From ff6b5b65a8b7af5dd283306c1a228461b30a0ba8 Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Sat, 22 Sep 2018 05:19:24 +0000
Subject: [PATCH] Remove more bin.lua packings.

---
 nselib/coap.lua  | 106 +++++++++++++------------------------------
 nselib/dhcp.lua  |  77 ++++++++++++++++----------------
 nselib/mqtt.lua  |   3 +-
 nselib/mysql.lua | 114 ++++++++++++++++++-----------------------------
 4 files changed, 116 insertions(+), 184 deletions(-)

diff --git a/nselib/coap.lua b/nselib/coap.lua
index 636b67b38..49e0fc508 100644
--- a/nselib/coap.lua
+++ b/nselib/coap.lua
@@ -1,4 +1,3 @@
-local bin = require "bin"
 local comm = require "comm"
 local json = require "json"
 local lpeg = require "lpeg"
@@ -329,22 +328,23 @@ COAP.header.build = function(options)
   code = COAP.header.codes.build(code)
 
   -- Build the fixed portion of the header.
-  local pkt = ""
 
   ver = ver << 6
   mtype = mtype << 4
 
-  pkt = pkt .. bin.pack("C", ver | mtype | tkl)
-  pkt = pkt .. code
-  pkt = pkt .. bin.pack(">S", id)
-  pkt = pkt .. token
+  local pkt = {
+    string.pack("B", ver | mtype | tkl),
+    code,
+    string.pack(">I2", id),
+    token,
+  }
 
   -- Include optional portions of the header.
   if options["options"] then
-    pkt = pkt .. COAP.header.options.build(options.options)
+    pkt[#pkt+1] = COAP.header.options.build(options.options)
   end
 
-  return pkt
+  return table.concat(pkt)
 end
 
 --- Parses a CoAP message header.
@@ -361,9 +361,6 @@ end
 --         string containing the error message on failure.
 COAP.header.parse = function(buf, pos)
   assert(type(buf) == "string")
-  if #buf < 4 then
-    return false, "Cannot parse a string of less than four bytes."
-  end
 
   if not pos or pos == 0 then
     pos = 1
@@ -371,14 +368,11 @@ COAP.header.parse = function(buf, pos)
   assert(type(pos) == "number")
   assert(pos <= #buf)
 
-  if pos + 4 - 1 > #buf then
+  if #buf - pos + 1 < 4 then
     return false, "Fixed header extends past end of buffer."
   end
 
-  local pos, ver_type_tkl, code, id = bin.unpack("CA>S", buf, pos)
-  if not pos then
-    return false, "Failed to parse fixed header."
-  end
+  local ver_type_tkl, code, id, pos = string.unpack(">Bc1I2", buf, pos)
 
   -- Parse the fixed header.
   local hdr = {}
@@ -486,7 +480,7 @@ COAP.header.codes.build = function(name)
 
   class = class << 5
 
-  return bin.pack("C", class | detail)
+  return string.pack("B", class | detail)
 end
 
 --- Parses a CoAP request or response code.
@@ -511,7 +505,7 @@ COAP.header.codes.parse = function(buf, pos)
   assert(type(pos) == "number")
   assert(pos <= #buf)
 
-  local pos, id = bin.unpack("C", buf, pos)
+  local id, pos = string.unpack("B", buf, pos)
   if not pos then
     return false, id
   end
@@ -1462,20 +1456,8 @@ COAP.header.options.value.uint.build = function(val)
   if val == 0 then
     return ""
   end
-
-  if val <= 255 then
-    return bin.pack("C", val)
-  end
-
-  if val <= 65535 then
-    return bin.pack(">S", val)
-  end
-
-  if val <= 16777215 then
-    return bin.pack(">I", val):sub(2, 5)
-  end
-
-  return bin.pack(">I", val)
+  -- strip leading null bytes to use smallest space
+  return string.pack(">I16", val):gsub("^\0*","")
 end
 
 --- Parses a CoAP message Uint header option value.
@@ -1490,25 +1472,15 @@ end
 COAP.header.options.value.uint.parse = function(buf)
   assert(type(buf) == "string")
   assert(#buf >= 0)
-  assert(#buf <= 4)
+  assert(#buf <= 16)
 
   if #buf == 0 then
     return 0
   end
 
-  local val, pos
-  if #buf == 1 then
-    pos, val = bin.unpack("C", buf)
-  elseif #buf == 2 then
-    pos, val = bin.unpack(">S", buf)
-  elseif #buf == 3 then
-    pos, val = bin.unpack(">I", string.char(0x00) .. buf)
-  else
-    pos, val = bin.unpack(">I", buf)
-  end
+  local val = string.unpack(">I" .. #buf, buf)
 
