本文主要是介绍网络编程之XDP技术应用，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
一、AF_XDP介绍
在上文中介绍了XDP技术，XDP技术的基本原理已经明白，但有一个问题，一个技术如何落地，如何在实际中应用？这就需要有一个承载其的具体的形式。举一个例子，网络编程一般使用Socket方式，那么能不能够在这种方式里使用XDP技术呢？答案是肯定的。
Linux在内核中提供了AF_XDP套接字编程，这就意味着，大部分的编程方式仍然可以以原来的套接字编程为主。这样的好处显而易见，对开发者和维护者来说，都是相对要容易理解和支持。AF_XDP类似于AF_NET（TCP/IP等）等一样，是一个协议族，大家有没有记得在TCP网络编程时经常写的一行代码“.sin_family = AF_INET”，就是这个意思。XDP中，可以通过XDP_REDIRECT进行数据的重定向，而AF_XDP则利用函数bpf_redirect_map实现数据的重定向。所谓重定向，其实就是把数据传输到指定的位置。一般来说这个位置是一块内存或一个设备等，此函数会重定向一块内存中，这就大大方便了开发者的数据处理方式。
在前面的XDP介绍中提到了其三种运行方式，而AF_XDP有两种模式，一种模式是驱动支持，则使用XDP_DRV；另外一种模式是驱动不支持，则使用XDP_SKB。一般情况下，如果在开发时显示指定了XDP_SKB或者驱动不支持XDP，则使用XDP_SKB。在官方的介绍里，推荐看一下Cilium项目，来进行学习和借鉴。
二、应用
AF_XDP套接字即XSK，在创建后，关联有两个环形队列即TX和RX。二者可以共同使用同一个内存区域即UMEM。这里需要介绍一下几个相关的术语：
1、UMEM：它是一块连续的虚拟内存，可以分割为相同大小的帧。而环形队列中的技术符可以通过偏移量（地址）来引用这引起帧。开发者通过内存分配,如malloc,mmap以及大页内存等方式分配内存并通过Socket套接字选项XDP_UMEM_REG来注册其成为内核所用部分。
UMEM也拥有两个环形队列，FILL ring和COMPLETION ring，前者用来下发地址，即Rx相关，通知内核写Rx数据，在收到数据后，Rx Ring则会引用这些帧。而后者则包含内核传输完成的相关帧地址，可被用户空间的TX使用，即Tx相关。
UMEM可以通过bind函数将SOCKET与相关队列ID绑定。
2、Ring
如果学习过前面的DPDK系列，则很容易明白，其实就是几个环形队列或者说环形缓冲区罢了。它有四种类型：
TX Ring：Tx Ring用来发送帧，其填充完成的struct xdp_desc描述符被sendmsg()系统调用。
RX Ring：同样其是用户空间的接收环形队列，其每个条目都是一个struct xdp_desc描述符这个描述符中包含着UMEM偏移量（地址）和数据长度。如果其未通过FILL Ring传递给内核则由用户层应用程序处理此数据。
UMEM FILL ring：其用于将UMEM的所有权从用户空间转到内核空间。
COMPLETION Ring：其用于将UMEM的所有权从内核空间转到用户空间。
注意：这四个队列都是单生产者单消费者模式。
3、XSKMAP / BPF_MAP_TYPE_XSKMAP
前者是XDP用来将分发数据到XSK的，即只有加载一个XDP程序并且XDKMAP中的一个XSK后，才可以由XSK获取用户空间的数据。后者用于BFP的映射，与bpf_redirect_map函数一起，将ingress的帧传递给Socket。而用户空间则通过bpf函数的系统调用来将Socket插入到相关的映射表。
需要注意的是，重定向的的位置必须与SOCKET匹配即网络设备（如eth0）与队列ID必须匹配，否则数据会被丢弃。
从上面的分析可以看出，AF_XDP的开发要有两个层面，一个是传统的网络编程用来处理套接字的相关行为；另外一种则是进行与内核通信的相关操作。
AF_XDP可以对应XDP中的几种Action：
1、XDP_DROP：驱动层上丢弃相关报文，可用于实现DDos或防火墙之类的安全处理
2、XDP_PASS：报文传送至内核网络协议栈，处理报文的CPU会分配并填充一个skb，将其传递到GRO引擎，然后回到正常路径
3、XDP_TX：BPF程序将数据报文从接收NIC发送出去即原路返回。
4、XDP_REDIRECT：与XDP_TX类似，但是通过另一个网卡将包发出去；也可以使用XDP_REDIRECT 还可以将包重定向到一个 BPF cpumap。这可以理解成是一个转发器。当前的CPU由于不用做数据处理准备动作，大大减少了开销。
5、XDP_ABORTED：程序出现异常，与 XDP_DROP相同，但XDP_ABORTED会流过trace_xdp_exception tracepoint，指导书通过tracing工具监控这种异常。
更多的知识点可以去内核的文档中查找相关资料，做为开源软件的领军标杆，文档写得还是相当不错的。
三、例程
首先看一个简单的例程：
#include <linux/bpf.h>#define SEC(NAME) __attribute__((section(NAME), used))SEC("xdp")
int xdp_drop_netdata(struct xdp_md *ctx) {return XDP_DROP;
}编译加载卸载：
[roo]# clang -O2 -target bpf -c xdp_drop_netdata.c -o xdp-test.o
[root]# ip link set dev ens19 xdp obj xdp-test.o sec xdp
[root]# ip link set dev ens19 xdp off这段代码非常简单，主要就是将收到的数据报文全部扔掉，它的结果就是导致网络设备不可用。如果将其卸载后则可正常使用。
下面看一个比较复杂的应用（代码源自Linux内核Samples\bpf\xdpsock_user.c xdpsock_kern.c）：
1、用户空间代码
// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2017 - 2018 Intel Corporation. */#include <errno.h>
#include <getopt.h>
#include <libgen.h>
#include <linux/bpf.h>
#include <linux/if_link.h>
#include <linux/if_xdp.h>
#include <linux/if_ether.h>
#include <linux/ip.h>
#include <linux/limits.h>
#include <linux/udp.h>
#include <arpa/inet.h>
#include <locale.h>
#include <net/ethernet.h>
#include <netinet/ether.h>
#include <net/if.h>
#include <poll.h>
#include <pthread.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/capability.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/un.h>
#include <time.h>
#include <unistd.h>
#include <sched.h>#include <bpf/libbpf.h>
#include <bpf/xsk.h>
#include <bpf/bpf.h>
#include "xdpsock.h"/* libbpf APIs for AF_XDP are deprecated starting from v0.7 */
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"#ifndef SOL_XDP
#define SOL_XDP 283
#endif#ifndef AF_XDP
#define AF_XDP 44
#endif#ifndef PF_XDP
#define PF_XDP AF_XDP
#endif#define NUM_FRAMES (4 * 1024)
#define MIN_PKT_SIZE 64#define DEBUG_HEXDUMP 0#define VLAN_PRIO_MASK 0xe000 /* Priority Code Point */
#define VLAN_PRIO_SHIFT 13
#define VLAN_VID_MASK 0x0fff /* VLAN Identifier */
#define VLAN_VID__DEFAULT 1
#define VLAN_PRI__DEFAULT 0#define NSEC_PER_SEC 1000000000UL
#define NSEC_PER_USEC 1000#define SCHED_PRI__DEFAULT 0typedef __u64 u64;
typedef __u32 u32;
typedef __u16 u16;
typedef __u8 u8;static unsigned long prev_time;
static long tx_cycle_diff_min;
static long tx_cycle_diff_max;
static double tx_cycle_diff_ave;
static long tx_cycle_cnt;enum benchmark_type {BENCH_RXDROP = 0,BENCH_TXONLY = 1,BENCH_L2FWD = 2,
};static enum benchmark_type opt_bench = BENCH_RXDROP;
static u32 opt_xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
static const char *opt_if = "";
static int opt_ifindex;
static int opt_queue;
static unsigned long opt_duration;
static unsigned long start_time;
static bool benchmark_done;
static u32 opt_batch_size = 64;
static int opt_pkt_count;
static u16 opt_pkt_size = MIN_PKT_SIZE;
static u32 opt_pkt_fill_pattern = 0x12345678;
static bool opt_vlan_tag;
static u16 opt_pkt_vlan_id = VLAN_VID__DEFAULT;
static u16 opt_pkt_vlan_pri = VLAN_PRI__DEFAULT;
static struct ether_addr opt_txdmac = {{ 0x3c, 0xfd, 0xfe,0x9e, 0x7f, 0x71 }};
static struct ether_addr opt_txsmac = {{ 0xec, 0xb1, 0xd7,0x98, 0x3a, 0xc0 }};
static bool opt_extra_stats;
static bool opt_quiet;
static bool opt_app_stats;
static const char *opt_irq_str = "";
static u32 irq_no;
static int irqs_at_init = -1;
static u32 sequence;
static int opt_poll;
static int opt_interval = 1;
static int opt_retries = 3;
static u32 opt_xdp_bind_flags = XDP_USE_NEED_WAKEUP;
static u32 opt_umem_flags;
static int opt_unaligned_chunks;
static int opt_mmap_flags;
static int opt_xsk_frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE;
static int opt_timeout = 1000;
static bool opt_need_wakeup = true;
static u32 opt_num_xsks = 1;
static u32 prog_id;
static bool opt_busy_poll;
static bool opt_reduced_cap;
static clockid_t opt_clock = CLOCK_MONOTONIC;
static unsigned long opt_tx_cycle_ns;
static int opt_schpolicy = SCHED_OTHER;
static int opt_schprio = SCHED_PRI__DEFAULT;
static bool opt_tstamp;struct vlan_ethhdr {unsigned char h_dest[6];unsigned char h_source[6];__be16 h_vlan_proto;__be16 h_vlan_TCI;__be16 h_vlan_encapsulated_proto;
};#define PKTGEN_MAGIC 0xbe9be955
struct pktgen_hdr {__be32 pgh_magic;__be32 seq_num;__be32 tv_sec;__be32 tv_usec;
