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-rw-r--r--Makefile53
-rw-r--r--README.md13
-rw-r--r--benchmark-user-with-burst.pngbin0 -> 5616 bytes
-rw-r--r--benchmark-user.pngbin0 -> 5509 bytes
-rw-r--r--benchmark-xdp-with-burst.pngbin0 -> 5147 bytes
-rw-r--r--benchmark-xdp.pngbin0 -> 4950 bytes
-rw-r--r--common.h5
-rwxr-xr-xgnuplot.script12
-rw-r--r--user_client.c85
-rw-r--r--user_server.c52
-rw-r--r--xdp_checksum.h94
-rw-r--r--xdp_loader.c70
-rw-r--r--xdp_manip.h28
-rw-r--r--xdp_parser.h132
-rw-r--r--xdp_udp_handler.c127
15 files changed, 671 insertions, 0 deletions
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..3edcf37
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,53 @@
+CC=clang-20
+IF=lo
+ifneq ($(DEBUG),)
+BPF_CFLAGS+=-DXDP_DEBUG=1
+endif
+
+all: xdp_udp_handler.o xdp_loader user_server user_client
+
+run: all
+ sudo ./xdp_loader $(IF)
+
+clean:
+ rm -f ./xdp_udp_handler.o ./xdp_loader ./user_server ./user_client
+ rm -f ./fit.log ./rtt.dat ./rtt_tmp.dat
+
+detach:
+ sudo bpftool net detach xdp dev $(IF)
+
+benchmark: all
+ @echo 'Running benchmark in user space..'
+ ./user_server &
+ ./user_client >./rtt_tmp.dat
+ cp ./rtt_tmp.dat ./rtt.dat
+ ./gnuplot.script
+ mv -v rtt.png benchmark-user-with-burst.png
+ # use only the last 90 data points
+ tail -n90 ./rtt_tmp.dat >./rtt.dat
+ ./gnuplot.script
+ mv -v rtt.png benchmark-user.png
+ @echo 'Running benchmark with XDP..'
+ $(MAKE) detach
+ $(MAKE) run
+ ./user_client >./rtt_tmp.dat
+ cp ./rtt_tmp.dat ./rtt.dat
+ ./gnuplot.script
+ mv -v rtt.png benchmark-xdp-with-burst.png
+ # use only the last 90 data points
+ tail -n90 ./rtt_tmp.dat >./rtt.dat
+ ./gnuplot.script
+ mv -v rtt.png benchmark-xdp.png
+ $(MAKE) detach
+
+xdp_udp_handler.o: xdp_udp_handler.c xdp_parser.h xdp_checksum.h
+ $(CC) -Wall -Wextra -O3 -g -target bpf -D__TARGET_ARCH_x86 $(BPF_CFLAGS) -c xdp_udp_handler.c -o xdp_udp_handler.o
+
+xdp_loader: xdp_loader.c
+ $(CC) -Wall -Wextra -O3 -g $(CFLAGS) xdp_loader.c -o xdp_loader $(shell pkg-config --cflags --libs libbpf) $(LDFLAGS)
+
+user_server: user_server.c
+ $(CC) -Wall -Wextra -O3 -g $(CFLAGS) user_server.c -o user_server
+
+user_client: user_client.c
+ $(CC) -Wall -Wextra -O3 -g $(CFLAGS) user_client.c -o user_client
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..1f013d6
--- /dev/null
+++ b/README.md
@@ -0,0 +1,13 @@
+Testing the performance of ring0 for packet decoding and manipulation.
+
+Just run: `make benchmark`, that's it!