   -- There should be no way for this to fail.
-  assert(pos)
   assert(val)
   assert(type(val) == "number")
 
@@ -1567,19 +1539,18 @@ COAP.header.options.delta_length.build = function(delta, length)
     end
 
     if num <= 268 then
-      return 13, bin.pack("C", num - 13)
+      return 13, string.pack("B", num - 13)
     end
 
-    return 14, bin.pack(">S", num - 269)
+    return 14, string.pack(">I2", num - 269)
   end
 
   local d1, d2 = build(delta)
   local l1, l2 = build(length)
 
   d1 = d1 << 4
-  bin.pack("C", d1 | l1)
 
-  return bin.pack("C", d1 | l1) .. d2 .. l2
+  return string.pack("B", d1 | l1) .. d2 .. l2
 end
 
 --- Parse the variable-length option delta and length field.
@@ -1613,7 +1584,7 @@ COAP.header.options.delta_length.parse = function(buf, pos)
   assert(type(pos) == "number")
   assert(pos <= #buf)
 
-  local pos, delta_and_length = bin.unpack("C", buf, pos)
+  local delta_and_length, pos = string.unpack("B", buf, pos)
   if not pos then
     return false, nil, nil, delta_and_length
   end
@@ -1636,20 +1607,20 @@ COAP.header.options.delta_length.parse = function(buf, pos)
 
   if delta == 13 then
     required_bytes = required_bytes + 1
-    dspec = "C"
+    dspec = "B"
   elseif delta == 14 then
     required_bytes = required_bytes + 2
     delta = 269
-    dspec = ">S"
+    dspec = ">I2"
   end
 
   if length == 13 then
     required_bytes = required_bytes + 1
-    lspec = "C"
+    lspec = "B"
   elseif length == 14 then
     required_bytes = required_bytes + 2
     length = 269
-    lspec = ">S"
+    lspec = ">I2"
   end
 
   if pos + required_bytes - 1 > #buf then
@@ -1659,7 +1630,7 @@ COAP.header.options.delta_length.parse = function(buf, pos)
   -- Extract the remaining bytes of each field.
   if dspec then
     local num
-    pos, num = bin.unpack(dspec, buf, pos)
+    num, pos = string.unpack(dspec, buf, pos)
     if not pos then
       return false, nil, nil, num
     end
@@ -1668,7 +1639,7 @@ COAP.header.options.delta_length.parse = function(buf, pos)
 
   if lspec then
     local num
-    pos, num = bin.unpack(lspec, buf, pos)
+    num, pos = string.unpack(lspec, buf, pos)
     if not pos then
       return false, nil, nil, num
     end
@@ -2426,7 +2397,7 @@ local tests = {
     {
       {["name"] = "etag", ["value"] = "ETAGETAG"},
     },
-    bin.pack("CA", 0x48, "ETAGETAG")
+    "\x48ETAGETAG"
   },
   {
     -- Before
@@ -2450,7 +2421,7 @@ local tests = {
       {["name"] = "uri_path", ["value"] = "foo"},
       {["name"] = "max_age", ["value"] = 0},
     },
-    bin.pack("CAC", 0xB3, "foo", 0x30)
+    "\xB3foo\x30"
   },
   {
     -- Before
@@ -2463,7 +2434,7 @@ local tests = {
       {["name"] = "uri_path", ["value"] = ".well-known"},
       {["name"] = "uri_path", ["value"] = "core"},
     },
-    bin.pack("CACA", 0xBB, ".well-known", 0x04, "core")
+    "\xBB.well-known\x04core"
   },
   {
     -- Before
@@ -2482,14 +2453,7 @@ local tests = {
       {["name"] = "uri_path", ["value"] = "core"},
       {["name"] = "max_age", ["value"] = 0},
     },
-    bin.pack(
-      "CACCACAC",
-      0x48, "ETAGETAG",    -- ID:  4, Delta: 4
-      0x10,                -- ID:  5, Delta: 1
-      0x6B, ".well-known", -- ID: 11, Delta: 6
-      0x04, "core",        -- ID: 11, Delta: 0
-      0x30                 -- ID: 14, Delta: 3
-    )
+    "\x48ETAGETAG\x10\x6B.well-known\x04core\x30"
   },
 }
 