};struct xsk_ring_stats {unsigned long rx_npkts;unsigned long tx_npkts;unsigned long rx_dropped_npkts;unsigned long rx_invalid_npkts;unsigned long tx_invalid_npkts;unsigned long rx_full_npkts;unsigned long rx_fill_empty_npkts;unsigned long tx_empty_npkts;unsigned long prev_rx_npkts;unsigned long prev_tx_npkts;unsigned long prev_rx_dropped_npkts;unsigned long prev_rx_invalid_npkts;unsigned long prev_tx_invalid_npkts;unsigned long prev_rx_full_npkts;unsigned long prev_rx_fill_empty_npkts;unsigned long prev_tx_empty_npkts;
};struct xsk_driver_stats {unsigned long intrs;unsigned long prev_intrs;
};struct xsk_app_stats {unsigned long rx_empty_polls;unsigned long fill_fail_polls;unsigned long copy_tx_sendtos;unsigned long tx_wakeup_sendtos;unsigned long opt_polls;unsigned long prev_rx_empty_polls;unsigned long prev_fill_fail_polls;unsigned long prev_copy_tx_sendtos;unsigned long prev_tx_wakeup_sendtos;unsigned long prev_opt_polls;
};struct xsk_umem_info {struct xsk_ring_prod fq;struct xsk_ring_cons cq;struct xsk_umem *umem;void *buffer;
};struct xsk_socket_info {struct xsk_ring_cons rx;struct xsk_ring_prod tx;struct xsk_umem_info *umem;struct xsk_socket *xsk;struct xsk_ring_stats ring_stats;struct xsk_app_stats app_stats;struct xsk_driver_stats drv_stats;u32 outstanding_tx;
};static const struct clockid_map {const char *name;clockid_t clockid;
} clockids_map[] = {{ "REALTIME", CLOCK_REALTIME },{ "TAI", CLOCK_TAI },{ "BOOTTIME", CLOCK_BOOTTIME },{ "MONOTONIC", CLOCK_MONOTONIC },{ NULL }
};static const struct sched_map {const char *name;int policy;
} schmap[] = {{ "OTHER", SCHED_OTHER },{ "FIFO", SCHED_FIFO },{ NULL }
};static int num_socks;
struct xsk_socket_info *xsks[MAX_SOCKS];
int sock;static int get_clockid(clockid_t *id, const char *name)
{const struct clockid_map *clk;for (clk = clockids_map; clk->name; clk++) {if (strcasecmp(clk->name, name) == 0) {*id = clk->clockid;return 0;}}return -1;
}static int get_schpolicy(int *policy, const char *name)
{const struct sched_map *sch;for (sch = schmap; sch->name; sch++) {if (strcasecmp(sch->name, name) == 0) {*policy = sch->policy;return 0;}}return -1;
}static unsigned long get_nsecs(void)
{struct timespec ts;clock_gettime(opt_clock, &ts);return ts.tv_sec * 1000000000UL + ts.tv_nsec;
}static void print_benchmark(bool running)
{const char *bench_str = "INVALID";if (opt_bench == BENCH_RXDROP)bench_str = "rxdrop";else if (opt_bench == BENCH_TXONLY)bench_str = "txonly";else if (opt_bench == BENCH_L2FWD)bench_str = "l2fwd";printf("%s:%d %s ", opt_if, opt_queue, bench_str);if (opt_xdp_flags & XDP_FLAGS_SKB_MODE)printf("xdp-skb ");else if (opt_xdp_flags & XDP_FLAGS_DRV_MODE)printf("xdp-drv ");elseprintf(" ");if (opt_poll)printf("poll() ");if (running) {printf("running...");fflush(stdout);}
}static int xsk_get_xdp_stats(int fd, struct xsk_socket_info *xsk)
{struct xdp_statistics stats;socklen_t optlen;int err;optlen = sizeof(stats);err = getsockopt(fd, SOL_XDP, XDP_STATISTICS, &stats, &optlen);if (err)return err;if (optlen == sizeof(struct xdp_statistics)) {xsk->ring_stats.rx_dropped_npkts = stats.rx_dropped;xsk->ring_stats.rx_invalid_npkts = stats.rx_invalid_descs;xsk->ring_stats.tx_invalid_npkts = stats.tx_invalid_descs;xsk->ring_stats.rx_full_npkts = stats.rx_ring_full;xsk->ring_stats.rx_fill_empty_npkts = stats.rx_fill_ring_empty_descs;xsk->ring_stats.tx_empty_npkts = stats.tx_ring_empty_descs;return 0;}return -EINVAL;
}static void dump_app_stats(long dt)
{int i;for (i = 0; i < num_socks && xsks[i]; i++) {char *fmt = "%-18s %'-14.0f %'-14lu\n";double rx_empty_polls_ps, fill_fail_polls_ps, copy_tx_sendtos_ps,tx_wakeup_sendtos_ps, opt_polls_ps;rx_empty_polls_ps = (xsks[i]->app_stats.rx_empty_polls -xsks[i]->app_stats.prev_rx_empty_polls) * 1000000000. / dt;fill_fail_polls_ps = (xsks[i]->app_stats.fill_fail_polls -xsks[i]->app_stats.prev_fill_fail_polls) * 1000000000. / dt;copy_tx_sendtos_ps = (xsks[i]->app_stats.copy_tx_sendtos -xsks[i]->app_stats.prev_copy_tx_sendtos) * 1000000000. / dt;tx_wakeup_sendtos_ps = (xsks[i]->app_stats.tx_wakeup_sendtos -xsks[i]->app_stats.prev_tx_wakeup_sendtos)* 1000000000. / dt;opt_polls_ps = (xsks[i]->app_stats.opt_polls -xsks[i]->app_stats.prev_opt_polls) * 1000000000. / dt;printf("\n%-18s %-14s %-14s\n", "", "calls/s", "count");printf(fmt, "rx empty polls", rx_empty_polls_ps, xsks[i]->app_stats.rx_empty_polls);printf(fmt, "fill fail polls", fill_fail_polls_ps,xsks[i]->app_stats.fill_fail_polls);printf(fmt, "copy tx sendtos", copy_tx_sendtos_ps,xsks[i]->app_stats.copy_tx_sendtos);printf(fmt, "tx wakeup sendtos", tx_wakeup_sendtos_ps,xsks[i]->app_stats.tx_wakeup_sendtos);printf(fmt, "opt polls", opt_polls_ps, xsks[i]->app_stats.opt_polls);xsks[i]->app_stats.prev_rx_empty_polls = xsks[i]->app_stats.rx_empty_polls;xsks[i]->app_stats.prev_fill_fail_polls = xsks[i]->app_stats.fill_fail_polls;xsks[i]->app_stats.prev_copy_tx_sendtos = xsks[i]->app_stats.copy_tx_sendtos;xsks[i]->app_stats.prev_tx_wakeup_sendtos = xsks[i]->app_stats.tx_wakeup_sendtos;xsks[i]->app_stats.prev_opt_polls = xsks[i]->app_stats.opt_polls;}if (opt_tx_cycle_ns) {printf("\n%-18s %-10s %-10s %-10s %-10s %-10s\n","", "period", "min", "ave", "max", "cycle");printf("%-18s %-10lu %-10lu %-10lu %-10lu %-10lu\n","Cyclic TX", opt_tx_cycle_ns, tx_cycle_diff_min,(long)(tx_cycle_diff_ave / tx_cycle_cnt),tx_cycle_diff_max, tx_cycle_cnt);}
}static bool get_interrupt_number(void)
{FILE *f_int_proc;char line[4096];bool found = false;f_int_proc = fopen("/proc/interrupts", "r");if (f_int_proc == NULL) {printf("Failed to open /proc/interrupts.\n");return found;}while (!feof(f_int_proc) && !found) {/* Make sure to read a full line at a time */if (fgets(line, sizeof(line), f_int_proc) == NULL ||line[strlen(line) - 1] != '\n') {printf("Error reading from interrupts file\n");break;}/* Extract interrupt number from line */if (strstr(line, opt_irq_str) != NULL) {irq_no = atoi(line);found = true;break;}}fclose(f_int_proc);return found;
}static int get_irqs(void)
{char count_path[PATH_MAX];int total_intrs = -1;FILE *f_count_proc;char line[4096];snprintf(count_path, sizeof(count_path),"/sys/kernel/irq/%i/per_cpu_count", irq_no);f_count_proc = fopen(count_path, "r");if (f_count_proc == NULL) {printf("Failed to open %s\n", count_path);return total_intrs;}if (fgets(line, sizeof(line), f_count_proc) == NULL ||line[strlen(line) - 1] != '\n') {printf("Error reading from %s\n", count_path);} else {static const char com[2] = ",";char *token;total_intrs = 0;token = strtok(line, com);while (token != NULL) {/* sum up interrupts across all cores */total_intrs += atoi(token);token = strtok(NULL, com);}}fclose(f_count_proc);return total_intrs;
