1
ssize_t recvfrom(int sockfd, void *buf, size_t len, int flags,
2
                 struct sockaddr *src_addr, socklen_t *addrlen);

1
ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
2
               const struct sockaddr *dest_addr, socklen_t addrlen);

1
int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t optlen);

1
#pragma once
2

3
#define NAMESIZE 16
4
#define SERVER_PORT "1999"
5

6
#include "stdint.h"
7
struct msg_st {
8
  uint8_t name[NAMESIZE];
9
  uint32_t math;
10
  uint32_t chinese;
11
} __attribute__((packed));

1
#include "proto.h"
2
#include "stdio.h"
3
#include "stdlib.h"
4
#include "string.h"
5
#include "sys/socket.h"
6
#include "unistd.h"
7
#include <arpa/inet.h>
8
#define BUFFSIZE 1024
9
#define IPSIZE 24
10

11
#define BCAST_SERVER "255.255.255.255"
12
int main(int argc, char *argv[]) {
13

14
  struct msg_st *sbuf_p;
15
  sbuf_p = malloc(sizeof(struct msg_st));
16
  if (sbuf_p == NULL) {
17
    perror("malloc()");
18
    exit(1);
19
  }
20
  sbuf_p->chinese = htonl(rand() % 100);
21
  sbuf_p->math = htonl(rand() % 100);
22
  strcpy(sbuf_p->name, "Jim");
23

24
  int sd = socket(AF_INET, SOCK_DGRAM, 0);
25
  if (sd < 0) {
26
    perror("socket()");
27
    exit(1);
28
  }
29
  int32_t opval = 1;
30
  //设置全局广播
31
  if (setsockopt(sd, SOL_SOCKET, SO_BROADCAST, &opval, sizeof(opval)) < 0) {
32
    perror("setsockopt()");
33
    exit(1);
34
  }
35

36
  struct sockaddr_in s_addr;
37
  s_addr.sin_family = AF_INET;
38
  s_addr.sin_port = htons(atoi(SERVER_PORT));
39
  inet_pton(AF_INET, BCAST_SERVER, &s_addr.sin_addr);
40
  socklen_t len;
41
  len = sizeof(s_addr);
42
  // bind(sd, (const struct sockaddr *)&s_addr, len);
43

44
  while (1) {
45
    sbuf_p->chinese = htonl(rand() % 100);
46
    sbuf_p->math = htonl(rand() % 100);
47
    if (sendto(sd, sbuf_p, sizeof(struct msg_st), 0,
48
               (const struct sockaddr *)&s_addr, len) < 0) {
49
      perror("sendto");
50
      exit(1);
51
    }
52
    puts("OK");
53
    sleep(1);
54
  }
55

56
  free(sbuf_p);
57

58
  return 0;
59
}

1
#include "arpa/inet.h"
2
#include "proto.h"
3
#include "stdio.h"
4
#include "stdlib.h"
5
#include "string.h"
6
#include "sys/socket.h"
7
int main(int argc, char *argv[]) {
8

9
  struct msg_st msg;
10

11
  int sd;
12
  sd = socket(AF_INET, SOCK_DGRAM, 0);
13
  if (sd < 0) {
14
    perror("socket()");
15
    exit(1);
16
  }
17

18
  struct sockaddr_in laddr;
19
  struct sockaddr_in saddr;
20

21
  socklen_t saddr_len;
22
  saddr_len = sizeof(saddr);
23

24
  laddr.sin_family = AF_INET;
25
  laddr.sin_port = htons(atoi(SERVER_PORT));
26

27
  inet_pton(AF_INET, "0.0.0.0", &laddr.sin_addr);
28
  socklen_t laddr_len;
29
  laddr_len = sizeof(laddr);
30

31
  if (bind(sd, (void *)&laddr, sizeof(laddr)) < 0) {
32
    perror("bind()");
33
    exit(1);
34
  }
35

36
  if (recvfrom(sd, &msg, sizeof(struct msg_st), 0, (struct sockaddr *)&saddr,
37
               &saddr_len) < 0) {
38
    perror("recvfrom()");
39
    exit(1);
40
  }
41
  char ipstr[20];
42
  inet_ntop(AF_INET, &saddr.sin_addr, ipstr, saddr_len);
43

44
  printf("--MESSAGE FROM %s:%d--\n", ipstr, ntohs(saddr.sin_port));
45
  printf("NAME=%s\n", msg.name);
46
  printf("CHINESE=%d\n", ntohl(msg.chinese));
47
  printf("MATH=%d\n", ntohl(msg.math));
48

49
  return 0;
50
}

1
#pragma once
2

3
#define NAMESIZE 16
4
#define SERVER_PORT "1999"
5
#define MTGROUP "224.2.2.2"
6

7
#include "stdint.h"
8
struct msg_st {
9
  uint8_t name[NAMESIZE];
10
  uint32_t math;
11
  uint32_t chinese;
12
} __attribute__((packed));

