LZ4 - add special magic number

For better defferentiation between normal and compressed traffic.
CESNET · Mar 28, 2024 · 0edfc31 · 0edfc31
1 parent 6690040
commit 0edfc31
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Showing 2 changed files with 12 additions and 1 deletion.
diff --git a/output/ipfix.cpp b/output/ipfix.cpp
@@ -1188,6 +1188,11 @@ int CompressBuffer::compress() {
    auto com = compressed;
    auto comSize = compressedSize;
 
+   // set the magic number
+   *reinterpret_cast<uint32_t *>(com) = htonl(LZ4_MAGIC);
+   com += sizeof(uint32_t);
+   comSize -= sizeof(uint32_t);
+
    if (shouldReset) {
       // when reset, the buffer must start at 0
       if (readIndex != 0) {

diff --git a/output/ipfix.hpp b/output/ipfix.hpp
@@ -419,7 +419,13 @@ class CompressBuffer {
    // the maximum aditional size required to send metadata that are needed to
    // to decompress the data, the +4 is there for four 0 bytes that identify
    // ipfix_start_compress_header_t
-   static constexpr size_t C_ADD_SIZE = sizeof(ipfix_compress_header_t) + sizeof(ipfix_start_compress_header_t) + 4;
+   static constexpr size_t C_ADD_SIZE =
+      sizeof(ipfix_compress_header_t)
+      + sizeof(ipfix_start_compress_header_t)
+      + sizeof(uint32_t) * 2;
+
+   // LZ4c
+   static constexpr uint32_t LZ4_MAGIC = 0x4c5a3463;
 
 private: