411 REFERENCE · Wikibooks
Oberon/A2/TFTP.Mod
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
MODULE TFTP; (** AUTHOR "be"; PURPOSE "TFTP client"; *)
IMPORT IP, UDP, Files, Random, KernelLog;
CONST
Ok = UDP.Ok;
(* General Settings *)
TFTPPort = 69;
MaxSocketRetries = 64;
MaxRetries = 5;
MaxWait = 3;
BlockSize = 512;
DataTimeout = 3000; (* ms *)
AckTimeout = 3000; (* ms *)
(* Packet Types *)
RRQ = 1;
WRQ = 2;
DATA = 3;
ACK = 4;
ERROR = 5;
TFTPId = "TFTP Client: ";
TYPE
ErrorMsg = ARRAY 32 OF CHAR;
TFTPClient* = OBJECT
(* Log functions *)
PROCEDURE LogEnter(level: SIGNED32);
BEGIN IF (TraceLevel >= level) THEN KernelLog.Enter END
END LogEnter;
PROCEDURE LogExit(level: SIGNED32);
BEGIN IF (TraceLevel >= level) THEN KernelLog.Exit END
END LogExit;
PROCEDURE Log(level: SIGNED32; s: ARRAY OF CHAR);
BEGIN IF (TraceLevel >= level) THEN KernelLog.String(s) END
END Log;
PROCEDURE LogInt(level, i: SIZE);
BEGIN IF (TraceLevel >= level) THEN KernelLog.Int(i, 0) END
END LogInt;
(* Get2 - reads a (big endian) 16bit value from 'buf' at position 'ofs'..'ofs'+1 *)
PROCEDURE Get2(VAR buf: ARRAY OF CHAR; ofs: SIGNED32): SIGNED32;
BEGIN RETURN ORD(buf[ofs])*100H + ORD(buf[ofs+1])
END Get2;
(* Put2 - writes a (big endian) 16bit value to 'buf' at position 'ofs'..'ofs'+1 *)
PROCEDURE Put2(VAR buf: ARRAY OF CHAR; ofs, value: SIGNED32);
BEGIN buf[ofs] := CHR(value DIV 100H MOD 100H); buf[ofs+1] := CHR(value MOD 100H)
END Put2;
(* PacketType - returns the type of a packet *)
PROCEDURE PacketType(VAR buf: ARRAY OF CHAR): SIGNED32;
BEGIN RETURN Get2(buf, 0)
END PacketType;
(* ExtractString - extracts a 0X terminated 8bit string from a buffer *)
PROCEDURE ExtractString(VAR buf: ARRAY OF CHAR; VAR ofs: SIGNED32; VAR s: ARRAY OF CHAR);
VAR pos: SIGNED32;
BEGIN
WHILE (ofs < LEN(buf)) & (buf[ofs] # 0X) DO
IF (pos < LEN(s)-1) THEN s[pos] := buf[ofs]; INC(pos) END;
INC(ofs)
END;
s[pos] := 0X; INC(ofs)
END ExtractString;
(* PutString - puts a 0X terminated 8bit string to a buffer *)
PROCEDURE PutString(VAR buf: ARRAY OF CHAR; VAR ofs: SIGNED32; s: ARRAY OF CHAR);
VAR pos: SIGNED32;
BEGIN
WHILE (pos < LEN(s)) & (s[pos] # 0X) DO
IF (ofs < LEN(buf)-1) THEN buf[ofs] := s[pos]; INC(ofs) END;
INC(pos)
END;
buf[ofs] := 0X; INC(ofs)
END PutString;
(* ReceiveAck - receives a server answer *)
PROCEDURE ReceiveAck(socket: UDP.Socket; VAR fip: IP.Adr; VAR fport: SIGNED32; blockNr: SIGNED32; VAR ack: ARRAY OF CHAR): BOOLEAN;
VAR ip: IP.Adr; port, ofs, wait: SIGNED32; len: SIZE; res: INTEGER; acked: BOOLEAN; msg: ARRAY 256 OF CHAR;
BEGIN
wait := 0;
REPEAT
INC(wait);
LogEnter(3); Log(3, TFTPId); Log(3, "waiting for ack... ");
IF (wait > 1) THEN Log(3, "(retry "); LogInt(3, wait); Log(3, ")") END;
LogExit(3);
acked := FALSE;
socket.Receive(ack, 0, LEN(ack), AckTimeout, ip, port, len, res);
