1 files changed, 163 insertions, 0 deletions
diff --git a/ednsoptions.cc b/ednsoptions.cc
new file mode 100644
index 0000000..8221f72
--- /dev/null
+++ b/ednsoptions.cc
@@ -0,0 +1,163 @@
+/*
+ * This file is part of PowerDNS or dnsdist.
+ * Copyright -- PowerDNS.COM B.V. and its contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * In addition, for the avoidance of any doubt, permission is granted to
+ * link this program with OpenSSL and to (re)distribute the binaries
+ * produced as the result of such linking.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#include "dns.hh"
+#include "ednsoptions.hh"
+#include "iputils.hh"
+
+bool getNextEDNSOption(const char* data, size_t dataLen, uint16_t& optionCode, uint16_t& optionLen)
+{
+  if (data == nullptr || dataLen < (sizeof(uint16_t) + sizeof(uint16_t))) {
+    return false;
+  }
+
+  size_t pos = 0;
+  const uint8_t* p = reinterpret_cast<const uint8_t*>(data);
+
+  optionCode = (static_cast<uint16_t>(p[pos]) * 256) + p[pos + 1];
+  pos += EDNS_OPTION_CODE_SIZE;
+
+  optionLen = (static_cast<uint16_t>(p[pos]) * 256) + p[pos + 1];
+  pos += EDNS_OPTION_LENGTH_SIZE;
+  (void) pos;
+
+  return true;
+}
+
+/* extract the position (relative to the optRR pointer!) and size of a specific EDNS0 option from a pointer on the beginning rdLen of the OPT RR */
+int getEDNSOption(const char* optRR, const size_t len, uint16_t wantedOption, size_t* optionValuePosition, size_t * optionValueSize)
+{
+  assert(optRR != nullptr);
+  assert(optionValuePosition != nullptr);
+  assert(optionValueSize != nullptr);
+  size_t pos = 0;
+  if (len < DNS_RDLENGTH_SIZE)
+    return EINVAL;
+
+  const uint16_t rdLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
+  size_t rdPos = 0;
+  pos += DNS_RDLENGTH_SIZE;
+  if ((pos + rdLen) > len) {
+    return EINVAL;
+  }
+
+  while(len >= (pos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE) &&
+        rdLen >= (rdPos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE)) {
+    uint16_t optionCode;
+    uint16_t optionLen;
+    if (!getNextEDNSOption(optRR + pos, len-pos, optionCode, optionLen)) {
+      break;
+    }
+
+    pos += EDNS_OPTION_CODE_SIZE;
+    rdPos += EDNS_OPTION_CODE_SIZE;
+    pos += EDNS_OPTION_LENGTH_SIZE;
+    rdPos += EDNS_OPTION_LENGTH_SIZE;
+
+    if (optionLen > (rdLen - rdPos) || optionLen > (len - pos)) {
+      return EINVAL;
+    }
+
+    if (optionCode == wantedOption) {
+      *optionValuePosition = pos - (EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE);
+      *optionValueSize = optionLen + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE;
+      return 0;
+    }
+    else {
+      /* skip this option */
+      pos += optionLen;
+      rdPos += optionLen;
+    }
+  }
+
+  return ENOENT;
+}
+
+/* extract all EDNS0 options from a pointer on the beginning rdLen of the OPT RR */
+int getEDNSOptions(const char* optRR, const size_t len, EDNSOptionViewMap& options)
+{
+  assert(optRR != nullptr);
+  size_t pos = 0;
+  if (len < DNS_RDLENGTH_SIZE)
+    return EINVAL;
+
+  const uint16_t rdLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
+  size_t rdPos = 0;
+  pos += DNS_RDLENGTH_SIZE;
+  if ((pos + rdLen) > len) {
+    return EINVAL;
+  }
+
+  while(len >= (pos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE) &&
+        rdLen >= (rdPos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE)) {
+    const uint16_t optionCode = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
+    pos += EDNS_OPTION_CODE_SIZE;
+    rdPos += EDNS_OPTION_CODE_SIZE;
+    const uint16_t optionLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]);
+    pos += EDNS_OPTION_LENGTH_SIZE;
+    rdPos += EDNS_OPTION_LENGTH_SIZE;
+    if (optionLen > (rdLen - rdPos) || optionLen > (len - pos))
+      return EINVAL;
+
+    EDNSOptionViewValue value;
+    value.content = optRR + pos;
+    value.size = optionLen;
+    options[optionCode].values.push_back(value);
+
+    /* skip this option */
+    pos += optionLen;
+    rdPos += optionLen;
+  }
+
+  return 0;
+}
+
+bool getEDNSOptionsFromContent(const std::string& content, std::vector<std::pair<uint16_t, std::string>>& options)
+{
+  size_t pos = 0;
+  uint16_t code, len;
+  const size_t contentLength = content.size();
+
+  while (pos < contentLength && (contentLength - pos) >= (EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE)) {
+    code = (static_cast<unsigned char>(content.at(pos)) * 256) + static_cast<unsigned char>(content.at(pos+1));
+    pos += EDNS_OPTION_CODE_SIZE;
+    len = (static_cast<unsigned char>(content.at(pos)) * 256) + static_cast<unsigned char>(content.at(pos+1));
+    pos += EDNS_OPTION_LENGTH_SIZE;
+
+    if (pos > contentLength || len > (contentLength - pos)) {
+      return false;
+    }
+
+    options.emplace_back(code, std::string(&content.at(pos), len));
+    pos += len;
+  }
+
+  return true;
+}
+
+void generateEDNSOption(uint16_t optionCode, const std::string& payload, std::string& res)
+{
+  const uint16_t ednsOptionCode = htons(optionCode);
+  const uint16_t payloadLen = htons(payload.length());
+  res.append((const char *) &ednsOptionCode, sizeof ednsOptionCode);
+  res.append((const char *) &payloadLen, sizeof payloadLen);
+  res.append(payload);
+}