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

#include "FTPd.h"
void do_child();
　
/* 输出到客户端 */
void outs(char *fmt, ...)
{
    static char tmp[80];
    
    va_list ap;
    va_start(ap, fmt);
    sprintf(tmp, "%s\r\n", fmt);
    vsprintf(genbuf, tmp, ap);
    send(connfd, genbuf, strlen(genbuf), 0);
    va_end(ap);
};
　
/* 将buf以空格做分隔符分解成两个字符串 */
void explode(char *buf, char **cmd, char **param)
{
    char *p;
    
    while ((p = &buf[strlen(buf)-1]) && (*p == '\r' || *p == '\n')) *p = 0;
    p = strchr(buf, ' ');
    *cmd = buf;
    if (!p) *param = NULL;
    else {
        *p = 0;
        *param = p+1;
    };
};
int MakePath(char *new_path, char* path, char* filename)
{
    return sprintf(new_path, "%s%s/%s", basedir, path, filename);
};

void Error(char *param) 
{
    switch (errno) {
        case ENOTEMPTY:
            ERRS("Directory not empty");
            break;
        case ENOSPC:
            ERRS("disk full");
            break;          
        case EEXIST:
            ERRS("File exists");
            break;
        case ENAMETOOLONG:
            ERRS("path is too long");
            break;
        case ENOENT:
            ERRS("No such file or directory");
            break;
        case ENOTDIR:
            ERRS("Not a directory");
            break;
        case EISDIR:
            ERRS("Is a directory");
        default:
            ERRS("Permission denied");
    };
}
int Check(char *cmd, char *param, int check)
{
    if (check & CHECK_LOGIN && !user_valid) {
        outs("530 Please login with USER and PASS");
        return 0;
    };
    
    if (check & CHECK_NOLOGIN && user_valid) {
        outs("503 You are already logged in!");
        return 0;
    };
    
    if (check & NEED_PARAM) {
        if (!param) outs("501 Invalid number of arguments, check more arguments.");
        return (param != NULL);
    };
    
    if (check & NO_PARAM) {
        if (param) outs("501 Invalid number of arguments.");
        return (param == NULL);
    };
    return 1;
};
void DataConnection(int mode, int transfer_type, char *filename)
{
    int datafd;
    struct sockaddr_in sa;
    socklen_t len = sizeof(sa);
    char buf[BUFSIZE], *p;
    int readlen;
    FILE *tmp;
    if (data_pid != 0 && kill(data_pid, 0) == 0) {
        outs("425 Try later, data connection in use.");
        return;
    };
            
    if ((data_pid = fork()) == 0) {
        if (pasv_mode) {
            if ((datafd = accept(pasvfd, (struct sockaddr *)&sa, &len)) == -1) {
                close(pasvfd);
                exit(-1);
            };
            
        } else {
            memset(&sa, 0, len);
        
            sa.sin_family      = AF_INET;
            sa.sin_addr.s_addr = remote_port.host;
            sa.sin_port        = remote_port.port;
            
            if ((datafd = socket(AF_INET, SOCK_STREAM, 0)) == -1 || connect(datafd, (struct sockaddr *)&sa, len) == -1) {
                exit(-1);
            };
        };
        
        outs("150 Opening %s mode data connection for %s.", (transfer_type == 'i')?"BINARY":"ASCII", filename);
        
        if (mode) {
            /* write */
            if (transfer_type == 'i') {
                while ((readlen = fread(buf, 1, BUFSIZE, data_file)) >0 ) {
                    send(datafd, buf, readlen, 0);
                };
            } else {
                while ((fgets(buf, BUFSIZE, data_file) != NULL)) {
                    while ((p = &buf[strlen(buf)-1]) && (*p == '\r' || *p == '\n')) *p = 0;
                    strcat(buf, "\r\n");
                    send(datafd, buf, strlen(buf), 0);
                };
            };
        } else {
            /* read */
            if (transfer_type == 'i') {
                while ((readlen = recv(datafd, buf, BUFSIZE, 0)) >0 ) {
                    if (fwrite(buf, 1, readlen, data_file) == -1) break;
                };
            } else {
                tmp = fdopen(datafd, "r");
                while ((fgets(buf, BUFSIZE, tmp) != NULL)) {
                    while ((p = &buf[strlen(buf)-1]) && (*p == '\r' || *p == '\n')) *p = 0;
                    strcat(buf, "\n");
                    if (fwrite(buf, 1, strlen(buf), data_file) == -1) break;
                };
            };
        };          
            