LogEnter(3); Log(3, TFTPId);
IF (res = UDP.Timeout) THEN Log(3, "timeout")
ELSIF (res = UDP.BufferOverflow) THEN Log(3, "buffer overflow ("); LogInt(3, -len); Log(3, " bytes)")
ELSIF (res = Ok) THEN
acked := (PacketType(ack) = ACK) & (Get2(ack, 2) = blockNr) & (IP.AdrsEqual(ip, fip)) & ((fport = port) OR (fport = -1));
IF acked THEN Log(3, "got ack") ELSE Log(3, "ack failed") END;
IF (PacketType(ack) = ERROR) THEN
wait := MaxWait + 1;
ofs := 4; ExtractString(ack, ofs, msg);
Log(3, "; error "); LogInt(3, Get2(ack, 2)); Log(3, ": "); Log(3, msg)
END
ELSE
Log(3, "unknown error "); LogInt(3, SIGNED32(res))
END;
LogExit(3)
UNTIL acked OR (res # Ok) OR (wait > MaxWait);
IF acked & (fport = -1) THEN fport := port END;
RETURN acked
END ReceiveAck;
(* SendAck - sends an ack packet *)
PROCEDURE SendAck(socket: UDP.Socket; fip: IP.Adr; fport: SIGNED32; blockNr: SIGNED32; VAR res: INTEGER);
VAR ackHdr: ARRAY 4 OF CHAR; retries: SIGNED32;
BEGIN
Put2(ackHdr, 0, ACK); Put2(ackHdr, 2, blockNr);
REPEAT
INC(retries);
socket.Send(fip, fport, ackHdr, 0, LEN(ackHdr), res);
UNTIL (res = Ok) OR (retries > MaxRetries)
END SendAck;
(* SendError - sends an error packet *)
PROCEDURE SendError(socket: UDP.Socket; fip: IP.Adr; fport: SIGNED32; errNo: SIGNED16; s: ErrorMsg; VAR res: INTEGER);
VAR errHdr: ARRAY BlockSize+4 OF CHAR; p, retries: SIGNED32;
BEGIN
Put2(errHdr, 0, ERROR); Put2(errHdr, 2, errNo);
IF ((errNo = 0) & (s = "")) OR ((errNo > 0) & (errNo < 8)) THEN s := errorMsg[errNo] END;
WHILE (p < BlockSize-1) & (s[p] # 0X) DO errHdr[4+p] := s[p]; INC(p) END;
errHdr[4+p] := 0X;
REPEAT
INC(retries);
socket.Send(fip, fport, errHdr, 0, p+4, res)
UNTIL (res = Ok) OR (retries > MaxRetries)
END SendError;
(* GetSocket - finds & initializes a free UDP socket *)
PROCEDURE GetSocket*(VAR socket: UDP.Socket): BOOLEAN;
VAR retries, lport: SIGNED32; res: INTEGER;
BEGIN
REPEAT
INC(retries); lport := 1024 + generator.Integer() MOD 64512;
NEW(socket, lport, res)
UNTIL (res # UDP.PortInUse) OR (retries > MaxSocketRetries);
IF (res = UDP.PortInUse) THEN socket := NIL END;
RETURN (socket # NIL)
END GetSocket;
(* Send - send a file to TFTP server at fip:fport *)
PROCEDURE Send*(localFN, remoteFN: ARRAY OF CHAR; fip: IP.Adr; fport: SIGNED32): BOOLEAN;
VAR buf, ack: ARRAY 4+BlockSize OF CHAR; socket: UDP.Socket; msg: ARRAY 256 OF CHAR;
file: Files.File; r: Files.Rider; ofs, retries, blockNr, errNo: SIGNED32; res: INTEGER; acked: BOOLEAN;
BEGIN
acked := FALSE;
file := Files.Old(localFN);
IF (file # NIL) THEN
IF GetSocket(socket) THEN
LogEnter(1); Log(1, TFTPId); Log(1, "sending '"); Log(1, localFN); Log(1, "'"); LogExit(1);
file.Set(r, 0);
(* issue a WRQ *)
Put2(buf, 0, WRQ);
ofs := 2;
PutString(buf, ofs, remoteFN);
PutString(buf, ofs, "netascii");
