C/S—心跳检测—heartbeat

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heartbeat-server.c

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// 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 <port>\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

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// 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 <addr> <port>\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;
}

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