/* vi: set sw=4 ts=4: */ /* * Simple FTP daemon, based on vsftpd 2.0.7 (written by Chris Evans) * * Author: Adam Tkac * * Licensed under GPLv2, see file LICENSE in this tarball for details. * * Only subset of FTP protocol is implemented but vast majority of clients * should not have any problem. You have to run this daemon via inetd. */ #include "libbb.h" #include #include #define FTP_DATACONN 150 #define FTP_NOOPOK 200 #define FTP_TYPEOK 200 #define FTP_PORTOK 200 #define FTP_STRUOK 200 #define FTP_MODEOK 200 #define FTP_ALLOOK 202 #define FTP_STATOK 211 #define FTP_STATFILE_OK 213 #define FTP_HELP 214 #define FTP_SYSTOK 215 #define FTP_GREET 220 #define FTP_GOODBYE 221 #define FTP_TRANSFEROK 226 #define FTP_PASVOK 227 /*#define FTP_EPRTOK 228*/ #define FTP_EPSVOK 229 #define FTP_LOGINOK 230 #define FTP_CWDOK 250 #define FTP_RMDIROK 250 #define FTP_DELEOK 250 #define FTP_RENAMEOK 250 #define FTP_PWDOK 257 #define FTP_MKDIROK 257 #define FTP_GIVEPWORD 331 #define FTP_RESTOK 350 #define FTP_RNFROK 350 #define FTP_TIMEOUT 421 #define FTP_BADSENDCONN 425 #define FTP_BADSENDNET 426 #define FTP_BADSENDFILE 451 #define FTP_BADCMD 500 #define FTP_COMMANDNOTIMPL 502 #define FTP_NEEDUSER 503 #define FTP_NEEDRNFR 503 #define FTP_BADSTRU 504 #define FTP_BADMODE 504 #define FTP_LOGINERR 530 #define FTP_FILEFAIL 550 #define FTP_NOPERM 550 #define FTP_UPLOADFAIL 553 #define STR1(s) #s #define STR(s) STR1(s) /* Convert a constant to 3-digit string, packed into uint32_t */ enum { /* Shift for Nth decimal digit */ SHIFT2 = 0 * BB_LITTLE_ENDIAN + 24 * BB_BIG_ENDIAN, SHIFT1 = 8 * BB_LITTLE_ENDIAN + 16 * BB_BIG_ENDIAN, SHIFT0 = 16 * BB_LITTLE_ENDIAN + 8 * BB_BIG_ENDIAN, }; #define STRNUM32(s) (uint32_t)(0 \ | (('0' + ((s) / 1 % 10)) << SHIFT0) \ | (('0' + ((s) / 10 % 10)) << SHIFT1) \ | (('0' + ((s) / 100 % 10)) << SHIFT2) \ ) struct globals { int pasv_listen_fd; int proc_self_fd; int local_file_fd; int start_time; int abs_timeout; int timeout; off_t local_file_pos; off_t restart_pos; len_and_sockaddr *local_addr; len_and_sockaddr *port_addr; char *ftp_cmd; char *ftp_arg; #if ENABLE_FEATURE_FTP_WRITE char *rnfr_filename; #endif }; #define G (*(struct globals*)&bb_common_bufsiz1) #define INIT_G() do { } while (0) static char * escape_text(const char *prepend, const char *str, unsigned escapee) { unsigned retlen, remainlen, chunklen; char *ret, *found; char append; append = (char)escapee; escapee >>= 8; remainlen = strlen(str); retlen = strlen(prepend); ret = xmalloc(retlen + remainlen * 2 + 1 + 1); strcpy(ret, prepend); for (;;) { found = strchrnul(str, escapee); chunklen = found - str + 1; /* Copy chunk up to and including escapee (or NUL) to ret */ memcpy(ret + retlen, str, chunklen); retlen += chunklen; if (*found == '\0') { /* It wasn't escapee, it was NUL! */ ret[retlen - 1] = append; /* replace NUL */ ret[retlen] = '\0'; /* add NUL */ break; } ret[retlen++] = escapee; /* duplicate escapee */ str = found + 1; } return ret; } /* Returns strlen as a bonus */ static unsigned replace_char(char *str, char from, char to) { char *p = str; while (*p) { if (*p == from) *p = to; p++; } return p - str; } /* NB: status_str is char[4] packed into uint32_t */ static void