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How can the PBKDF2 function be done in PostgreSQL? There does not appear to be a native implementation.
Moved Answer out of Question to adhere to Stack Overflow guidelines. See original revision of post.
Original post (Revision link)
Not able to find it natively, and based on PHP code found on the 'net, I came up with this PBKDF2 function for PostgreSQL. Enjoy.
create or replace function PBKDF2
(salt bytea, pw text, count integer, desired_length integer, algorithm text)
returns bytea
immutable
language plpgsql
as $$
declare
hash_length integer;
block_count integer;
output bytea;
the_last bytea;
xorsum bytea;
i_as_int32 bytea;
i integer;
j integer;
k integer;
begin
algorithm := lower(algorithm);
case algorithm
when 'md5' then
hash_length := 16;
when 'sha1' then
hash_length = 20;
when 'sha256' then
hash_length = 32;
when 'sha512' then
hash_length = 64;
else
raise exception 'Unknown algorithm "%"', algorithm;
end case;
block_count := ceil(desired_length::real / hash_length::real);
for i in 1 .. block_count loop
i_as_int32 := E'\\000\\000\\000'::bytea || chr(i)::bytea;
i_as_int32 := substring(i_as_int32, length(i_as_int32) - 3);
the_last := salt::bytea || i_as_int32;
xorsum := HMAC(the_last, pw::bytea, algorithm);
the_last := xorsum;
for j in 2 .. count loop
the_last := HMAC(the_last, pw::bytea, algorithm);
--
-- xor the two
--
for k in 1 .. length(xorsum) loop
xorsum := set_byte(xorsum, k - 1, get_byte(xorsum, k - 1) # get_byte(the_last, k - 1));
end loop;
end loop;
if output is null then
output := xorsum;
else
output := output || xorsum;
end if;
end loop;
return substring(output from 1 for desired_length);
end $$;
I've tested against other implementations without deviation, but be sure to test it yourself.
CREATE OR REPLACE FUNCTION array_replace(INT[]) RETURNS float[] AS $$
DECLARE
arrFloats ALIAS FOR $1;
J int=0;
x int[]=ARRAY[2,4];
-- xx float[]=ARRAY[2.22,4.33];
b float=2.22;
c float=3.33;
retVal float[];
BEGIN
FOR I IN array_lower(arrFloats, 1)..array_upper(arrFloats, 1) LOOP
FOR K IN array_lower(x, 1)..array_upper(x, 1) LOOP
IF (arrFloats[I]= x[K])THEN
retVal[j] :=b;
j:=j+1;
retVal[j] :=c;
j:=j+1;
ELSE
retVal[j] := arrFloats[I];
j:=j+1;
END IF;
END LOOP;
END LOOP;
RETURN retVal;
END;
$$ LANGUAGE plpgsql STABLE RETURNS NULL ON NULL INPUT;
When I run this query
SELECT array_replace(array[1,20,2,5]);
it give me output like this
"[0:8]={1,1,20,20,2.22,3.33,2,5,5}"
Now I do not know why it is coming this duplicate values. I mean it is straight away a nested loop ...
I need a output like this one
"[0:8]={1,20,2.22,3.33,5}"
You have a double loop with the x array having two elements. On every iteration you push elements onto the result array, hence you get twice as many values.