@@ -2537,15 +2501,7 @@ local tests = {
         {["name"] = "uri_path", ["value"] = "core"},
       },
     },
-    bin.pack(
-      "CC>SACACA",
-      0x48,
-      0x01,
-      0x1234,
-      "nmapcoap",
-      0xBB, ".well-known",
-      0x04, "core"
-    )
+    "\x48\x01\x12\x34nmapcoap\xBB.well-known\x04core"
   },
 }
 
diff --git a/nselib/dhcp.lua b/nselib/dhcp.lua
index 575c508dc..bffa0cae0 100644
--- a/nselib/dhcp.lua
+++ b/nselib/dhcp.lua
@@ -14,7 +14,6 @@
 --   o Added possibility to override transaction id
 --   o Added WPAD action
 
-local bin = require "bin"
 local datetime = require "datetime"
 local ipOps = require "ipOps"
 local math = require "math"
@@ -67,7 +66,7 @@ local function read_ip(data, pos, length)
       local results = {}
       for i=1, length, 4 do
         local value
-        pos, value = bin.unpack(">I", data, pos)
+        value, pos = string.unpack(">I4", data, pos)
         table.insert(results, ipOps.fromdword(value))
       end
 
@@ -75,7 +74,7 @@ local function read_ip(data, pos, length)
     end
   else
     local value
-    pos, value = bin.unpack(">I", data, pos)
+    value, pos = string.unpack(">I4", data, pos)
 
     return pos, ipOps.fromdword(value)
   end
@@ -89,7 +88,8 @@ end
 --@return The new position (will always be pos + length, no matter what we think it should be)
 --@return The value of the field, or nil if the field length was wrong.
 local function read_string(data, pos, length)
-  return bin.unpack(string.format("A%d", length), data, pos)
+  local value, pos = string.unpack(("c%d"):format(length), data, pos)
+  return pos, value
 end
 
 ---Read a single byte. Print an error if the length isn't 1.
@@ -105,7 +105,8 @@ local function read_1_byte(data, pos, length)
     pos = pos + length
     return pos, nil
   end
-  return bin.unpack("C", data, pos)
+  local value, pos = string.unpack("B", data, pos)
+  return pos, value
 end
 
 ---Read a message type. This is a single-byte value that's looked up in the <code>request_types_str</code>
@@ -163,7 +164,8 @@ local function read_2_bytes(data, pos, length)
     pos = pos + length
     return pos, nil
   end
-  return bin.unpack(">S", data, pos)
+  local value, pos = string.unpack(">I2", data, pos)
+  return pos, value
 end
 
 
@@ -185,7 +187,7 @@ local function read_2_bytes_list(data, pos, length)
     local results = {}
     for i=1, length, 2 do
       local value
-      pos, value = bin.unpack(">S", data, pos)
+      value, pos = string.unpack(">I2", data, pos)
       table.insert(results, value)
     end
 
@@ -207,7 +209,8 @@ local function read_4_bytes(data, pos, length)
     pos = pos + length
     return pos, nil
   end
-  return bin.unpack(">I", data, pos)
+  local value, pos = string.unpack(">I4", data, pos)
+  return pos, value
 end
 
 ---Read a 4-byte unsigned little endian value, and interpret it as a time offset value. Print an
@@ -225,7 +228,7 @@ local function read_time(data, pos, length)
     pos = pos + length
     return pos, nil
   end
-  pos, result = bin.unpack(">I", data, pos)
+  result, pos = string.unpack(">I4", data, pos)
 
   return pos, datetime.format_time(result)
 end
@@ -426,34 +429,32 @@ function dhcp_build(request_type, ip_address, mac_address, options, request_opti
   end
 
