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藍森林 http://www.lslnet.com 2006年6月6日 10:18
 關於路由套接口的相關問題
1。複製掩碼是什麼概念，和網絡掩碼有什麼區別？
2。以下是我寫的一個小程序，CORE DUMP，不知道出錯在哪裡？
[code]#include <stdio.h>;
#include <unistd.h>;
#include <stropts.h>;
#include <sys/types.h>;
#include <sys/socket.h>;
#include <sys/ioctl.h>;
#include <net/route.h>;
#define SEQ 8888
#define BUFLEN sizeof(struct rt_msghdr)+512
#define RTA_MAX 8
main(int argc, char **argv)
{
char *buf;
struct rt_msghdr *bufptr;
struct sockaddr_in *sockptr;
struct sockaddr_in *sa, *result[RTA_MAX]; //RTA_MAX = 8
int sockfd, n, i;
if (argc != 2) {
printf("Usage: %s <ip>;\n", argv[0]);
exit(-1);
}
sockfd = socket(AF_ROUTE, SOCK_RAW, 0 ); //create route socket
buf = (char *)calloc(1, BUFLEN);
bufptr = (struct rt_msghdr *)buf;
bufptr->;rtm_msglen = sizeof(struct rt_msghdr) + sizeof(struct sockaddr_in);
bufptr->;rtm_version = RTM_VERSION;
bufptr->;rtm_type = RTM_GET;
bufptr->;rtm_addrs = RTA_DST;
bufptr->;rtm_pid = getpid();
bufptr->;rtm_seq = SEQ;
sockptr = (struct sockaddr_in *)(bufptr+1);
sockptr->;sin_family = AF_INET;
(sockptr->;sin_addr).s_addr = inet_addr(argv[1]);
write(sockfd, bufptr, bufptr->;rtm_msglen);
write(sockfd, bufptr, bufptr->;rtm_msglen);
/***
The route sockets may be opened by other process, so when the kernel send mess
ages to all route sockets, we must used type, pid and seq to get what we wants
***/
do {
n = read(sockfd, bufptr, BUFLEN);
}while (bufptr->;rtm_type != RTM_GET || bufptr->;rtm_pid != getpid() || bufptr->;
rtm_seq != SEQ);
for (i = 0; i < RTA_MAX; i++){
bzero(result[i], sizeof(struct sockaddr_in));
if (bufptr->;rtm_addrs == RTA_DST)
memcpy(result[0], sockptr, sizeof(struct sockaddr_in));
if (bufptr->;rtm_addrs == RTA_GATEWAY)
memcpy(result[1], sockptr+1, sizeof(struct sockaddr_in));
if (bufptr->;rtm_addrs == RTA_NETMASK)
memcpy(result[2], sockptr+2, sizeof(struct sockaddr_in));
if (bufptr->;rtm_addrs == RTA_GENMASK)
memcpy(result[3], sockptr+3, sizeof(struct sockaddr_in));
}
printf("out for\n");
if ((sa = result[RTA_DST]) != NULL)
printf("Dest: %s\n", inet_ntoa(sa->;sin_addr));
if ((sa = result[RTA_GATEWAY]) != NULL)
printf("Gateway: %s\n", inet_ntoa(sa->;sin_addr));
if ((sa = result[RTA_NETMASK]) != NULL)
printf("Netmask: %s\n", inet_ntoa(sa->;sin_addr));
if ((sa = result[RTA_GENMASK]) != NULL)
printf("Genmask: %s\n", inet_ntoa(sa->;sin_addr));
}[/code] |
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