1 files changed, 118 insertions, 0 deletions
diff --git a/include/dnsjit/core/object/dns/label.lua b/include/dnsjit/core/object/dns/label.lua
new file mode 100644
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--- /dev/null
+++ b/include/dnsjit/core/object/dns/label.lua
@@ -0,0 +1,118 @@
+-- Copyright (c) 2018-2021, OARC, Inc.
+-- All rights reserved.
+--
+-- This file is part of dnsjit.
+--
+-- dnsjit is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- dnsjit is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with dnsjit.  If not, see <http://www.gnu.org/licenses/>.
+
+-- dnsjit.core.object.dns.label
+-- Container of a DNS label
+--
+-- The object that describes a DNS label.
+-- To extract a domain name label first check that
+-- .I have_dn
+-- is set, then use
+-- .I "offset + 1"
+-- to indicate where in the payload the label start and
+-- .I length
+-- for how many bytes long it is.
+-- .SS Attributes
+-- .TP
+-- is_end
+-- .TP
+-- have_length
+-- Set if there is a length.
+-- .TP
+-- have_offset
+-- Set if there is an offset.
+-- .TP
+-- have_extension_bits
+-- Set if there is extension bits.
+-- .TP
+-- have_dn
+-- Set if the label contained a domain name.
+-- .TP
+-- extension_bits
+-- The extension bits.
+-- .TP
+-- length
+-- The length of the domain name.
+-- .TP
+-- offset
+-- If
+-- .I have_dn
+-- is set then this contains the offset within the payload to where this label
+-- start otherwise it contains the offset to another label.
+module(...,package.seeall)
+
+require("dnsjit.core.object.dns_h")
+local ffi = require("ffi")
+
+local Label = {}
+
+-- Create a new array of labels.
+function Label.new(size)
+    return ffi.new("core_object_dns_label_t[?]", size)
+end
+
+-- Returns labels as a string and an offset to the next label.
+-- The string may be nil if the first label was an offset.
+-- The offset may be nil if the last label was an extension bits or end marker.
+function Label.tostring(dns, labels, num_labels, offset_labels)
+    if offset_labels == nil then
+        offset_labels = 0
+    end
+    local dn
+    for n = 1, tonumber(num_labels) do
+        local label = labels[n - 1 + offset_labels]
+
+        if label.have_dn == 1 then
+            if dn == nil then
+                dn = ""
+            end
+            dn = dn .. ffi.string(dns.payload + label.offset + 1, label.length) .. "."
+        elseif label.have_offset == 1 then
+            return dn, label.offset
+        else
+            return dn, nil
+        end
+    end
+    return dn, nil
+end
+
+-- Returns labels as a string which also includes a textual notation of the
+-- offset in the form of
+-- .IR "<offset>label" .
+function Label.tooffstr(dns, labels, num_labels, offset_labels)
+    if offset_labels == nil then
+        offset_labels = 0
+    end
+    local dn = ""
+    for n = 1, tonumber(num_labels) do
+        local label = labels[n - 1 + offset_labels]
+
+        if label.have_dn == 1 then
+            dn = dn .. "<" .. tonumber(label.offset) .. ">" .. ffi.string(dns.payload + label.offset + 1, label.length) .. "."
+        elseif label.have_offset == 1 then
+            dn = dn .. "<" .. tonumber(label.offset) .. ">"
+            break
+        else
+            break
+        end
+    end
+    return dn
+end
+
+-- dnsjit.core.object.dns (3)
+return Label