cmdio_write(uint32_t status_str, const char *str) { char *response; int len; /* FTP allegedly uses telnet protocol for command link. * In telnet, 0xff is an escape char, and needs to be escaped: */ response = escape_text((char *) &status_str, str, (0xff << 8) + '\r'); /* ?! does FTP send embedded LFs as NULs? wow */ len = replace_char(response, '\n', '\0'); response[len++] = '\n'; /* tack on trailing '\n' */ xwrite(STDOUT_FILENO, response, len); free(response); } static void cmdio_write_ok(int status) { fdprintf(STDOUT_FILENO, "%u Operation successful\r\n", status); } /* TODO: output strerr(errno) if errno != 0? */ static void cmdio_write_error(int status) { fdprintf(STDOUT_FILENO, "%u Error\r\n", status); } static void cmdio_write_raw(const char *p_text) { xwrite_str(STDOUT_FILENO, p_text); } static void timeout_handler(int sig UNUSED_PARAM) { off_t pos; int sv_errno = errno; if (monotonic_sec() - G.start_time > G.abs_timeout) goto timed_out; if (!G.local_file_fd) goto timed_out; pos = xlseek(G.local_file_fd, 0, SEEK_CUR); if (pos == G.local_file_pos) goto timed_out; G.local_file_pos = pos; alarm(G.timeout); errno = sv_errno; return; timed_out: cmdio_write_raw(STR(FTP_TIMEOUT)" Timeout\r\n"); /* TODO: do we need to abort (as opposed to usual shutdown) data transfer? */ exit(1); } /* Simple commands */ static void handle_pwd(void) { char *cwd, *response; cwd = xrealloc_getcwd_or_warn(NULL); if (cwd == NULL) cwd = xstrdup(""); /* We have to promote each " to "" */ response = escape_text(" \"", cwd, ('"' << 8) + '"'); free(cwd); cmdio_write(STRNUM32(FTP_PWDOK), response); free(response); } static void handle_cwd(void) { if (!G.ftp_arg || chdir(G.ftp_arg) != 0) { cmdio_write_error(FTP_FILEFAIL); return; } cmdio_write_ok(FTP_CWDOK); } static void handle_cdup(void) { G.ftp_arg = (char*)".."; handle_cwd(); } static void handle_stat(void) { cmdio_write_raw(STR(FTP_STATOK)"-FTP server status:\r\n" " TYPE: BINARY\r\n" STR(FTP_STATOK)" Ok\r\n"); } /* TODO: implement FEAT. Example: # nc -vvv ftp.kernel.org 21 ftp.kernel.org (130.239.17.4:21) open 220 Welcome to ftp.kernel.org. FEAT 211-Features: EPRT EPSV MDTM PASV REST STREAM SIZE TVFS UTF8 211 End HELP 214-The following commands are recognized. ABOR ACCT ALLO APPE CDUP CWD DELE EPRT EPSV FEAT HELP LIST MDTM MKD MODE NLST NOOP OPTS PASS PASV PORT PWD QUIT REIN REST RETR RMD RNFR RNTO SITE SIZE SMNT STAT STOR STOU STRU SYST TYPE USER XCUP XCWD XMKD XPWD XRMD 214 Help OK. */ static void handle_help(void) { cmdio_write_raw(STR(FTP_HELP)"-Commands:\r\n" " ALLO CDUP CWD EPSV HELP LIST\r\n" " MODE NLST NOOP PASS PASV PORT PWD QUIT\r\n" " REST RETR SIZE STAT STRU SYST TYPE USER\r\n" #if ENABLE_FEATURE_FTP_WRITE " APPE DELE MKD RMD RNFR RNTO STOR STOU\r\n" #endif STR(FTP_HELP)" Ok\r\n"); } /* Download commands */ static inline int port_active(void) { return (G.port_addr != NULL); } static inline int pasv_active(void) { return (G.pasv_listen_fd > STDOUT_FILENO); } static void port_pasv_cleanup(void) { free(G.port_addr); G.port_addr = NULL; if (G.pasv_listen_fd > STDOUT_FILENO) close(G.pasv_listen_fd); G.pasv_listen_fd = -1; } /* On error, emits error code to the peer */ static int ftpdataio_get_pasv_fd(void) { int