If I understand you logic correctly, you want to scan the input array for values of another array in that same order. If the same, then replace these values with another array, leaving other values intact. There are no built-in functions to help you here, so you have to do this from scratch:
CREATE FUNCTION array_replace(arrFloats float[]) RETURNS float[] AS $$
DECLARE
searchArr float[] := ARRAY[1.,20.];
replaceArr float[] := ARRAY[1.11,1.,111.,20.2,20.222];
retVal float[];
i int;
ndx int;
len int;
upp int;
low int
BEGIN
low := array_lower(searchArr, 1)
upp := array_upper(searchArr, 1);
len := upp - low + 1;
i := array_lower(arrFloats, 1);
WHILE i <= array_upper(arrFloats, 1) LOOP -- Use WHILE LOOP so can update i
ndx := i; -- index into arrFloats for inner loop
FOR j IN low .. upp LOOP
IF arrFloats[ndx] != searchArr[j] THEN
-- No match so put current element of arrFloats in the result and update i
retVal := retVal || arrFloats[i];
i := i + 1;
EXIT; -- No need to look further, break out of inner loop
END IF;
ndx := ndx + 1;
IF j = upp THEN
-- We have a match so append the replaceArr to retVal and
-- increase i by length of search_array
retVal := retVal || replaceArr;
i := i + len;
END IF;
END LOOP;
END LOOP;
RETURN retVal;
END;
$$ LANGUAGE plpgsql STABLE STRICT;
This function would become much more flexible if you made searchArr and replaceArr into parameters as well.
Test
patrick#puny:~$ psql -d test
psql (9.5.0, server 9.4.5)
Type "help" for help.
test=# select array_replace(array[1,20,2,5]);
array_replace
------------------------------
{1.11,1,111,20.2,20.222,2,5}
(1 row)
test=# select array_replace(array[1,20,2,5,1,20.1,1,20]);
array_replace
------------------------------------------------------------
{1.11,1,111,20.2,20.222,2,5,1,20.1,1.11,1,111,20.2,20.222}
(1 row)
As you can see it works for multiple occurrences of the search array.
On the server side, text is entered into a memobox. This text is then sent to the Server side using this code:
var
ftmpstr :String;
buf :array[0..255] of char;
msize, nyites :dword;
i :Integer;
..
Command := Socket.ReceiveText;
if split(Command,'|', 0) = 'IBATCH' then
begin
ftmpstr := IBat.Memo1.Text;
nyites := 1;
msize := length(ftmpstr);
Server.Socket.Connections[ListView1.Selected.Index].SendText(IntToStr(msize));
while msize>255 do
begin
for i := 0 to 255 do
buf[i] := ftmpstr[nyites+i];
Server.Socket.Connections[Form1.ListView1.Selected.Index].SendBuf(buf,256);
dec(msize,256);
inc(nyites,256);
end;
if msize>0 then
begin
for i := 0 to msize-1 do
buf[i] := ftmpstr[nyites+i];
Server.Socket.Connections[Form1.ListView1.Selected.Index].SendBuf(buf,msize);
end;
end;
Code on the Server side:
Socket.SendText('IBATCH');
ftmpstr:='';
mbytesleft := strtoint(Socket.ReceiveText);
SetLength(ftmpstr,mbytesleft);
nyites:=1;
while mbytesleft>255 do
begin
Socket.ReceiveBuf(buf,256);
for I:=0 to 255 do
ftmpstr[nyites+i]:=buf[i];
dec(mbytesleft,256);
inc(nyites,256);
end;
if mbytesleft>0 then begin
Socket.ReceiveBuf(buf,mbytesleft);
for I:=0 to mbytesleft-1 do
ftmpstr[nyites+i]:=buf[i];
end;
nfile:=TempDir+IntToStr(GetTickCount)+'.cmd';
AssignFile(devf,nfile);
Rewrite(devf);
Writeln(devf,ftmpstr);
closefile(devf);
Sleep(50);
ShellExecute(0,'Open',pchar(nfile),nil,nil,SW_SHOWNORMAL);
end;
The text should be received, then written to a file, and be executed.
I did however find the code online and modify it to work with TServerSocket and TClientSocket components. I created a successful connection between the client and server, but the above code just doesn't want to work. Maybe someone with more expertise could help me get this working.
Any help would be greatly appreciated.
Your code has no structured protocol to it. TCP is a stream of raw bytes, and you are sending everything as strings (and not doing a very good job of it - no error handling, no partial send/receive handling, etc). You need to delimit your fields/messages from one another. Then the receiver can look for those delimiters. You would have to read everything from the socket into an intermediate buffer, checking the buffer for a message terminator, and then extract only completed messages and process them as needed.
