1 files changed, 75 insertions, 0 deletions

diff --git a/server/src/trace.cpp b/server/src/trace.cpp
new file mode 100644
index 0000000..e7c00d0
--- /dev/null
+++ b/server/src/trace.cpp
@@ -0,0 +1,75 @@
+module;
+
+// Might as well since we're using OpenSSL
+#include <openssl/err.h>
+#include <openssl/rand.h>
+
+module routemon:trace$impl;
+
+import :trace;
+
+namespace routemon::trace {
+
+uuid7::uuid7()
+{
+  namespace chrono = std::chrono;
+  auto const unix_time_ms_signed = static_cast<std::int64_t>(
+      chrono::duration_cast<chrono::milliseconds>(
+          chrono::system_clock::now().time_since_epoch())
+          .count());
+  if (unix_time_ms_signed < 0)
+    throw std::runtime_error{"system time before UNIX epoch"};
+  auto const unix_time_ms = static_cast<std::uint64_t>(unix_time_ms_signed);
+  if (std::countl_zero(unix_time_ms) < 16)
+    throw std::runtime_error{"system time too great"};
+
+  auto rand = std::array<unsigned char, 10>{};
+  int s = RAND_bytes(rand.data(), static_cast<int>(rand.size()));
+  if (s != 1)
+  {
+    unsigned long e = ERR_get_error();
+    throw std::runtime_error{std::format(
+        "failed to generate UUID(v7): {} ({}, code {})",
+        ERR_reason_error_string(e), ERR_lib_error_string(e), e)};
+  }
+
+  auto version = std::uint64_t{0b0111};
+  auto variant = std::uint64_t{0b10};
+
+  hi_ |= unix_time_ms << 16;
+  hi_ |= version << 12;
+  hi_ |= std::uint64_t{rand[0]} << 4;
+  hi_ |= std::uint64_t{rand[1]};
+  lo_ |= variant << 62;
+  lo_ |= std::uint64_t{rand[2]} << 54;
+  lo_ |= std::uint64_t{rand[3]} << 48;
+  lo_ |= std::uint64_t{rand[4]} << 40;
+  lo_ |= std::uint64_t{rand[5]} << 32;
+  lo_ |= std::uint64_t{rand[6]} << 24;
+  lo_ |= std::uint64_t{rand[7]} << 16;
+  lo_ |= std::uint64_t{rand[8]} << 8;
+  lo_ |= std::uint64_t{rand[9]};
+}
+
+auto uuid7::format(std::array<char, 37>& target) -> void
+{
+  auto p____hi_hi = (hi_ & 0xffff'ffff'0000'0000) >> 32;
+  auto p_hi_lo_hi = (hi_ & 0x0000'0000'ffff'0000) >> 16;
+  auto p_lo_lo_hi = (hi_ & 0x0000'0000'0000'ffff) >> 0;
+  auto p____hi_lo = (lo_ & 0xffff'0000'0000'0000) >> 48;
+  auto p____lo_lo = (lo_ & 0x0000'ffff'ffff'ffff) >> 0;
+
+  std::format_to(
+      target.begin(), "{:0>8x}-{:0>4x}-{:0>4x}-{:0>4x}-{:0>12x}", p____hi_hi,
+      p_hi_lo_hi, p_lo_lo_hi, p____hi_lo, p____lo_lo);
+  target.back() = '\0';
+}
+
+id::id() { uuid7{}.format(chars_); }
+
+auto id::as_string() const -> util::zstring_view
+{
+  return util::zstring_view{chars_.data(), chars_.size() - 1};
+}
+
+} // namespace routemon::trace