   -- Header
-  packet = packet .. bin.pack(">CCCC", overrides['op'] or 1, overrides['htype'] or 1, overrides['hlen'] or 6, overrides['hops'] or 0)  -- BOOTREQUEST, 10mb ethernet, 6 bytes long, 0 hops
+  packet = packet .. string.pack(">BBBB", overrides['op'] or 1, overrides['htype'] or 1, overrides['hlen'] or 6, overrides['hops'] or 0) -- BOOTREQUEST, 10mb ethernet, 6 bytes long, 0 hops
   packet = packet .. ( overrides['xid'] or transaction_id )                                                         -- Transaction ID =
-  packet = packet .. bin.pack(">SS", overrides['secs'] or 0, overrides['flags'] or 0x0000)     -- Secs, flags
+  packet = packet .. string.pack(">I2I2", overrides['secs'] or 0, overrides['flags'] or 0x0000) -- Secs, flags
   packet = packet .. ip_address                                                 -- Client address
-  packet = packet .. bin.pack("<I", overrides['yiaddr'] or 0)                                  -- yiaddr
-  packet = packet .. bin.pack("<I", overrides['siaddr'] or 0)                                  -- siaddr
-  packet = packet .. bin.pack("<I", overrides['giaddr'] or 0)                                  -- giaddr
+  packet = packet .. string.pack("<I4I4I4", overrides['yiaddr'] or 0,
+    overrides['siaddr'] or 0,
+    overrides['giaddr'] or 0)
   packet = packet .. mac_address .. string.rep('\0', 16 - #mac_address)                        -- chaddr (MAC address)
   packet = packet .. (overrides['sname'] or string.rep('\0', 64))                              -- sname
   packet = packet .. (overrides['file'] or string.rep('\0', 128))                              -- file
-  packet = packet .. bin.pack(">I", overrides['cookie'] or 0x63825363)                         -- Magic cookie
+  packet = packet .. string.pack(">I4", overrides['cookie'] or 0x63825363) -- Magic cookie
 
   -- Options
-  packet = packet .. bin.pack(">CCC", 0x35, 1, request_type)                                   -- Request type
+  packet = packet .. string.pack(">BBB", 0x35, 1, request_type) -- Request type
 
   for _, option in ipairs(options or {}) do
-    packet = packet .. bin.pack(">C", option.number)
-    if ( "string" == option.type ) then
-      packet = packet .. bin.pack("p", option.value)
-    elseif( "ip" == option.type ) then
-      packet = packet .. bin.pack(">CI", 4, option.value)
+    packet = packet .. string.pack(">B", option.number)
+    if ( "string" == option.type or "ip" == option.type ) then
+      packet = packet .. string.pack("s1", option.value)
     end
   end
 
-  packet = packet .. bin.pack(">CCA", 0x37, #request_options, request_options)                 -- Request options
-  packet = packet .. bin.pack(">CCI", 0x33, 4, lease_time or 1)                                -- Lease time
+  packet = packet .. string.pack(">Bs1", 0x37, request_options) -- Request options
+  packet = packet .. string.pack(">BBI4", 0x33, 4, lease_time or 1) -- Lease time
 
-  packet = packet .. bin.pack(">C", 0xFF)                                                      -- Termination
+  packet = packet .. "\xFF" -- Termination
 
   return true, strbuf.dump(packet)
 end
@@ -473,26 +474,26 @@ function dhcp_parse(data, transaction_id)
   local result = {}
 
   -- Receive the first bit and make sure we got the correct operation back
-  pos, result['op'], result['htype'], result['hlen'], result['hops'] = bin.unpack(">CCCC", data, pos)
+  result.op, result.htype, result.hlen, result.hops, pos = string.unpack(">BBBB", data, pos)
   if(result['op'] ~= 2) then
     return false, string.format("DHCP server returned invalid reply ('op' wasn't BOOTREPLY (it was 0x%02x))", result['op'])
   end
 
   -- Confirm the transaction id
-  pos, result['xid'] = bin.unpack("A4", data, pos)
+  result.xid, pos = string.unpack("c4", data, pos)
   if(result['xid'] ~= transaction_id) then
     return false, string.format("DHCP server returned invalid reply (transaction id didn't match (%s != %s))", result['xid'], transaction_id)
   end
 
