Referans

Hizli Referans ve Kaynaklar

BPF primitive’leri, helper fonksiyonlar ve ek kaynaklar icin toplu referans. BPF’te belirli bir gorevi nasil yapacaginizi hizlica bulmak icin bu sayfayi kullanin.

Hizli Referans

Ihtiyac	Cozum	Notlar
Bir listeden IP’leri engelleme	IP key’leri ile `BPF_MAP_TYPE_HASH`	DDoS engine ve IP blocklist’te kullanilir
Kaynak basina paket sayma	`BPF_MAP_TYPE_PERCPU_HASH` veya `BPF_MAP_TYPE_LRU_HASH`	Per-CPU variant lock contention’i onler
Rate limiting	`BPF_MAP_TYPE_HASH` + BPF’te token bucket	Her key icin timestamp ve token sayisi saklayin
Round-robin backend secimi	`BPF_MAP_TYPE_ARRAY` + atomic counter	`__sync_fetch_and_add` ile backend array’e index
Consistent hashing	5-tuple hash, mod N backend	`jhash` veya benzeri kullanin; referans icin Katran’a bakin
DNS query inceleme	L3/L4 header’lardan sonra UDP payload’i parse edin	DNS wire format’taki QNAME field’i uzerinde eslestirme
Paketi kernel stack’e gecirme	`XDP_PASS` return edin	Islem gerekmediginde varsayilan davranis
Paketi dusurme	`XDP_DROP` return edin	Kernel’deki en hizli discard path
Baska bir interface’e yonlendirme	`bpf_redirect()` + `XDP_REDIRECT` return	Load balancer forwarding icin gerekli
MAC adreslerini yeniden yazma	`xdp_md->data` uzerinden dogrudan header degisikligi	Dogru L2 header’i ayarlamak icin redirect sonrasi gerekli
XDP ve user space arasinda state paylasimi	`BPF_MAP_TYPE_HASH` veya `BPF_MAP_TYPE_ARRAY`	Program reload’lari arasinda kalicilik icin map’leri BPFFS’e pinleyin
Baska bir BPF programina tail call	`BPF_MAP_TYPE_PROG_ARRAY` + `bpf_tail_call()`	Katran’in `xdp_root.c` dosyasinda program chaining icin kullanilir
IP blocklist (CIDR aralik)	`BPF_MAP_TYPE_LPM_TRIE`	Subnet seviyesinde engelleme icin longest prefix match
DNS query log	`BPF_MAP_TYPE_RINGBUF` + Go consumer	Polling olmadan event’leri userspace’e stream etme
Debug output	`bpf_printk()` + `bpftool prog trace`	Kernel trace pipe; yalnizca gelistirme sirasinda kullanin
Routing lookup	`bpf_fib_lookup()`	Kernel FIB’den next-hop MAC ve interface cozumleme
String karsilastirma	`bpf_strncmp()`	Degisken string’i bir sabit ile karsilastirma
Substring arama	`bpf_strstr()` (kernel 6.x+)	Bir buffer icinde bir alt string bulma
Kernel memory okuma	`bpf_probe_read_kernel_str()`	Kernel adres alanindan guvenli okuma
User memory okuma	`bpf_probe_read_user_str()`	User adres alanindan guvenli okuma
Process adini alma	`bpf_get_current_comm()`	Calisan task’in comm (ad) degerini dondurur
Port donusumu (network to host)	`bpf_ntohs()`	16-bit network byte order’dan host byte order’a
IP donusumu (network to host)	`bpf_ntohl()`	32-bit network byte order’dan host byte order’a

Okuma Materyalleri

Kaynak	Referans Verildigi Yer
Computer Networking Fundamentals	Struct, Memory Layout ve Byte Order
XDP Paper	XDP Temelleri
Cilium BPF Architecture	Program Type’lar ve Derin Dalis
Cilium Network Concepts	Program Type’lar ve Derin Dalis
Unimog Blog	Packet Rewriting ve Load Balancing
Facebook BPF Firewall	Rate Limiting ve IP Blocklist
Cilium Performance Tuning	Observability

Ek Kaynaklar

Load Balancer Challenge - L4 LB eBPF-XDP load balancer
Deep Dive into Cloudflare’s Cache Mechanism - Cloudflare cache ic yapisi
Scratch to Success LB - Adim adim LB yapimi
VLAN Filter Support - Bridge VLAN filtering
Edge-FaaS Scheduling