}static void dump_driver_stats(long dt)
{int i;for (i = 0; i < num_socks && xsks[i]; i++) {char *fmt = "%-18s %'-14.0f %'-14lu\n";double intrs_ps;int n_ints = get_irqs();if (n_ints < 0) {printf("error getting intr info for intr %i\n", irq_no);return;}xsks[i]->drv_stats.intrs = n_ints - irqs_at_init;intrs_ps = (xsks[i]->drv_stats.intrs - xsks[i]->drv_stats.prev_intrs) *1000000000. / dt;printf("\n%-18s %-14s %-14s\n", "", "intrs/s", "count");printf(fmt, "irqs", intrs_ps, xsks[i]->drv_stats.intrs);xsks[i]->drv_stats.prev_intrs = xsks[i]->drv_stats.intrs;}
}static void dump_stats(void)
{unsigned long now = get_nsecs();long dt = now - prev_time;int i;prev_time = now;for (i = 0; i < num_socks && xsks[i]; i++) {char *fmt = "%-18s %'-14.0f %'-14lu\n";double rx_pps, tx_pps, dropped_pps, rx_invalid_pps, full_pps, fill_empty_pps,tx_invalid_pps, tx_empty_pps;rx_pps = (xsks[i]->ring_stats.rx_npkts - xsks[i]->ring_stats.prev_rx_npkts) *1000000000. / dt;tx_pps = (xsks[i]->ring_stats.tx_npkts - xsks[i]->ring_stats.prev_tx_npkts) *1000000000. / dt;printf("\n sock%d@", i);print_benchmark(false);printf("\n");printf("%-18s %-14s %-14s %-14.2f\n", "", "pps", "pkts",dt / 1000000000.);printf(fmt, "rx", rx_pps, xsks[i]->ring_stats.rx_npkts);printf(fmt, "tx", tx_pps, xsks[i]->ring_stats.tx_npkts);xsks[i]->ring_stats.prev_rx_npkts = xsks[i]->ring_stats.rx_npkts;xsks[i]->ring_stats.prev_tx_npkts = xsks[i]->ring_stats.tx_npkts;if (opt_extra_stats) {if (!xsk_get_xdp_stats(xsk_socket__fd(xsks[i]->xsk), xsks[i])) {dropped_pps = (xsks[i]->ring_stats.rx_dropped_npkts -xsks[i]->ring_stats.prev_rx_dropped_npkts) *1000000000. / dt;rx_invalid_pps = (xsks[i]->ring_stats.rx_invalid_npkts -xsks[i]->ring_stats.prev_rx_invalid_npkts) *1000000000. / dt;tx_invalid_pps = (xsks[i]->ring_stats.tx_invalid_npkts -xsks[i]->ring_stats.prev_tx_invalid_npkts) *1000000000. / dt;full_pps = (xsks[i]->ring_stats.rx_full_npkts -xsks[i]->ring_stats.prev_rx_full_npkts) *1000000000. / dt;fill_empty_pps = (xsks[i]->ring_stats.rx_fill_empty_npkts -xsks[i]->ring_stats.prev_rx_fill_empty_npkts) *1000000000. / dt;tx_empty_pps = (xsks[i]->ring_stats.tx_empty_npkts -xsks[i]->ring_stats.prev_tx_empty_npkts) *1000000000. / dt;printf(fmt, "rx dropped", dropped_pps,xsks[i]->ring_stats.rx_dropped_npkts);printf(fmt, "rx invalid", rx_invalid_pps,xsks[i]->ring_stats.rx_invalid_npkts);printf(fmt, "tx invalid", tx_invalid_pps,xsks[i]->ring_stats.tx_invalid_npkts);printf(fmt, "rx queue full", full_pps,xsks[i]->ring_stats.rx_full_npkts);printf(fmt, "fill ring empty", fill_empty_pps,xsks[i]->ring_stats.rx_fill_empty_npkts);printf(fmt, "tx ring empty", tx_empty_pps,xsks[i]->ring_stats.tx_empty_npkts);xsks[i]->ring_stats.prev_rx_dropped_npkts =xsks[i]->ring_stats.rx_dropped_npkts;xsks[i]->ring_stats.prev_rx_invalid_npkts =xsks[i]->ring_stats.rx_invalid_npkts;xsks[i]->ring_stats.prev_tx_invalid_npkts =xsks[i]->ring_stats.tx_invalid_npkts;xsks[i]->ring_stats.prev_rx_full_npkts =xsks[i]->ring_stats.rx_full_npkts;xsks[i]->ring_stats.prev_rx_fill_empty_npkts =xsks[i]->ring_stats.rx_fill_empty_npkts;xsks[i]->ring_stats.prev_tx_empty_npkts =xsks[i]->ring_stats.tx_empty_npkts;} else {printf("%-15s\n", "Error retrieving extra stats");}}}if (opt_app_stats)dump_app_stats(dt);if (irq_no)dump_driver_stats(dt);
}static bool is_benchmark_done(void)
{if (opt_duration > 0) {unsigned long dt = (get_nsecs() - start_time);if (dt >= opt_duration)benchmark_done = true;}return benchmark_done;
}static void *poller(void *arg)
{(void)arg;while (!is_benchmark_done()) {sleep(opt_interval);dump_stats();}return NULL;
}static void remove_xdp_program(void)
{u32 curr_prog_id = 0;if (bpf_xdp_query_id(opt_ifindex, opt_xdp_flags, &curr_prog_id)) {printf("bpf_xdp_query_id failed\n");exit(EXIT_FAILURE);}if (prog_id == curr_prog_id)bpf_xdp_detach(opt_ifindex, opt_xdp_flags, NULL);else if (!curr_prog_id)printf("couldn't find a prog id on a given interface\n");elseprintf("program on interface changed, not removing\n");
}static void int_exit(int sig)
{benchmark_done = true;
}static void __exit_with_error(int error, const char *file, const char *func,int line)
{fprintf(stderr, "%s:%s:%i: errno: %d/\"%s\"\n", file, func,line, error, strerror(error));if (opt_num_xsks > 1)remove_xdp_program();exit(EXIT_FAILURE);
}#define exit_with_error(error) __exit_with_error(error, __FILE__, __func__, __LINE__)static void xdpsock_cleanup(void)
{struct xsk_umem *umem = xsks[0]->umem->umem;int i, cmd = CLOSE_CONN;dump_stats();for (i = 0; i < num_socks; i++)xsk_socket__delete(xsks[i]->xsk);(void)xsk_umem__delete(umem);if (opt_reduced_cap) {if (write(sock, &cmd, sizeof(int)) < 0)exit_with_error(errno);}if (opt_num_xsks > 1)remove_xdp_program();
}static void swap_mac_addresses(void *data)
{struct ether_header *eth = (struct ether_header *)data;struct ether_addr *src_addr = (struct ether_addr *)ð->ether_shost;struct ether_addr *dst_addr = (struct ether_addr *)ð->ether_dhost;struct ether_addr tmp;tmp = *src_addr;*src_addr = *dst_addr;*dst_addr = tmp;
}static void hex_dump(void *pkt, size_t length, u64 addr)
{const unsigned char *address = (unsigned char *)pkt;const unsigned char *line = address;size_t line_size = 32;unsigned char c;char buf[32];int i = 0;if (!DEBUG_HEXDUMP)return;sprintf(buf, "addr=%llu", addr);printf("length = %zu\n", length);printf("%s | ", buf);while (length-- > 0) {printf("%02X ", *address++);if (!(++i % line_size) || (length == 0 && i % line_size)) {if (length == 0) {while (i++ % line_size)printf("__ ");}printf(" | "); /* right close */while (line < address) {c = *line++;printf("%c", (c < 33 || c == 255) ? 0x2E : c);}printf("\n");if (length > 0)printf("%s | ", buf);}}printf("\n");
}static void *memset32_htonl(void *dest, u32 val, u32 size)
{u32 *ptr = (u32 *)dest;int i;val = htonl(val);for (i = 0; i < (size & (~0x3)); i += 4)ptr[i >> 2] = val;for (; i < size; i++)((char *)dest)[i] = ((char *)&val)[i & 3];return dest;
}/** This function code has been taken from* Linux kernel lib/checksum.c*/
static inline unsigned short from32to16(unsigned int x)
{/* add up 16-bit and 16-bit for 16+c bit */x = (x & 0xffff) + (x >> 16);/* add up carry.. */x = (x & 0xffff) + (x >> 16);return x;
}/** This function code has been taken from* Linux kernel lib/checksum.c*/
