运行于linux平台下的小型ftp服务器

/*************************************************************************** * connections.c * * Copyright 2005 Dimitur Kirov * dkirov@gmail.com ****************************************************************************/ /* * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include <stdio.h> #include <unistd.h> #include <netinet/tcp.h> #include <sys/socket.h> #include <sys/types.h> #include <sys/stat.h> #include <arpa/inet.h> #include <string.h> #include <stdlib.h> #include <sys/wait.h> #include <signal.h> #include <assert.h> #include <netdb.h> #include <errno.h> #include <dirent.h> #include "defines.h" #include "cmdparser.h" #include "fileutils.h" int open_connections; bool max_limit_notify; int raiseerr(int err_code) { printf("Error %d\n",err_code); return -1; } /** * This is neccessary for future use of glib and gettext based localization. */ const char * _(const char* message) { return message; } /** * Guess the transfer type, given the client requested type. * Actually in unix there is no difference between binary and * ascii mode when we work with file descriptors. * If #type is not recognized as a valid client request, -1 is returned. */ int get_type(const char *type) { if(type==NULL) return -1; int len = strlen(type); if(len==0) return -1; switch(type[0]) { case 'I': return 1; case 'A': return 2; case 'L': if(len<3) return -1; if(type[2]=='7') return 3; if(type[2]=='8') return 4; } return -1; } /** * Create a new connection to a (address,port) tuple, retrieved from * the PORT command. This connection will be used for data transfers * in commands like "LIST","STOR","RETR" */ int make_client_connection(int sock_fd,int client_port,const char* client_addr) { if(client_port<1) { send_repl(sock_fd,REPL_425); return -1; } int sock=-1; struct sockaddr_in servaddr; servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr = inet_addr(client_addr); servaddr.sin_port = htons (client_port); if ((sock = socket (PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) { send_repl(sock,REPL_425); raiseerr(15); return -1; } int status = connect (sock, (struct sockaddr *)&servaddr, sizeof (servaddr)); if(status!=0) { send_repl(sock,REPL_425); return -1; } return sock; } /** * Close the connection to the client and exit the child proccess. * Although it is the same as close(sock_fd), in the future it can be used for * logging some stats about active and closed sessions. */ void close_conn(int sock_fd) { if (close(sock_fd) < 0) { raiseerr (5); } exit(0); } /** * Get the next command from the client socket. */ int get_command(int conn_fd,char *read_buff1,char *data_buff) { char read_buff[RCVBUFSIZE]; memset((char *)&read_buff, 0, RCVBUFSIZE); read_buff[0]='\0'; char *rcv=read_buff; int cmd_status = -1; int recvbuff = recv(conn_fd,read_buff,RCVBUFSIZE,0); if(recvbuff<1) { return CMD_CLOSE; } if(recvbuff==RCVBUFSIZE) { return CMD_UNKNOWN; } // printf("Received:%s\n",rcv); cmd_status = parse_input(rcv,data_buff); return cmd_status; } /** * A handler, which is called on child proccess exit. */ void sig_chld_handler(void) { open_connections--; while (waitpid(-1, NULL, WNOHANG) > 0); } /** * Send reply to the client socket, given the reply. */ int send_repl(int send_sock,char *msg) { if (send(send_sock, msg, strlen(msg),0) < 0) { raiseerr (4); close(send_sock); exit(0); } return 0; } /** * Send single reply to the client socket, given the reply and its length. */ int send_repl_client_len(int send_sock,char *msg,int len) { if (send(send_sock, msg, len,0) < 0) { raiseerr (4); close(send_sock); } return 0; } /* Izprashtane na edinishen otgovor do dopulnitelnia socket za transfer */ int send_repl_client(int send_sock,char *msg) { send_repl_client_len(send_sock,msg,strlen(msg)); return 0; } /** * Send single reply to the additional transfer socket, given the raply and its length. */ int send_repl_len(int send_sock,char *msg,int len) { if (send(send_sock, msg, len,0) < 0) { raiseerr (4); close(send_sock); exit(0); } return 0; } /** * Parses the results from the PORT command, writes the * address in "client_addt" and returnes the port */ int parse_port_data(char *data_buff,char *client_addr) { client_addr[0]='\0'; int len=0; int port=0; int _toint=0; char *result; result = strtok(data_buff, PORTDELIM); _toint=toint(result,FALSE); if(_toint<1 || _toint>254) return -1; len += strlen(result); strcpy(client_addr,result); client_addr[len]='\0'; strcat(client_addr,"."); len++; result = strtok(NULL, PORTDELIM); _toint=toint(result,FALSE); if(_toint<0 || _toint>254) return -1; len += strlen(result); strcat(client_addr,result); client_addr[len]='\0'; strcat(client_addr,"."); len++; result = strtok(NULL, PORTDELIM); if(_toint<0 || _toint>254) return -1; len += strlen(result); strcat(client_addr,result); client_addr[len]='\0'; strcat(client_addr,"."); len++; result = strtok(NULL, PORTDELIM); if(_toint<0 || _toint>254) return -1; len += strlen(result); strcat(client_addr,result); client_addr[len]='\0'; result = strtok(NULL, PORTDELIM); len = toint(result,FALSE); if(_toint<0 || _toint>255) return -1; port = 256*len; result = strtok(NULL, PORTDELIM); len = toint(result,FALSE); if(_toint<0 || _toint>255) return -1; port +=len; return port; } void print_help(int sock) { send_repl(sock," Some help message.\r\n Probably nobody needs help from telnet.\r\n See rfc959.\r\n"); } /** * Main cycle for client<->server communication. * This is done synchronously. On each client message, it is parsed and recognized, * certain action is performed. After that we wait for the next client message * */ int interract(int conn_fd,cmd_opts *opts) { static int BANNER_LEN = strlen(REPL_220); int userid = opts->userid; int client_fd=-1; int len; int _type ; int type = 2; // ASCII TYPE by default if(userid>0) { int status = setreuid(userid,userid); if(status != 0) { switch(errno) { case EPERM: break; case EAGAIN: break; default: break; } close_conn(conn_fd); } } if(max_limit_notify) { send_repl(conn_fd,REPL_120); close_conn(conn_fd); } char current_dir[MAXPATHLEN]; char parent_dir[MAXPATHLEN]; char virtual_dir[MAXPATHLEN]; char reply[SENDBUFSIZE]; char data_buff[DATABUFSIZE]; char read_buff[RCVBUFSIZE]; char *str; bool is_loged = FALSE; bool state_user = FALSE; char rename_from[MAXPATHLEN]; memset((char *)&current_dir, 0, MAXPATHLEN); strcpy(current_dir,opts->chrootdir); strcpy(parent_dir,opts->chrootdir); free(opts); chdir(current_dir); if((getcwd(current_dir,MAXPATHLEN)==NULL)) { raiseerr(19); close_conn(conn_fd); } memset((char *)&data_buff, 0, DATABUFSIZE); memset((char *)&read_buff, 0, RCVBUFSIZE); reply[0]='\0'; int client_port = 0; char client_addr[ADDRBUFSIZE]; send_repl_len(conn_fd,REPL_220,BANNER_LEN); while(1) { data_buff[0]='\0'; int result = get_command(conn_fd,read_buff,data_buff); if(result != CMD_RNFR && result != CMD_RNTO && result != CMD_NOOP) rename_from[0]='\0'; switch(result) { case CMD_UNKNOWN: case -1: send_repl(conn_fd,REPL_500); break; case CMD_EMPTY: ca