basic.p4 aciklamali cozumu

rev.1
This commit is contained in:
yigid balaban 2024-10-09 17:05:12 +03:00
parent 01ed2c499d
commit e98b920436
Signed by: fyb
GPG Key ID: CF1BBD1336C0A3D6

View File

@ -4,10 +4,6 @@
const bit<16> TYPE_IPV4 = 0x800;
/*************************************************************************
*********************** H E A D E R S ***********************************
*************************************************************************/
typedef bit<9> egressSpec_t;
typedef bit<48> macAddr_t;
typedef bit<32> ip4Addr_t;
@ -42,35 +38,36 @@ struct headers {
ipv4_t ipv4;
}
/*************************************************************************
*********************** P A R S E R ***********************************
*************************************************************************/
parser MyParser(packet_in packet,
out headers hdr,
inout metadata meta,
inout standard_metadata_t standard_metadata) {
/* each IPv4 thing is wrapped in Ethernet headers so the state is parse_ether
by default */
state start {
/* TODO: add parser logic */
transition parse_ether;
}
state parse_ether {
packet.extract(hdr.ethernet);
transition select(hdr.ethernet.etherType) {
TYPE_IPV4: parse_ipv4;
default: accept;
}
}
state parse_ipv4 {
packet.extract(hdr.ipv4);
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) {
@ -79,9 +76,30 @@ control MyIngress(inout headers hdr,
}
action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) {
/* TODO: fill out code in action body */
/* bu satiri aciklamaya calisirken switch'lerin portlarina bagli cihazlarin
MAC adreslerini nasil ogrendigini ve nasil sakladigini arastirdim. takip eden ipv4_lpm kismi bu muammanin yanitini verecek. */
/* disari yonlu paketin switch'in hangi portundan ayrilmasi gerektigi ayarlanir */
standard_metadata.egress_spec = port;
/* paketin kaynagi artik biziz, srcAddr header'dan dstAddr olarak ayarlanir */
hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
/* hedef adres, bir sonraki hop'un alicisi olarak ayarlanir */
hdr.ethernet.dstAddr = dstAddr;
hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
}
/* burasi cokomelli: LPM "Longest Prefix Match"in kisaltmasi
IP yonlendirmede kullanilan bir teknik. Verilen bir IP adres icin hangi
(cihaz MAC'i - port) demetinin kullanilacagini seciyor.
tablonun kendisi ise IP_prefix : (MAC, port) seklinde bir veri yapisi
cunku IP_prefix aslinda bir IP agini ifade ediyor (10.0.1.0/24 gibi)
biz de burada hedef IPv4 adresimizi LPM tablosundan esleyerek hangi
porttan cikacagimizi belirliyor ya da tabloda olmayan bir yol sayesinde
o paketi dropluyoruz (cunku bagli hicbir cihaz o yola sahip degil) */
table ipv4_lpm {
key = {
hdr.ipv4.dstAddr: lpm;
@ -96,27 +114,23 @@ control MyIngress(inout headers hdr,
}
apply {
/* TODO: fix ingress control logic
* - ipv4_lpm should be applied only when IPv4 header is valid
*/
ipv4_lpm.apply();
/* buradaki basta sihirli gorunen isValid, P4 tarafindan tanimlanan ve
bir header'in duzgunce parse edilip pakette yer aldigini dogrulayan bir
fonksiyonmus. */
/* eger elimizdeki paket IPv4 paketi ise LPM tablosundaki kurallar
uygulanacak. */
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 { }
}
/*************************************************************************
************* C H E C K S U M C O M P U T A T I O N **************
*************************************************************************/
control MyComputeChecksum(inout headers hdr, inout metadata meta) {
apply {
update_checksum(
@ -137,21 +151,14 @@ control MyComputeChecksum(inout headers hdr, inout metadata meta) {
}
}
/*************************************************************************
*********************** D E P A R S E R *******************************
*************************************************************************/
control MyDeparser(packet_out packet, in headers hdr) {
/* paketi aldigimiz gibi birakiyoruz :) */
apply {
/* TODO: add deparser logic */
packet.emit(hdr.ethernet);
packet.emit(hdr.ipv4);
}
}
/*************************************************************************
*********************** S W I T C H *******************************
*************************************************************************/
V1Switch(
MyParser(),
MyVerifyChecksum(),