static unsigned int do_csum(const unsigned char *buff, int len)
{unsigned int result = 0;int odd;if (len <= 0)goto out;odd = 1 & (unsigned long)buff;if (odd) {
#ifdef __LITTLE_ENDIANresult += (*buff << 8);
#elseresult = *buff;
#endiflen--;buff++;}if (len >= 2) {if (2 & (unsigned long)buff) {result += *(unsigned short *)buff;len -= 2;buff += 2;}if (len >= 4) {const unsigned char *end = buff +((unsigned int)len & ~3);unsigned int carry = 0;do {unsigned int w = *(unsigned int *)buff;buff += 4;result += carry;result += w;carry = (w > result);} while (buff < end);result += carry;result = (result & 0xffff) + (result >> 16);}if (len & 2) {result += *(unsigned short *)buff;buff += 2;}}if (len & 1)
#ifdef __LITTLE_ENDIANresult += *buff;
#elseresult += (*buff << 8);
#endifresult = from32to16(result);if (odd)result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
out:return result;
}/** This is a version of ip_compute_csum() optimized for IP headers,* which always checksum on 4 octet boundaries.* This function code has been taken from* Linux kernel lib/checksum.c*/
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{return (__sum16)~do_csum(iph, ihl * 4);
}/** Fold a partial checksum* This function code has been taken from* Linux kernel include/asm-generic/checksum.h*/
static inline __sum16 csum_fold(__wsum csum)
{u32 sum = (u32)csum;sum = (sum & 0xffff) + (sum >> 16);sum = (sum & 0xffff) + (sum >> 16);return (__sum16)~sum;
}/** This function code has been taken from* Linux kernel lib/checksum.c*/
static inline u32 from64to32(u64 x)
{/* add up 32-bit and 32-bit for 32+c bit */x = (x & 0xffffffff) + (x >> 32);/* add up carry.. */x = (x & 0xffffffff) + (x >> 32);return (u32)x;
}__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,__u32 len, __u8 proto, __wsum sum);/** This function code has been taken from* Linux kernel lib/checksum.c*/
__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,__u32 len, __u8 proto, __wsum sum)
{unsigned long long s = (u32)sum;s += (u32)saddr;s += (u32)daddr;
#ifdef __BIG_ENDIAN__s += proto + len;
#elses += (proto + len) << 8;
#endifreturn (__wsum)from64to32(s);
}/** This function has been taken from* Linux kernel include/asm-generic/checksum.h*/
static inline __sum16
csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,__u8 proto, __wsum sum)
{return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
}static inline u16 udp_csum(u32 saddr, u32 daddr, u32 len,u8 proto, u16 *udp_pkt)
{u32 csum = 0;u32 cnt = 0;/* udp hdr and data */for (; cnt < len; cnt += 2)csum += udp_pkt[cnt >> 1];return csum_tcpudp_magic(saddr, daddr, len, proto, csum);
}#define ETH_FCS_SIZE 4#define ETH_HDR_SIZE (opt_vlan_tag ? sizeof(struct vlan_ethhdr) : \sizeof(struct ethhdr))
#define PKTGEN_HDR_SIZE (opt_tstamp ? sizeof(struct pktgen_hdr) : 0)
#define PKT_HDR_SIZE (ETH_HDR_SIZE + sizeof(struct iphdr) + \sizeof(struct udphdr) + PKTGEN_HDR_SIZE)
#define PKTGEN_HDR_OFFSET (ETH_HDR_SIZE + sizeof(struct iphdr) + \sizeof(struct udphdr))
#define PKTGEN_SIZE_MIN (PKTGEN_HDR_OFFSET + sizeof(struct pktgen_hdr) + \ETH_FCS_SIZE)#define PKT_SIZE (opt_pkt_size - ETH_FCS_SIZE)
#define IP_PKT_SIZE (PKT_SIZE - ETH_HDR_SIZE)
#define UDP_PKT_SIZE (IP_PKT_SIZE - sizeof(struct iphdr))
#define UDP_PKT_DATA_SIZE (UDP_PKT_SIZE - \(sizeof(struct udphdr) + PKTGEN_HDR_SIZE))static u8 pkt_data[XSK_UMEM__DEFAULT_FRAME_SIZE];static void gen_eth_hdr_data(void)
{struct pktgen_hdr *pktgen_hdr;struct udphdr *udp_hdr;struct iphdr *ip_hdr;if (opt_vlan_tag) {struct vlan_ethhdr *veth_hdr = (struct vlan_ethhdr *)pkt_data;u16 vlan_tci = 0;udp_hdr = (struct udphdr *)(pkt_data +sizeof(struct vlan_ethhdr) +sizeof(struct iphdr));ip_hdr = (struct iphdr *)(pkt_data +sizeof(struct vlan_ethhdr));pktgen_hdr = (struct pktgen_hdr *)(pkt_data +sizeof(struct vlan_ethhdr) +sizeof(struct iphdr) +sizeof(struct udphdr));/* ethernet & VLAN header */memcpy(veth_hdr->h_dest, &opt_txdmac, ETH_ALEN);memcpy(veth_hdr->h_source, &opt_txsmac, ETH_ALEN);veth_hdr->h_vlan_proto = htons(ETH_P_8021Q);vlan_tci = opt_pkt_vlan_id & VLAN_VID_MASK;vlan_tci |= (opt_pkt_vlan_pri << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;veth_hdr->h_vlan_TCI = htons(vlan_tci);veth_hdr->h_vlan_encapsulated_proto = htons(ETH_P_IP);} else {struct ethhdr *eth_hdr = (struct ethhdr *)pkt_data;udp_hdr = (struct udphdr *)(pkt_data +sizeof(struct ethhdr) +sizeof(struct iphdr));ip_hdr = (struct iphdr *)(pkt_data +sizeof(struct ethhdr));pktgen_hdr = (struct pktgen_hdr *)(pkt_data +sizeof(struct ethhdr) +sizeof(struct iphdr) +sizeof(struct udphdr));/* ethernet header */memcpy(eth_hdr->h_dest, &opt_txdmac, ETH_ALEN);memcpy(eth_hdr->h_source, &opt_txsmac, ETH_ALEN);eth_hdr->h_proto = htons(ETH_P_IP);}/* IP header */ip_hdr->version = IPVERSION;ip_hdr->ihl = 0x5; /* 20 byte header */ip_hdr->tos = 0x0;ip_hdr->tot_len = htons(IP_PKT_SIZE);ip_hdr->id = 0;ip_hdr->frag_off = 0;ip_hdr->ttl = IPDEFTTL;ip_hdr->protocol = IPPROTO_UDP;ip_hdr->saddr = htonl(0x0a0a0a10);ip_hdr->daddr = htonl(0x0a0a0a20);/* IP header checksum */ip_hdr->check = 0;ip_hdr->check = ip_fast_csum((const void *)ip_hdr, ip_hdr->ihl);/* UDP header */udp_hdr->source = htons(0x1000);udp_hdr->dest = htons(0x1000);udp_hdr->len = htons(UDP_PKT_SIZE);if (opt_tstamp)pktgen_hdr->pgh_magic = htonl(PKTGEN_MAGIC);/* UDP data */memset32_htonl(pkt_data + PKT_HDR_SIZE, opt_pkt_fill_pattern,UDP_PKT_DATA_SIZE);/* UDP header checksum */udp_hdr->check = 0;udp_hdr->check = udp_csum(ip_hdr->saddr, ip_hdr->daddr, UDP_PKT_SIZE,IPPROTO_UDP, (u16 *)udp_hdr);
}static void gen_eth_frame(struct xsk_umem_info *umem, u64 addr)
{memcpy(xsk_umem__get_data(umem->buffer, addr), pkt_data,PKT_SIZE);
}static struct xsk_umem_info *xsk_configure_umem(void *buffer, u64 size)
{struct xsk_umem_info *umem;struct xsk_umem_config cfg = {/* We recommend that you set the fill ring size >= HW RX ring size +* AF_XDP RX ring size. Make sure you fill up the fill ring* with buffers at regular intervals, and you will with this setting* avoid allocation failures in the driver. These are usually quite* expensive since drivers have not been written to assume that* allocation failures are common. For regular sockets, kernel* allocated memory is used that only runs out in OOM situations* that should be rare.*/.fill_size = XSK_RING_PROD__DEFAULT_NUM_DESCS * 2,.comp_size = XSK_RING_CONS__DEFAULT_NUM_DESCS,.frame_size = opt_xsk_frame_size,.frame_headroom = XSK_UMEM__DEFAULT_FRAME_HEADROOM,.flags = opt_umem_flags};int ret;umem = calloc(1, sizeof(*umem));if (!umem)exit_with_error(errno);ret = xsk_umem__create(&umem->umem, buffer, size, &umem->fq, &umem->cq,&cfg);if (ret)exit_with_error(-ret);umem->buffer = buffer;return umem;
