -190,7 +193,8 @@ static int br_common(struct __sk_buff *skb, int which_br) {
  goto xmit;
  }
 
- PROTO(ip) {
+ ip: {
+ struct ip_t *ip = cursor_advance(cursor, sizeof(*ip));
  goto xmit;
  }
 

diff --git a/tests/cc/test_clang.py b/tests/cc/test_clang.py
@@ -13,12 +13,10 @@ def test_printk(self):
  text = """
 #include <bcc/proto.h>
 int handle_packet(void *ctx) {
- BEGIN(ethernet);
- PROTO(ethernet) {
- bpf_trace_printk("ethernet->dst = %llx, ethernet->src = %llx\\n",
- ethernet->dst, ethernet->src);
- }
-EOP:
+ u8 *cursor = 0;
+ struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet));
+ bpf_trace_printk("ethernet->dst = %llx, ethernet->src = %llx\\n",
+ ethernet->dst, ethernet->src);
  return 0;
 }
 """