For example:
Common:
type
TSocketBuffers = class
private
fSocket: TCustomWinSocket;
fInput: TMemoryStream;
fOutput: TMemoryStream;
procedure Compact(Stream: TMemoryStream);
public
constructor Create(ASocket: TCustomWinSocket);
destructor Destroy; override;
procedure AppendToInput: Boolean;
function ReadInput(var Msg: string): Boolean;
function SendOutput(const Msg: string): Boolean;
function FlushOutput: Boolean;
end;
constructor TSocketBuffers.Create(ASocket: TCustomWinSocket);
begin
inherited Create;
fSocket := ASocket;
fInput := TMemoryStream.Create;
fOutput := TMemoryStream.Create;
end;
destructor TSocketBuffers.Destroy;
begin
fInput.Free;
fOutput.Free;
inherited;
end;
procedure TSocketBuffers.Compact(Stream: TMemoryStream);
begin
if Stream.Position < Stream.Size then
begin
Move(Pointer(Longint(Stream.Memory) + Stream.Position)^, Stream.Memory^, Stream.Size - Stream.Position);
Stream.Size := Stream.Position;
Stream.Position := 0;
end else begin
Stream.Clear;
end;
end;
function TSocketBuffers.AppendToInput: Boolean;
var
buf: array[0..255] of Byte;
nBuf: Integer;
begin
nBuf := fSocket.ReceiveBuf(buf[0], sizeof(buf));
if nBuf > 0 then
begin
fInput.Seek(0, soEnd);
fInput.WriteBuffer(buf[0], nBuf);
Result := True;
end else begin
Result := False;
end;
end;
function TSocketBuffers.ReadInput(var Msg: string): Boolean;
var
b: Byte;
tmp: string;
needed: Integer;
begin
Result := False;
Msg := '';
fInput.Position := 0;
while fInput.Position < fInput.Size do
begin
fInput.ReadBuffer(b, 1);
if b = Ord('|') then
begin
SetString(tmp, PAnsiChar(fInput.Memory), fInput.Position-1);
needed := StrToInt(tmp);
if needed > 0 then
begin
if (fInput.Size - fInput.Position) < Int64(needed) then
Exit;
SetLength(Msg, needed);
fInput.ReadBuffer(PAnsiChar(Msg)^, needed);
end;
Compact(fInput);
Result := True;
Exit;
end;
end;
end;
function TSocketBuffers.SendOutput(const Msg: string): Boolean;
var
tmp: AnsiString;
nSent: Integer;
begin
Result := True;
tmp := IntToStr(Length(Msg)) + '|' + Msg;
if fOutput.Size = 0 then
begin
repeat
nSent := fSocket.SendBuf(PAnsiChar(tmp)^, Length(tmp));
if nSent < 0 then
begin
if WSAGetLastError() <> WSAEWOULDBLOCK then
begin
Result := True;
Exit;
end;
Break;
end;
Delete(tmp, 1, nSent);
until tmp = '';
end;
if tmp <> '' then
begin
fOutput.Seek(0, soEnd);
fOutput.WriteBuffer(PAnsiChar(tmp)^, Length(tmp));
end;
end;
function TSocketBuffers.FlushOutput: Boolean;
var
buf: array[0..255] of Byte;
nBuf, nSent: Integer;
begin
Result := True;
fOutput.Position := 0;
while fOutput.Position < fOutput.Size do
begin
nBuf := fOutput.Read(buf[0], sizeof(buf));
nSent := fSocket.SendBuf(buf[0], nBuf);
if nSent < 0 then
begin
if WSAGetLastError() <> WSAEWOULDBLOCK then
begin
fOutput.Seek(-nBuf, soCurrent);
Result := False;
end;
Break;
end;
end;
if fOutput.Position > 0 then
Compact(fOutput);
end;
Server:
procedure TForm1.ServerSocketConnect(Sender: TObject; Socket: TCustomWinSocket);
begin
Socket.Data := TSocketBuffers.Create(Socket);
end;
procedure TForm1.ServerSocketDisconnect(Sender: TObject; Socket: TCustomWinSocket);
begin
TSocketBuffers(Socket.Data).Free;
end;
procedure TForm1.ServerSocketRead(Sender: TObject; Socket: TCustomWinSocket);
var
bufs: TSocketBuffers;
Command: string;
begin
bufs := TSocketBuffers(Socket.Data);
if not bufs.AppendToInput then Exit;
while bufs.ReadInput(Command) do
begin
if split(Command, '|', 0) = 'IBATCH' then
bufs.SendOutput(IBat.Memo1.Text);
end;
end;
procedure TForm1.ServerSocketWrite(Sender: TObject; Socket: TCustomWinSocket);
begin
TSocketBuffers(Socket.Data).FlushOutput;
end;
Client:
bufs := TSocketBuffers.Create(Client.Socket);
...