1
#include "net/if.h"
2
#include "netinet/in.h"
3
#include "netinet/ip.h"
4
#include "proto.h"
5
#include "stdio.h"
6
#include "stdlib.h"
7
#include "string.h"
8
#include "sys/socket.h"
9
#include "unistd.h"
10
#include <arpa/inet.h>
11

12
#define BUFFSIZE 1024
13
#define IPSIZE 24
14

15

16
int main(int argc, char *argv[]) {
17

18
  struct msg_st *sbuf_p;
19
  sbuf_p = malloc(sizeof(struct msg_st));
20
  if (sbuf_p == NULL) {
21
    perror("malloc()");
22
    exit(1);
23
  }
24
  sbuf_p->chinese = htonl(rand() % 100);
25
  sbuf_p->math = htonl(rand() % 100);
26
  // sbuf_p->name = "Jim";
27
  strcpy(sbuf_p->name, "Jim");
28

29
  int sd = socket(AF_INET, SOCK_DGRAM, 0);
30
  if (sd < 0) {
31
    perror("socket()");
32
    exit(1);
33
  }
34
  struct ip_mreqn mreq;
35
  inet_pton(AF_INET, MTGROUP, &mreq.imr_multiaddr);
36
  inet_pton(AF_INET, "0.0.0.0", &mreq.imr_address);
37
  mreq.imr_ifindex = if_nametoindex("wlp0s20f3");
38
  if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_IF, &mreq,
39
                 sizeof(struct ip_mreqn)) < 0) {
40
    perror("setsockopt() IP_MULTICAST_IF");
41
    exit(1);
42
  }
43

44
  struct sockaddr_in s_addr;
45
  s_addr.sin_family = AF_INET;
46
  s_addr.sin_port = htons(atoi(SERVER_PORT));
47
  inet_pton(AF_INET, MTGROUP, &s_addr.sin_addr);
48
  socklen_t len;
49
  len = sizeof(s_addr);
50
  // bind(sd, (const struct sockaddr *)&s_addr, len);
51

52

53

54
  while (1) {
55
    sbuf_p->chinese = htonl(rand() % 100);
56
    sbuf_p->math = htonl(rand() % 100);
57
    if (sendto(sd, sbuf_p, sizeof(struct msg_st), 0,
58
               (const struct sockaddr *)&s_addr, len) < 0) {
59
      perror("sendto");
60
      exit(1);
61
    }
62
    puts("OK");
63
    sleep(1);
64
  }
65

66
  free(sbuf_p);
67

68
  return 0;
69
}

1
#include "arpa/inet.h"
2
#include "net/if.h"
3
#include "proto.h"
4
#include "stdio.h"
5
#include "stdlib.h"
6
#include "string.h"
7
#include "sys/socket.h"
8
int main(int argc, char *argv[]) {
9

10
  struct msg_st msg;
11

12
  int sd;
13
  sd = socket(AF_INET, SOCK_DGRAM, 0);
14
  if (sd < 0) {
15
    perror("socket()");
16
    exit(1);
17
  }
18
  struct ip_mreqn mreq;
19

20
  inet_pton(AF_INET, MTGROUP, &mreq.imr_multiaddr);
21
  inet_pton(AF_INET, "0.0.0.0", &mreq.imr_address);
22
  mreq.imr_ifindex = if_nametoindex("wlp0s20f3");
23

24
  if (setsockopt(sd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq,
25
                 sizeof(struct ip_mreqn)) < 0) {
26
    perror("setsockop()");
27
    exit(1);
28
  }
29

30
  struct sockaddr_in laddr;
31
  struct sockaddr_in saddr;
32

33
  socklen_t saddr_len;
34
  saddr_len = sizeof(saddr);
35

36
  laddr.sin_family = AF_INET;
37
  laddr.sin_port = htons(atoi(SERVER_PORT));
38

39
  inet_pton(AF_INET, "0.0.0.0", &laddr.sin_addr);
40
  socklen_t laddr_len;
41
  laddr_len = sizeof(laddr);
42

43
  if (bind(sd, (void *)&laddr, sizeof(laddr)) < 0) {
44
    perror("bind()");
45
    exit(1);
46
  }
47

48
  if (recvfrom(sd, &msg, sizeof(struct msg_st), 0, (struct sockaddr *)&saddr,
49
               &saddr_len) < 0) {
50
    perror("recvfrom()");
51
    exit(1);
52
  }
53
  char ipstr[20];
54
  inet_ntop(AF_INET, &saddr.sin_addr, ipstr, saddr_len);
55

56
  printf("--MESSAGE FROM %s:%d--\n", ipstr, ntohs(saddr.sin_port));
57
  printf("NAME=%s\n", msg.name);
58
  printf("CHINESE=%d\n", ntohl(msg.chinese));
59
  printf("MATH=%d\n", ntohl(msg.math));
60

61
  return 0;
62
}