| /* tftpd.c - TFTP server. |
| * |
| * Copyright 2013 Ranjan Kumar <ranjankumar.bth@gmail.com> |
| * Copyright 2013 Kyungwan Han <asura321@gmail.com> |
| * |
| * No Standard. |
| |
| USE_TFTPD(NEWTOY(tftpd, "rcu:l", TOYFLAG_BIN)) |
| |
| config TFTPD |
| bool "tftpd" |
| default n |
| help |
| usage: tftpd [-cr] [-u USER] [DIR] |
| |
| Transfer file from/to tftp server. |
| |
| -r read only |
| -c Allow file creation via upload |
| -u run as USER |
| -l Log to syslog (inetd mode requires this) |
| */ |
| |
| #define FOR_tftpd |
| #include "toys.h" |
| |
| GLOBALS( |
| char *user; |
| |
| long sfd; |
| struct passwd *pw; |
| ) |
| |
| #define TFTPD_BLKSIZE 512 // as per RFC 1350. |
| |
| // opcodes |
| #define TFTPD_OP_RRQ 1 // Read Request RFC 1350, RFC 2090 |
| #define TFTPD_OP_WRQ 2 // Write Request RFC 1350 |
| #define TFTPD_OP_DATA 3 // Data chunk RFC 1350 |
| #define TFTPD_OP_ACK 4 // Acknowledgement RFC 1350 |
| #define TFTPD_OP_ERR 5 // Error Message RFC 1350 |
| #define TFTPD_OP_OACK 6 // Option acknowledgment RFC 2347 |
| |
| // Error Codes: |
| #define TFTPD_ER_NOSUCHFILE 1 // File not found |
| #define TFTPD_ER_ACCESS 2 // Access violation |
| #define TFTPD_ER_FULL 3 // Disk full or allocation exceeded |
| #define TFTPD_ER_ILLEGALOP 4 // Illegal TFTP operation |
| #define TFTPD_ER_UNKID 5 // Unknown transfer ID |
| #define TFTPD_ER_EXISTS 6 // File already exists |
| #define TFTPD_ER_UNKUSER 7 // No such user |
| #define TFTPD_ER_NEGOTIATE 8 // Terminate transfer due to option negotiation |
| |
| /* TFTP Packet Formats |
| * Type Op # Format without header |
| * 2 bytes string 1 byte string 1 byte |
| * ----------------------------------------------- |
| * RRQ/ | 01/02 | Filename | 0 | Mode | 0 | |
| * WRQ ----------------------------------------------- |
| * 2 bytes 2 bytes n bytes |
| * --------------------------------- |
| * DATA | 03 | Block # | Data | |
| * --------------------------------- |
| * 2 bytes 2 bytes |
| * ------------------- |
| * ACK | 04 | Block # | |
| * -------------------- |
| * 2 bytes 2 bytes string 1 byte |
| * ---------------------------------------- |
| * ERROR | 05 | ErrorCode | ErrMsg | 0 | |
| * ---------------------------------------- |
| */ |
| |
| static char *g_errpkt = toybuf + TFTPD_BLKSIZE; |
| |
| // Create and send error packet. |
| static void send_errpkt(struct sockaddr *dstaddr, |
| socklen_t socklen, char *errmsg) |
| { |
| error_msg_raw(errmsg); |
| g_errpkt[1] = TFTPD_OP_ERR; |
| strcpy(g_errpkt + 4, errmsg); |
| if (sendto(TT.sfd, g_errpkt, strlen(errmsg)+5, 0, dstaddr, socklen) < 0) |
| perror_exit("sendto failed"); |
| } |
| |
| // Used to send / receive packets. |
| static void do_action(struct sockaddr *srcaddr, struct sockaddr *dstaddr, |
| socklen_t socklen, char *file, int opcode, int tsize, int blksize) |
| { |
| int fd, done = 0, retry_count = 12, timeout = 100, len; |
| uint16_t blockno = 1, pktopcode, rblockno; |
| char *ptr, *spkt, *rpkt; |
| struct pollfd pollfds[1]; |
| |
| spkt = xzalloc(blksize + 4); |
| rpkt = xzalloc(blksize + 4); |
| ptr = spkt+2; //point after opcode. |
| |
| pollfds[0].fd = TT.sfd; |
| // initialize groups, setgid and setuid |
| if (TT.pw) xsetuser(TT.pw); |
| |
| if (opcode == TFTPD_OP_RRQ) fd = open(file, O_RDONLY, 0666); |