// this is assuming TClientSocekt is set to blocking mode
// otherwise you have to use the OnRead and OnWrite events...
if bufs.SendOutput('IBATCH') then
begin
while bufs.AppendToInput do
begin
if bufs.ReadInput(ftmpstr) then
begin
nfile := TempDir+IntToStr(GetTickCount) + '.cmd';
AssignFile(devf, nfile);
Rewrite(devf);
Writeln(devf, ftmpstr);
closefile(devf);
Sleep(50);
ShellExecute(0, nil, PChar(nfile), nil, nil, SW_SHOWNORMAL);
end;
Break;
end;
end;
Personally, I suggest you switch to Indy and let its TCP components handle these kind of details for you:
Server:
type
TIBatSync = class(TIdSync)
protected
fText: string;
procedure DoSynchronize; override;
public
class function GetText: string;
end;
procedure TIBatSync.DoSynchronize;
begin
fText := Form1.IBat.Memo1.Text;
end;
class function TIBatSync.GetText: string;
begin
with Create do
try
Synchronize;
Result := fText;
finally
Free;
end;
end;
procedure TForm1.IdTCPServerExecue(AContext: TIdContext);
var
Command, tmp: string;
begin
tmp := AContext.Connection.IOHandler.ReadLn('|');
Command := AContext.Connection.IOHandler.ReadString(StrToInt(tmp));
if split(Command, '|', 0) = 'IBATCH' then
begin
tmp := TIBatSync.GetText;
AContext.Connection.IOHandler.Write(Length(tmp) + '|' + tmp);
end;
end;
Client:
Client.IOHandler.Write('6|IBATCH');
ftmpstr := Client.IOHandler.ReadLn('|');
ftmpstr := Client.IOHandler.ReadString(StrToInt(ftmpstr));
nfile := TempDir+IntToStr(GetTickCount) + '.cmd';
AssignFile(devf, nfile);
Rewrite(devf);
Writeln(devf, ftmpstr);
closefile(devf);
Sleep(50);
ShellExecute(0, nil, PChar(nfile), nil, nil, SW_SHOWNORMAL);
I'm playing around with plpgsql and have put together a function that assembles a dynamic query. I've tested it and it executes (i've included a test wrapper to output the assembled query).
Where I'm stumbling is capturing the output of the EXECUTE command once it's run, because I'd like to return some or all of the values, depending on the nature of the dynamic query. I've set up a type userprofile, and have the setProfileDynamic function return this type.
With the full complement of parameters, the output checks out (except for the second query, more on that in a bit). But when some of the parameters are missing (ie not all the user preferences are updated, only one eg: measuresystem) then the output is corrupted, so that measuresystem_id might appear as username in the output.
Secondly, is how to get the result of the second query (updateDefaultMealplan) into the userprofile type (where the columns mealplan_id and mealplan_name are waiting patiently). Currently this query returns into mp_id (and mp_name is filled from the _values array if 'defaultmealplan' key is present).
I'm quite new to this and I might be trying to do too much in one function, and I might be doing it completely the wrong way, so I don't mind whatever corrections might come to pass.