+
+XDP (ring0):
+
+![XDP](benchmark-xdp.png)
+![XDP with bursts](benchmark-xdp-with-burst.png)
+
+Classic (ring3):
+
+![Userspace](benchmark-user.png)
+![Userspace with bursts](benchmark-user-with-burst.png)
diff --git a/benchmark-user-with-burst.png b/benchmark-user-with-burst.png
new file mode 100644
index 0000000..f0d669c
--- /dev/null
+++ b/benchmark-user-with-burst.png
Binary files differ
diff --git a/benchmark-user.png b/benchmark-user.png
new file mode 100644
index 0000000..bf544b9
--- /dev/null
+++ b/benchmark-user.png
Binary files differ
diff --git a/benchmark-xdp-with-burst.png b/benchmark-xdp-with-burst.png
new file mode 100644
index 0000000..c5f0bcb
--- /dev/null
+++ b/benchmark-xdp-with-burst.png
Binary files differ
diff --git a/benchmark-xdp.png b/benchmark-xdp.png
new file mode 100644
index 0000000..1226523
--- /dev/null
+++ b/benchmark-xdp.png
Binary files differ
diff --git a/common.h b/common.h
new file mode 100644
index 0000000..da4cb92
--- /dev/null
+++ b/common.h
@@ -0,0 +1,5 @@
+#define UDP_PORT 50000
+#define MAX_UDP_PACKETS 100
+
+#define PAYLOAD_REQUEST 0x01, 0x08, 0x00, 0x00, 0x05, 0x01, 0x01, 0x01, 0x05, 0x22, 0x01
+#define PAYLOAD_RESPONSE 0x01, 0x04, 0x00, 0x00, 0x05, 0x01, 0x01, 0x02
diff --git a/gnuplot.script b/gnuplot.script
new file mode 100755
index 0000000..a75243a
--- /dev/null
+++ b/gnuplot.script
@@ -0,0 +1,12 @@
+#!/usr/bin/env gnuplot
+
+set terminal png
+set output "rtt.png"
+f(x) = mean_rtt
+fit f(x) 'rtt.dat' u 1:2 via mean_rtt
+stddev_rtt = sqrt(FIT_WSSR / (FIT_NDF + 1 ))
+set title "Packets vs. RTT"
+set xlabel "Packet Number"
+set ylabel "RTT in usec"
+
+plot "rtt.dat" with lines, mean_rtt w l lt 3, stddev_rtt w l lt 3 lc rgb '#bbbbdd'
diff --git a/user_client.c b/user_client.c
new file mode 100644
index 0000000..68c79af
--- /dev/null
+++ b/user_client.c
@@ -0,0 +1,85 @@
+// udp client driver program
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "common.h"
+
+static const unsigned char payload_request[] = { PAYLOAD_REQUEST, 0xFF};
+
+struct {
+ unsigned long long int send_start;
+ unsigned long long int received_end;
+} timings[MAX_UDP_PACKETS];
+
+static int set_ts(unsigned long long int * const out) {
+ struct timeval tv = {};
+
+ if (gettimeofday(&tv, NULL) != 0)
+ return 1;
+
+ *out = (tv.tv_sec * 1000 * 1000) + tv.tv_usec;
+ return 0;
+}
+
+int main() {
+ char buffer[BUFSIZ];
+ int sockfd;
+ struct sockaddr_in servaddr = {};
+
+ servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
+ servaddr.sin_port = htons(UDP_PORT);
+ servaddr.sin_family = AF_INET;
+ sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+ if (sockfd < 0) {
+ perror("udp socket");
+ return 1;
+ }
+
+ if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) {
+ perror("udp connect");
+ return 1;
+ }
+
+ size_t i;
+ ssize_t n;
+ for (i = 0; i < MAX_UDP_PACKETS; ++i) {
+ if (set_ts(&timings[i].send_start) != 0) {
+ n = -1;
+ break;
+ }
+
+ n = sendto(sockfd, payload_request, sizeof(payload_request), 0, NULL, 0);
+ if (n < 0) {
+ perror("udp sendto");
+ break;
+ }
+
+ n = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr *)NULL,
+ NULL);
+ if (n < 0) {
+ perror("udp recvfrom");
+ break;
+ }
+
+ if (set_ts(&timings[i].received_end) != 0) {
+ n = -1;
+ break;
+ }
+ }
+