}static void xsk_populate_fill_ring(struct xsk_umem_info *umem)
{int ret, i;u32 idx;ret = xsk_ring_prod__reserve(&umem->fq,XSK_RING_PROD__DEFAULT_NUM_DESCS * 2, &idx);if (ret != XSK_RING_PROD__DEFAULT_NUM_DESCS * 2)exit_with_error(-ret);for (i = 0; i < XSK_RING_PROD__DEFAULT_NUM_DESCS * 2; i++)*xsk_ring_prod__fill_addr(&umem->fq, idx++) =i * opt_xsk_frame_size;xsk_ring_prod__submit(&umem->fq, XSK_RING_PROD__DEFAULT_NUM_DESCS * 2);
}static struct xsk_socket_info *xsk_configure_socket(struct xsk_umem_info *umem,bool rx, bool tx)
{struct xsk_socket_config cfg;struct xsk_socket_info *xsk;struct xsk_ring_cons *rxr;struct xsk_ring_prod *txr;int ret;xsk = calloc(1, sizeof(*xsk));if (!xsk)exit_with_error(errno);xsk->umem = umem;cfg.rx_size = XSK_RING_CONS__DEFAULT_NUM_DESCS;cfg.tx_size = XSK_RING_PROD__DEFAULT_NUM_DESCS;if (opt_num_xsks > 1 || opt_reduced_cap)cfg.libbpf_flags = XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD;elsecfg.libbpf_flags = 0;cfg.xdp_flags = opt_xdp_flags;cfg.bind_flags = opt_xdp_bind_flags;rxr = rx ? &xsk->rx : NULL;txr = tx ? &xsk->tx : NULL;ret = xsk_socket__create(&xsk->xsk, opt_if, opt_queue, umem->umem,rxr, txr, &cfg);if (ret)exit_with_error(-ret);ret = bpf_xdp_query_id(opt_ifindex, opt_xdp_flags, &prog_id);if (ret)exit_with_error(-ret);xsk->app_stats.rx_empty_polls = 0;xsk->app_stats.fill_fail_polls = 0;xsk->app_stats.copy_tx_sendtos = 0;xsk->app_stats.tx_wakeup_sendtos = 0;xsk->app_stats.opt_polls = 0;xsk->app_stats.prev_rx_empty_polls = 0;xsk->app_stats.prev_fill_fail_polls = 0;xsk->app_stats.prev_copy_tx_sendtos = 0;xsk->app_stats.prev_tx_wakeup_sendtos = 0;xsk->app_stats.prev_opt_polls = 0;return xsk;
}static struct option long_options[] = {{"rxdrop", no_argument, 0, 'r'},{"txonly", no_argument, 0, 't'},{"l2fwd", no_argument, 0, 'l'},{"interface", required_argument, 0, 'i'},{"queue", required_argument, 0, 'q'},{"poll", no_argument, 0, 'p'},{"xdp-skb", no_argument, 0, 'S'},{"xdp-native", no_argument, 0, 'N'},{"interval", required_argument, 0, 'n'},{"retries", required_argument, 0, 'O'},{"zero-copy", no_argument, 0, 'z'},{"copy", no_argument, 0, 'c'},{"frame-size", required_argument, 0, 'f'},{"no-need-wakeup", no_argument, 0, 'm'},{"unaligned", no_argument, 0, 'u'},{"shared-umem", no_argument, 0, 'M'},{"force", no_argument, 0, 'F'},{"duration", required_argument, 0, 'd'},{"clock", required_argument, 0, 'w'},{"batch-size", required_argument, 0, 'b'},{"tx-pkt-count", required_argument, 0, 'C'},{"tx-pkt-size", required_argument, 0, 's'},{"tx-pkt-pattern", required_argument, 0, 'P'},{"tx-vlan", no_argument, 0, 'V'},{"tx-vlan-id", required_argument, 0, 'J'},{"tx-vlan-pri", required_argument, 0, 'K'},{"tx-dmac", required_argument, 0, 'G'},{"tx-smac", required_argument, 0, 'H'},{"tx-cycle", required_argument, 0, 'T'},{"tstamp", no_argument, 0, 'y'},{"policy", required_argument, 0, 'W'},{"schpri", required_argument, 0, 'U'},{"extra-stats", no_argument, 0, 'x'},{"quiet", no_argument, 0, 'Q'},{"app-stats", no_argument, 0, 'a'},{"irq-string", no_argument, 0, 'I'},{"busy-poll", no_argument, 0, 'B'},{"reduce-cap", no_argument, 0, 'R'},{0, 0, 0, 0}
};static void usage(const char *prog)
{const char *str =" Usage: %s [OPTIONS]\n"" Options:\n"" -r, --rxdrop Discard all incoming packets (default)\n"" -t, --txonly Only send packets\n"" -l, --l2fwd MAC swap L2 forwarding\n"" -i, --interface=n Run on interface n\n"" -q, --queue=n Use queue n (default 0)\n"" -p, --poll Use poll syscall\n"" -S, --xdp-skb=n Use XDP skb-mod\n"" -N, --xdp-native=n Enforce XDP native mode\n"" -n, --interval=n Specify statistics update interval (default 1 sec).\n"" -O, --retries=n Specify time-out retries (1s interval) attempt (default 3).\n"" -z, --zero-copy Force zero-copy mode.\n"" -c, --copy Force copy mode.\n"" -m, --no-need-wakeup Turn off use of driver need wakeup flag.\n"" -f, --frame-size=n Set the frame size (must be a power of two in aligned mode, default is %d).\n"" -u, --unaligned Enable unaligned chunk placement\n"" -M, --shared-umem Enable XDP_SHARED_UMEM (cannot be used with -R)\n"" -F, --force Force loading the XDP prog\n"" -d, --duration=n Duration in secs to run command.\n"" Default: forever.\n"" -w, --clock=CLOCK Clock NAME (default MONOTONIC).\n"" -b, --batch-size=n Batch size for sending or receiving\n"" packets. Default: %d\n"" -C, --tx-pkt-count=n Number of packets to send.\n"" Default: Continuous packets.\n"" -s, --tx-pkt-size=n Transmit packet size.\n"" (Default: %d bytes)\n"" Min size: %d, Max size %d.\n"" -P, --tx-pkt-pattern=nPacket fill pattern. Default: 0x%x\n"" -V, --tx-vlan Send VLAN tagged packets (For -t|--txonly)\n"" -J, --tx-vlan-id=n Tx VLAN ID [1-4095]. Default: %d (For -V|--tx-vlan)\n"" -K, --tx-vlan-pri=n Tx VLAN Priority [0-7]. Default: %d (For -V|--tx-vlan)\n"" -G, --tx-dmac=<MAC> Dest MAC addr of TX frame in aa:bb:cc:dd:ee:ff format (For -V|--tx-vlan)\n"" -H, --tx-smac=<MAC> Src MAC addr of TX frame in aa:bb:cc:dd:ee:ff format (For -V|--tx-vlan)\n"" -T, --tx-cycle=n Tx cycle time in micro-seconds (For -t|--txonly).\n"" -y, --tstamp Add time-stamp to packet (For -t|--txonly).\n"" -W, --policy=POLICY Schedule policy. Default: SCHED_OTHER\n"" -U, --schpri=n Schedule priority. Default: %d\n"" -x, --extra-stats Display extra statistics.\n"" -Q, --quiet Do not display any stats.\n"" -a, --app-stats Display application (syscall) statistics.\n"" -I, --irq-string Display driver interrupt statistics for interface associated with irq-string.\n"" -B, --busy-poll Busy poll.\n"" -R, --reduce-cap Use reduced capabilities (cannot be used with -M)\n""\n";fprintf(stderr, str, prog, XSK_UMEM__DEFAULT_FRAME_SIZE,opt_batch_size, MIN_PKT_SIZE, MIN_PKT_SIZE,XSK_UMEM__DEFAULT_FRAME_SIZE, opt_pkt_fill_pattern,VLAN_VID__DEFAULT, VLAN_PRI__DEFAULT,SCHED_PRI__DEFAULT);exit(EXIT_FAILURE);
}static void parse_command_line(int argc, char **argv)
