tcp端口扫描程序，connetct方法

#include <stdio.h> #include <sys/socket.h> #include <sys/types.h> #include <sys/select.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <netinet/in.h> #include <errno.h> #include <netdb.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #define MINPORT 0 #define MAXPORT 1000 int main(int argc,char **argv) { int fd[MAXPORT]; int flags,n,i,rst,maxfd,count=0; int port[MAXPORT]; struct sockaddr_in addr[MAXPORT]; fd_set rset,wset; struct timeval tm; int addrsize=sizeof(struct sockaddr); struct servent *sent; FD_ZERO(&rset); FD_ZERO(&wset); tm.tv_sec=5; tm.tv_usec=0; for(i=MINPORT;i<MAXPORT;i++) /* 可能在此循环完前就有connect返回 */ { if((fd[i]=socket(AF_INET,SOCK_STREAM,0))==-1) { perror("Socket"); exit(-1); } /* 设置fd为非阻塞 */ flags=fcntl(fd[i],F_GETFL,0); fcntl(fd[i],F_SETFL,flags|O_NONBLOCK); port[i]=i+1; bzero((struct sockaddr*)&addr[i],addrsize); addr[i].sin_family=AF_INET; addr[i].sin_addr.s_addr=inet_addr(argv[1]); addr[i].sin_port=htons((short)port[i]); if((n=connect(fd[i],(struct sockaddr *)&addr[i],addrsize))<0) if(errno!=EINPROGRESS) {printf("Connecting 1 error!\n"); exit(1);} else if(n==0) { //This case may be happen on localhost printf("Connecting 1 success! \n"); exit(0); } FD_SET(fd[i],&rset); } wset=rset; sleep(1); rst=select(MAXPORT+3, &rset,&wset,NULL,&tm); switch (rst) { case -1: perror("Select error"); exit(-1); case 0: for(i=MINPORT;i<MAXPORT;i++) close(fd[i]); printf("Timed Out!\n"); break; default: for(i=MINPORT;i<MAXPORT;i++) { if (FD_ISSET(fd[i],&rset)||FD_ISSET(fd[i],&wset)) { int error; socklen_t len = sizeof (error); if(getsockopt(fd[i],SOL_SOCKET,SO_ERROR,&error,&len) < 0) { printf ("getsockopt fail,connected fail\n"); return -1; } if(error==0) { if((sent=getservbyport(htons(i+1),"tcp"))==NULL) { printf("Unknown service(port %d) is available. \n",i+1); } else { printf("%s\tservice(port %d) is avilable. \n",sent->s_name,i+1); } count++; } } close(fd[i]); } } if(count==0) printf("There is no port open or the domain has down!\n"); return 0; }