Debug prints

Summary:
Adding debug prints to TPR prog, handy for debugging/investigation.
Disabled with macro by default.

Note on bpf_endian.h., copied from katran/lib, TPR code is using skeleton (while main katran not yet) and requires different includes. Also we've been keeping TPR and main katran lib somewhat independent.

Reviewed By: sharmafb

Differential Revision: D45824117

fbshipit-source-id: 18cd776d3d1ad15ee8b294b8eb4704e8df639b8f

katran/tpr/bpf/bpf_endian.h

@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __BPF_ENDIAN__
+#define __BPF_ENDIAN__
+
+#ifdef KATRAN_CMAKE_BUILD
+#include "vmlinux.h"
+#else
+#include <bpf/vmlinux/vmlinux.h>
+#endif
+
+/* LLVM's BPF target selects the endianness of the CPU
+ * it compiles on, or the user specifies (bpfel/bpfeb),
+ * respectively. The used __BYTE_ORDER__ is defined by
+ * the compiler, we cannot rely on __BYTE_ORDER from
+ * libc headers, since it doesn't reflect the actual
+ * requested byte order.
+ *
+ * Note, LLVM's BPF target has different __builtin_bswapX()
+ * semantics. It does map to BPF_ALU | BPF_END | BPF_TO_BE
+ * in bpfel and bpfeb case, which means below, that we map
+ * to cpu_to_be16(). We could use it unconditionally in BPF
+ * case, but better not rely on it, so that this header here
+ * can be used from application and BPF program side, which
+ * use different targets.
+ */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define __bpf_ntohs(x) __builtin_bswap16(x)
+#define __bpf_htons(x) __builtin_bswap16(x)
+#define __bpf_constant_ntohs(x) ___constant_swab16(x)
+#define __bpf_constant_htons(x) ___constant_swab16(x)
+#define __bpf_ntohl(x) __builtin_bswap32(x)
+#define __bpf_htonl(x) __builtin_bswap32(x)
+#define __bpf_constant_ntohl(x) ___constant_swab32(x)
+#define __bpf_constant_htonl(x) ___constant_swab32(x)
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define __bpf_ntohs(x) (x)
+#define __bpf_htons(x) (x)
+#define __bpf_constant_ntohs(x) (x)
+#define __bpf_constant_htons(x) (x)
+#define __bpf_ntohl(x) (x)
+#define __bpf_htonl(x) (x)
+#define __bpf_constant_ntohl(x) (x)
+#define __bpf_constant_htonl(x) (x)
+#else
+#error "Fix your compiler's __BYTE_ORDER__?!"
+#endif
+
+#define bpf_htons(x) \
+  (__builtin_constant_p(x) ? __bpf_constant_htons(x) : __bpf_htons(x))
+#define bpf_ntohs(x) \
+  (__builtin_constant_p(x) ? __bpf_constant_ntohs(x) : __bpf_ntohs(x))
+#define bpf_htonl(x) \
+  (__builtin_constant_p(x) ? __bpf_constant_htonl(x) : __bpf_htonl(x))
+#define bpf_ntohl(x) \
+  (__builtin_constant_p(x) ? __bpf_constant_ntohl(x) : __bpf_ntohl(x))
+
+#endif /* __BPF_ENDIAN__ */

katran/tpr/bpf/tcp_pkt_router_common.h

@@ -10,10 +10,66 @@
 
 #include <bpf/bpf_helpers.h>
 
+#include "bpf_endian.h"
 #include "tcp_pkt_router_consts.h"
 #include "tcp_pkt_router_maps.h"
 #include "tcp_pkt_router_structs.h"
 