+ close(sockfd);
+
+ printf("# packet_number rtt\n");
+ for (size_t i = 0; i < MAX_UDP_PACKETS; ++i) {
+ printf("%zu %lld\n", i, timings[i].received_end - timings[i].send_start);
+ }
+
+ return !(i == MAX_UDP_PACKETS);
+}
diff --git a/user_server.c b/user_server.c
new file mode 100644
index 0000000..de2054f
--- /dev/null
+++ b/user_server.c
@@ -0,0 +1,52 @@
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <strings.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "common.h"
+
+static const unsigned char payload_response[] = {PAYLOAD_RESPONSE};
+
+int main() {
+ unsigned char buffer[BUFSIZ];
+ int listenfd;
+ socklen_t len;
+ struct sockaddr_in servaddr = {};
+ struct sockaddr_in cliaddr;
+
+ listenfd = socket(AF_INET, SOCK_DGRAM, 0);
+ servaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+ servaddr.sin_port = htons(UDP_PORT);
+ servaddr.sin_family = AF_INET;
+
+ if (bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) != 0) {
+ perror("udp bind");
+ return 1;
+ }
+
+ size_t i;
+ ssize_t n;
+ for (i = 0; i < MAX_UDP_PACKETS; ++i) {
+ len = sizeof(cliaddr);
+ n = recvfrom(listenfd, buffer, sizeof(buffer), 0,
+ (struct sockaddr *)&cliaddr, &len);
+ if (n < 0) {
+ perror("udp recvfrom");
+ break;
+ }
+
+ n = sendto(listenfd, payload_response, sizeof(payload_response), 0,
+ (struct sockaddr *)&cliaddr, sizeof(cliaddr));
+ if (n < 0) {
+ perror("udp sendto");
+ break;
+ }
+ }
+
+ close(listenfd);
+
+ return !(i == MAX_UDP_PACKETS);
+}
diff --git a/xdp_checksum.h b/xdp_checksum.h
new file mode 100644
index 0000000..1d35565
--- /dev/null
+++ b/xdp_checksum.h
@@ -0,0 +1,94 @@
+#ifndef XDP_CHECKSUM_H
+#define XDP_CHECKSUM_H 1
+
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <stdlib.h>
+
+static __always_inline __u16 ip_checksum(struct iphdr *iph) {
+ __u32 sum = 0;
+ __u16 *ptr = (__u16 *)iph;
+
+// IP header is iph->ihl * 4 bytes in size --> iph->ihl * 2 16 bit works
+#pragma unroll
+ for (int i = 0; i < 10; i++) { // max 20 bytes (5 * 4)
+ if (i >= iph->ihl * 2)
+ break;
+ if (i == 5)
+ continue; // checksum field at offset 10–11, skip for calc
+ sum += (__u32)ptr[i];
+ }
+
+ while (sum >> 16)
+ sum = (sum & 0xFFFF) + (sum >> 16);
+
+ return ~sum;
+}
+
+static __always_inline __u16 csum_fold_helper(__u32 sum) {
+ while (sum >> 16)
+ sum = (sum & 0xffff) + (sum >> 16);
+ return ~sum;
+}
+
+static __always_inline __u16 csum_add(__u32 sum, __u32 value) {
+ sum += value;
+ return sum;
+}
+
+static __always_inline __u32 csum16_add(__u32 sum, __u16 val) {
+ sum += val;
+ if (sum > 0xffff)
+ sum -= 0xffff;
+ return sum;
+}
+
+static __always_inline __u16 udp_checksum(struct iphdr *iph,
+ struct udphdr *udph, void *data_end) {
+ __u32 sum = 0;
+
+ // IP header source/dest address + layer4 protocol
+ sum = csum16_add(sum, (__u16)(iph->saddr >> 16));
+ sum = csum16_add(sum, (__u16)(iph->saddr & 0xffff));
+ sum = csum16_add(sum, (__u16)(iph->daddr >> 16));
+ sum = csum16_add(sum, (__u16)(iph->daddr & 0xffff));
+ sum = csum16_add(sum, __constant_htons(IPPROTO_UDP));
+ // UDP header length
+ sum = csum16_add(sum, udph->len);
+ // UDP header checksum
+ __u16 *ptr = (__u16 *)udph;
+#pragma unroll
+ for (size_t i = 0; i < sizeof(struct udphdr) / 2; i++) {
+ if ((void *)(ptr + 1) > data_end)
+ break;
