ftpserverdemo.c

一个简单的运行在LINUX下的FTPServer,仅完成文件传输及目录操作等常见的功能

    
    if (data_mode && stat(tmp, &s) == -1) 
    {
        Error(param);
        return;
    };
    if ((data_file = fopen(tmp, mode)) == NULL) {
        Error(param);
        return;
    };
    
    if (open_mode != 'a') fseek(data_file, file_rest, SEEK_SET);
    if (data_mode) {
        sprintf(tmp, "%s (%d bytes)", param, s.st_size - file_rest);
    } else {
        strcpy(tmp, param);
    };
    
    DataConnection(data_mode, transfer_type, tmp);
};
void Retr(char *param)
{
    PreConnection(param, 'r', 1);
};
void Stor(char *param)
{
    PreConnection(param, 'w', 0);
};
void Appe(char *param)
{
    PreConnection(param, 'a', 0);
};
void Abor(char *param)
{
    if (data_pid != 0) {
        kill(data_pid, SIGTERM);
    };
    
    outs("226 ABOR command successful.");
};
void Mdtm(char *param)
{
    struct stat s;
    struct tm *tms;
    
    if (stat(param, &s) == -1) {
        Error(param);
    } else {
        tms = localtime((const time_t *)&s.st_mtime);
        outs("213 %4d%2d%2d%2d%2d%2d", tms->tm_year, tms->tm_mon, tms->tm_mday, tms->tm_hour, tms->tm_min, tms->tm_sec);
    };
};
void Syst(char *param)
{
    outs("215 UNIX Type: L8");
};
void Rest(char *param)
{
    int r;
    
    r = atoi(param);
    
    if (r < 0 || (r == 0 && param[0] != '0')) {
        outs("501 REST requires a value greater than or equal to 0.");
        return;
    };
    
    file_rest = r;
    outs("350 Restarting at %u. Send STORE or RETRIEVE to initiate transfer.", file_rest);
};
void Rnfr(char *param)
{
    char tmp[PATH_MAX];
    struct stat s;
    
    MakePath(tmp, path, param);
    if (stat(tmp, &s) == -1) {
        Error(tmp);
    } else {
        outs("350 File or directory exists, ready for destination name.");
        strncpy(rename_file, param, PATH_MAX);
    };
};
void Rnto(char *param)
{
    char tmp[PATH_MAX];
    
    if (strcmp(rename_file, "") == 0) {
        outs("503 Bad sequence of commands.");
        return;
    };
    MakePath(tmp, path, param);
    if (rename(rename_file, tmp) == -1) {
        Error(tmp);
    } else {
        outs("250 RNTO command successful.");
        strcpy(rename_file, "");
    };
};
    
void Site(char *param)
{
    int i, mode;
    static char buf[BUFSIZE] = "250 ";
    FILE *f;
    char *p1, *p2, *p3, *p4, tmp[PATH_MAX], tmp2[PATH_MAX];
        
    explode(param, &p1, &p2);
    if (p1 == NULL || p2 == NULL || strncasecmp(p1, "CHMOD", 5) != 0) {
        outs("501 SITE option not supported.");
        return;
    };
    
    explode(p2, &p3, &p4);
    if (p3 == NULL || p4 == NULL) {
        outs("501 SITE option not supported.");
        return;
    };
    mode = strtol(p3, (char **)NULL, 8);
    if (chmod(p4, mode) == -1) {
        outs("501 SITE option not supported.");
    } else {
        outs("250 SITE command successful.");
    };
};
void Port(char *param)
{
    int i;
    struct _port tmp;
    unsigned char r, *ptr = (unsigned char *)&tmp;
    char *p, *ori = param;
    
    for (i=0;i<6;i++) {
        r = atoi(ori);
        if (r == 0 && *ori != '0') {
            outs("501 Syntax error in parameters or arguments.");
            return;
        };
        ptr[i] = r;
        p = strchr(ori, ',');
        if (p == NULL) {
            if (i != 5) {
                outs("501 Syntax error in parameters or arguments.");
                return;
            };
        } else {
            *p = 0;
            ori = p+1;
        };
    };
        
    memcpy(&remote_port, &tmp, sizeof(remote_port));
    pasv_mode = 0;
    outs("200 PORT Command successful.");
};
void Pasv(char *param)
{
    int port = port_base;
    struct sockaddr_in sa;
    char tmp[30], t2[10];
    int len, i;
    
