Bring back len and cap fields

tap/tlstapper/bpf/golang_uprobes.c

@@ -18,6 +18,8 @@ struct golang_read_write {
     __u32 conn_addr;
     bool is_request;
     bool is_gzip_chunk;
+    __u32 len;
+    __u32 cap;
     __u8 data[BUFFER_SIZE_READ_WRITE];
 };
 
@@ -56,6 +58,8 @@ static __always_inline int golang_crypto_tls_write_uprobe(struct pt_regs *ctx) {
     b->conn_addr = ctx->rsi; // go.itab.*net.TCPConn,net.Conn address
     b->is_request = true;
     b->is_gzip_chunk = false;
+    b->len = ctx->rcx;
+    b->cap = ctx->rdi;
 
     struct socket x = {
         .pid = s->pid,
@@ -103,6 +107,8 @@ static __always_inline int golang_crypto_tls_read_uprobe(struct pt_regs *ctx) {
     b->conn_addr = ctx->rsi; // go.itab.*net.TCPConn,net.Conn address
     b->is_request = false;
     b->is_gzip_chunk = false;
+    b->len = ctx->rcx;
+    b->cap = ctx->rcx; // no cap info
 
     void* stack_addr = (void*)ctx->rsp;
     __u64 data_p;

tap/tlstapper/tls_poller.go

@@ -185,12 +185,12 @@ func (p *tlsPoller) pollGolangReadWrite(rd *ringbuf.Reader, emitter api.Emitter,
 			go dissect(p.extension, connection.ClientReader, options)
 			go dissect(p.extension, connection.ServerReader, options)
 
-			request := make([]byte, len(b.Data[:]))
+			request := make([]byte, len(b.Data[:b.Len]))
-			copy(request, b.Data[:])
+			copy(request, b.Data[:b.Len])
 			connection.ClientReader.send(request)
 		} else {
-			response := make([]byte, len(b.Data[:]))
+			response := make([]byte, len(b.Data[:b.Len]))
-			copy(response, b.Data[:])
+			copy(response, b.Data[:b.Len])
 			connection.ServerReader.send(response)
 		}
 	}

tap/tlstapper/tlstapper_bpfeb.go

@@ -19,8 +19,10 @@ type tlsTapperGolangReadWrite struct {
 	ConnAddr    uint32
 	IsRequest   bool
 	IsGzipChunk bool
-	Data        [524288]uint8
 	_           [2]byte
+	Len         uint32
+	Cap         uint32
+	Data        [524288]uint8
 }
 
 type tlsTapperTlsChunk struct {

tap/tlstapper/tlstapper_bpfel.go

@@ -19,8 +19,10 @@ type tlsTapperGolangReadWrite struct {
 	ConnAddr    uint32
 	IsRequest   bool
 	IsGzipChunk bool
-	Data        [524288]uint8
 	_           [2]byte
+	Len         uint32
+	Cap         uint32
+	Data        [524288]uint8
 }
 
 type tlsTapperTlsChunk struct {