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prosody
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util/dbuffer.lua @ 12480:7e9ebdc75ce4
net: isolate LuaSec-specifics
For this, various accessor functions are now provided directly on the
sockets, which reach down into the LuaSec implementation to obtain the
information.
While this may seem of little gain at first, it hides the implementation
detail of the LuaSec+LuaSocket combination that the actual socket and
the TLS layer are separate objects.
The net gain here is that an alternative implementation does not have to
emulate that specific implementation detail and "only" has to expose
LuaSec-compatible data structures on the new functions.
author | Jonas Schäfer <jonas@wielicki.name> |
---|---|
date | Wed, 27 Apr 2022 17:44:14 +0200 |
parent | 11637:19cddf92fcc2 |
child | 12762:79b89f382290 |
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local queue = require "util.queue"; local s_byte, s_sub = string.byte, string.sub; local dbuffer_methods = {}; local dynamic_buffer_mt = { __name = "dbuffer", __index = dbuffer_methods }; function dbuffer_methods:write(data) if self.max_size and #data + self._length > self.max_size then return nil; end local ok = self.items:push(data); if not ok then self:collapse(); ok = self.items:push(data); end if not ok then return nil; end self._length = self._length + #data; return true; end function dbuffer_methods:read_chunk(requested_bytes) local chunk, consumed = self.items:peek(), self.front_consumed; if not chunk then return; end local chunk_length = #chunk; local remaining_chunk_length = chunk_length - consumed; if not requested_bytes then requested_bytes = remaining_chunk_length; end if remaining_chunk_length <= requested_bytes then self.front_consumed = 0; self._length = self._length - remaining_chunk_length; self.items:pop(); assert(#chunk:sub(consumed + 1, -1) == remaining_chunk_length); return chunk:sub(consumed + 1, -1), remaining_chunk_length; end local end_pos = consumed + requested_bytes; self.front_consumed = end_pos; self._length = self._length - requested_bytes; assert(#chunk:sub(consumed + 1, end_pos) == requested_bytes); return chunk:sub(consumed + 1, end_pos), requested_bytes; end function dbuffer_methods:read(requested_bytes) local chunks; if requested_bytes and requested_bytes > self._length then return nil; end local chunk, read_bytes = self:read_chunk(requested_bytes); if not requested_bytes then return chunk; elseif chunk then requested_bytes = requested_bytes - read_bytes; if requested_bytes == 0 then -- Already read everything we need return chunk; end chunks = {}; else return nil; end -- Need to keep reading more chunks while chunk do table.insert(chunks, chunk); if requested_bytes > 0 then chunk, read_bytes = self:read_chunk(requested_bytes); requested_bytes = requested_bytes - read_bytes; else break; end end return table.concat(chunks); end -- Read to, and including, the specified character sequence (return nil if not found) function dbuffer_methods:read_until(char) local buffer_pos = 0; for i, chunk in self.items:items() do local start = 1 + ((i == 1) and self.front_consumed or 0); local char_pos = chunk:find(char, start, true); if char_pos then return self:read(1 + buffer_pos + char_pos - start); end buffer_pos = buffer_pos + #chunk - (start - 1); end return nil; end function dbuffer_methods:discard(requested_bytes) if requested_bytes > self._length then return nil; end local chunk, read_bytes = self:read_chunk(requested_bytes); if chunk then requested_bytes = requested_bytes - read_bytes; if requested_bytes == 0 then -- Already read everything we need return true; end else return nil; end while chunk do if requested_bytes > 0 then chunk, read_bytes = self:read_chunk(requested_bytes); requested_bytes = requested_bytes - read_bytes; else break; end end return true; end -- Normalize i, j into absolute offsets within the -- front chunk (accounting for front_consumed), and -- ensure there is enough data in the first chunk -- to cover any subsequent :sub() or :byte() operation function dbuffer_methods:_prep_sub(i, j) if j == nil then j = -1; end if j < 0 then j = self._length + (j+1); end if i < 0 then i = self._length + (i+1); end if i < 1 then i = 1; end if j > self._length then j = self._length; end if i > j then return nil; end self:collapse(j); if self.front_consumed > 0 then i = i + self.front_consumed; j = j + self.front_consumed; end return i, j; end function dbuffer_methods:sub(i, j) i, j = self:_prep_sub(i, j); if not i then return ""; end return s_sub(self.items:peek(), i, j); end function dbuffer_methods:byte(i, j) i = i or 1; j = j or i; i, j = self:_prep_sub(i, j); if not i then return; end return s_byte(self.items:peek(), i, j); end function dbuffer_methods:length() return self._length; end dbuffer_methods.len = dbuffer_methods.length; -- strings have :len() dynamic_buffer_mt.__len = dbuffer_methods.length; -- support # operator function dbuffer_methods:collapse(bytes) bytes = bytes or self._length; local front_chunk = self.items:peek(); if not front_chunk or #front_chunk - self.front_consumed >= bytes then return; end local front_chunks = { front_chunk:sub(self.front_consumed+1) }; local front_bytes = #front_chunks[1]; while front_bytes < bytes do self.items:pop(); local chunk = self.items:peek(); front_bytes = front_bytes + #chunk; table.insert(front_chunks, chunk); end self.items:replace(table.concat(front_chunks)); self.front_consumed = 0; end local function new(max_size, max_chunks) if max_size and max_size <= 0 then return nil; end return setmetatable({ front_consumed = 0; _length = 0; max_size = max_size; items = queue.new(max_chunks or 32); }, dynamic_buffer_mt); end return { new = new; };