    len = 1;
    close(pasvfd);
    if ((pasvfd = socket(AF_INET, SOCK_STREAM, 0)) == -1 || setsockopt(pasvfd, SOL_SOCKET, SO_REUSEADDR, (const char *)&len, sizeof(int)) == -1) 
    {
        outs("550 PASV command failed.");
        return;
    };
    memset(&sa, 0, sizeof(sa));
    sa.sin_family      = AF_INET;
    sa.sin_addr.s_addr = htonl(INADDR_ANY);
    do {
        port++;
        if (port == 65535) {
            outs("550 Can\'t bind any port.");
            return;
        };
        sa.sin_port = htons(port);
    } while (bind(pasvfd, (struct sockaddr *)&sa, sizeof(sa)) == -1 || listen(pasvfd, 1) == -1);
    local_port.port = htons(port);
    memset(tmp, 0, 18);
    for (i=0;i<6;i++) {
        sprintf(t2, "%u", ((unsigned char *)&local_port)[i]);
        strcat(tmp, t2);
        if (i!=5) strcat(tmp, ",");
    };
    
    pasv_mode = 1;
    outs("227 Entering Passive Mode (%s)", tmp);
};

struct _cmd_list cmd_list[] = {
    {"USER",    User,   CHECK_NOLOGIN | NEED_PARAM  },
    {"PASS",    Pass,   CHECK_NOLOGIN   },
    {"ACCT"},
    {"CWD",     Cwd,    CHECK_LOGIN | NEED_PARAM    },
    {"XCWD",    Cwd,    CHECK_LOGIN | NEED_PARAM    },
    {"CDUP",    Cdup,   CHECK_LOGIN | NO_PARAM      },
    {"XCUP",    Cdup,   CHECK_LOGIN | NO_PARAM      },
    {"SMNT"},
    {"QUIT",    Quit,   NO_CHECK    },
    {"REIN"},
    {"PORT",    Port,   CHECK_LOGIN | NEED_PARAM    },
    {"PASV",    Pasv,   CHECK_LOGIN | NO_PARAM      },
    {"TYPE",    Type,   CHECK_LOGIN | NEED_PARAM    },
    {"STRU"},
    {"MODE"},
    {"RETR",    Retr,   CHECK_LOGIN | NEED_PARAM    },
    {"STOR",    Stor,   CHECK_LOGIN | NEED_PARAM    },
    {"STOU"},
    {"APPE",    Appe,   CHECK_LOGIN | NEED_PARAM    },
    {"ALLO"},
    {"REST",    Rest,   CHECK_LOGIN | NEED_PARAM    },
    {"RNFR",    Rnfr,   CHECK_LOGIN | NEED_PARAM    },
    {"RNTO",    Rnto,   CHECK_LOGIN | NEED_PARAM    },
    {"ABOR",    Abor,   CHECK_LOGIN | NO_PARAM      },
    {"DELE",    Dele,   CHECK_LOGIN | NEED_PARAM    },
    {"MDTM",    Mdtm,   CHECK_LOGIN | NEED_PARAM    },
    {"RMD",     Rmd,    CHECK_LOGIN | NEED_PARAM    },
    {"XRMD",    Rmd,    CHECK_LOGIN | NEED_PARAM    },
    {"MKD",     Mkd,    CHECK_LOGIN | NEED_PARAM    },
    {"XMKD",    Mkd,    CHECK_LOGIN | NEED_PARAM    },
    {"PWD",     Pwd,    CHECK_LOGIN | NO_PARAM      },
    {"XPWD",    Pwd,    CHECK_LOGIN | NO_PARAM      },
    {"SIZE",    Size,   CHECK_LOGIN | NEED_PARAM    },
    {"LIST",    List,   CHECK_LOGIN },
    {"NLST",    List,   CHECK_LOGIN },
    {"SITE",    Site,   CHECK_LOGIN | NEED_PARAM    },
    {"SYST",    Syst,   CHECK_LOGIN },
    {"STAT",    Stat,   CHECK_LOGIN | NEED_PARAM    },
    {"HELP",    Help,   NO_CHECK    },
    {"NOOP",    Noop,   NO_CHECK    },
    {""}
};  
void do_alarm()
{
    outs("421 No Transfer Timeout (%d seconds): closing control connection", timeout);
    fclose(file);
    close(connfd);
    exit(0);
};
void do_child()
{
    int pid, ret;
    
    while ((pid = waitpid(-1, &ret, WNOHANG|WUNTRACED)) > 0) {
        if (pid == data_pid) {
            if (WIFEXITED(ret) && WEXITSTATUS(ret) == 0) outs("226 Transfer complete.");
            else if (WIFSIGNALED(ret) && WTERMSIG(ret) == SIGTERM) outs("425 Transfer aborted.");
            else outs("425 Transfer error.");
                
            fclose(data_file);
            if (pasv_mode) close(pasvfd);
            pasv_mode = 0;
            transfer = 0;
            data_pid = 0;
            file_rest = 0;
        };
    };
};
    
void do_term()
{
    outs("425 Transfer aborted.");
    exit(0);
};
int init()
{
    int n, i;
    struct sockaddr_in sa;
    struct hostent *host;
    struct in_addr ia;
    
