changeset 1111:f665f065fe87

Add tftpd
author Ashwini Sharma <ak.ashwini@gmail.com>
date Sun, 10 Nov 2013 14:16:31 -0600
parents 241ee03473db
children f7bec236efd3
files toys/pending/tftpd.c
diffstat 1 files changed, 336 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toys/pending/tftpd.c	Sun Nov 10 14:16:31 2013 -0600
@@ -0,0 +1,336 @@
+/* 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:", TOYFLAG_BIN))
+
+config TFTPD
+  bool "tftpd"
+  default y
+  help
+    usage: tftpd [-cr] [-u USER] [DIR]
+
+    Transfer file from/to tftp server.
+
+    -r	Prohibit upload
+    -c	Allow file creation via upload
+    -u	Access files as USER
+*/
+#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_buff[TFTPD_BLKSIZE];
+static char g_errpkt[TFTPD_BLKSIZE];
+
+static void bind_and_connect(struct sockaddr *srcaddr,
+    struct sockaddr *dstaddr, socklen_t socklen)
+{
+  int set = 1;
+
+  TT.sfd = xsocket(dstaddr->sa_family, SOCK_DGRAM, 0);
+  if (setsockopt(TT.sfd, SOL_SOCKET, SO_REUSEADDR, (const void *)&set,
+        sizeof(set)) < 0) perror_exit("setsockopt failed");
+  if (bind(TT.sfd, srcaddr, socklen)) perror_exit("bind");
+  if (connect(TT.sfd, dstaddr, socklen) < 0)
+    perror_exit("can't connect to remote host");
+}
+
+// Create and send error packet.
+static void send_errpkt(struct sockaddr *dstaddr,
+    socklen_t socklen, char *errmsg)
+{
+  error_msg(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) {
+    if (change_identity(TT.pw)) perror_exit("Failed to change identity");
+    endgrent();
+  }
+
+  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_IN:
+    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_IN;
+    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_IN;
+    } 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) {
+      switch(rblockno) {
+        case TFTPD_ER_NOSUCHFILE: error_msg("File not found"); break;
+        case TFTPD_ER_ACCESS: error_msg("Access violation"); break;
+        case TFTPD_ER_FULL: error_msg("Disk full or allocation exceeded");
+             break;
+        case TFTPD_ER_ILLEGALOP: error_msg("Illegal TFTP operation"); break;
+        case TFTPD_ER_UNKID: error_msg("Unknown transfer ID"); break;
+        case TFTPD_ER_EXISTS: error_msg("File already exists"); break;
+        case TFTPD_ER_UNKUSER: error_msg("No such user"); break;
+        case TFTPD_ER_NEGOTIATE:
+             error_msg("Terminate transfer due to option negotiation"); break;
+        default: error_msg("DATA Check failure."); break;
+      }
+      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_IN;
+  } // end of loop
+
+CLEAN_APP:
+  if (CFG_TOYBOX_FREE) {
+    free(spkt);
+    free(rpkt);
+    close(fd);
+  }
+}
+
+void tftpd_main(void)
+{
+  int recvmsg_len, rbuflen, opcode, blksize = TFTPD_BLKSIZE, tsize = 0;
+  struct sockaddr_storage srcaddr, dstaddr;
+  static socklen_t socklen = sizeof(struct sockaddr_storage);
+  char *buf = g_buff;
+
+  TT.pw = NULL;
+  memset(&srcaddr, 0, sizeof(srcaddr));
+  if (getsockname(STDIN_FILENO, (struct sockaddr*)&srcaddr, &socklen)) {
+    toys.exithelp = 1;
+    error_exit(NULL);
+  }
+
+  if (toys.optflags & FLAG_u) {
+    struct passwd *pw = getpwnam(TT.user);
+    if (!pw) error_exit("unknown user %s", TT.user);
+    TT.pw = pw;
+  }
+  if (*toys.optargs) {
+    if (chroot(*toys.optargs))
+      perror_exit("can't change root directory to '%s'", *toys.optargs);
+    if (chdir("/")) perror_exit("can't change directory to '/'");
+  }
+
+  recvmsg_len = recvfrom(STDIN_FILENO, g_buff, TFTPD_BLKSIZE, 0,
+      (struct sockaddr*)&dstaddr, &socklen);
+  bind_and_connect((struct sockaddr*)&srcaddr, (struct sockaddr*)&dstaddr, socklen);
+  // Error condition.
+  if (recvmsg_len < 4 || recvmsg_len > TFTPD_BLKSIZE
+		  || g_buff[recvmsg_len-1] != '\0') {
+    send_errpkt((struct sockaddr*)&dstaddr, socklen, "packet format error");
+    return;
+  }
+
+  // request is either upload or Download.
+  opcode = ntohs(*(uint16_t*)buf);
+  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 >= (g_buff + 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 = g_buff + 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, g_buff + 2, opcode, tsize, blksize);
+  if (CFG_TOYBOX_FREE) close(STDIN_FILENO);
+}