{int option_index, c;opterr = 0;for (;;) {c = getopt_long(argc, argv,"Frtli:q:pSNn:w:O:czf:muMd:b:C:s:P:VJ:K:G:H:T:yW:U:xQaI:BR",long_options, &option_index);if (c == -1)break;switch (c) {case 'r':opt_bench = BENCH_RXDROP;break;case 't':opt_bench = BENCH_TXONLY;break;case 'l':opt_bench = BENCH_L2FWD;break;case 'i':opt_if = optarg;break;case 'q':opt_queue = atoi(optarg);break;case 'p':opt_poll = 1;break;case 'S':opt_xdp_flags |= XDP_FLAGS_SKB_MODE;opt_xdp_bind_flags |= XDP_COPY;break;case 'N':/* default, set below */break;case 'n':opt_interval = atoi(optarg);break;case 'w':if (get_clockid(&opt_clock, optarg)) {fprintf(stderr,"ERROR: Invalid clock %s. Default to CLOCK_MONOTONIC.\n",optarg);opt_clock = CLOCK_MONOTONIC;}break;case 'O':opt_retries = atoi(optarg);break;case 'z':opt_xdp_bind_flags |= XDP_ZEROCOPY;break;case 'c':opt_xdp_bind_flags |= XDP_COPY;break;case 'u':opt_umem_flags |= XDP_UMEM_UNALIGNED_CHUNK_FLAG;opt_unaligned_chunks = 1;opt_mmap_flags = MAP_HUGETLB;break;case 'F':opt_xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;break;case 'f':opt_xsk_frame_size = atoi(optarg);break;case 'm':opt_need_wakeup = false;opt_xdp_bind_flags &= ~XDP_USE_NEED_WAKEUP;break;case 'M':opt_num_xsks = MAX_SOCKS;break;case 'd':opt_duration = atoi(optarg);opt_duration *= 1000000000;break;case 'b':opt_batch_size = atoi(optarg);break;case 'C':opt_pkt_count = atoi(optarg);break;case 's':opt_pkt_size = atoi(optarg);if (opt_pkt_size > (XSK_UMEM__DEFAULT_FRAME_SIZE) ||opt_pkt_size < MIN_PKT_SIZE) {fprintf(stderr,"ERROR: Invalid frame size %d\n",opt_pkt_size);usage(basename(argv[0]));}break;case 'P':opt_pkt_fill_pattern = strtol(optarg, NULL, 16);break;case 'V':opt_vlan_tag = true;break;case 'J':opt_pkt_vlan_id = atoi(optarg);break;case 'K':opt_pkt_vlan_pri = atoi(optarg);break;case 'G':if (!ether_aton_r(optarg,(struct ether_addr *)&opt_txdmac)) {fprintf(stderr, "Invalid dmac address:%s\n",optarg);usage(basename(argv[0]));}break;case 'H':if (!ether_aton_r(optarg,(struct ether_addr *)&opt_txsmac)) {fprintf(stderr, "Invalid smac address:%s\n",optarg);usage(basename(argv[0]));}break;case 'T':opt_tx_cycle_ns = atoi(optarg);opt_tx_cycle_ns *= NSEC_PER_USEC;break;case 'y':opt_tstamp = 1;break;case 'W':if (get_schpolicy(&opt_schpolicy, optarg)) {fprintf(stderr,"ERROR: Invalid policy %s. Default to SCHED_OTHER.\n",optarg);opt_schpolicy = SCHED_OTHER;}break;case 'U':opt_schprio = atoi(optarg);break;case 'x':opt_extra_stats = 1;break;case 'Q':opt_quiet = 1;break;case 'a':opt_app_stats = 1;break;case 'I':opt_irq_str = optarg;if (get_interrupt_number())irqs_at_init = get_irqs();if (irqs_at_init < 0) {fprintf(stderr, "ERROR: Failed to get irqs for %s\n", opt_irq_str);usage(basename(argv[0]));}break;case 'B':opt_busy_poll = 1;break;case 'R':opt_reduced_cap = true;break;default:usage(basename(argv[0]));}}if (!(opt_xdp_flags & XDP_FLAGS_SKB_MODE))opt_xdp_flags |= XDP_FLAGS_DRV_MODE;opt_ifindex = if_nametoindex(opt_if);if (!opt_ifindex) {fprintf(stderr, "ERROR: interface \"%s\" does not exist\n",opt_if);usage(basename(argv[0]));}if ((opt_xsk_frame_size & (opt_xsk_frame_size - 1)) &&!opt_unaligned_chunks) {fprintf(stderr, "--frame-size=%d is not a power of two\n",opt_xsk_frame_size);usage(basename(argv[0]));}if (opt_reduced_cap && opt_num_xsks > 1) {fprintf(stderr, "ERROR: -M and -R cannot be used together\n");usage(basename(argv[0]));}
}static void kick_tx(struct xsk_socket_info *xsk)
{int ret;ret = sendto(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL, 0);if (ret >= 0 || errno == ENOBUFS || errno == EAGAIN ||errno == EBUSY || errno == ENETDOWN)return;exit_with_error(errno);
}static inline void complete_tx_l2fwd(struct xsk_socket_info *xsk)
{struct xsk_umem_info *umem = xsk->umem;u32 idx_cq = 0, idx_fq = 0;unsigned int rcvd;size_t ndescs;if (!xsk->outstanding_tx)return;/* In copy mode, Tx is driven by a syscall so we need to use e.g. sendto() to* really send the packets. In zero-copy mode we do not have to do this, since Tx* is driven by the NAPI loop. So as an optimization, we do not have to call* sendto() all the time in zero-copy mode for l2fwd.*/if (opt_xdp_bind_flags & XDP_COPY) {xsk->app_stats.copy_tx_sendtos++;kick_tx(xsk);}ndescs = (xsk->outstanding_tx > opt_batch_size) ? opt_batch_size :xsk->outstanding_tx;/* re-add completed Tx buffers */rcvd = xsk_ring_cons__peek(&umem->cq, ndescs, &idx_cq);if (rcvd > 0) {unsigned int i;int ret;ret = xsk_ring_prod__reserve(&umem->fq, rcvd, &idx_fq);while (ret != rcvd) {if (ret < 0)exit_with_error(-ret);if (opt_busy_poll || xsk_ring_prod__needs_wakeup(&umem->fq)) {xsk->app_stats.fill_fail_polls++;recvfrom(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL,NULL);}ret = xsk_ring_prod__reserve(&umem->fq, rcvd, &idx_fq);}for (i = 0; i < rcvd; i++)*xsk_ring_prod__fill_addr(&umem->fq, idx_fq++) =*xsk_ring_cons__comp_addr(&umem->cq, idx_cq++);xsk_ring_prod__submit(&xsk->umem->fq, rcvd);xsk_ring_cons__release(&xsk->umem->cq, rcvd);xsk->outstanding_tx -= rcvd;}
}static inline void complete_tx_only(struct xsk_socket_info *xsk,int batch_size)
{unsigned int rcvd;u32 idx;if (!xsk->outstanding_tx)return;if (!opt_need_wakeup || xsk_ring_prod__needs_wakeup(&xsk->tx)) {xsk->app_stats.tx_wakeup_sendtos++;kick_tx(xsk);}rcvd = xsk_ring_cons__peek(&xsk->umem->cq, batch_size, &idx);if (rcvd > 0) {xsk_ring_cons__release(&xsk->umem->cq, rcvd);xsk->outstanding_tx -= rcvd;}
}static void rx_drop(struct xsk_socket_info *xsk)
{unsigned int rcvd, i;u32 idx_rx = 0, idx_fq = 0;int ret;rcvd = xsk_ring_cons__peek(&xsk->rx, opt_batch_size, &idx_rx);if (!rcvd) {if (opt_busy_poll || xsk_ring_prod__needs_wakeup(&xsk->umem->fq)) {xsk->app_stats.rx_empty_polls++;recvfrom(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL, NULL);}return;}ret = xsk_ring_prod__reserve(&xsk->umem->fq, rcvd, &idx_fq);while (ret != rcvd) {if (ret < 0)exit_with_error(-ret);if (opt_busy_poll || xsk_ring_prod__needs_wakeup(&xsk->umem->fq)) {xsk->app_stats.fill_fail_polls++;recvfrom(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL, NULL);}ret = xsk_ring_prod__reserve(&xsk->umem->fq, rcvd, &idx_fq);}for (i = 0; i < rcvd; i++) {u64 addr = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx)->addr;u32 len = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx++)->len;u64 orig = xsk_umem__extract_addr(addr);addr = xsk_umem__add_offset_to_addr(addr);char *pkt = xsk_umem__get_data(xsk->umem->buffer, addr);hex_dump(pkt, len, addr);*xsk_ring_prod__fill_addr(&xsk->umem->fq, idx_fq++) = orig;}xsk_ring_prod__submit(&xsk->umem->fq, rcvd);xsk_ring_cons__release(&xsk->rx, rcvd);xsk->ring_stats.rx_npkts += rcvd;
