我開發了一個C軟件,它使用不同的循環來打開IP和端口上的套接字(例如192.168.1.10端口= 80),並檢查是否有人被打開; 下面是代碼:如何管理大量的套接字
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>
int main(void)
{
int sockfd = 0,n = 0;
char recvBuff[1024];
struct sockaddr_in serv_addr;
memset(recvBuff, '0' ,sizeof(recvBuff));
if((sockfd = socket(AF_INET, SOCK_STREAM, 0))< 0)
{
printf("\n Error : Could not create socket \n");
}
serv_addr.sin_family = AF_INET;
int i;
char buf[15];
for (i = 1; i < 255; i++) {
sprintf(buf, "192.168.1.%d", i); // puts string into buffer
for (int port = 0; port<=1024; port++) {
// Problem
// int sockfd = 0,n = 0;
// char recvBuff[1024];
// struct sockaddr_in serv_addr;
//
// memset(recvBuff, '0' ,sizeof(recvBuff));
// if((sockfd = socket(AF_INET, SOCK_STREAM, 0))< 0)
// {
// printf("\n Error : Could not create socket \n");
// return 1;
// }
serv_addr.sin_port = htons(port);
serv_addr.sin_addr.s_addr = inet_addr(buf);
if(connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr))<0)
{
// printf("The port %d of host %s is not open \n",port,buf);
}else{
printf("The port %d of host %s is open \n",port,buf);
}
}
}
return 0;
}
在我已經添加了connection_nonblocking方法,它可以減少可能出現的問題這第二個版本。 這是使用OpenMP指令來提高性能的版本;你有什麼想法來改進它嗎?
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>
#include <time.h>
#include <omp.h>
int connect_nonblock (int sockfd, const struct sockaddr *saptr, socklen_t salen)
{
int n, valopt;
socklen_t len;
fd_set rset;
struct timeval tv;
long int arg;
arg = fcntl(sockfd, F_GETFL, NULL);
arg |= O_NONBLOCK;
fcntl(sockfd, F_SETFL, arg);
n = connect(sockfd, saptr, salen);
if (n == 0) {
// completed immediately
arg &= (~O_NONBLOCK);
fcntl(sockfd, F_SETFL, arg);
close(sockfd);
return 0;
}
if (n < 0) {
if (errno != EINPROGRESS) {
// fail somehow...
arg &= (~O_NONBLOCK);
fcntl(sockfd, F_SETFL, arg);
close(sockfd);
return -1;
}
else {
tv.tv_sec = 0;
tv.tv_usec = 10000;
FD_ZERO(&rset);
FD_SET(sockfd, &rset);
n = select(sockfd + 1, NULL, &rset, NULL, &tv);
if (n < 0 && errno != EINTR) {
arg &= (~O_NONBLOCK);
fcntl(sockfd, F_SETFL, arg);
close(sockfd);
return -1;
}
else if (n > 0) {
len = sizeof(int);
getsockopt(sockfd, SOL_SOCKET, SO_ERROR, (void*)(&valopt), &len);
if (valopt != 0) {
arg &= (~O_NONBLOCK);
fcntl(sockfd, F_SETFL, arg);
close(sockfd);
return -1;
}
}
else {
arg &= (~O_NONBLOCK);
fcntl(sockfd, F_SETFL, arg);
close(sockfd);
return -1;
}
}
}
arg &= (~O_NONBLOCK);
fcntl(sockfd, F_SETFL, arg);
close(sockfd);
return 0;
}
int main(void)
{
int sockfd = 0;
struct sockaddr_in serv_addr;
int i, port;
char buf[15];
double end, start = omp_get_wtime();
for (i = 1; i <= 255; i++) {
sprintf(buf, "192.168.1.%d", i); // puts string into buffer
fprintf(stdout, "Checking address: %s\n", buf);
//omp_set_num_threads(1);
#pragma omp parallel for private(sockfd,serv_addr,port)
for (port = 0; port <= 1024; port++) {
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
perror("socket");
}
memset(&serv_addr, 0, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(port);
serv_addr.sin_addr.s_addr = inet_addr(buf);
if (connect_nonblock(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
/* uncoment this but if you want */
//fprintf(stdout, "The port %d of host %s is not open.\n", port, buf);
;
}
else {
fprintf(stdout, "The port %d of host %s is open.\n", port, buf);
}
}
}
end = omp_get_wtime();
printf("Elapsed time = %f sec\n", end-start);
return 0;
}
一個建議:我覺得你的意思'memset的(recvBuff,0,的sizeof(recvBuff));' – 2015-02-17 20:14:21
你可以用」連接成功後,請在同一個套接字上反覆調用連接。您需要在每次成功連接後創建一個新套接字(並跟蹤所有這些套接字)或關閉現有套接字並重新創建套接字。在前一種情況下,如果網絡中有大量計算機,則可能會用完文件描述符。如果連接的呼叫似乎掛起,那麼目標機器不存在或者沒有應答,並且您沒有收到ICMP消息告訴你這麼快。相反,連接調用在很長一段時間後最終會超時。 – jschultz410 2015-02-17 20:25:08
謝謝。我還沒有完全理解如何關閉和重新打開套接字。你能修改我使用這些操作發佈的代碼嗎? – 2015-02-17 20:33:29