+ sum = csum16_add(sum, *ptr);
+ ptr++;
+ }
+
+ // UDP payload checksum
+ void *payload = (void *)udph + sizeof(struct udphdr);
+ int payload_len = __constant_ntohs(udph->len) - sizeof(struct udphdr);
+ ptr = (__u16 *)payload;
+
+ for (int i = 0; i < 256; i++) { // max 512 bytes
+ if (payload_len <= 0)
+ break;
+ if ((void *)(ptr + 1) > data_end)
+ break;
+ sum = csum16_add(sum, *ptr);
+ ptr++;
+ payload_len -= 2;
+ }
+
+ // if payload length off: pad wiuth null
+ if (payload_len == 1) {
+ __u8 *last = (__u8 *)ptr;
+ if ((void *)(last + 1) <= data_end) {
+ sum = csum16_add(sum, (*last) << 8);
+ }
+ }
+
+ return csum_fold_helper(sum);
+}
+
+#endif
diff --git a/xdp_loader.c b/xdp_loader.c
new file mode 100644
index 0000000..6f620b8
--- /dev/null
+++ b/xdp_loader.c
@@ -0,0 +1,70 @@
+#include <arpa/inet.h>
+#include <errno.h>
+#include <net/if.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+#include <linux/if_link.h>
+
+int main(int argc, char **argv) {
+ if (argc != 2) {
+ fprintf(stderr, "Usage: %s <iface>\n", argv[0]);
+ return 1;
+ }
+
+ const char *const iface = argv[1];
+
+ int ifindex = if_nametoindex(iface);
+ if (!ifindex) {
+ perror("if_nametoindex");
+ return 1;
+ }
+
+ struct bpf_object *obj;
+ int prog_fd;
+ const char *const xdp_file = "xdp_udp_handler.o";
+
+ obj = bpf_object__open_file(xdp_file, NULL);
+ if (!obj) {
+ fprintf(stderr, "Error opening BPF object file: `%s'\n", xdp_file);
+ return 1;
+ }
+
+ if (bpf_object__load(obj)) {
+ fprintf(stderr, "Error loading BPF object\n");
+ return 1;
+ }
+
+ struct bpf_program *const prog =
+ bpf_object__find_program_by_name(obj, "xdp_udp_handler");
+ if (!prog) {
+ fprintf(stderr, "Couldn't find program\n");
+ return 1;
+ }
+
+ prog_fd = bpf_program__fd(prog);
+ if (prog_fd < 0) {
+ fprintf(stderr, "Invalid program FD\n");
+ return 1;
+ }
+
+ printf("Attaching BPF program in driver (native) mode..\n");
+ if (bpf_xdp_attach(ifindex, prog_fd,
+ XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_DRV_MODE,
+ NULL) < 0) {
+ perror("bpf_xdp_attach");
+ printf("Attaching BPF program in kernel mode..\n");
+ if (bpf_xdp_attach(ifindex, prog_fd, XDP_FLAGS_UPDATE_IF_NOEXIST, NULL) <
+ 0) {
+ perror("bpf_xdp_attach");
+ return 1;
+ }
+ }
+
+ printf("XDP program loaded\n");
+ return 0;
+}
diff --git a/xdp_manip.h b/xdp_manip.h
new file mode 100644
index 0000000..70eba28
--- /dev/null
+++ b/xdp_manip.h
@@ -0,0 +1,28 @@
+#ifndef XDP_MANIP_H
+#define XDP_MANIP_H 1
+
+#include <linux/if_ether.h>
+#include <linux/ip.h>
+#include <linux/udp.h>
+
+static __always_inline void swap_eth_addr(struct ethhdr *const ethhdr) {
+ unsigned char src_eth[ETH_ALEN];
+
+ __builtin_memcpy(src_eth, ethhdr->h_source, sizeof(ethhdr->h_source));
+ __builtin_memcpy(ethhdr->h_source, ethhdr->h_dest, sizeof(ethhdr->h_source));
+ __builtin_memcpy(ethhdr->h_dest, src_eth, sizeof(src_eth));
+}
+
+static __always_inline void swap_ip4_addr(struct iphdr *const iphdr) {
+ __be32 src_ip = iphdr->saddr;
+ iphdr->saddr = iphdr->daddr;
+ iphdr->daddr = src_ip;
+}
+
+static __always_inline void swap_udp_port(struct udphdr *const udphdr) {
+ __be16 src_port = udphdr->source;
+ udphdr->source = udphdr->dest;
+ udphdr->dest = src_port;
+}
+
+#endif
diff --git a/xdp_parser.h b/xdp_parser.h