}static void rx_drop_all(void)
{struct pollfd fds[MAX_SOCKS] = {};int i, ret;for (i = 0; i < num_socks; i++) {fds[i].fd = xsk_socket__fd(xsks[i]->xsk);fds[i].events = POLLIN;}for (;;) {if (opt_poll) {for (i = 0; i < num_socks; i++)xsks[i]->app_stats.opt_polls++;ret = poll(fds, num_socks, opt_timeout);if (ret <= 0)continue;}for (i = 0; i < num_socks; i++)rx_drop(xsks[i]);if (benchmark_done)break;}
}static int tx_only(struct xsk_socket_info *xsk, u32 *frame_nb,int batch_size, unsigned long tx_ns)
{u32 idx, tv_sec, tv_usec;unsigned int i;while (xsk_ring_prod__reserve(&xsk->tx, batch_size, &idx) <batch_size) {complete_tx_only(xsk, batch_size);if (benchmark_done)return 0;}if (opt_tstamp) {tv_sec = (u32)(tx_ns / NSEC_PER_SEC);tv_usec = (u32)((tx_ns % NSEC_PER_SEC) / 1000);}for (i = 0; i < batch_size; i++) {struct xdp_desc *tx_desc = xsk_ring_prod__tx_desc(&xsk->tx,idx + i);tx_desc->addr = (*frame_nb + i) * opt_xsk_frame_size;tx_desc->len = PKT_SIZE;if (opt_tstamp) {struct pktgen_hdr *pktgen_hdr;u64 addr = tx_desc->addr;char *pkt;pkt = xsk_umem__get_data(xsk->umem->buffer, addr);pktgen_hdr = (struct pktgen_hdr *)(pkt + PKTGEN_HDR_OFFSET);pktgen_hdr->seq_num = htonl(sequence++);pktgen_hdr->tv_sec = htonl(tv_sec);pktgen_hdr->tv_usec = htonl(tv_usec);hex_dump(pkt, PKT_SIZE, addr);}}xsk_ring_prod__submit(&xsk->tx, batch_size);xsk->ring_stats.tx_npkts += batch_size;xsk->outstanding_tx += batch_size;*frame_nb += batch_size;*frame_nb %= NUM_FRAMES;complete_tx_only(xsk, batch_size);return batch_size;
}static inline int get_batch_size(int pkt_cnt)
{if (!opt_pkt_count)return opt_batch_size;if (pkt_cnt + opt_batch_size <= opt_pkt_count)return opt_batch_size;return opt_pkt_count - pkt_cnt;
}static void complete_tx_only_all(void)
{bool pending;int i;do {pending = false;for (i = 0; i < num_socks; i++) {if (xsks[i]->outstanding_tx) {complete_tx_only(xsks[i], opt_batch_size);pending = !!xsks[i]->outstanding_tx;}}sleep(1);} while (pending && opt_retries-- > 0);
}static void tx_only_all(void)
{struct pollfd fds[MAX_SOCKS] = {};u32 frame_nb[MAX_SOCKS] = {};unsigned long next_tx_ns = 0;int pkt_cnt = 0;int i, ret;if (opt_poll && opt_tx_cycle_ns) {fprintf(stderr,"Error: --poll and --tx-cycles are both set\n");return;}for (i = 0; i < num_socks; i++) {fds[0].fd = xsk_socket__fd(xsks[i]->xsk);fds[0].events = POLLOUT;}if (opt_tx_cycle_ns) {/* Align Tx time to micro-second boundary */next_tx_ns = (get_nsecs() / NSEC_PER_USEC + 1) *NSEC_PER_USEC;next_tx_ns += opt_tx_cycle_ns;/* Initialize periodic Tx scheduling variance */tx_cycle_diff_min = 1000000000;tx_cycle_diff_max = 0;tx_cycle_diff_ave = 0.0;}while ((opt_pkt_count && pkt_cnt < opt_pkt_count) || !opt_pkt_count) {int batch_size = get_batch_size(pkt_cnt);unsigned long tx_ns = 0;struct timespec next;int tx_cnt = 0;long diff;int err;if (opt_poll) {for (i = 0; i < num_socks; i++)xsks[i]->app_stats.opt_polls++;ret = poll(fds, num_socks, opt_timeout);if (ret <= 0)continue;if (!(fds[0].revents & POLLOUT))continue;}if (opt_tx_cycle_ns) {next.tv_sec = next_tx_ns / NSEC_PER_SEC;next.tv_nsec = next_tx_ns % NSEC_PER_SEC;err = clock_nanosleep(opt_clock, TIMER_ABSTIME, &next, NULL);if (err) {if (err != EINTR)fprintf(stderr,"clock_nanosleep failed. Err:%d errno:%d\n",err, errno);break;}/* Measure periodic Tx scheduling variance */tx_ns = get_nsecs();diff = tx_ns - next_tx_ns;if (diff < tx_cycle_diff_min)tx_cycle_diff_min = diff;if (diff > tx_cycle_diff_max)tx_cycle_diff_max = diff;tx_cycle_diff_ave += (double)diff;tx_cycle_cnt++;} else if (opt_tstamp) {tx_ns = get_nsecs();}for (i = 0; i < num_socks; i++)tx_cnt += tx_only(xsks[i], &frame_nb[i], batch_size, tx_ns);pkt_cnt += tx_cnt;if (benchmark_done)break;if (opt_tx_cycle_ns)next_tx_ns += opt_tx_cycle_ns;}if (opt_pkt_count)complete_tx_only_all();
}static void l2fwd(struct xsk_socket_info *xsk)
{unsigned int rcvd, i;u32 idx_rx = 0, idx_tx = 0;int ret;complete_tx_l2fwd(xsk);rcvd = xsk_ring_cons__peek(&xsk->rx, opt_batch_size, &idx_rx);if (!rcvd) {if (opt_busy_poll || xsk_ring_prod__needs_wakeup(&xsk->umem->fq)) {xsk->app_stats.rx_empty_polls++;recvfrom(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL, NULL);}return;}xsk->ring_stats.rx_npkts += rcvd;ret = xsk_ring_prod__reserve(&xsk->tx, rcvd, &idx_tx);while (ret != rcvd) {if (ret < 0)exit_with_error(-ret);complete_tx_l2fwd(xsk);if (opt_busy_poll || xsk_ring_prod__needs_wakeup(&xsk->tx)) {xsk->app_stats.tx_wakeup_sendtos++;kick_tx(xsk);}ret = xsk_ring_prod__reserve(&xsk->tx, rcvd, &idx_tx);}for (i = 0; i < rcvd; i++) {u64 addr = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx)->addr;u32 len = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx++)->len;u64 orig = addr;addr = xsk_umem__add_offset_to_addr(addr);char *pkt = xsk_umem__get_data(xsk->umem->buffer, addr);swap_mac_addresses(pkt);hex_dump(pkt, len, addr);xsk_ring_prod__tx_desc(&xsk->tx, idx_tx)->addr = orig;xsk_ring_prod__tx_desc(&xsk->tx, idx_tx++)->len = len;}xsk_ring_prod__submit(&xsk->tx, rcvd);xsk_ring_cons__release(&xsk->rx, rcvd);xsk->ring_stats.tx_npkts += rcvd;xsk->outstanding_tx += rcvd;
}static void l2fwd_all(void)
{struct pollfd fds[MAX_SOCKS] = {};int i, ret;for (;;) {if (opt_poll) {for (i = 0; i < num_socks; i++) {fds[i].fd = xsk_socket__fd(xsks[i]->xsk);fds[i].events = POLLOUT | POLLIN;xsks[i]->app_stats.opt_polls++;}ret = poll(fds, num_socks, opt_timeout);if (ret <= 0)continue;}for (i = 0; i < num_socks; i++)l2fwd(xsks[i]);if (benchmark_done)break;}
}static void load_xdp_program(char **argv, struct bpf_object **obj)
{struct bpf_prog_load_attr prog_load_attr = {.prog_type = BPF_PROG_TYPE_XDP,};char xdp_filename[256];int prog_fd;snprintf(xdp_filename, sizeof(xdp_filename), "%s_kern.o", argv[0]);prog_load_attr.file = xdp_filename;if (bpf_prog_load_xattr(&prog_load_attr, obj, &prog_fd))exit(EXIT_FAILURE);if (prog_fd < 0) {fprintf(stderr, "ERROR: no program found: %s\n",strerror(prog_fd));exit(EXIT_FAILURE);}if (bpf_xdp_attach(opt_ifindex, prog_fd, opt_xdp_flags, NULL) < 0) {fprintf(stderr, "ERROR: link set xdp fd failed\n");exit(EXIT_FAILURE);}
}static void enter_xsks_into_map(struct bpf_object *obj)