remote_fd; remote_fd = accept(G.pasv_listen_fd, NULL, 0); if (remote_fd < 0) { cmdio_write_error(FTP_BADSENDCONN); return remote_fd; } setsockopt(remote_fd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); return remote_fd; } /* Clears port/pasv data. * This means we dont waste resources, for example, keeping * PASV listening socket open when it is no longer needed. * On error, emits error code to the peer (or exits). * On success, emits p_status_msg to the peer. */ static int get_remote_transfer_fd(const char *p_status_msg) { int remote_fd; if (pasv_active()) /* On error, emits error code to the peer */ remote_fd = ftpdataio_get_pasv_fd(); else /* Exits on error */ remote_fd = xconnect_stream(G.port_addr); port_pasv_cleanup(); if (remote_fd < 0) return remote_fd; cmdio_write(STRNUM32(FTP_DATACONN), p_status_msg); return remote_fd; } /* If there were neither PASV nor PORT, emits error code to the peer */ static int port_or_pasv_was_seen(void) { if (!pasv_active() && !port_active()) { cmdio_write_raw(STR(FTP_BADSENDCONN)" Use PORT or PASV first\r\n"); return 0; } return 1; } /* Exits on error */ static unsigned bind_for_passive_mode(void) { int fd; unsigned port; port_pasv_cleanup(); G.pasv_listen_fd = fd = xsocket(G.local_addr->u.sa.sa_family, SOCK_STREAM, 0); setsockopt_reuseaddr(fd); set_nport(G.local_addr, 0); xbind(fd, &G.local_addr->u.sa, G.local_addr->len); xlisten(fd, 1); getsockname(fd, &G.local_addr->u.sa, &G.local_addr->len); port = get_nport(&G.local_addr->u.sa); port = ntohs(port); return port; } /* Exits on error */ static void handle_pasv(void) { unsigned port; char *addr, *response; port = bind_for_passive_mode(); if (G.local_addr->u.sa.sa_family == AF_INET) addr = xmalloc_sockaddr2dotted_noport(&G.local_addr->u.sa); else /* seen this in the wild done by other ftp servers: */ addr = xstrdup("0.0.0.0"); replace_char(addr, '.', ','); response = xasprintf(STR(FTP_PASVOK)" Entering Passive Mode (%s,%u,%u)\r\n", addr, (int)(port >> 8), (int)(port & 255)); free(addr); cmdio_write_raw(response); free(response); } /* Exits on error */ static void handle_epsv(void) { unsigned port; char *response; port = bind_for_passive_mode(); response = xasprintf(STR(FTP_EPSVOK)" EPSV Ok (|||%u|)\r\n", port); cmdio_write_raw(response); free(response); } /* libbb candidate */ static len_and_sockaddr* get_peer_lsa(int fd) { len_and_sockaddr *lsa; socklen_t len = 0; if (getpeername(fd, NULL, &len) != 0) return NULL; lsa = xzalloc(LSA_LEN_SIZE + len); lsa->len = len; getpeername(fd, &lsa->u.sa, &lsa->len); return lsa; } static void handle_port(void) { unsigned port, port_hi; char *raw, *comma; #ifdef WHY_BOTHER_WE_CAN_ASSUME_IP_MATCHES socklen_t peer_ipv4_len; struct sockaddr_in peer_ipv4; struct in_addr port_ipv4_sin_addr; #endif port_pasv_cleanup(); raw = G.ftp_arg; /* PORT command format makes sense only over IPv4 */ if (!raw #ifdef WHY_BOTHER_WE_CAN_ASSUME_IP_MATCHES || G.local_addr->u.sa.sa_family != AF_INET #endif ) { bail: cmdio_write_error(FTP_BADCMD); return; } comma = strrchr(raw, ','); if (comma == NULL) goto bail; *comma = '\0'; port = bb_strtou(&comma[1], NULL, 10); if (errno || port > 0xff) goto bail; comma = strrchr(raw, ','); if (comma == NULL) goto bail; *comma = '\0'; port_hi = bb_strtou(&comma[1], NULL, 10); if (errno || port_hi > 0xff) goto bail; port |= port_hi << 8; #ifdef WHY_BOTHER_WE_CAN_ASSUME_IP_MATCHES replace_char(raw, ',', '.'); /* We are verifying that PORT's IP matches getpeername(). * Otherwise peer can make us open data connections * to other hosts (security problem!) * This code would be too simplistic: * lsa = xdotted2sockaddr(raw, port); * if (lsa == NULL) goto bail; */ if (!inet_aton(raw, &port_ipv4_sin_addr)) goto bail; peer_ipv4_len = sizeof(peer_ipv4); if (getpeername(STDIN_FILENO, &peer_ipv4, &peer_ipv4_len) != 0) goto bail; if (memcmp(&port_ipv4_sin_addr, &peer_ipv4.sin_addr, sizeof(struct in_addr)) != 0) goto bail; G.port_addr = xdotted2sockaddr(raw, port); #else G.port_addr = get_peer_lsa(STDIN_FILENO); set_nport(G.port_addr, port); #endif cmdio_write_ok(FTP_PORTOK); } static void handle_rest(void) { /* When ftp_arg == NULL simply restart from beginning */ G.restart_pos = G.ftp_arg ? xatoi_u(G.ftp_arg) : 0; cmdio_write_ok(FTP_RESTOK); } static void handle_retr(void) { struct stat statbuf; off_t bytes_transferred; int remote_fd; int local_file_fd; off_t offset = G.restart_pos; char *response; G.restart_pos = 0; if (!port_or_pasv_was_seen()) return; /* port_or_pasv_was_seen emitted error response */ /* O_NONBLOCK is useful if file happens to be a device node */ local_file_fd = G.ftp_arg ? open(G.ftp_arg, O_RDONLY | O_NONBLOCK) : -1; if (local_file_fd < 0) { cmdio_write_error(FTP_FILEFAIL); return; } if (fstat(local_file_fd, &statbuf) != 0 || !S_ISREG(statbuf.st_mode)) { /* Note - pretend open failed */ cmdio_write_error(FTP_FILEFAIL); goto file_close_out; } G.local_file_fd = local_file_fd; /* Now deactive O_NONBLOCK, otherwise we have a problem * on DMAPI filesystems such as XFS DMAPI. */ ndelay_off(local_file_fd); /* Set the download offset (from REST) if any */ if (offset != 0) xlseek(local_file_fd, offset, SEEK_SET); response = xasprintf( " Opening BINARY mode data connection for %s (%"OFF_FMT"u bytes)", G.ftp_arg, statbuf.st_size); remote_fd = get_remote_transfer_fd(response); free(response); if (remote_fd < 0) goto file_close_out; bytes_transferred = bb_copyfd_eof(local_file_fd, remote_fd); close(remote_fd); if (bytes_transferred < 0) cmdio_write_error(FTP_BADSENDFILE); else cmdio_write_ok(FTP_TRANSFEROK); file_close_out: close(local_file_fd); G.local_file_fd = 0; } /* List commands */ static int popen_ls(const char *opt) { char *cwd; const char *argv[5] = { "ftpd", opt, NULL, G.ftp_arg, NULL }; struct fd_pair outfd; pid_t pid; cwd = xrealloc_getcwd_or_warn(NULL); xpiped_pair(outfd); /*fflush(NULL); - so far we dont use stdio on output */ pid = vfork(); switch (pid) { case -1: /* failure */ bb_perror_msg_and_die("vfork"); case 0: /* child */ /* NB: close _first_, then move fds! */ close(outfd.rd); xmove_fd(outfd.wr, STDOUT_FILENO); close(STDIN_FILENO); /* xopen("/dev/null", O_RDONLY); - chroot may lack it! */ if (fchdir(G.proc_self_fd) == 0) { close(G.proc_self_fd); argv[2] = cwd; /* ftpd ls helper chdirs to argv[2], * preventing peer from seeing /proc/self */ execv("exe", (char**) argv); } _exit(127); } /* parent */ close(outfd.wr); free(cwd); return outfd.rd; } enum { USE_CTRL_CONN = 1, LONG_LISTING = 2, }; static void handle_dir_common(int opts) { FILE *ls_fp; char *line; int ls_fd; if (!