        close(datafd);
        exit(0);
    };
};


void Help(char *param)
{
    if (!param) {
        outs("214 The following commands are recognized (* =>'s unimplemented).");
        outs("214   USER    PASS    ACCT*   CWD     XCWD    CDUP    XCUP    SMNT*   ");
        outs("214   QUIT    REIN*   PORT    PASV    TYPE    STRU*   MODE*   RETR    ");
        outs("214   STOR    STOU*   APPE    ALLO*   REST    RNFR    RNTO    ABOR    ");
        outs("214   DELE    MDTM    RMD     XRMD    MKD     XMKD    PWD     XPWD    ");
        outs("214   SIZE    LIST    NLST    SITE    SYST    STAT    HELP    NOOP    ");
        outs("214 Direct comments to [e-mail]");
    } else {
        outs("214 Sorry, I haven't write the topic help.");
    };
};
void User(char *param)
{
    if (user_valid) {
        outs("503 You are already logged in!");
        return;
    };
    
    if (!param) {
        outs("500 \'USER\': command requires a parameter.");
        return;
    };
    
    strncpy(username, param, 100);
    if (strcasecmp(username, "anonymous") == 0) {
        anonymous_login = 1;
        strncpy(username, "ftp", 100);
        outs("331 Anonymous login ok, send your complete e-mail address as password.");
    } else outs("331 Password required for %s", username);
    
    input_user = 1;
};
void Pass(char *param)
{
    struct passwd *pw;
    struct spwd *spw;
    char *passwd, salt[13];
    
    if (!input_user) {
        outs("503 Login with USER first.");
        return;
    };
    
    /* judge and chdir to its home directory */
    if (!anonymous_login) {
        if (system_uid != 0) {
            outs("530 Login incorrect.");
            input_user = 0;
            return;
        };
                
        if ((pw = getpwnam(username)) == NULL) {
            outs("530 Login incorrect.");
            input_user = 0;
            return;
        };
    
        passwd = pw->pw_passwd;
        if (passwd == NULL || strcmp(passwd, "x") == 0) {
            spw = getspnam(username);
            if (spw == NULL || (passwd = spw->sp_pwdp) == NULL) {
                outs("530 Login incorrect.");
                input_user = 0;
                return;
            };
        };
        strncpy(salt, passwd, 12);
        if (strcmp(passwd, crypt(param, salt)) != 0) {
            outs("530 Login incorrect.");
            input_user = 0;
            return;
        };
        strcpy(path, "");
        setuid(pw->pw_uid);
        if (pw->pw_dir) strncpy(path, pw->pw_dir, PATH_MAX);
            else strcpy(path, "/");
        outs("230 User %s logged in.", username);
        chdir(path);
        getcwd(path, PATH_MAX);
        user_valid = 1;
    
    } else {
        if ((pw = getpwuid(system_uid)) == NULL) {
            outs("530 Login incorrect.");
            input_user = 0;
            return;
        };
        if (pw->pw_dir) strncpy(basedir, pw->pw_dir, PATH_MAX); 
            else strcpy(basedir, "");
        
        strcpy(path, "/");
        chdir(basedir);
        getcwd(basedir, PATH_MAX);
        user_valid = 1;
        outs("230 Anonymous access granted, restrictions apply.");
    };
    user_valid = 1;
    outs("230 Anonymous access granted, restrictions apply.");
};
void Pwd(char *param)
{
    outs("257 \"%s\" is current directory.", path);
};
void Cwd(char *param)
{
    char tmp[PATH_MAX];
    
