// SPDX-License-Identifier: GPL-2.0 /* * Verify that consecutive sends over packet tx_ring are mirrored * with their original content intact. */ #define _GNU_SOURCE #include <arpa/inet.h>#include <assert.h>#include <error.h>#include <errno.h>#include <fcntl.h>#include <linux/filter.h>#include <linux/if_packet.h>#include <net/ethernet.h>#include <net/if.h>#include <netinet/in.h>#include <netinet/ip.h>#include <netinet/udp.h>#include <poll.h>#include <pthread.h>#include <sched.h>#include <sys/ioctl.h>#include <sys/mman.h>#include <sys/socket.h>#include <sys/time.h>#include <sys/types.h>#include <sys/utsname.h>#include <stdbool.h>#include <stdint.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h> const int eth_off = TPACKET_HDRLEN - sizeof(struct sockaddr_ll);const int cfg_frame_size = 1000; static void build_packet(void *buffer, size_t blen, char payload_char){	struct udphdr *udph;	struct ethhdr *eth;	struct iphdr *iph;	size_t off = 0; 	memset(buffer, 0, blen); 	eth = buffer;	eth->h_proto = htons(ETH_P_IP); 	off += sizeof(*eth);	iph = buffer + off;	iph->ttl	= 8;	iph->ihl	= 5;	iph->version	= 4;	iph->saddr	= htonl(INADDR_LOOPBACK);	iph->daddr	= htonl(INADDR_LOOPBACK + 1);	iph->protocol	= IPPROTO_UDP;	iph->tot_len	= htons(blen - off);	iph->check	= 0; 	off += sizeof(*iph);	udph = buffer + off;	udph->dest	= htons(8000);	udph->source	= htons(8001);	udph->len	= htons(blen - off);	udph->check	= 0; 	off += sizeof(*udph);	memset(buffer + off, payload_char, blen - off);} static int setup_rx(void){	int fdr; 	fdr = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP));	if (fdr == -1)		error(1, errno, "socket r"); 	return fdr;} static int setup_tx(char **ring){	struct sockaddr_ll laddr = {};	struct tpacket_req req = {};	int fdt; 	fdt = socket(PF_PACKET, SOCK_RAW, 0);	if (fdt == -1)		error(1, errno, "socket t"); 	laddr.sll_family = AF_PACKET;	laddr.sll_protocol = htons(0);	laddr.sll_ifindex = if_nametoindex("lo");	if (!laddr.sll_ifindex)		error(1, errno, "if_nametoindex"); 	if (bind(fdt, (void *)&laddr, sizeof(laddr)))		error(1, errno, "bind fdt"); 	req.tp_block_size = getpagesize();	req.tp_block_nr   = 1;	req.tp_frame_size = getpagesize();	req.tp_frame_nr   = 1; 	if (setsockopt(fdt, SOL_PACKET, PACKET_TX_RING,		       (void *)&req, sizeof(req)))		error(1, errno, "setsockopt ring"); 	*ring = mmap(0, req.tp_block_size * req.tp_block_nr,		     PROT_READ | PROT_WRITE, MAP_SHARED, fdt, 0);	if (*ring == MAP_FAILED)		error(1, errno, "mmap"); 	return fdt;} static void send_pkt(int fdt, void *slot, char payload_char){	struct tpacket_hdr *header = slot;	int ret; 	while (header->tp_status != TP_STATUS_AVAILABLE)		usleep(1000); 	build_packet(slot + eth_off, cfg_frame_size, payload_char); 	header->tp_len = cfg_frame_size;	header->tp_status = TP_STATUS_SEND_REQUEST; 	ret = sendto(fdt, NULL, 0, 0, NULL, 0);	if (ret == -1)		error(1, errno, "kick tx");} static int read_verify_pkt(int fdr, char payload_char){	char buf[100];	int ret; 	ret = read(fdr, buf, sizeof(buf));	if (ret != sizeof(buf))		error(1, errno, "read"); 	if (buf[60] != payload_char) {		printf("wrong pattern: 0x%x != 0x%x\n", buf[60], payload_char);		return 1;	} 	printf("read: %c (0x%x)\n", buf[60], buf[60]);	return 0;} int main(int argc, char **argv){	const char payload_patterns[] = "ab";	char *ring;	int fdr, fdt, ret = 0; 	fdr = setup_rx();	fdt = setup_tx(&ring); 	send_pkt(fdt, ring, payload_patterns[0]);	send_pkt(fdt, ring, payload_patterns[1]); 	ret |= read_verify_pkt(fdr, payload_patterns[0]);	ret |= read_verify_pkt(fdr, payload_patterns[1]); 	if (close(fdt))		error(1, errno, "close t");	if (close(fdr))		error(1, errno, "close r"); 	return ret;}