| else fd = open(file, ((toys.optflags & FLAG_c) ? |
| (O_WRONLY|O_TRUNC|O_CREAT) : (O_WRONLY|O_TRUNC)) , 0666); |
| if (fd < 0) { |
| g_errpkt[3] = TFTPD_ER_NOSUCHFILE; |
| send_errpkt(dstaddr, socklen, "can't open file"); |
| goto CLEAN_APP; |
| } |
| // For download -> blockno will be 1. |
| // 1st ACK will be from dst,which will have blockno-=1 |
| // Create and send ACK packet. |
| if (blksize != TFTPD_BLKSIZE || tsize) { |
| pktopcode = TFTPD_OP_OACK; |
| // add "blksize\000blksize_val\000" in send buffer. |
| if (blksize != TFTPD_BLKSIZE) { |
| strcpy(ptr, "blksize"); |
| ptr += strlen("blksize") + 1; |
| ptr += snprintf(ptr, 6, "%d", blksize) + 1; |
| } |
| if (tsize) {// add "tsize\000tsize_val\000" in send buffer. |
| struct stat sb; |
| |
| sb.st_size = 0; |
| fstat(fd, &sb); |
| strcpy(ptr, "tsize"); |
| ptr += strlen("tsize") + 1; |
| ptr += sprintf(ptr, "%lu", (unsigned long)sb.st_size)+1; |
| } |
| goto SEND_PKT; |
| } |
| // upload -> ACK 1st packet with filename, as it has blockno 0. |
| if (opcode == TFTPD_OP_WRQ) blockno = 0; |
| |
| // Prepare DATA and/or ACK pkt and send it. |
| for (;;) { |
| int poll_ret; |
| |
| retry_count = 12, timeout = 100, pktopcode = TFTPD_OP_ACK; |
| ptr = spkt+2; |
| *((uint16_t*)ptr) = htons(blockno); |
| blockno++; |
| ptr += 2; |
| if (opcode == TFTPD_OP_RRQ) { |
| pktopcode = TFTPD_OP_DATA; |
| len = readall(fd, ptr, blksize); |
| if (len < 0) { |
| send_errpkt(dstaddr, socklen, "read-error"); |
| break; |
| } |
| if (len != blksize) done = 1; //last pkt. |
| ptr += len; |
| } |
| SEND_PKT: |
| // 1st ACK will be from dst, which will have blockno-=1 |
| *((uint16_t*)spkt) = htons(pktopcode); //append send pkt's opcode. |
| RETRY_SEND: |
| if (sendto(TT.sfd, spkt, (ptr - spkt), 0, dstaddr, socklen) <0) |
| perror_exit("sendto failed"); |
| // if "block size < 512", send ACK and exit. |
| if ((pktopcode == TFTPD_OP_ACK) && done) break; |
| |
| POLL_INPUT: |
| pollfds[0].events = POLLIN; |
| pollfds[0].fd = TT.sfd; |
| poll_ret = poll(pollfds, 1, timeout); |
| if (poll_ret < 0 && (errno == EINTR || errno == ENOMEM)) goto POLL_INPUT; |
| if (!poll_ret) { |
| if (!--retry_count) { |
| error_msg("timeout"); |
| break; |
| } |
| timeout += 150; |
| goto RETRY_SEND; |
| } else if (poll_ret == 1) { |
| len = read(pollfds[0].fd, rpkt, blksize + 4); |
| if (len < 0) { |
| send_errpkt(dstaddr, socklen, "read-error"); |
| break; |
| } |
| if (len < 4) goto POLL_INPUT; |
| } else { |
| perror_msg("poll"); |
| break; |
| } |
| // Validate receive packet. |
| pktopcode = ntohs(((uint16_t*)rpkt)[0]); |
| rblockno = ntohs(((uint16_t*)rpkt)[1]); |
| if (pktopcode == TFTPD_OP_ERR) { |
| char *message = "DATA Check failure."; |
| char *arr[] = {"File not found", "Access violation", |
| "Disk full or allocation exceeded", "Illegal TFTP operation", |
| "Unknown transfer ID", "File already exists", |
| "No such user", "Terminate transfer due to option negotiation"}; |
| |
| if (rblockno && (rblockno < 9)) message = arr[rblockno - 1]; |
| error_msg_raw(message); |
| break; // Break the for loop. |
| } |
| |
| // if download requested by client, |
| // server will send data pkt and will receive ACK pkt from client. |
| if ((opcode == TFTPD_OP_RRQ) && (pktopcode == TFTPD_OP_ACK)) { |
