Hello, I got some problem when I tried truncate one packet and then recirculate it. When the packet is recirculated, other modification still remains, but truncate does not works. Here is a simplified sample to show my problem:
/*************************************************************************
*********************** H E A D E R S ***********************************
*************************************************************************/
typedef bit<9> egressSpec_t;
typedef bit<32> cloneSpec_t;
typedef bit<32> cloneSession_t;
typedef bit<48> macAddr_t;
typedef bit<32> ip4Addr_t;
header ethernet_t {
macAddr_t dstAddr;
macAddr_t srcAddr;
bit<16> etherType;
}
header ipv4_t {
bit<4> version;
bit<4> ihl;
bit<8> diffserv;
bit<16> totalLen;
bit<16> identification;
bit<3> flags;
bit<13> fragOffset;
bit<8> ttl;
bit<8> protocol;
bit<16> hdrChecksum;
ip4Addr_t srcAddr;
ip4Addr_t dstAddr;
}
header test_t {
bit<8> test_info;
}
struct metadata { }
struct headers {
ethernet_t ethernet;
ipv4_t ipv4;
test_t test;
}
/*************************************************************************
*********************** P A R S E R ***********************************
*************************************************************************/
parser MyParser(packet_in packet,
out headers hdr,
inout metadata meta,
inout standard_metadata_t standard_metadata) {
state start {
transition parse_ethernet;
}
state parse_ethernet {
packet.extract(hdr.ethernet);
transition select(hdr.ethernet.etherType) {
TYPE_IPV4: parse_ipv4;
default: accept;
}
}
state parse_ipv4 {
packet.extract(hdr.ipv4);
transition select(packet.lookahead<test_t>().test_info) {
65 : parse_test;
default: accept;
}
}
state parse_test {
packet.extract(hdr.test);
transition accept;
}
}
/*************************************************************************
************ C H E C K S U M V E R I F I C A T I O N *************
*************************************************************************/
control MyVerifyChecksum(inout headers hdr, inout metadata meta) {
apply { }
}
/*************************************************************************
************** I N G R E S S P R O C E S S I N G *******************
*************************************************************************/
control MyIngress(inout headers hdr,
inout metadata meta,
inout standard_metadata_t standard_metadata) {
action drop() {
mark_to_drop(standard_metadata);
}
action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) {
standard_metadata.egress_spec = port;
hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
hdr.ethernet.dstAddr = dstAddr;
hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
}
table ipv4_lpm {
key = {
hdr.ipv4.dstAddr: lpm;
}
actions = {
ipv4_forward;
drop;
NoAction;
}
size = 1024;
default_action = NoAction();
}
apply {
if (standard_metadata.instance_type == PKT_INSTANCE_TYPE_NORMAL) {
clone_packet();
}
if (hdr.ipv4.isValid()) {
ipv4_lpm.apply();
}
}
}
/*************************************************************************
**************** E G R E S S P R O C E S S I N G *******************
*************************************************************************/
control MyEgress(inout headers hdr,
inout metadata meta,
inout standard_metadata_t standard_metadata) {
apply {
if (hdr.test_first.isValid()) {
if (standard_metadata.instance_type == PKT_INSTANCE_TYPE_INGRESS_CLONE) {
hdr.ipv4.totalLen = hdr.ipv4.minSizeInBytes();
truncate((bit<32>)hdr.ethernet.minSizeInBytes() + (bit<32>)hdr.ipv4.minSizeInBytes());
recirculate(standard_metadata);
}
}
}
}
I’m not familiar with recirculate and I am wondering is there anything I got wrong?