    if (param[0] == '/') MakePath(tmp, "", param); else MakePath(tmp, path, param);
    if (chdir(tmp) == -1) {
        Error(param);
    } else {
        if (getcwd(tmp, PATH_MAX) == NULL) ERRS("Permission denied");
        else {
            if (anonymous_login) {
                if (strncmp(basedir, tmp, strlen(basedir)) != 0) {
                    chdir(basedir);
                    strcpy(path, "/");
                } else {
                    strncpy(path, &tmp[strlen(basedir)], PATH_MAX);
                    strcat(path, "/");
                };
            } else strcpy(path, tmp);
            outs("250 CWD command successful.");
        };
    };
};
void Cdup(char *param)
{
    Cwd("..");
};
void Mkd(char *param)
{
    if (mkdir(param, 0755) == -1) {
        Error(param);
    } else {
        outs("257 \"%s/%s\" - Directory successfully created.", path, param);
    };
};
void Rmd(char *param)
{
    if (rmdir(param) == -1) {
        Error(param);
    } else {
        outs("250 RMD command successful.");
    };
};
void Type(char *param)
{
    if (strcasecmp(param, "i") == 0) {
        outs("200 Type set to I");
        transfer_type = 'i';
        return;
    };
    
    if (strcasecmp(param, "a") == 0) {
        outs("200 Type set to A");
        transfer_type = 'a';
        return;
    };
    
    outs("500 \'TYPE %s\' not understood.", param);
};
void Size(char *param)
{
    struct stat s;
    if (stat(param, &s) == -1) {
        Error(param);
    } else {
        if (S_ISREG(s.st_mode)) outs("213 %d", s.st_size);
            else outs("550 %s: not a regular file.", param);
    };
};
void Stat(char *param)
{
    FILE *f;
    static char tmp[PATH_MAX], tmp2[PATH_MAX];
    static char statbuf[BUFSIZE];
    
    outs("211-status of \"%s\":", param);
    if (strchr(param, ' ') != NULL) sprintf(tmp2, "\"%s\"", param); 
        else sprintf(tmp2, "%s", param);
    sprintf(tmp, "/bin/ls -l --color=never %s", tmp2);
    if ((f = popen(tmp, "r")) != NULL) {
        while (fgets(statbuf, BUFSIZE, f) != NULL) {
            if (statbuf[0] == 't') continue;
            send(connfd, statbuf, strlen(statbuf), 0);
        };
        pclose(f);
    };
    outs("211 End of Status");
};
void Dele(char *param)
{
    if (unlink(param) == -1) {
        Error(param);
    } else {
        FIXME: outs("250 DELE command successful.", param);
    };
};
    
void Quit(char *param)
{
    outs("221 Goodbye");
    fclose(file);
    exit(0);
};
void Noop(char *param)
{
    outs("200 NOOP command successful");
};
void DoList(char *param, char *cmd)
{
    char tmp[PATH_MAX], tmp2[PATH_MAX];
    char *mode = "r";
    
    MakePath(tmp, path, param);
    if (param) {
        if (strchr(param, ' ') != NULL) sprintf(tmp2, "\"%s\"", param); 
            else sprintf(tmp2, "%s", param);
    } else strcpy(tmp2, "");
    sprintf(tmp, "/bin/ls %s --color=never %s", cmd, tmp2);
    if ((data_file = popen(tmp, mode)) == NULL) {
        Error("LIST");
        return;
    };
    
    DataConnection(1, 'a', "/bin/ls");
};
void List(char *param)
{
    DoList(param, "-l");
};
void Nlst(char *param)
{
    DoList(param, "-1");
};
void PreConnection(char *param, char open_mode, int data_mode)
{
    char tmp[PATH_MAX];
    char mode[3];
    struct stat s;
    
    MakePath(tmp, path, param);
    mode[0] = open_mode;
    if (transfer_type == 'i') mode[1] = 'b'; else mode[1] = 't';
    mode[2] = 0;