   -- Unpack the secs, flags, addresses, sname, and file
-  pos, result['secs'], result['flags'] = bin.unpack(">SS", data, pos)
-  pos, result['ciaddr'] = bin.unpack(">I", data, pos)
-  pos, result['yiaddr'] = bin.unpack(">I", data, pos)
-  pos, result['siaddr'] = bin.unpack(">I", data, pos)
-  pos, result['giaddr'] = bin.unpack(">I", data, pos)
-  pos, result['chaddr'] = bin.unpack("A16", data, pos)
-  pos, result['sname']  = bin.unpack("A64", data, pos)
-  pos, result['file']   = bin.unpack("A128", data, pos)
+  result.secs, result.flags,
+  result.ciaddr,
+  result.yiaddr,
+  result.siaddr,
+  result.giaddr,
+  result.chaddr,
+  result.sname,
+  result.file, pos = string.unpack(">I2I2 I4I4I4I4 c16 c64 c128", data, pos)
 
   -- Convert the addresses to strings
   result['ciaddr_str'] = ipOps.fromdword(result['ciaddr'])
@@ -501,7 +502,7 @@ function dhcp_parse(data, transaction_id)
   result['giaddr_str'] = ipOps.fromdword(result['giaddr'])
 
   -- Confirm the cookie
-  pos, result['cookie'] = bin.unpack(">I", data, pos)
+  result.cookie, pos = string.unpack(">I4", data, pos)
   if(result['cookie'] ~= 0x63825363) then
     return false, "DHCP server returned invalid reply (the magic cookie was invalid)"
   end
@@ -515,7 +516,7 @@ function dhcp_parse(data, transaction_id)
     end
 
     local option, length
-    pos, option, length = bin.unpack(">CC", data, pos)
+    option, length, pos = string.unpack(">BB", data, pos)
 
     -- Check for termination condition
     if(option == 0xFF) then
@@ -611,10 +612,10 @@ end
 --@return The parsed response, as a table.
 function make_request(target, request_type, ip_address, mac_address, options, request_options, overrides, lease_time)
   -- A unique id that identifies this particular session (and lets us filter out what we don't want to see)
-  local transaction_id = overrides and overrides['xid'] or bin.pack("<I", math.random(0, 0x7FFFFFFF))
+  local transaction_id = overrides and overrides['xid'] or string.pack("<I4", math.random(0, 0x7FFFFFFF))
 
   -- Generate the packet
-  local status, packet = dhcp_build(request_type, bin.pack(">I", ipOps.todword(ip_address)), mac_address, options, request_options, overrides, lease_time, transaction_id)
+  local status, packet = dhcp_build(request_type, ipOps.ip_to_str(ip_address), mac_address, options, request_options, overrides, lease_time, transaction_id)
   if(not(status)) then
     stdnse.debug1("dhcp: Couldn't build packet: " .. packet)
     return false, "Couldn't build packet: "  .. packet
diff --git a/nselib/mqtt.lua b/nselib/mqtt.lua
index 6e20ed9e7..822ef680a 100644
--- a/nselib/mqtt.lua
+++ b/nselib/mqtt.lua
@@ -920,7 +920,8 @@ MQTT.utf8_parse = function(buf, pos)
     return false, ("Buffer at position %d has no space for a %d-byte UTF-8 string."):format(pos, str_length)
   end
 
-  return string.unpack(">s2", buf, pos)
+  local value, pos = string.unpack(">s2", buf, pos)
+  return pos, value
 end
 
 --- Prefix the body of an MQTT packet with a fixed header.
diff --git a/nselib/mysql.lua b/nselib/mysql.lua
index 2c2143d28..2e84431b5 100644
--- a/nselib/mysql.lua
+++ b/nselib/mysql.lua
@@ -7,7 +7,6 @@
 --
 -- @author Patrik Karlsson <patrik@cqure.net>
 
-local bin = require "bin"
 local nmap = require "nmap"
 local stdnse = require "stdnse"
 local string = require "string"
@@ -91,7 +90,7 @@ local function decodeHeader( data, pos )
   local response = {}
   local pos, tmp = pos or 1, 0
 
-  pos, tmp = bin.unpack( "<I", data, pos )
+  tmp, pos = string.unpack( "<I4", data, pos )
   response.len = ( tmp & 255 )
   response.number = ( tmp >> 24 )
 