The userprofile type:
DROP TYPE IF EXISTS userprofile CASCADE;
CREATE TYPE userprofile AS (
username text,
measuresystem_id int,
blanksymbol_id int,
mealplan_id int,
mealplan_name text
);
The main function
DROP FUNCTION IF EXISTS setProfileDynamic (int, text, text[], text[]);
CREATE OR REPLACE FUNCTION setProfileDynamic (_userid int, _token text, _keys text[], _values text[])
RETURNS userprofile AS $$
DECLARE
_query text;
numkeys int;
i int;
_update text[];
_from text[];
_where text[];
_return text[];
_into text[];
test text[];
up userprofile;
mp_name text;
mp_id int;
u text;
f text;
w text;
r text;
c_update int := 1;
c_from int := 1;
c_where int := 3;
c_return int := 1;
runupdate boolean := false; --bc passing default mealplan through this fn too.
changedefaultmp boolean := false;
BEGIN
test[1] := 'users.id';
test[2] := 'users.token';
test[3] := _userid;
test[4] := _token;
numkeys := array_length(_keys, 1);
raise notice 'numkeys = %', numkeys;
_where[1] := test[1] || ' = ' || quote_literal(test[3]);
_where[2] := test[2] || ' = ' || quote_literal(test[4]);
--raise notice '_where[1] = %', _where[1];
--raise notice '_where[2] = %', _where[2];
for i in 1..numkeys loop
raise notice 'keys[%] = %', i, _keys[i];
CASE _keys[i]
WHEN 'email' THEN
runupdate := true;
_update[c_update] := quote_ident(_keys[i]) || ' = ' || quote_literal(_values[i]);
c_update := c_update + 1;
WHEN 'password' THEN
runupdate := true;
_update[c_update] := quote_ident(_keys[i]) || ' = ' || quote_literal(_values[i]);
c_update := c_update + 1;
WHEN 'username' THEN
runupdate := true;
_update[c_update] := quote_ident(_keys[i]) || ' = ' || quote_literal(_values[i]);
c_update := c_update + 1;
_return[c_return] := quote_ident(_keys[i]);
c_return := c_return + 1;
WHEN 'measuresystem' THEN
runupdate := true;
_update[c_update] := 'measuresystem_id = ms.id';
c_update := c_update + 1;
_from[c_from] := 'measuresystem as ms';
c_from := c_from + 1;
_where[c_where] := 'ms.name = ' || quote_literal(_values[i]);
c_where := c_where + 1;
_return[c_return] := 'ms.id';
c_return := c_return + 1;
WHEN 'blanksymbol' THEN
runupdate := true;
_update[c_update] := 'blanksymbol_id = bs.id';
c_update := c_update + 1;
_from[c_from] := 'blanksymbol as bs';
c_from := c_from + 1;
_where[c_where] := 'bs.name = ' || quote_literal(_values[i]);
c_where := c_where + 1;
_return[c_return] := 'bs.id';
c_return := c_return + 1;
ELSE
changedefaultmp := true;
mp_name := _values[i];
END CASE;
end loop;
u := 'UPDATE users SET ' || array_to_string(_update, ', ');
f := 'FROM ' || array_to_string(_from, ', '); --if a_t_s is null, the whole f is null and not included so no error
w := 'WHERE ' || array_to_string(_where, ' AND ');
r := 'RETURNING ' || array_to_string(_return, ', ');
raise notice 'u = %', u;
raise notice 'f = %', f;
raise notice 'w = %', w;
raise notice 'r = %', r;
_query = concat_ws(' ', u, f, w, r);
raise notice '_query = %', _query;
IF runupdate THEN
if r IS NULL THEN
EXECUTE _query;
ELSE
EXECUTE _query INTO up;
END IF;
END IF;
IF changedefaultmp THEN
SELECT into mp_id updateDefaultMealplan(_userid, mp_name);
END IF;
return up;
END
$$ LANGUAGE PLPGSQL;
This is the wrapper function where you can see the query generated for different inputs:
DROP FUNCTION IF EXISTS T ();
CREATE OR REPLACE FUNCTION T ()
RETURNS setof userprofile AS $$
declare
_keys text[];
_values text[];
_userid int := 1;
_token text := 'beet';
begin
_keys := ARRAY['email', 'password', 'username', 'measuresystem', 'blanksymbol', 'defaultmealplan'];
_values := ARRAY['s#p.com', 'secret', 'myname', 'metric', '?', 'new'];
--_keys := ARRAY['email', 'blanksymbol'];
--_values := ARRAY['k#d.com', '[]'];
return query
SELECT * from setProfileDynamic(_userid, _token, _keys, _values);
end
$$ LANGUAGE PLPGSQL;
I realize it's a lot of code to get through, I hope the T function helps to clarify things. 'email' and 'password' params are not returning. 'defaultmealplan' triggers the second query. Any of 'username', 'measuresystem', 'blanksymbol' or 'defaultmealplan' should return a value into the userprofile type. Thanks for any forthcoming feedback.