| if (rblockno == (uint16_t) (blockno - 1)) { |
| if (!done) continue; // Send next chunk of data. |
| break; |
| } |
| } |
| |
| // server will receive DATA pkt and write the data. |
| if ((opcode == TFTPD_OP_WRQ) && (pktopcode == TFTPD_OP_DATA)) { |
| if (rblockno == blockno) { |
| int nw = writeall(fd, &rpkt[4], len-4); |
| if (nw != len-4) { |
| g_errpkt[3] = TFTPD_ER_FULL; |
| send_errpkt(dstaddr, socklen, "write error"); |
| break; |
| } |
| |
| if (nw != blksize) done = 1; |
| } |
| continue; |
| } |
| goto POLL_INPUT; |
| } // end of loop |
| |
| CLEAN_APP: |
| if (CFG_TOYBOX_FREE) { |
| free(spkt); |
| free(rpkt); |
| close(fd); |
| } |
| } |
| |
| void tftpd_main(void) |
| { |
| int fd = 0, recvmsg_len, rbuflen, opcode, blksize = TFTPD_BLKSIZE, tsize = 0, set =1; |
| struct sockaddr_storage srcaddr, dstaddr; |
| socklen_t socklen = sizeof(struct sockaddr_storage); |
| char *buf = toybuf; |
| |
| memset(&srcaddr, 0, sizeof(srcaddr)); |
| if (getsockname(0, (struct sockaddr *)&srcaddr, &socklen)) help_exit(0); |
| |
| if (TT.user) TT.pw = xgetpwnam(TT.user); |
| if (*toys.optargs) xchroot(*toys.optargs); |
| |
| recvmsg_len = recvfrom(fd, toybuf, blksize, 0, (void *)&dstaddr, &socklen); |
| |
| TT.sfd = xsocket(dstaddr.ss_family, SOCK_DGRAM, 0); |
| if (setsockopt(TT.sfd, SOL_SOCKET, SO_REUSEADDR, (const void *)&set, |
| sizeof(set)) < 0) perror_exit("setsockopt failed"); |
| xbind(TT.sfd, (void *)&srcaddr, socklen); |
| xconnect(TT.sfd, (void *)&dstaddr, socklen); |
| // Error condition. |
| if (recvmsg_len<4 || recvmsg_len>TFTPD_BLKSIZE || toybuf[recvmsg_len-1]) { |
| send_errpkt((struct sockaddr*)&dstaddr, socklen, "packet format error"); |
| return; |
| } |
| |
| // request is either upload or Download. |
| opcode = buf[1]; |
| if (((opcode != TFTPD_OP_RRQ) && (opcode != TFTPD_OP_WRQ)) |
| || ((opcode == TFTPD_OP_WRQ) && (toys.optflags & FLAG_r))) { |
| send_errpkt((struct sockaddr*)&dstaddr, socklen, |
| (opcode == TFTPD_OP_WRQ) ? "write error" : "packet format error"); |
| return; |
| } |
| |
| buf += 2; |
| if (*buf == '.' || strstr(buf, "/.")) { |
| send_errpkt((struct sockaddr*)&dstaddr, socklen, "dot in filename"); |
| return; |
| } |
| |
| buf += strlen(buf) + 1; //1 '\0'. |
| // As per RFC 1350, mode is case in-sensitive. |
| if (buf >= toybuf+recvmsg_len || strcasecmp(buf, "octet")) { |
| send_errpkt((struct sockaddr*)&dstaddr, socklen, "packet format error"); |
| return; |
| } |
| |
| //RFC2348. e.g. of size type: "ttype1\0ttype1_val\0...ttypeN\0ttypeN_val\0" |
| buf += strlen(buf) + 1; |
| rbuflen = toybuf + recvmsg_len - buf; |
| if (rbuflen) { |
| int jump = 0, bflag = 0; |
| |
| for (; rbuflen; rbuflen -= jump, buf += jump) { |
| if (!bflag && !strcasecmp(buf, "blksize")) { //get blksize |
| errno = 0; |
| blksize = strtoul(buf, NULL, 10); |
| if (errno || blksize > 65564 || blksize < 8) blksize = TFTPD_BLKSIZE; |
| bflag ^= 1; |
| } else if (!tsize && !strcasecmp(buf, "tsize")) tsize ^= 1; |
| |
| jump += strlen(buf) + 1; |
| } |
| tsize &= (opcode == TFTPD_OP_RRQ); |
| } |
| |
| //do send / receive file. |
| do_action((struct sockaddr*)&srcaddr, (struct sockaddr*)&dstaddr, |
| socklen, toybuf + 2, opcode, tsize, blksize); |
| if (CFG_TOYBOX_FREE) close(STDIN_FILENO); |
| } |