(opts & USE_CTRL_CONN) && !port_or_pasv_was_seen()) return; /* port_or_pasv_was_seen emitted error response */ /* -n prevents user/groupname display, * which can be problematic in chroot */ ls_fd = popen_ls((opts & LONG_LISTING) ? "-l" : "-1"); ls_fp = fdopen(ls_fd, "r"); if (!ls_fp) /* never happens. paranoia */ bb_perror_msg_and_die("fdopen"); if (opts & USE_CTRL_CONN) { /* STAT */ cmdio_write_raw(STR(FTP_STATFILE_OK)"-Status follows:\r\n"); while (1) { line = xmalloc_fgetline(ls_fp); if (!line) break; cmdio_write(0, line); /* hack: 0 results in no status at all */ free(line); } cmdio_write_ok(FTP_STATFILE_OK); } else { /* LIST/NLST [] */ int remote_fd = get_remote_transfer_fd(" Here comes the directory listing"); if (remote_fd >= 0) { while (1) { line = xmalloc_fgetline(ls_fp); if (!line) break; /* I've seen clients complaining when they * are fed with ls output with bare '\n'. * Pity... that would be much simpler. */ xwrite_str(remote_fd, line); xwrite(remote_fd, "\r\n", 2); free(line); } } close(remote_fd); cmdio_write_ok(FTP_TRANSFEROK); } fclose(ls_fp); /* closes ls_fd too */ } static void handle_list(void) { handle_dir_common(LONG_LISTING); } static void handle_nlst(void) { handle_dir_common(0); } static void handle_stat_file(void) { handle_dir_common(LONG_LISTING + USE_CTRL_CONN); } static void handle_size(void) { struct stat statbuf; char buf[sizeof(STR(FTP_STATFILE_OK)" %"OFF_FMT"u\r\n") + sizeof(off_t)*3]; if (!G.ftp_arg || stat(G.ftp_arg, &statbuf) != 0 || !S_ISREG(statbuf.st_mode) ) { cmdio_write_error(FTP_FILEFAIL); return; } sprintf(buf, STR(FTP_STATFILE_OK)" %"OFF_FMT"u\r\n", statbuf.st_size); cmdio_write_raw(buf); } /* Upload commands */ #if ENABLE_FEATURE_FTP_WRITE static void handle_mkd(void) { if (!G.ftp_arg || mkdir(G.ftp_arg, 0777) != 0) { cmdio_write_error(FTP_FILEFAIL); return; } cmdio_write_ok(FTP_MKDIROK); } static void handle_rmd(void) { if (!G.ftp_arg || rmdir(G.ftp_arg) != 0) { cmdio_write_error(FTP_FILEFAIL); return; } cmdio_write_ok(FTP_RMDIROK); } static void handle_dele(void) { if (!G.ftp_arg || unlink(G.ftp_arg) != 0) { cmdio_write_error(FTP_FILEFAIL); return; } cmdio_write_ok(FTP_DELEOK); } static void handle_rnfr(void) { free(G.rnfr_filename); G.rnfr_filename = xstrdup(G.ftp_arg); cmdio_write_ok(FTP_RNFROK); } static void handle_rnto(void) { int retval; /* If we didn't get a RNFR, throw a wobbly */ if (G.rnfr_filename == NULL || G.ftp_arg == NULL) { cmdio_write_raw(STR(FTP_NEEDRNFR)" RNFR required first\r\n"); return; } retval = rename(G.rnfr_filename, G.ftp_arg); free(G.rnfr_filename); G.rnfr_filename = NULL; if (retval) { cmdio_write_error(FTP_FILEFAIL); return; } cmdio_write_ok(FTP_RENAMEOK); } static void handle_upload_common(int is_append, int is_unique) { struct stat statbuf; char *tempname; off_t bytes_transferred; off_t offset; int local_file_fd; int remote_fd; offset = G.restart_pos; G.restart_pos = 0; if (!port_or_pasv_was_seen()) return; /* port_or_pasv_was_seen emitted error response */ tempname = NULL; local_file_fd = -1; if (is_unique) { tempname = xstrdup(" FILE: uniq.XXXXXX"); local_file_fd = mkstemp(tempname + 7); } else if (G.ftp_arg) { int flags = O_WRONLY | O_CREAT | O_TRUNC; if (is_append) flags = O_WRONLY | O_CREAT | O_APPEND; if (offset) flags = O_WRONLY | O_CREAT; local_file_fd = open(G.ftp_arg, flags, 0666); } if (local_file_fd < 0 || fstat(local_file_fd, &statbuf) != 0 || !S_ISREG(statbuf.st_mode) ) { cmdio_write_error(FTP_UPLOADFAIL); if (local_file_fd >= 0) goto close_local_and_bail; return; } G.local_file_fd = local_file_fd; if (offset) xlseek(local_file_fd, offset, SEEK_SET); remote_fd = get_remote_transfer_fd(tempname ? tempname : " Ok to send data"); free(tempname); if (remote_fd < 0) goto close_local_and_bail; bytes_transferred = bb_copyfd_eof(remote_fd, local_file_fd); close(remote_fd); if (bytes_transferred < 0) cmdio_write_error(FTP_BADSENDFILE); else cmdio_write_ok(FTP_TRANSFEROK); close_local_and_bail: close(local_file_fd); G.local_file_fd = 0; } static void handle_stor(void) { handle_upload_common(0, 0); } static void handle_appe(void) { G.restart_pos = 0; handle_upload_common(1, 0); } static void handle_stou(void) { G.restart_pos = 0; handle_upload_common(0, 1); } #endif /* ENABLE_FEATURE_FTP_WRITE */ static uint32_t cmdio_get_cmd_and_arg(void) { size_t len; uint32_t cmdval; char *cmd; alarm(G.timeout); free(G.ftp_cmd); len = 8 * 1024; /* Paranoia. Peer may send 1 gigabyte long cmd... */ G.ftp_cmd = cmd = xmalloc_reads(STDIN_FILENO, NULL, &len); if (!cmd) exit(0); /* Trailing '\n' is already stripped, strip '\r' */ len = strlen(cmd) - 1; while ((ssize_t)len >= 0 && cmd[len] == '\r') { cmd[len] = '\0'; len--; } G.ftp_arg = strchr(cmd, ' '); if (G.ftp_arg != NULL) *G.ftp_arg++ = '\0'; /* Uppercase and pack into uint32_t first word of the command */ cmdval = 0; while (*cmd) cmdval = (cmdval << 8) + ((unsigned char)*cmd++ & (unsigned char)~0x20); return cmdval; } #define mk_const4(a,b,c,d) (((a * 0x100 + b) * 0x100 + c) * 0x100 + d) #define mk_const3(a,b,c) ((a * 0x100 + b) * 0x100 + c) enum { const_ALLO = mk_const4('A', 'L', 'L', 'O'), const_APPE = mk_const4('A', 'P', 'P', 'E'), const_CDUP = mk_const4('C', 'D', 'U', 'P'), const_CWD = mk_const3('C', 'W', 'D'), const_DELE = mk_const4('D', 'E', 'L', 'E'), const_EPSV = mk_const4('E', 'P', 'S', 'V'), const_HELP = mk_const4('H', 'E', 'L', 'P'), const_LIST = mk_const4('L', 'I', 'S', 'T'), const_MKD = mk_const3('M', 'K', 'D'), const_MODE = mk_const4('M', 'O', 'D', 'E'), const_NLST = mk_const4('N', 'L', 'S', 'T'), const_NOOP = mk_const4('N', 'O', 'O', 'P'), const_PASS = mk_const4('P', 'A', 'S', 'S'), const_PASV = mk_const4('P', 'A', 'S', 'V'), const_PORT = mk_const4('P', 'O', 'R', 'T'), const_PWD = mk_const3('P', 'W', 'D'), const_QUIT = mk_const4('Q', 'U', 'I', 'T'), const_REST = mk_const4('R', 'E', 'S', 'T'), const_RETR = mk_const4('R', 'E', 'T', 'R'), const_RMD = mk_const3('R', 'M', 'D'), const_RNFR = mk_const4('R', 'N', 'F', 'R'), const_RNTO = mk_const4('R', 'N', 'T', 'O'), const_SIZE = mk_const4('S', 'I', 'Z', 'E'), const_STAT = mk_const4('S', 'T', 'A', 'T'), const_STOR = mk_const4('S', 'T', 'O', 'R'), const_STOU = mk_const4('S', 'T', 'O', 'U'), const_STRU = mk_const4('S', 'T', 'R', 'U'), const_SYST = mk_const4('S', 