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  • epoll—linux c language —UDP Broadcast

    http://neokentblog.blogspot.com/2012/11/udp-broadcast-socket-programming-example.html

    server.c

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    1. // gcc server.c -o server
    2. // indent -npro -kr -i8 -ts8 -sob -l280 -ss -ncs -cp1 *

    4. #include <stdio.h>        // for printf() and fprintf()
    5. #include <sys/socket.h>        // for socket(), bind(), and connect()
    6. #include <arpa/inet.h>        // for sockaddr_in and inet_ntoa()
    7. #include <stdlib.h>        // for atoi() and exit()
    8. #include <string.h>        // for memset()
    9. #include <unistd.h>        // for close()
    10. #include <fcntl.h>        // for fcntl()
    11. #include <errno.h>

    13. #include <sys/epoll.h>

    15. #define BUFSIZE 1024        // Size of receive buffer

    17. static int make_socket_non_blocking(int sfd)
    18. {
    19.     int flags, s;

    21.     flags = fcntl(sfd, F_GETFL, 0);

    23.     if (flags == -1) {
    24.         perror("fcntl");
    25.         return -1;
    26.     }

    28.     flags |= O_NONBLOCK;
    29.     s = fcntl(sfd, F_SETFL, flags);

    31.     if (s == -1) {
    32.         perror("fcntl");
    33.         return -1;
    34.     }

    36.     return 0;
    37. }

    39. int main(int argc, char *argv[])
    40. {
    41.     int sockfd;        // Socket descriptors for server
    42.     int broadcast = 1;    // Socket Option.
    43.     struct sockaddr_in srvaddr;    // Broadcast Server Address
    44.     struct sockaddr_in dstaddr;    // Broadcast Destination Address
    45.     struct sockaddr_in cliaddr;    // Broadcast Response Client Address
    46.     int cliaddr_len = sizeof(cliaddr);

    48.     char buffer[BUFSIZE];    // Input and Receive buffer
    49.     int i;            // For loop use
    50.     int running = 1;    // Main Loop

    52.     int epfd;        // EPOLL File Descriptor.
    53.     struct epoll_event ev;    // Used for EPOLL.
    54.     struct epoll_event events[5];    // Used for EPOLL.
    55.     int noEvents;        // EPOLL event number.

    57.     printf("This process is a UDP broadcast process!. ");

    59.     // Test for correct number of arguments

    61.     if (argc < 4) {
    62.         fprintf(stderr, "Usage: %s <Local Port> <IP> <Remote Port> ... ", argv[0]);
    63.         exit(1);
    64.     }
    65.     // Create Socket

    67.     if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
    68.         perror("Create Sockfd Fail!! ");
    69.         exit(1);
    70.     }
    71.     // Setup Broadcast Option

    73.     if ((setsockopt(sockfd, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof(broadcast))) == -1) {
    74.         perror("Setsockopt - SO_SOCKET Fail!! ");
    75.         exit(1);
    76.     }
    77.     // Nonblocking

    79.     make_socket_non_blocking(sockfd);

    81.     // Reset the addresses

    83.     memset(&srvaddr, 0, sizeof(srvaddr));
    84.     memset(&dstaddr, 0, sizeof(dstaddr));

    86.     // Setup the addresses

    88.     srvaddr.sin_family = AF_INET;
    89.     srvaddr.sin_port = htons(atoi(argv[1]));
    90.     srvaddr.sin_addr.s_addr = INADDR_ANY;

    92.     if (bind(sockfd, (struct sockaddr *)&srvaddr, sizeof(srvaddr)) == -1) {
    93.         perror("bind");
    94.         exit(1);
    95.     }

    97.     dstaddr.sin_family = AF_INET;
    98.     dstaddr.sin_port = htons(atoi(argv[3]));
    99.     inet_pton(AF_INET, argv[2], &(dstaddr.sin_addr.s_addr));

    101.     // Create epoll file descriptor.

    103.     epfd = epoll_create(5);

    105.     // Add socket into the EPOLL set.

    107.     ev.data.fd = sockfd;
    108.     ev.events = EPOLLIN | EPOLLET;
    109.     epoll_ctl(epfd, EPOLL_CTL_ADD, sockfd, &ev);

    111.     // Add STDIN into the EPOLL set.

    113.     ev.data.fd = STDIN_FILENO;
    114.     ev.events = EPOLLIN | EPOLLET;
    115.     epoll_ctl(epfd, EPOLL_CTL_ADD, STDIN_FILENO, &ev);

    117.     while (running) {
    118.         // Wait for events.
    119.         // int epoll_wait(int epfd, struct epoll_event *events, int maxevents, int timeout);
    120.         // Specifying a timeout of -1 makes epoll_wait() wait indefinitely.

    122.         noEvents = epoll_wait(epfd, events, FD_SETSIZE, -1);

    124.         for (i = 0; i < noEvents; i++) {
    125.             if (events[i].events & EPOLLIN && STDIN_FILENO == events[i].data.fd) {
    126.                 memset(buffer, 0, BUFSIZE);
    127.                 fgets(buffer, 1024, stdin);

    129.                 if (strncmp(buffer, "bye", 3) == 0) {
    130.                     printf("Bye. ");
    131.                     running = 0;
    132.                 }

    134.                 if (sendto(sockfd, buffer, strlen(buffer), 0, (struct sockaddr *)&dstaddr, sizeof(dstaddr)) != -1) {
    135.                     printf("Sent a brocast message: %s", buffer);
    136.                 } else {
    137.                     printf("Sent a brocast message FAIL!! ");
    138.                     running = 0;
    139.                 }
    140.             } else if (events[i].events & EPOLLIN && sockfd == events[i].data.fd) {
    141.                 memset(buffer, 0, BUFSIZE);