@@ -121,42 +120,38 @@ function receiveGreeting( socket )
   end
 
   local is_error
-  pos, is_error = bin.unpack( "C", data, pos )
+  is_error, pos = string.unpack("B", data, pos)
 
   if ( is_error == 0xff ) then
-    pos, response.errorcode = bin.unpack( "<S", data, pos )
-    pos, response.errormsg = bin.unpack("A" .. (#data - pos + 1), data, pos )
+    response.errorcode, pos = string.unpack( "<I2", data, pos )
+    response.errormsg = data:sub(pos)
 
     return false, response.errormsg
   end
 
   response.proto = is_error
-  pos, response.version = bin.unpack( "z", data, pos )
-  pos, response.threadid = bin.unpack( "<I", data, pos )
+  response.version, response.threadid, pos = string.unpack( "<zI4", data, pos )
 
   if response.proto == 10 then
-    pos, response.salt, _ = bin.unpack( "A8C", data, pos )
-    pos, response.capabilities = bin.unpack( "<S", data, pos )
-    if pos < #data then
-      pos, response.charset = bin.unpack( "C", data, pos )
-      pos, response.status = bin.unpack( "<S", data, pos )
-      pos, response.extcapabilities = bin.unpack( "<S", data, pos) -- capabilities, upper 2 bytes
+    response.salt, response.capabilities, pos = string.unpack("<c8xI2", data, pos)
       local auth_plugin_len
-      pos, auth_plugin_len = bin.unpack("C", data, pos)
-      pos, tmp = bin.unpack( "A10", data, pos )
+    if pos < #data then
+      response.charset, response.status,
+      response.extcapabilities, -- capabilities, upper 2 bytes
+      auth_plugin_len, tmp, pos = string.unpack( "<BI2 I2 Bc10", data, pos )
       if tmp ~= "\0\0\0\0\0\0\0\0\0\0" then
         stdnse.debug2("reserved bytes are not nulls")
       end
       if response.capabilities & Capabilities.Support41Auth > 0 then
-        pos, tmp, _ = bin.unpack("A" .. (math.max(13, auth_plugin_len - 8) - 1) .. "x", data, pos)
+        tmp, pos = string.unpack("c" .. (math.max(13, auth_plugin_len - 8) - 1) .. "x", data, pos)
         response.salt = response.salt .. tmp
       end
       if response.extcapabilities & ExtCapabilities.SupportsAuthPlugins > 0 then
-        response.auth_plugin_name = bin.unpack("z", data, pos)
+        response.auth_plugin_name = string.unpack("z", data, pos)
       end
     end
   elseif response.proto == 9 then
-    pos, response.auth_plugin_data = bin.unpack( "z", data, pos )
+    response.auth_plugin_data, pos = string.unpack( "z", data, pos )
   else
     stdnse.debug2("Unknown MySQL protocol version: %d", response.proto)
   end
@@ -189,8 +184,8 @@ local function createLoginHash(pass, salt)
   hash_stage3 = openssl.sha1( salt .. hash_stage2 )
 
   for pos=1, hash_stage1:len() do
-    _, b1 = bin.unpack( "C", hash_stage1, pos )
-    _, b2 = bin.unpack( "C", hash_stage3, pos )
+    b1 = string.unpack( "B", hash_stage1, pos )
+    b2 = string.unpack( "B", hash_stage3, pos )
 
     reply[pos] = string.char( b2 ~ b1 )
   end
@@ -244,7 +239,7 @@ function loginRequest( socket, params, username, password, salt )
     hash = createLoginHash( password, salt )
   end
 
-  local packet = bin.pack( "<SSICAzp",
+  local packet = string.pack( "<I2I2I4B c23 zs1",
     clicap,
     extcapabilities,
     MAXPACKET,
@@ -256,7 +251,7 @@ function loginRequest( socket, params, username, password, salt )
 
   local tmp = packet:len() + ( packetno << 24 )
 
-  packet = bin.pack( "<I", tmp ) .. packet
+  packet = string.pack( "<I4", tmp ) .. packet
 
   try( socket:send(packet) )
   packet = try( socket:receive_bytes(HEADER_SIZE) )
@@ -270,26 +265,24 @@ function loginRequest( socket, params, username, password, salt )
 
   local is_error
 
-  pos, is_error = bin.unpack( "C", packet, pos )
+  is_error, pos = string.unpack( "B", packet, pos )
 
   if is_error > 0 then
-    pos, response.errorcode = bin.unpack( "<S", packet, pos )
-
     local has_sqlstate
-    pos, has_sqlstate = bin.unpack( "C", packet, pos )
+    response.errorcode, has_sqlstate, pos = string.unpack( "<I2B", packet, pos )
 
     if has_sqlstate == 35 then
-      pos, response.sqlstate = bin.unpack( "A5", packet, pos )
+      response.sqlstate, pos = string.unpack( "c5", packet, pos )
     end
 