socket.Send(fip, fport, buf, 0, ofs, res);
(* wait for ACK/ERROR *)
fport := -1; (* allow change of fport *)
IF ReceiveAck(socket, fip, fport, 0, ack) THEN
(* send file *)
blockNr := 0; acked := TRUE;
WHILE ~r.eof & acked DO
INC(blockNr);
Put2(buf, 0, DATA);
Put2(buf, 2, blockNr);
file.ReadBytes(r, buf, 4, BlockSize);
REPEAT
INC(retries);
LogEnter(3); Log(3, TFTPId); Log(3, "sending block "); LogInt(3, blockNr);
Log(3, " ("); LogInt(3, BlockSize-r.res); Log(3, " bytes) ");
IF (retries > 1) THEN Log(3, "(retry "); LogInt(3, retries); Log(3, ")") END;
LogExit(3);
socket.Send(fip, fport, buf, 0, 4 + BlockSize - r.res, res);
acked := ReceiveAck(socket, fip, fport, blockNr, ack)
UNTIL acked OR (retries > MaxRetries);
END;
LogEnter(1); Log(1, TFTPId);
IF r.eof & acked THEN Log(1, "file successfully sent")
ELSE
Log(1, "sending failed");
IF (PacketType(ack) = ERROR) THEN
Log(1, ":");
errNo := Get2(ack, 2);
IF (errNo > 0) & (errNo < 8) THEN Log(1, errorMsg[errNo])
ELSIF (errNo = 0) THEN
ofs := 4;
ExtractString(ack, ofs, msg);
Log(1, msg)
END
END
END;
LogExit(1)
ELSE (* no ACK or block number # 0 *)
LogEnter(1); Log(1, TFTPId); Log(1, TFTPId); Log(1, "sending failed");
IF (PacketType(ack) = ERROR) THEN
Log(1, ": ");
errNo := Get2(ack, 2);
IF (errNo > 0) & (errNo < 8) THEN Log(1, errorMsg[errNo])
ELSIF (errNo = 0) THEN
ofs := 4;
ExtractString(ack, ofs, msg);
Log(1, msg)
END
END;
LogExit(1)
END;
socket.Close
ELSE
LogEnter(1); Log(1, TFTPId); Log(1, "can't get a free socket"); LogExit(1)
END
ELSE
LogEnter(1); Log(1, TFTPId); Log(1, "file not found"); LogExit(1)
END;
RETURN acked
END Send;
(* Receive - receive a file from TFTP server at source:port *)
PROCEDURE Receive*(remoteFN, localFN: ARRAY OF CHAR; fip: IP.Adr; fport: SIGNED32): BOOLEAN;
VAR socket: UDP.Socket; ofs, blockNr, port, retries, waitPacket: SIGNED32; len: SIZE; res: INTEGER; ok, Abort: BOOLEAN; ip: IP.Adr;
buf: ARRAY 4+BlockSize OF CHAR; file: Files.File; r: Files.Rider;
BEGIN
ok := FALSE;
IF GetSocket(socket) THEN
LogEnter(1); Log(1, TFTPId); Log(1, "receiving '"); Log(1, remoteFN); Log(1, "'"); LogExit(1);
(* issue a RRQ *)
Put2(buf, 0, RRQ);
ofs := 2;
PutString(buf, ofs, remoteFN);
PutString(buf, ofs, "netascii");
socket.Send(fip, fport, buf, 0, ofs, res);
fport := -1; (* allow change of fport *)
file := Files.New(localFN);
ASSERT(file # NIL);
file.Set(r, 0);
Files.Register(file);
blockNr := 0;
REPEAT
INC(blockNr);
LogEnter(3); Log(3, TFTPId); Log(3, "receiving block "); LogInt(3, blockNr);
IF (retries > 1) THEN Log(3, " (retry "); LogInt(3, retries); Log(3, ")") END;
LogExit(3);
REPEAT
socket.Receive(buf, 0, LEN(buf), DataTimeout, ip, port, len, res);
DEC(len, 4);
IF (res = Ok) THEN
res := -1;
IF (IP.AdrsEqual(ip, fip)) & ((fport = port) OR (fport = -1)) THEN
IF (fport = -1) THEN fport := port END;
