我有一个用C写的ping程序，编译后可以正常运行，但是在运行一段时间后，就会出现段错误，通过gdb分析发现是gettimeofday这个函数这里出现了问题，下面是代码，希望有人帮我分析下问题所在，谢谢：
#include <stdio.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <unistd.h>
#include <signal.h>
#include <arpa/inet.h>
#include <errno.h>
#include <sys/time.h>
#include <string.h>
#include <netdb.h>
#include <pthread.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip.h>
#define PACKET_SEND_MAX_NUM 4000
char *ipaddress = "114.114.114.114";
typedef struct ping_packet_status
{
struct timeval begin_time;
struct timeval end_time;
int flag; //发送标志,1为已发送
int seq; //包的序列号
}ping_packet_status;
ping_packet_status ping_packet[PACKET_SEND_MAX_NUM];
int alive;
int rawsock;
int send_count;
int recv_count;
pid_t pid;
struct sockaddr_in dest;
struct timeval start_time;
struct timeval end_time;
struct timeval time_interval;
/*校验和算法*/
unsigned short cal_chksum(unsigned short *addr,int len)
{ int nleft=len;
int sum=0;
unsigned short *w=addr;
unsigned short answer=0;
/*把ICMP报头二进制数据以2字节为单位累加起来*/
while(nleft>1)
{
sum+=*w++;
nleft-=2;
}
/*若ICMP报头为奇数个字节，会剩下最后一字节。把最后一个字节视为一个2字节数据的高字节，这个2字节数据的低字节为0，继续累加*/
if( nleft==1)
{
*(unsigned char *)(&answer)=*(unsigned char *)w;
sum+=answer;
}
sum=(sum>>16)+(sum&0xffff);
sum+=(sum>>16);
answer=~sum;
return answer;
}
struct timeval cal_time_offset(struct timeval begin, struct timeval end)
{
struct timeval ans;
ans.tv_sec = end.tv_sec - begin.tv_sec;
ans.tv_usec = end.tv_usec - begin.tv_usec;
if(ans.tv_usec < 0) //如果接收时间的usec小于发送时间的usec，则向sec域借位
{
ans.tv_sec--;
ans.tv_usec+=1000000;
}
return ans;
}
void icmp_pack(struct icmp* icmphdr, int seq, int length)
{
int i = 0;
icmphdr->icmp_type = ICMP_ECHO;
icmphdr->icmp_code = 0;
icmphdr->icmp_cksum = 0;
icmphdr->icmp_seq = seq;
icmphdr->icmp_id = pid & 0xffff;
for(i=0;i<length;i++)
{
icmphdr->icmp_data[i] = i;
}
icmphdr->icmp_cksum = cal_chksum((unsigned short*)icmphdr, length);
}
int icmp_unpack(char* buf, int len)
{
int iphdr_len;
struct timeval begin_time, recv_time, offset_time;
int rtt; //round trip time
struct ip* ip_hdr = (struct ip *)buf;
iphdr_len = ip_hdr->ip_hl*4;
struct icmp* icmp = (struct icmp*)(buf+iphdr_len);
len-=iphdr_len; //icmp包长度
if(len < 8) //判断长度是否为ICMP包长度
{
fprintf(stderr, "Invalid icmp packet.Its length is less than 8\n");
return -1;
}
//判断该包是ICMP回送回答包且该包是我们发出去的
if((icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == (pid & 0xffff)))
{
// if((icmp->icmp_seq < 0) || (icmp->icmp_seq > PACKET_SEND_MAX_NUM))
// {
// fprintf(stderr, "icmp packet seq is out of range!\n");
// alive = 0;
// return -1;
// }
ping_packet[icmp->icmp_seq].flag = 0;
begin_time = ping_packet[icmp->icmp_seq].begin_time;
gettimeofday(&recv_time, NULL);
offset_time = cal_time_offset(begin_time, recv_time);
rtt = offset_time.tv_sec*1000 + offset_time.tv_usec/1000; //毫秒为单位
printf("%d byte from %s: icmp_seq=%u ttl=%d rtt=%d \n",
len, inet_ntoa(ip_hdr->ip_src), icmp->icmp_seq, ip_hdr->ip_ttl, rtt);
}
else
{
fprintf(stderr, "Invalid ICMP packet! Its id is not matched!\n");
return -1;
}
return 0;
}
void ping_send()
{
char send_buf[128];
memset(send_buf, 0, sizeof(send_buf));
gettimeofday(&start_time, NULL); //记录第一个ping包发出的时间
while(alive)
{
int size = 0;
gettimeofday(&(ping_packet[send_count].begin_time), NULL);
ping_packet[send_count].flag = 1; //将该标记为设置为该包已发送
icmp_pack((struct icmp*)send_buf, send_count, 64); //封装icmp包
size = sendto(rawsock, send_buf, 64, 0, (struct sockaddr*)&dest, sizeof(dest));