-    pos, response.errormessage = bin.unpack( "z", packet, pos )
+    response.errormessage, pos = string.unpack( "z", packet, pos )
 
     return false, response.errormessage
   else
     response.errorcode = 0
-    pos, response.affectedrows = bin.unpack( "C", packet, pos )
-    pos, response.serverstatus = bin.unpack( "<S", packet, pos )
-    pos, response.warnings = bin.unpack( "<S", packet, pos )
+    response.affectedrows,
+    response.serverstatus,
+    response.warnings, pos = string.unpack( "<BI2I2", packet, pos )
   end
 
   return true, response
@@ -309,36 +302,19 @@ end
 --         <code>length</code> and <code>type</code>
 function decodeField( data, pos )
 
-  local header, len
-  local def, _
+  local _
   local field = {}
 
-  pos, len = bin.unpack( "C", data, pos )
-  pos, field.catalog = bin.unpack( "A" .. len, data, pos )
-
-  pos, len = bin.unpack( "C", data, pos )
-  pos, field.database = bin.unpack( "A" .. len, data, pos )
-
-  pos, len = bin.unpack( "C", data, pos )
-  pos, field.table = bin.unpack( "A" .. len, data, pos )
-
-  pos, len = bin.unpack( "C", data, pos )
-  pos, field.orig_table = bin.unpack( "A" .. len, data, pos )
-
-  pos, len = bin.unpack( "C", data, pos )
-  pos, field.name = bin.unpack( "A" .. len, data, pos )
-
-  pos, len = bin.unpack( "C", data, pos )
-  pos, field.orig_name = bin.unpack( "A" .. len, data, pos )
-
-  -- should be 0x0C
-  pos, _ = bin.unpack( "C", data, pos )
-
-  -- charset, in my case 0x0800
-  pos, _ = bin.unpack( "<S", data, pos )
-
-  pos, field.length = bin.unpack( "<I", data, pos )
-  pos, field.type = bin.unpack( "A6", data, pos )
+  field.catalog,
+  field.database,
+  field.table,
+  field.orig_table,
+  field.name,
+  field.orig_name,
+  _, -- should be 0x0C
+  _, -- charset, in my case 0x0800
+  field.length,
+  field.type, pos = string.unpack( "<s1s1s1s1s1s1BI2I4c6", data, pos )
 
   return pos, field
 
@@ -403,7 +379,7 @@ function decodeQueryResponse( socket )
       end
 
       if header.len > 0 then
-        local _, b = bin.unpack("C", data, pos )
+        local b = string.unpack("B", data, pos )
 
         -- Is this the EOF packet?
         if b == EOF_MARKER then
@@ -465,13 +441,11 @@ end
 -- @return number containing the amount of fields
 function decodeResultSetHeader( data )
 
-  local _, fields
-
   if data:len() ~= HEADER_SIZE + 1 then
     return false, "Result set header was incorrect"
   end
 
-  _, fields = bin.unpack( "C", data, HEADER_SIZE + 1 )
+  local fields = string.unpack( "B", data, HEADER_SIZE + 1 )
 
   return true, fields
 end
@@ -486,16 +460,16 @@ end
 -- @return rows table containing row tables
 function decodeDataPackets( data, count )
 
-  local len, pos = 0, 1, 1
-  local header, row, rows = {}, {}, {}
+  local pos = 1
+  local rows = {}
 
-  while pos < data:len() do
-    row = {}
+  while pos <= data:len() do
+    local row = {}
+    local header
     pos, header = decodeHeader( data, pos )
 
     for i=1, count do
-      pos, len = bin.unpack("C", data, pos )
-      pos, row[i] = bin.unpack("A" .. len, data, pos)
+      row[i], pos = string.unpack("s1", data, pos)
     end
 
     table.insert( rows, row )
@@ -521,7 +495,7 @@ function sqlQuery( socket, query )
   local packet, packet_len, pos, header
   local status, fields, field_count, rows, rs
 
-  packet = bin.pack("<ICA", querylen, Command.Query, query )
+  packet = string.pack("<I4B", querylen, Command.Query) .. query
 
   --
   -- http://forge.mysql.com/wiki/MySQL_Internals_ClientServer_Protocol#Result_Set_Header_Packet