'Y', 'S', 'T'), const_TYPE = mk_const4('T', 'Y', 'P', 'E'), const_USER = mk_const4('U', 'S', 'E', 'R'), OPT_l = (1 << 0), OPT_1 = (1 << 1), OPT_v = (1 << 2), OPT_S = (1 << 3), OPT_w = (1 << 4), }; int ftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int ftpd_main(int argc, char **argv) { smallint opts; INIT_G(); G.start_time = monotonic_sec(); G.abs_timeout = 1 * 60 * 60; G.timeout = 2 * 60; opt_complementary = "t+:T+"; opts = getopt32(argv, "l1vS" USE_FEATURE_FTP_WRITE("w") "t:T:", &G.timeout, &G.abs_timeout); if (opts & (OPT_l|OPT_1)) { /* Our secret backdoor to ls */ memset(&G, 0, sizeof(G)); /* TODO: pass -n too? */ xchdir(argv[2]); argv[2] = (char*)"--"; return ls_main(argc, argv); } G.local_addr = get_sock_lsa(STDIN_FILENO); if (!G.local_addr) { /* This is confusing: * bb_error_msg_and_die("stdin is not a socket"); * Better: */ bb_show_usage(); /* Help text says that ftpd must be used as inetd service, * which is by far the most usual cause of get_sock_lsa * failure */ } if (!(opts & OPT_v)) logmode = LOGMODE_NONE; if (opts & OPT_S) { /* LOG_NDELAY is needed since we may chroot later */ openlog(applet_name, LOG_PID | LOG_NDELAY, LOG_DAEMON); logmode |= LOGMODE_SYSLOG; } G.proc_self_fd = xopen("/proc/self", O_RDONLY | O_DIRECTORY); if (argv[optind]) { xchdir(argv[optind]); chroot("."); } //umask(077); - admin can set umask before starting us /* Signals. We'll always take -EPIPE rather than a rude signal, thanks */ signal(SIGPIPE, SIG_IGN); /* Set up options on the command socket (do we need these all? why?) */ setsockopt(STDIN_FILENO, IPPROTO_TCP, TCP_NODELAY, &const_int_1, sizeof(const_int_1)); setsockopt(STDIN_FILENO, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); setsockopt(STDIN_FILENO, SOL_SOCKET, SO_OOBINLINE, &const_int_1, sizeof(const_int_1)); cmdio_write_ok(FTP_GREET); signal(SIGALRM, timeout_handler); #ifdef IF_WE_WANT_TO_REQUIRE_LOGIN { smallint user_was_specified = 0; while (1) { uint32_t cmdval = cmdio_get_cmd_and_arg(); if (cmdval == const_USER) { if (G.ftp_arg == NULL || strcasecmp(G.ftp_arg, "anonymous") != 0) cmdio_write_raw(STR(FTP_LOGINERR)" Server is anonymous only\r\n"); else { user_was_specified = 1; cmdio_write_raw(STR(FTP_GIVEPWORD)" Please specify the password\r\n"); } } else if (cmdval == const_PASS) { if (user_was_specified) break; cmdio_write_raw(STR(FTP_NEEDUSER)" Login with USER\r\n"); } else if (cmdval == const_QUIT) { cmdio_write_ok(FTP_GOODBYE); return 0; } else { cmdio_write_raw(STR(FTP_LOGINERR)" Login with USER and PASS\r\n"); } } } cmdio_write_ok(FTP_LOGINOK); #endif /* RFC-959 Section 5.1 * The following commands and options MUST be supported by every * server-FTP and user-FTP, except in cases where the underlying * file system or operating system does not allow or support * a particular command. * Type: ASCII Non-print, IMAGE, LOCAL 8 * Mode: Stream * Structure: File, Record* * (Record structure is REQUIRED only for hosts whose file * systems support record structure). * Commands: * USER, PASS, ACCT, [bbox: ACCT not supported] * PORT, PASV, * TYPE, MODE, STRU, * RETR, STOR, APPE, * RNFR, RNTO, DELE, * CWD, CDUP, RMD, MKD, PWD, * LIST, NLST, * SYST, STAT, * HELP, NOOP, QUIT. */ /* ACCOUNT (ACCT) * "The argument field is a Telnet string identifying the user's account. * The command is not necessarily related to the USER command, as some * sites may require an account for login and others only for specific * access, such as storing files. In the latter case the command may * arrive at any time. * There are reply codes to differentiate these cases for the automation: * when account information is required for login, the response to * a successful PASSword command is reply code 332. On the other hand, * if account information is NOT required for login, the reply to * a successful PASSword command is 230; and if the account information * is needed for a command issued later in the dialogue, the server * should return a 332 or 532 reply depending on whether it stores * (pending receipt of the ACCounT command) or discards the command, * respectively." */ while (1) { uint32_t cmdval = cmdio_get_cmd_and_arg(); if (cmdval == const_QUIT) { cmdio_write_ok(FTP_GOODBYE); return 0; } else if (cmdval == const_USER) cmdio_write_ok(FTP_GIVEPWORD); else if (cmdval == const_PASS) cmdio_write_ok(FTP_LOGINOK); else if (cmdval == const_NOOP) cmdio_write_ok(FTP_NOOPOK); else if (cmdval == const_TYPE) cmdio_write_ok(FTP_TYPEOK); else if (cmdval == const_STRU) cmdio_write_ok(FTP_STRUOK); else if (cmdval == const_MODE) cmdio_write_ok(FTP_MODEOK); else if (cmdval == const_ALLO) cmdio_write_ok(FTP_ALLOOK); else if (cmdval == const_SYST) cmdio_write_raw(STR(FTP_SYSTOK)" UNIX Type: L8\r\n"); else if (cmdval == const_PWD) handle_pwd(); else if (cmdval == const_CWD) handle_cwd(); else if (cmdval == const_CDUP) /* cd .. */ handle_cdup(); else if (cmdval == const_HELP) handle_help(); else if (cmdval == const_LIST) /* ls -l */ handle_list(); else if (cmdval == const_NLST) /* "name list", bare ls */ handle_nlst(); else if (cmdval == const_SIZE) handle_size(); else if (cmdval == const_STAT) { if (G.ftp_arg == NULL) handle_stat(); else handle_stat_file(); } else if (cmdval == const_PASV) handle_pasv(); else if (cmdval == const_EPSV) handle_epsv(); else if (cmdval == const_RETR) handle_retr(); else if (cmdval == const_PORT) handle_port(); else if (cmdval == const_REST) handle_rest(); #if ENABLE_FEATURE_FTP_WRITE else if (opts & OPT_w) { if (cmdval == const_STOR) handle_stor(); else if (cmdval == const_MKD) handle_mkd(); else if (cmdval == const_RMD) handle_rmd(); else if (cmdval == const_DELE) handle_dele(); else if (cmdval == const_RNFR) /* "rename from" */ handle_rnfr(); else if (cmdval == const_RNTO) /* "rename to" */ handle_rnto(); else if (cmdval == const_APPE) handle_appe(); else if (cmdval == const_STOU) /* "store unique" */ handle_stou(); } #endif #if 0 else if (cmdval == const_STOR || cmdval == const_MKD || cmdval == const_RMD || cmdval == const_DELE || cmdval == const_RNFR || cmdval == const_RNTO || cmdval == const_APPE || cmdval == const_STOU ) { cmdio_write_raw(STR(FTP_NOPERM)" Permission denied\r\n"); } #endif else { /* Which unsupported commands were seen in the wild? * (doesn't necessarily mean "we must support them") * lftp 3.6.3: FEAT - is it useful? * MDTM - works fine without it anyway */ cmdio_write_raw(STR(FTP_BADCMD)" Unknown command\r\n"); } } }