new file mode 100644
index 0000000..a227204
--- /dev/null
+++ b/xdp_parser.h
@@ -0,0 +1,132 @@
+#ifndef XDP_PARSER_H
+#define XDP_PARSER_H 1
+
+#include <linux/if_ether.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/udp.h>
+#include <stdlib.h>
+
+#ifndef VLAN_MAX_DEPTH
+#define VLAN_MAX_DEPTH 2
+#endif
+
+#define VLAN_VID_MASK 0x0fff /* VLAN Identifier */
+
+struct hdr_cursor {
+ union {
+ void *pos;
+ __u8 *pos_u8;
+ };
+};
+
+struct vlan_hdr {
+ __be16 h_vlan_TCI;
+ __be16 h_vlan_encapsulated_proto;
+};
+
+struct collect_vlans {
+ __u16 id[VLAN_MAX_DEPTH];
+};
+
+static __always_inline int proto_is_vlan(__u16 h_proto) {
+ return !!(h_proto == __constant_htons(ETH_P_8021Q) ||
+ h_proto == __constant_htons(ETH_P_8021AD));
+}
+
+static __always_inline int parse_ethhdr_vlan(struct hdr_cursor *nh,
+ void *data_end,
+ struct ethhdr **ethhdr,
+ struct collect_vlans *vlans) {
+ struct ethhdr *eth = nh->pos;
+ int hdrsize = sizeof(*eth);
+ struct vlan_hdr *vlh;
+ __u16 h_proto;
+ int i;
+
+ if (nh->pos + hdrsize > data_end)
+ return -1;
+
+ nh->pos += hdrsize;
+ *ethhdr = eth;
+ vlh = nh->pos;
+ h_proto = eth->h_proto;
+
+#pragma unroll
+ for (i = 0; i < VLAN_MAX_DEPTH; i++) {
+ if (!proto_is_vlan(h_proto))
+ break;
+
+ if (vlh + 1 > (struct vlan_hdr *)data_end)
+ break;
+
+ h_proto = vlh->h_vlan_encapsulated_proto;
+ if (vlans) /* collect VLAN ids */
+ vlans->id[i] = (__constant_ntohs(vlh->h_vlan_TCI) & VLAN_VID_MASK);
+
+ vlh++;
+ }
+
+ nh->pos = vlh;
+ return h_proto; /* network-byte-order */
+}
+
+static __always_inline int parse_ethhdr(struct hdr_cursor *nh, void *data_end,
+ struct ethhdr **ethhdr) {
+ return parse_ethhdr_vlan(nh, data_end, ethhdr, NULL);
+}
+
+static __always_inline int parse_ip6hdr(struct hdr_cursor *nh, void *data_end,
+ struct ipv6hdr **ip6hdr) {
+ struct ipv6hdr *ip6h = nh->pos;
+
+ if (ip6h + 1 > (struct ipv6hdr *)data_end)
+ return -1;
+
+ nh->pos = ip6h + 1;
+ *ip6hdr = ip6h;
+
+ return ip6h->nexthdr;
+}
+
+static __always_inline int parse_iphdr(struct hdr_cursor *nh, void *data_end,
+ struct iphdr **iphdr) {
+ struct iphdr *iph = (struct iphdr *)nh->pos;
+ size_t hdrsize;
+
+ if (iph + 1 > (struct iphdr *)data_end)
+ return -1;
+
+ hdrsize = iph->ihl * 4;
+ if (hdrsize < sizeof(*iph))
+ return -1;
+
+ /* Variable-length IPv4 header, need to use byte-based arithmetic */
+ if (nh->pos + hdrsize > data_end)
+ return -1;
+
+ nh->pos += hdrsize;
+ *iphdr = iph;
+
+ return iph->protocol;
+}
+
+static __always_inline int parse_udphdr(struct hdr_cursor *nh, void *data_end,
+ struct udphdr **udphdr) {
+ int len;
+ struct udphdr *h = nh->pos;
+
+ if (h + 1 > (struct udphdr *)data_end)
+ return -1;
+
+ nh->pos = h + 1;
+ *udphdr = h;
+
+ len = __constant_ntohs(h->len) - sizeof(struct udphdr);
+ if (len < 0)
+ return -1;
+
+ return len;
+}
+
+#endif
diff --git a/xdp_udp_handler.c b/xdp_udp_handler.c
new file mode 100644
index 0000000..930667f
--- /dev/null
+++ b/xdp_udp_handler.c
@@ -0,0 +1,127 @@
+#include <linux/bpf.h>
+#include <linux/in.h>
+
+#include <bpf/bpf_helpers.h>
+
+#include "xdp_checksum.h"
+#include "xdp_manip.h"
+#include "xdp_parser.h"
+
+#ifdef XDP_DEBUG
+#define dbg_bpf_printk(fmt, args...) bpf_printk(fmt, ##args)
+#else
+#define dbg_bpf_printk(fmt, args...)
