C/S—心跳检测—heartbeat

heartbeat-server.c

// gcc heartbeat-server.c -o heartbeat-server
// indent -npro -kr -i8 -ts8 -sob -l280 -ss -ncs -cp1 *
/* heartbeat-server.c
 *
 * Copyright (c) 2000 Sean Walton and Macmillan Publishers. Use may be in
 * whole or in part in accordance to the General Public License (GPL).
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
*/
/*****************************************************************************/
/*** heartbeat-server.c ***/
/*** ***/
/*** Demonstrates how to keep track of the server using a "heartbeat". If ***/
/*** the heartbeat is lost, the connection can be reestablished and the ***/
/*** session resumed. ***/
/*****************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <strings.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <resolv.h>
#include <signal.h>
#include <sys/wait.h>
int client;
struct sigaction act;
/*---------------------------------------------------------------------
    sig_handler - catch and send heartbeat.
 ---------------------------------------------------------------------*/
void sig_handler(int signum)
{
    if (signum == SIGURG) {
        char c;
        recv(client, &c, sizeof(c), MSG_OOB);
        if (c == '?')
            /* Are you alive? */
            send(client, "Y", 1, MSG_OOB);    /* */
    } else if (signum == SIGCHLD)
        wait(0);
}

/*---------------------------------------------------------------------
    servlet - process requests
 ---------------------------------------------------------------------*/
void servlet(void)
{
    int bytes;
    char buffer[1024];
    bzero(&act, sizeof(act));
    act.sa_handler = sig_handler;
    act.sa_flags = SA_RESTART;
    sigaction(SIGURG, &act, 0);    /* connect SIGURG signal */
    if (fcntl(client, F_SETOWN, getpid()) != 0)
        perror("Can't claim SIGIO and SIGURG");
    do {
        bytes = recv(client, buffer, sizeof(buffer), 0);
        if (bytes > 0)
            send(client, buffer, bytes, 0);
    }
    while (bytes > 0);
    close(client);
    exit(0);
}

/*---------------------------------------------------------------------
    main - set up client and begin the heartbeat.
 ---------------------------------------------------------------------*/
int main(int count, char *strings[])
{
    int sd;
    struct sockaddr_in addr;
    if (count != 2) {
        printf("usage: %s \n", strings[0]);
        exit(0);
    }
    bzero(&act, sizeof(act));
    act.sa_handler = sig_handler;
    act.sa_flags = SA_NOCLDSTOP | SA_RESTART;
    if (sigaction(SIGCHLD, &act, 0) != 0)
        perror("sigaction()");
    sd = socket(PF_INET, SOCK_STREAM, 0);
    bzero(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(atoi(strings[1]));
    addr.sin_addr.s_addr = INADDR_ANY;
    if (bind(sd, (struct sockaddr *)&addr, sizeof(addr)) != 0)
        perror("bind()");
    listen(sd, 15);
    for (;;) {
        client = accept(sd, 0, 0);
        if (client > 0) {
            if (fork() == 0) {
                close(sd);
                servlet();
            } else
                close(client);
        } else
            perror("accept()");
    }
    close(sd);
    return 0;
}

heartbeat-client.c

// gcc heartbeat-client.c -o heartbeat-client
// indent -npro -kr -i8 -ts8 -sob -l280 -ss -ncs -cp1 *
/* heartbeat-client.c
 *
 * Copyright (c) 2000 Sean Walton and Macmillan Publishers. Use may be in
 * whole or in part in accordance to the General Public License (GPL).
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
*/
/*****************************************************************************/
/*** heartbeat-client.c ***/
/*** ***/
/*** Demonstrates how to keep track of the server using a "heartbeat". If ***/
/*** the heartbeat is lost, the connection can be reestablished and the ***/
/*** session resumed. ***/
/*****************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <resolv.h>
#include <netinet/tcp.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define DELAY 5            /*seconds */
int serverfd, got_reply = 1;

/*---------------------------------------------------------------------
    sig_handler - if the single is OOB, set flag. If ALARM, send heartbeat.
 ---------------------------------------------------------------------*/
void sig_handler(int signum)
{
    if (signum == SIGURG) {
        char c;
        recv(serverfd, &c, sizeof(c), MSG_OOB);
        got_reply = (c == 'Y');    /* Got reply */
        fprintf(stderr, "[server is alive]");
    } else if (signum == SIGALRM)
        if (got_reply) {
            send(serverfd, "?", 1, MSG_OOB);    /* Alive?? */
            alarm(DELAY);    /* Wait a while */
            got_reply = 0;
        } else
            fprintf(stderr, "Lost connection to server!");
}

/*---------------------------------------------------------------------
    main - set up client and begin the heartbeat.
 ---------------------------------------------------------------------*/
int main(int count, char *strings[])
{
    struct sockaddr_in addr;
    struct sigaction act;
    int bytes;
    char line[100];
    if (count != 3) {
        printf("usage: %s  \n", strings[0]);
        exit(0);
    }
    bzero(&act, sizeof(act));
    act.sa_handler = sig_handler;
    act.sa_flags = SA_RESTART;
    sigaction(SIGURG, &act, 0);
    sigaction(SIGALRM, &act, 0);
    serverfd = socket(PF_INET, SOCK_STREAM, 0);
    /*---claim SIGIO/SIGURG signals---*/
    if (fcntl(serverfd, F_SETOWN, getpid()) != 0)
        perror("Can't claim SIGURG and SIGIO");

    bzero(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(atoi(strings[2]));
    inet_aton(strings[1], &addr.sin_addr);
    if (connect(serverfd, (struct sockaddr *)&addr, sizeof(addr)) == 0) {
        alarm(DELAY);
        do {
            gets(line);
            printf("send [%s]\n", line);
            send(serverfd, line, strlen(line), 0);
            bytes = recv(serverfd, line, sizeof(line), 0);
        }
        while (bytes > 0);
    } else
        perror("connect failed");
    close(serverfd);
    return 0;
}