+// Uncomment to enable debug prints and check license
+// #define TPR_DEBUG
+
+#ifdef TPR_DEBUG
+static inline const char* sk_op_str(__u32 op) {
+  switch (op) {
+    case BPF_SOCK_OPS_VOID:
+      return "VOID";
+    case BPF_SOCK_OPS_TIMEOUT_INIT:
+      return "TIMEOUT_INIT";
+    case BPF_SOCK_OPS_RWND_INIT:
+      return "RWND_INIT";
+    case BPF_SOCK_OPS_TCP_CONNECT_CB:
+      return "TCP_CONNECT_CB";
+    case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
+      return "ACTIVE_ESTABLISHED_CB";
+    case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
+      return "PASSIVE_ESTABLISHED_CB";
+    case BPF_SOCK_OPS_NEEDS_ECN:
+      return "NEEDS_ECN";
+    case BPF_SOCK_OPS_BASE_RTT:
+      return "BASE_RTT";
+    case BPF_SOCK_OPS_RTO_CB:
+      return "RTO_CB";
+    case BPF_SOCK_OPS_RETRANS_CB:
+      return "RETRANS_CB";
+    case BPF_SOCK_OPS_STATE_CB:
+      return "STATE_CB";
+    case BPF_SOCK_OPS_TCP_LISTEN_CB:
+      return "TCP_LISTEN_CB";
+    case BPF_SOCK_OPS_RTT_CB:
+      return "RTT_CB";
+    case BPF_SOCK_OPS_PARSE_HDR_OPT_CB:
+      return "PARSE_HDR_OPT_CB";
+    case BPF_SOCK_OPS_HDR_OPT_LEN_CB:
+      return "HDR_OPT_LEN_CB";
+    case BPF_SOCK_OPS_WRITE_HDR_OPT_CB:
+      return "WRITE_HDR_OPT_CB";
+    default:
+      return "UNKNOWN";
+  }
+}
+
+#define TPR_PRINT(skops, fmtStr, ...)      \
+  bpf_printk(                              \
+      "[op=%s rport=%d lport=%d] " fmtStr, \
+      sk_op_str(skops->op),                \
+      bpf_ntohl(skops->remote_port),       \
+      skops->local_port,                   \
+      ##__VA_ARGS__);
+
+#else
+#define TPR_PRINT(skops, fmtStr, ...) ;
+#endif // TPR_DEBUG
+
 #define _LIKELY(expr) __builtin_expect(!!(expr), 1)
 #define _UNLIKELY(expr) __builtin_expect(!!(expr), 0)
 

katran/tpr/bpf/tcp_pkt_router_kern.c

@@ -19,6 +19,7 @@ static inline int handle_passive_cb(
     struct bpf_sock_ops* skops,
     struct stats* stat,
     const struct server_info* s_info) {
+  TPR_PRINT(skops, "passive cb", skops->op);
   int err;
 
   switch (skops->op) {
@@ -60,6 +61,7 @@ static inline int handle_passive_cb(
 static inline int handle_active_cb(
     struct bpf_sock_ops* skops,
     struct stats* stat) {
+  TPR_PRINT(skops, "active cb", skops->op);
   switch (skops->op) {
     case BPF_SOCK_OPS_TCP_CONNECT_CB:
       /* Called before SYN is sent on active side: nth to do */
@@ -117,6 +119,6 @@ int tcp_pkt_router(struct bpf_sock_ops* skops) {
   return CG_OK;
 }
 
-// It requires GPL to run bpf_printk
+// bpf_printk requires GPL license
 char _license[] SEC("license") = "Facebook";
 int _version SEC("version") = 1;

katran/tpr/bpf/tcp_pkt_router_passive_hdlr.h

@@ -39,8 +39,9 @@ static inline int handle_passive_parse_hdr(
     stat->error_bad_id++;
     return PASS;
   } else {
-    // no need to keep writing this once peer sends the right server_id.
     stat->server_id_read++;
+    TPR_PRINT(skops, "passive received server-id option");
+    // no need to keep writing this once peer sends the right server_id.
     err = unset_parse_hdr_cb_flags(skops, stat);
     err |= unset_write_hdr_cb_flags(skops, stat);
     return err;
@@ -64,6 +65,7 @@ static inline int handle_passive_write_hdr_opt(
     return err;
   }
   stat->server_id_set++;
+  TPR_PRINT(skops, "passive wrote option");
   return SUCCESS;
 }