IF (PacketType(buf) = DATA) THEN
IF (Get2(buf, 2) = blockNr) THEN
file.WriteBytes(r, buf, 4, len);
file.Update();
IF (r.res = 0) THEN
LogEnter(3); Log(3, TFTPId); LogInt(3, len); Log(3, " bytes written"); LogExit(3);
SendAck(socket, fip, fport, blockNr, res);
Abort := res # Ok
ELSE
LogEnter(3); Log(3, TFTPId); Log(3, errorMsg[3]); LogExit(3);
SendError(socket, fip, fport, 3, "", res);
Abort := TRUE
END
ELSE (* bad block number *)
INC(waitPacket); len := BlockSize;
LogEnter(3); Log(3, TFTPId); Log(3, "Bad block number (expected "); LogInt(3, blockNr);
Log(3, ", got "); LogInt(3, Get2(buf, 2)); Log(3, ")"); LogExit(3)
END
ELSE (* wrong packet type *)
LogEnter(3); Log(3, TFTPId); Log(3, errorMsg[4]); LogExit(3);
SendError(socket, fip, fport, 4, "", res);
Abort := TRUE
END
ELSE (* ip/port changed *)
LogEnter(3); Log(3, TFTPId); Log(3, errorMsg[5]); LogExit(3);
SendError(socket, fip, fport, 5,"", res)
END
ELSIF (res = UDP.Timeout) THEN
INC(waitPacket); len := BlockSize;
LogEnter(3); Log(3, TFTPId); Log(3, "Timeout ("); LogInt(3, waitPacket); Log(3, ")"); LogExit(3)
ELSE (* unknown error (UDP/IP error) *)
LogEnter(3); Log(3, TFTPId); Log(3, errorMsg[0]); LogExit(3);
SendError(socket, fip, fport, 0, "", res);
Abort := TRUE
END;
UNTIL (res = Ok) OR Abort OR (waitPacket > MaxWait);
UNTIL Abort OR (waitPacket > MaxWait) OR (len < BlockSize);
LogEnter(1); Log(1, TFTPId);
IF ~Abort & (waitPacket <= MaxWait) & (len < BlockSize) THEN
Log(1, "file successfully received");
file.Update();
ok := TRUE;
ELSE
Log(1, "error receiveing file")
END;
LogExit(1);
socket.Close
ELSE
LogEnter(1); Log(1, TFTPId); Log(1, "can't get a free socket"); LogExit(1)
END;
RETURN ok
END Receive;
END TFTPClient;
VAR TraceLevel: SIGNED32;
errorMsg: ARRAY 8 OF ErrorMsg;
generator: Random.Generator;
PROCEDURE Send*(localFN, remoteFN: ARRAY OF CHAR; ip: IP.Adr): BOOLEAN;
VAR client: TFTPClient;
BEGIN
NEW(client);
RETURN client.Send(localFN, remoteFN, ip, TFTPPort)
END Send;
PROCEDURE Receive*(removeFN, localFN: ARRAY OF CHAR; ip: IP.Adr): BOOLEAN;
VAR client: TFTPClient;
BEGIN
NEW(client);
RETURN client.Receive(removeFN, localFN, ip, TFTPPort)
END Receive;
PROCEDURE TraceLevel0*;
BEGIN TraceLevel := 0
END TraceLevel0;
PROCEDURE TraceLevel1*;
BEGIN TraceLevel := 1
END TraceLevel1;
PROCEDURE TraceLevel2*;
BEGIN TraceLevel := 2
END TraceLevel2;
PROCEDURE TraceLevel3*;
BEGIN TraceLevel := 3
END TraceLevel3;
BEGIN
errorMsg[0] := "Undefined error.";
errorMsg[1] := "File not found.";
errorMsg[2] := "Access violation.";
errorMsg[3] := "Disk full.";
errorMsg[4] := "Illegal TFTP operation.";
errorMsg[5] := "Unknown transfer ID.";
errorMsg[6] := "File already exists.";
errorMsg[7] := "No such user.";
TraceLevel := 1;
NEW(generator)
END TFTP.
TFTP.TraceLevel3
TestTFTP.Mod