    143.                 while (recvfrom(sockfd, buffer, BUFSIZE, 0, (struct sockaddr *)&cliaddr, (socklen_t *) & cliaddr_len) != -1) {
    144.                     printf("Response from %s_%d: %s", inet_ntoa(cliaddr.sin_addr), ntohs(cliaddr.sin_port), buffer);
    145.                 }

    147.                 if (errno != EAGAIN) {
    148.                     printf("Receive the brocast message response FAIL!! ");
    149.                     running = 0;
    150.                 }
    151.             }
    152.         }
    153.     }

    155.     // Close the socket

    157.     close(sockfd);
    158.     close(epfd);

    160.     return 0;
    161. }
    client.c

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    1. // gcc client.c -o client
    2. // indent -npro -kr -i8 -ts8 -sob -l280 -ss -ncs -cp1 *

    4. #include <stdio.h>        // for printf() and fprintf()
    5. #include <sys/socket.h>        // for socket(), bind(), and connect()
    6. #include <arpa/inet.h>        // for sockaddr_in and inet_ntoa()
    7. #include <stdlib.h>        // for atoi() and exit()
    8. #include <string.h>        // for memset()
    9. #include <unistd.h>        // for close()
    10. #include <fcntl.h>        // for fcntl()
    11. #include <errno.h>

    13. #include <sys/epoll.h>

    15. #define BUFSIZE 1024        // Size of receive buffer

    17. static int make_socket_non_blocking(int sfd)
    18. {
    19.     int flags, s;

    21.     flags = fcntl(sfd, F_GETFL, 0);

    23.     if (flags == -1) {
    24.         perror("fcntl");
    25.         return -1;
    26.     }

    28.     flags |= O_NONBLOCK;
    29.     s = fcntl(sfd, F_SETFL, flags);

    31.     if (s == -1) {
    32.         perror("fcntl");
    33.         return -1;
    34.     }

    36.     return 0;
    37. }

    39. int main(int argc, char *argv[])
    40. {
    41.     int sockfd;        // Socket descriptors for server
    42.     int broadcast = 1;    // Socket Option.
    43.     struct sockaddr_in cliaddr;    // Broadcast Receiver Address
    44.     struct sockaddr_in srvaddr;    // Broadcast Server Address
    45.     int srvaddr_len = sizeof(srvaddr);

    47.     char buffer[BUFSIZE];    // Input and Receive buffer
    48.     int i;            // For loop use
    49.     int running = 1;    // Main Loop
    50.     int rcvlen = 0;        // Receive Message Size

    52.     int epfd;        // EPOLL File Descriptor.
    53.     struct epoll_event ev;    // Used for EPOLL.
    54.     struct epoll_event events[5];    // Used for EPOLL.
    55.     int noEvents;        // EPOLL event number.

    57.     printf("This process is a UDP broadcast echo client process!. ");

    59.     // Test for correct number of arguments

    61.     if (argc < 2) {
    62.         fprintf(stderr, "Usage: %s <Local Port> ... ", argv[0]);
    63.         exit(1);
    64.     }
    65.     // Create Socket

    67.     if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
    68.         perror("Create Sockfd Fail!! ");
    69.         exit(1);
    70.     }
    71.     // Nonblocking

    73.     make_socket_non_blocking(sockfd);

    75.     // Reset the addresses

    77.     memset(&cliaddr, 0, sizeof(cliaddr));

    79.     // Setup the addresses

    81.     cliaddr.sin_family = AF_INET;
    82.     cliaddr.sin_port = htons(atoi(argv[1]));
    83.     cliaddr.sin_addr.s_addr = INADDR_ANY;

    85.     if (bind(sockfd, (struct sockaddr *)&cliaddr, sizeof(cliaddr)) == -1) {
    86.         perror("bind");
    87.         exit(1);
    88.     }
    89.     // Create epoll file descriptor.

    91.     epfd = epoll_create(5);

    93.     // Add socket into the EPOLL set.

    95.     ev.data.fd = sockfd;
    96.     ev.events = EPOLLIN | EPOLLET;
    97.     epoll_ctl(epfd, EPOLL_CTL_ADD, sockfd, &ev);

    99.     while (running) {
    100.         // Wait for events.
    101.         // int epoll_wait(int epfd, struct epoll_event *events, int maxevents, int timeout);
    102.         // Specifying a timeout of -1 makes epoll_wait() wait indefinitely.

    104.         noEvents = epoll_wait(epfd, events, FD_SETSIZE, -1);

    106.         for (i = 0; i < noEvents; i++) {
    107.             if (events[i].events & EPOLLIN && sockfd == events[i].data.fd) {
    108.                 memset(buffer, 0, BUFSIZE);

    110.                 while ((rcvlen = recvfrom(sockfd, buffer, BUFSIZE, 0, (struct sockaddr *)&srvaddr, (socklen_t *) & srvaddr_len))
    111.                  != -1) {
    112.                     printf("Receive from %s_%d: %s", inet_ntoa(srvaddr.sin_addr), ntohs(srvaddr.sin_port), buffer);

    114.                     if (sendto(sockfd, buffer, rcvlen, 0, (struct sockaddr *)&srvaddr, sizeof(srvaddr)) == -1) {
    115.                         printf("Send Fail! ");
    116.                         running = 0;
    117.                         continue;
    118.                     }
    119.                 }

    121.                 if (errno != EAGAIN) {
    122.                     perror("Receive the brocast message response FAIL!! ");
    123.                     running = 0;
    124.                 }
    125.             }
    126.         }
    127.     }

    129.     // Close the socket

    131.     close(sockfd);
    132.     close(epfd);

    134.     return 0;
    135. }



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  • 原文地址：https://www.cnblogs.com/ztguang/p/12649510.html
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