the basic issue is so your dynamic query doesn't returns all necessary columns, second issue - you probably expecting, but it is not valid expectation, so records are assigned with respecting field' names. But when you assign some values to some composite type, postgres dosn't check name - only order is important. So you have to use NULLs for filling gaps and return all field.
you can simplify your code with array concating
DECLARE _return_cols text[] = '{}';
BEGIN
_return_cols := _return_cols || quote_ident('some_column');
_return_cols := _return_cols || quote_ident('some_other_column');
...
Is there a function in PostgreSQL that can convert a base 10 number like 30 into a base 36 representation like u?
There are base-64 functions (such as encode) but nothing for base-36. But you could write one of your own or use this one:
CREATE OR REPLACE FUNCTION base36_encode(IN digits bigint, IN min_width int = 0) RETURNS varchar AS $$
DECLARE
chars char[];
ret varchar;
val bigint;
BEGIN
chars := ARRAY['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'];
val := digits;
ret := '';
IF val < 0 THEN
val := val * -1;
END IF;
WHILE val != 0 LOOP
ret := chars[(val % 36)+1] || ret;
val := val / 36;
END LOOP;
IF min_width > 0 AND char_length(ret) < min_width THEN
ret := lpad(ret, min_width, '0');
END IF;
RETURN ret;
END;
$$ LANGUAGE plpgsql IMMUTABLE;
I think you should ask yourself if the database is the right place for dealing with this sort of data formatting though, presentational issues like this might be better handled closer to final viewing level of your stack.
here's a version that can take numbers of any size, it uses the data type "numeric" which is the postgresql implementation of bignum.
CREATE OR REPLACE FUNCTION base36_encode(IN digits numeric, IN min_width int = 0) RETURNS text AS $$
DECLARE
chars char[] := ARRAY['0','1','2','3','4','5','6','7','8','9','A','B'
,'C','D','E','F','G','H','I','J','K','L','M','N'
,'O','P','Q','R','S','T','U','V','W','X','Y','Z' ] ;
ret text:='';
val numeric:= digits;
BEGIN
IF digits < 0 THEN
val := -val;
END IF;
WHILE val > 0 OR min_width > 0 LOOP
ret := chars[(mod(val,36))+1] || ret;
val := div(val,36);
min_width := min_width-1;
END LOOP;
IF digits < 0 THEN
ret := '-'||ret;
END IF;
RETURN ret;
END;
$$ LANGUAGE plpgsql IMMUTABLE;
Modified Implementation
Modified from other implementation to increase the readability. Any kind of update or modification or suggestion appreciated to increase the readability.
CREATE OR REPLACE FUNCTION fn_base36_encode(IN base10 bigint)
RETURNS varchar
LANGUAGE plpgsql
AS $BODY$
DECLARE
base36 varchar := '';
intval bigint := abs(base10);
char0z char[] := regexp_split_to_array('0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ', '');
BEGIN
WHILE intval != 0 LOOP
base36 := char0z[(intval % 36)+1] || base36;
intval := intval / 36;
END LOOP;
IF base10 = 0 THEN base36 := '0'; END IF;
RETURN base36;
END;
$BODY$;