    /* register the signal handler */
    signal(SIGCHLD, do_child);
    signal(SIGTERM, do_term);
    
    /* init network */  
    memset(&sa, 0, sizeof(sa));
    sa.sin_family      = AF_INET;
    sa.sin_addr.s_addr = htonl(INADDR_ANY);
    sa.sin_port        = htons(ftp_port);
    
    if (gethostname(hostname, BUFSIZE) == -1) strcpy(hostname, "");
        
    i = 1;
    if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1 || setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, (const char *)&i, sizeof(int)) == -1) 
    {
        perror("Pacific FTP:");
        return -1;
    };
    
    if (bind(listenfd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
        fprintf(stderr, "Pacific FTP: Can not bind port %d\n", ftp_port);
        return -1;
    };
    if (listen(listenfd, max_conn) == -1) {
        perror("Pacific FTP:");
        return -1;
    };
    /* set the program a daemon */
    if(fork()) exit(0);
    for (n = 0; n<3; n++) close(n);
    open("/dev/null", O_RDONLY);
    dup2(0,1);
    dup2(0,2);
    if((n=open("/dev/tty",O_RDWR)) > 0) {
        ioctl(n, TIOCNOTTY, 0) ;
        close(n);
    }
    setsid();
    
    if(fork()) exit(0);
    /* get the uid */
    system_uid = getuid();
}
int main(int argc, char **argv)
{
    struct sockaddr_in sa;
    int len, cur;
    int okay=1, i;
    char *cmd, *param;
    /* get the param */
    for (i=1; i<argc; i++) {
        if (argv[i][0] != '-' || argv[i][2] != ':') okay = 0;
        switch (argv[i][1]) {
            case 'p':
                ftp_port = atoi(&argv[i][3]);
                if (ftp_port == 0) okay = 0;
                break;
            case 'm':
                max_conn = atoi(&argv[i][3]);
                if (max_conn == 0) okay = 0;
                break;
            case 't':
                timeout = atoi(&argv[i][3]);
                if (timeout == 0) okay = 0;
                break;
            default:
                okay = 0;
        };
        if (!okay) break;
    };      
        
    if (!okay) {    
        printf("Usage: %s [-p:port] [-m:maxconn] [-t:timeout]\n\tport: default is 21.\n\tmaxconn: the max client num connected.\n", argv[0]);
        return -1;
    };
    if (init() == -1) return -1;
    
    /* main loop */
    while (1) 
    {
        len = sizeof(sa);
        connfd = accept(listenfd, (struct sockaddr *)&sa, &len);
        
        if (connfd == -1) continue;
        
        if (fork() == 0) 
        {
            len = sizeof(sa);
            getsockname(connfd, (struct sockaddr *)&sa, &len);
            local_port.host = sa.sin_addr.s_addr;
            file = fdopen(connfd, "rt+");
            setbuf(file, (char *)0);
            getcwd(path, PATH_MAX);
            outs("220 PacificFTP ready, hostname: %s", hostname);
            signal(SIGALRM, do_alarm);
            alarm(timeout);
            /* child process's main loop */
            while (fgets(inbuf, BUFSIZE, file) != NULL)
            {
                explode(inbuf, &cmd, &param);
                if (strcmp(cmd, "") == 0) continue;
                /* Make cmd UPPERCASE */
                for (i=0;i<strlen(cmd);i++) cmd[i]=toupper(cmd[i]);
                cur = 0;
                okay = 0;
                while (strcmp(cmd_list[cur].cmd, "") != 0) 
                {
                    if (strcmp(cmd_list[cur].cmd, cmd) == 0) {
                        if (cmd_list[cur].func == NULL) outs("502 %s command unimplemented.", cmd);
                        else 
                            if ((cmd_list[cur].check & NO_CHECK) || Check(cmd, param, cmd_list[cur].check))
                                (*cmd_list[cur].func)(param);
                        
                        okay = 1;
                        break;
                    };
                    cur++;
                };
                if (!okay) outs("500 %s not understood", cmd);
            };                                  
                    
            fclose(file);
            exit(0);
        };
        close(connfd);
    };
}