{struct bpf_map *map;int i, xsks_map;map = bpf_object__find_map_by_name(obj, "xsks_map");xsks_map = bpf_map__fd(map);if (xsks_map < 0) {fprintf(stderr, "ERROR: no xsks map found: %s\n",strerror(xsks_map));exit(EXIT_FAILURE);}for (i = 0; i < num_socks; i++) {int fd = xsk_socket__fd(xsks[i]->xsk);int key, ret;key = i;ret = bpf_map_update_elem(xsks_map, &key, &fd, 0);if (ret) {fprintf(stderr, "ERROR: bpf_map_update_elem %d\n", i);exit(EXIT_FAILURE);}}
}static void apply_setsockopt(struct xsk_socket_info *xsk)
{int sock_opt;if (!opt_busy_poll)return;sock_opt = 1;if (setsockopt(xsk_socket__fd(xsk->xsk), SOL_SOCKET, SO_PREFER_BUSY_POLL,(void *)&sock_opt, sizeof(sock_opt)) < 0)exit_with_error(errno);sock_opt = 20;if (setsockopt(xsk_socket__fd(xsk->xsk), SOL_SOCKET, SO_BUSY_POLL,(void *)&sock_opt, sizeof(sock_opt)) < 0)exit_with_error(errno);sock_opt = opt_batch_size;if (setsockopt(xsk_socket__fd(xsk->xsk), SOL_SOCKET, SO_BUSY_POLL_BUDGET,(void *)&sock_opt, sizeof(sock_opt)) < 0)exit_with_error(errno);
}static int recv_xsks_map_fd_from_ctrl_node(int sock, int *_fd)
{char cms[CMSG_SPACE(sizeof(int))];struct cmsghdr *cmsg;struct msghdr msg;struct iovec iov;int value;int len;iov.iov_base = &value;iov.iov_len = sizeof(int);msg.msg_name = 0;msg.msg_namelen = 0;msg.msg_iov = &iov;msg.msg_iovlen = 1;msg.msg_flags = 0;msg.msg_control = (caddr_t)cms;msg.msg_controllen = sizeof(cms);len = recvmsg(sock, &msg, 0);if (len < 0) {fprintf(stderr, "Recvmsg failed length incorrect.\n");return -EINVAL;}if (len == 0) {fprintf(stderr, "Recvmsg failed no data\n");return -EINVAL;}cmsg = CMSG_FIRSTHDR(&msg);*_fd = *(int *)CMSG_DATA(cmsg);return 0;
}static int
recv_xsks_map_fd(int *xsks_map_fd)
{struct sockaddr_un server;int err;sock = socket(AF_UNIX, SOCK_STREAM, 0);if (sock < 0) {fprintf(stderr, "Error opening socket stream: %s", strerror(errno));return errno;}server.sun_family = AF_UNIX;strcpy(server.sun_path, SOCKET_NAME);if (connect(sock, (struct sockaddr *)&server, sizeof(struct sockaddr_un)) < 0) {close(sock);fprintf(stderr, "Error connecting stream socket: %s", strerror(errno));return errno;}err = recv_xsks_map_fd_from_ctrl_node(sock, xsks_map_fd);if (err) {fprintf(stderr, "Error %d receiving fd\n", err);return err;}return 0;
}int main(int argc, char **argv)
{struct __user_cap_header_struct hdr = { _LINUX_CAPABILITY_VERSION_3, 0 };struct __user_cap_data_struct data[2] = { { 0 } };bool rx = false, tx = false;struct sched_param schparam;struct xsk_umem_info *umem;struct bpf_object *obj;int xsks_map_fd = 0;pthread_t pt;int i, ret;void *bufs;parse_command_line(argc, argv);if (opt_reduced_cap) {if (capget(&hdr, data) < 0)fprintf(stderr, "Error getting capabilities\n");data->effective &= CAP_TO_MASK(CAP_NET_RAW);data->permitted &= CAP_TO_MASK(CAP_NET_RAW);if (capset(&hdr, data) < 0)fprintf(stderr, "Setting capabilities failed\n");if (capget(&hdr, data) < 0) {fprintf(stderr, "Error getting capabilities\n");} else {fprintf(stderr, "Capabilities EFF %x Caps INH %x Caps Per %x\n",data[0].effective, data[0].inheritable, data[0].permitted);fprintf(stderr, "Capabilities EFF %x Caps INH %x Caps Per %x\n",data[1].effective, data[1].inheritable, data[1].permitted);}} else {/* Use libbpf 1.0 API mode */libbpf_set_strict_mode(LIBBPF_STRICT_ALL);if (opt_num_xsks > 1)load_xdp_program(argv, &obj);}/* Reserve memory for the umem. Use hugepages if unaligned chunk mode */bufs = mmap(NULL, NUM_FRAMES * opt_xsk_frame_size,PROT_READ | PROT_WRITE,MAP_PRIVATE | MAP_ANONYMOUS | opt_mmap_flags, -1, 0);if (bufs == MAP_FAILED) {printf("ERROR: mmap failed\n");exit(EXIT_FAILURE);}/* Create sockets... */umem = xsk_configure_umem(bufs, NUM_FRAMES * opt_xsk_frame_size);if (opt_bench == BENCH_RXDROP || opt_bench == BENCH_L2FWD) {rx = true;xsk_populate_fill_ring(umem);}if (opt_bench == BENCH_L2FWD || opt_bench == BENCH_TXONLY)tx = true;for (i = 0; i < opt_num_xsks; i++)xsks[num_socks++] = xsk_configure_socket(umem, rx, tx);for (i = 0; i < opt_num_xsks; i++)apply_setsockopt(xsks[i]);if (opt_bench == BENCH_TXONLY) {if (opt_tstamp && opt_pkt_size < PKTGEN_SIZE_MIN)opt_pkt_size = PKTGEN_SIZE_MIN;gen_eth_hdr_data();for (i = 0; i < NUM_FRAMES; i++)gen_eth_frame(umem, i * opt_xsk_frame_size);}if (opt_num_xsks > 1 && opt_bench != BENCH_TXONLY)enter_xsks_into_map(obj);if (opt_reduced_cap) {ret = recv_xsks_map_fd(&xsks_map_fd);if (ret) {fprintf(stderr, "Error %d receiving xsks_map_fd\n", ret);exit_with_error(ret);}if (xsks[0]->xsk) {ret = xsk_socket__update_xskmap(xsks[0]->xsk, xsks_map_fd);if (ret) {fprintf(stderr, "Update of BPF map failed(%d)\n", ret);exit_with_error(ret);}}}signal(SIGINT, int_exit);signal(SIGTERM, int_exit);signal(SIGABRT, int_exit);setlocale(LC_ALL, "");prev_time = get_nsecs();start_time = prev_time;if (!opt_quiet) {ret = pthread_create(&pt, NULL, poller, NULL);if (ret)exit_with_error(ret);}/* Configure sched priority for better wake-up accuracy */memset(&schparam, 0, sizeof(schparam));schparam.sched_priority = opt_schprio;ret = sched_setscheduler(0, opt_schpolicy, &schparam);if (ret) {fprintf(stderr, "Error(%d) in setting priority(%d): %s\n",errno, opt_schprio, strerror(errno));goto out;}if (opt_bench == BENCH_RXDROP)rx_drop_all();else if (opt_bench == BENCH_TXONLY)tx_only_all();elsel2fwd_all();out:benchmark_done = true;if (!opt_quiet)pthread_join(pt, NULL);xdpsock_cleanup();munmap(bufs, NUM_FRAMES * opt_xsk_frame_size);return 0;
}2、内核空间代码
// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "xdpsock.h"/* This XDP program is only needed for the XDP_SHARED_UMEM mode.* If you do not use this mode, libbpf can supply an XDP program for you.*/struct {__uint(type, BPF_MAP_TYPE_XSKMAP);__uint(max_entries, MAX_SOCKS);__uint(key_size, sizeof(int));__uint(value_size, sizeof(int));
} xsks_map SEC(".maps");static unsigned int rr;SEC("xdp_sock") int xdp_sock_prog(struct xdp_md *ctx)
{rr = (rr + 1) & (MAX_SOCKS - 1);return bpf_redirect_map(&xsks_map, rr, XDP_DROP);
}上面的代码需要较高的内核版本，如果不够的话可能需要自己处理一下，安装相关的内核以及相关的高版本的编译器。
在内核的示例和相关的网络部分以及工具部分都有XDP相关的代码实现和调用实现，有兴趣可以认真的钻研一下，一定会收获很多。再加上推荐的那个Cilium项目，大约就可以入门XDP的开发了。
四、总结
网络技术可能是近几年发展速度比较快的一个方向了，毕竟无论是现在大火的AI还是大数据以及车联网最终都与网络通信有着密切的关系。这就直接或者间接的推动着网络技术必须不断的适应上层应用的需求。从原来简单的文字浏览，到后来的静态图片视频，再到交互式应用直到高并发的在线视频网站、视频通信等等，都对网络处理的速度和效率提出了非常苛刻的要求。
也没有让技术人员们失望，新的技术不断的出现，也算满足了目前的需求，XDP也算是其中之一。以后会不会出现更好的技术呢？一定会。
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