+#endif
+
+#include "common.h"
+
+SEC("xdp")
+int xdp_udp_handler(struct xdp_md *ctx) {
+ void *data_end = (void *)(long)ctx->data_end;
+ void *data = (void *)(long)ctx->data;
+ __u32 action = XDP_PASS; /* Default action */
+ struct hdr_cursor nh = {.pos = data};
+ int nh_type;
+ struct ethhdr *ethhdr;
+ struct iphdr *iphdr = NULL;
+ struct ipv6hdr *ip6hdr = NULL;
+ struct udphdr *udphdr;
+ static const __u8 payload_request[] = {PAYLOAD_REQUEST};
+ static const __u32 payload_request_size = sizeof(payload_request);
+ static const __u8 payload_response[] = {PAYLOAD_RESPONSE};
+ __u32 payload_size;
+
+ nh_type = parse_ethhdr(&nh, data_end, &ethhdr);
+
+ switch (__constant_ntohs(nh_type)) {
+ case ETH_P_IP:
+ nh_type = parse_iphdr(&nh, data_end, &iphdr);
+ break;
+ case ETH_P_IPV6:
+ nh_type = parse_ip6hdr(&nh, data_end, &ip6hdr);
+ break;
+ default:
+ goto out;
+ }
+
+ if (nh_type != IPPROTO_UDP) {
+ goto out;
+ }
+ if (parse_udphdr(&nh, data_end, &udphdr) < 0) {
+ action = XDP_ABORTED;
+ goto out;
+ }
+ if (udphdr->dest != __constant_htons(UDP_PORT)) {
+ goto out;
+ }
+
+ payload_size = (__u8 *)data_end - (__u8 *)nh.pos;
+ if (payload_size < payload_request_size) {
+ goto out;
+ }
+
+ if (nh.pos_u8 + payload_request_size + 1 > (__u8 *)data_end) {
+ goto out;
+ }
+ if (__builtin_memcmp(nh.pos_u8, payload_request, sizeof(payload_request)) !=
+ 0) {
+ goto out;
+ }
+
+ dbg_bpf_printk("Received UDP Ping Request #%u with size %u", nh.pos_u8[11],
+ payload_size);
+
+ /* Shrink UDP packet for Ping Reply */
+ if (bpf_xdp_adjust_tail(ctx, payload_request_size - payload_size) != 0) {
+ return XDP_ABORTED;
+ }
+
+ /* Set data pointers (may not be valid anymore) */
+ data = (void *)(long)ctx->data;
+ data_end = (void *)(long)ctx->data_end;
+ nh.pos = data;
+
+ if (parse_ethhdr(&nh, data_end, &ethhdr) < 0) {
+ action = XDP_ABORTED;
+ goto out;
+ }
+
+ payload_size -= 4;
+
+ if (iphdr != NULL) {
+ if (parse_iphdr(&nh, data_end, &iphdr) < 0) {
+ action = XDP_ABORTED;
+ goto out;
+ }
+ if (parse_udphdr(&nh, data_end, &udphdr) < 0) {
+ action = XDP_ABORTED;
+ goto out;
+ }
+ swap_eth_addr(ethhdr);
+ udphdr->len = __constant_htons(payload_size + sizeof(*udphdr));
+ iphdr->tot_len =
+ __constant_htons(iphdr->ihl * 4 + payload_size + sizeof(*udphdr));
+ swap_ip4_addr(iphdr);
+ iphdr->check = ip_checksum(iphdr);
+ if (nh.pos_u8 + sizeof(payload_response) > (__u8 *)data_end) {
+ action = XDP_ABORTED;
+ goto out;
+ }
+ __builtin_memcpy(nh.pos_u8, payload_response, sizeof(payload_response));
+ swap_udp_port(udphdr);
+ udphdr->check = udp_checksum(iphdr, udphdr, data_end);
+ } else if (ip6hdr != NULL) {
+ parse_ip6hdr(&nh, data_end, &ip6hdr);
+ goto out; // TODO: Implement!
+ } else {
+ action = XDP_ABORTED;
+ goto out;
+ }
+
+ action = XDP_TX;
+out:
+ return action;
+}
+
+char _license[] SEC("license") =
+ "GPL"; // Please keep this to prevent tainting kernel
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