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7
8#define _GNU_SOURCE
9
10#include <arpa/inet.h>
11#include <assert.h>
12#include <error.h>
13#include <errno.h>
14#include <fcntl.h>
15#include <linux/filter.h>
16#include <linux/if_packet.h>
17#include <net/ethernet.h>
18#include <net/if.h>
19#include <netinet/in.h>
20#include <netinet/ip.h>
21#include <netinet/udp.h>
22#include <poll.h>
23#include <pthread.h>
24#include <sched.h>
25#include <sys/ioctl.h>
26#include <sys/mman.h>
27#include <sys/socket.h>
28#include <sys/time.h>
29#include <sys/types.h>
30#include <sys/utsname.h>
31#include <stdbool.h>
32#include <stdint.h>
33#include <stdio.h>
34#include <stdlib.h>
35#include <string.h>
36#include <unistd.h>
37
38const int eth_off = TPACKET_HDRLEN - sizeof(struct sockaddr_ll);
39const int cfg_frame_size = 1000;
40
41static void build_packet(void *buffer, size_t blen, char payload_char)
42{
43 struct udphdr *udph;
44 struct ethhdr *eth;
45 struct iphdr *iph;
46 size_t off = 0;
47
48 memset(buffer, 0, blen);
49
50 eth = buffer;
51 eth->h_proto = htons(ETH_P_IP);
52
53 off += sizeof(*eth);
54 iph = buffer + off;
55 iph->ttl = 8;
56 iph->ihl = 5;
57 iph->version = 4;
58 iph->saddr = htonl(INADDR_LOOPBACK);
59 iph->daddr = htonl(INADDR_LOOPBACK + 1);
60 iph->protocol = IPPROTO_UDP;
61 iph->tot_len = htons(blen - off);
62 iph->check = 0;
63
64 off += sizeof(*iph);
65 udph = buffer + off;
66 udph->dest = htons(8000);
67 udph->source = htons(8001);
68 udph->len = htons(blen - off);
69 udph->check = 0;
70
71 off += sizeof(*udph);
72 memset(buffer + off, payload_char, blen - off);
73}
74
75static int setup_rx(void)
76{
77 int fdr;
78
79 fdr = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP));
80 if (fdr == -1)
81 error(1, errno, "socket r");
82
83 return fdr;
84}
85
86static int setup_tx(char **ring)
87{
88 struct sockaddr_ll laddr = {};
89 struct tpacket_req req = {};
90 int fdt;
91
92 fdt = socket(PF_PACKET, SOCK_RAW, 0);
93 if (fdt == -1)
94 error(1, errno, "socket t");
95
96 laddr.sll_family = AF_PACKET;
97 laddr.sll_protocol = htons(0);
98 laddr.sll_ifindex = if_nametoindex("lo");
99 if (!laddr.sll_ifindex)
100 error(1, errno, "if_nametoindex");
101
102 if (bind(fdt, (void *)&laddr, sizeof(laddr)))
103 error(1, errno, "bind fdt");
104
105 req.tp_block_size = getpagesize();
106 req.tp_block_nr = 1;
107 req.tp_frame_size = getpagesize();
108 req.tp_frame_nr = 1;
109
110 if (setsockopt(fdt, SOL_PACKET, PACKET_TX_RING,
111 (void *)&req, sizeof(req)))
112 error(1, errno, "setsockopt ring");
113
114 *ring = mmap(0, req.tp_block_size * req.tp_block_nr,
115 PROT_READ | PROT_WRITE, MAP_SHARED, fdt, 0);
116 if (*ring == MAP_FAILED)
117 error(1, errno, "mmap");
118
119 return fdt;
120}
121
122static void send_pkt(int fdt, void *slot, char payload_char)
123{
124 struct tpacket_hdr *header = slot;
125 int ret;
126
127 while (header->tp_status != TP_STATUS_AVAILABLE)
128 usleep(1000);
129
130 build_packet(slot + eth_off, cfg_frame_size, payload_char);
131
132 header->tp_len = cfg_frame_size;
133 header->tp_status = TP_STATUS_SEND_REQUEST;
134
135 ret = sendto(fdt, NULL, 0, 0, NULL, 0);
136 if (ret == -1)
137 error(1, errno, "kick tx");
138}
139
140static int read_verify_pkt(int fdr, char payload_char)
141{
142 char buf[100];
143 int ret;
144
145 ret = read(fdr, buf, sizeof(buf));
146 if (ret != sizeof(buf))
147 error(1, errno, "read");
148
149 if (buf[60] != payload_char) {
150 printf("wrong pattern: 0x%x != 0x%x\n", buf[60], payload_char);
151 return 1;
152 }
153
154 printf("read: %c (0x%x)\n", buf[60], buf[60]);
155 return 0;
156}
157
158int main(int argc, char **argv)
159{
160 const char payload_patterns[] = "ab";
161 char *ring;
162 int fdr, fdt, ret = 0;
163
164 fdr = setup_rx();
165 fdt = setup_tx(&ring);
166
167 send_pkt(fdt, ring, payload_patterns[0]);
168 send_pkt(fdt, ring, payload_patterns[1]);
169
170 ret |= read_verify_pkt(fdr, payload_patterns[0]);
171 ret |= read_verify_pkt(fdr, payload_patterns[1]);
172
173 if (close(fdt))
174 error(1, errno, "close t");
175 if (close(fdr))
176 error(1, errno, "close r");
177
178 return ret;
179}
180