send_count++; //记录发出ping包的数量
if(size < 0)
{
fprintf(stderr, "send icmp packet fail!\n");
continue;
}
usleep(10000);
}
}
void ping_recv()
{
struct timeval tv;
tv.tv_usec = 200; //设置select函数的超时时间为200us
tv.tv_sec = 0;
fd_set read_fd;
char recv_buf[512];
memset(recv_buf, 0 ,sizeof(recv_buf));
while(alive)
{
int ret = 0;
FD_ZERO(&read_fd);
FD_SET(rawsock, &read_fd);
ret = select(rawsock+1, &read_fd, NULL, NULL, &tv);
switch(ret)
{
case -1:
fprintf(stderr,"fail to select!\n");
break;
case 0:
break;
default:
{
int size = recv(rawsock, recv_buf, sizeof(recv_buf), 0);
if(size < 0)
{
fprintf(stderr,"recv data fail!\n");
continue;
}
ret = icmp_unpack(recv_buf, size); //对接收的包进行解封
if(ret == -1) //不是属于自己的icmp包，丢弃不处理
{
continue;
}
recv_count++; //接收包计数
}
break;
}
}
}
void icmp_sigint(int signo)
{
alive = 0;
gettimeofday(&end_time, NULL);
time_interval = cal_time_offset(start_time, end_time);
}
void ping_stats_show()
{
long time = time_interval.tv_sec*1000+time_interval.tv_usec/1000;
/*注意除数不能为零，这里send_count有可能为零，所以运行时提示错误*/
printf("%d packets transmitted, %d recieved, %d%c packet loss, time %ldms\n",
send_count, recv_count, (send_count-recv_count)*100/send_count, '%', time);
}
int test()
{
int size = 512*1024;//128k
struct protoent* protocol = NULL;
char dest_addr_str[80];
memset(dest_addr_str, 0, 80);
unsigned int inaddr = 1;
struct hostent* host = NULL;
pthread_t send_id,recv_id;
/*if(argc < 2)
{
printf("Invalid IP ADDRESS!\n");
return -1;
}*/
protocol = getprotobyname("icmp"); //获取协议类型ICMP
if(protocol == NULL)
{
printf("Fail to getprotobyname!\n");
return -1;
}
memcpy(dest_addr_str, ipaddress, strlen(ipaddress)+1);
rawsock = socket(AF_INET,SOCK_RAW,protocol->p_proto);
if(rawsock < 0)
{
printf("Fail to create socket!\n");
return -1;
}
pid = getpid();
setsockopt(rawsock, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size)); //增大接收缓冲区至128K
bzero(&dest,sizeof(dest));
dest.sin_family = AF_INET;
inaddr = inet_addr(ipaddress);
if(inaddr == INADDR_NONE) //判断用户输入的是否为IP地址还是域名
{
//输入的是域名地址
host = gethostbyname(ipaddress);
if(host == NULL)
{
printf("Fail to gethostbyname!\n");
return -1;
}
memcpy((char*)&dest.sin_addr, host->h_addr, host->h_length);
}
else
{
memcpy((char*)&dest.sin_addr, &inaddr, sizeof(inaddr));//输入的是IP地址
}
inaddr = dest.sin_addr.s_addr;
printf("PING %s, (%d.%d.%d.%d) 56(84) bytes of data.\n",dest_addr_str,
(inaddr&0x000000ff), (inaddr&0x0000ff00)>>8,
(inaddr&0x00ff0000)>>16, (inaddr&0xff000000)>>24);
alive = 1; //控制ping的发送和接收
signal(SIGINT, icmp_sigint);
if(pthread_create(&send_id, NULL, (void*)ping_send, NULL))
{
printf("Fail to create ping send thread!\n");
return -1;
}
// if(pthread_create(&recv_id, NULL, (void*)ping_recv, NULL))
// {
// printf("Fail to create ping recv thread!\n");
// return -1;
// }
pthread_join(send_id, NULL);//等待send ping线程结束后进程再结束
// pthread_join(recv_id, NULL);//等待recv ping线程结束后进程再结束
ping_stats_show();
close(rawsock);
return 0;
}
int main(int argc, char* argv[]){
test();
return 0;
}
通过gdb分析得出的错误如下：
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `./icmp'.
Program terminated with signal 11, Segmentation fault.
#0 0x00007fff49903cbf in gettimeofday ()
Missing separate debuginfos, use: debuginfo-install glibc-2.17-157.el7_3.2.x86_64
(gdb) where
#0 0x00007fff49903cbf in gettimeofday ()
#1 0x0000000000401092 in ping_send () at a.c:152
#2 0x00007f8540e93dc5 in start_thread () from /lib64/libpthread.so.0
#3 0x00007f8540bc276d in clone () from /lib64/libc.so.6
