Verify downloaded file against content-md5 response header

wxdata/include/scwx/util/digest.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <istream>
+#include <vector>
+
+#include <openssl/evp.h>
+
+namespace scwx
+{
+namespace util
+{
+
+bool ComputeDigest(const EVP_MD*              mdtype,
+                   std::istream&              is,
+                   std::vector<std::uint8_t>& digest);
+
+} // namespace util
+} // namespace scwx

wxdata/source/scwx/util/digest.cpp

@@ -0,0 +1,82 @@
+#include <scwx/util/digest.hpp>
+#include <scwx/util/logger.hpp>
+
+namespace scwx
+{
+namespace util
+{
+
+static const std::string logPrefix_ = "scwx::util::digest";
+static const auto        logger_    = scwx::util::Logger::Create(logPrefix_);
+
+bool ComputeDigest(const EVP_MD*              mdtype,
+                   std::istream&              is,
+                   std::vector<std::uint8_t>& digest)
+{
+   int         mdsize;
+   EVP_MD_CTX* mdctx = nullptr;
+
+   digest.clear();
+
+   if ((mdsize = EVP_MD_get_size(mdtype)) < 1)
+   {
+      logger_->error("Invalid digest");
+      return false;
+   }
+
+   if ((mdctx = EVP_MD_CTX_new()) == nullptr)
+   {
+      logger_->error("Error allocating a digest context");
+      return false;
+   }
+
+   if (!EVP_DigestInit_ex(mdctx, mdtype, nullptr))
+   {
+      logger_->error("Message digest initialization failed");
+      EVP_MD_CTX_free(mdctx);
+      return false;
+   }
+
+   is.seekg(0, std::ios_base::end);
+   const std::size_t streamSize = is.tellg();
+   is.seekg(0, std::ios_base::beg);
+
+   std::size_t bytesRead = 0;
+   std::size_t chunkSize = 4096;
+   std::string fileData;
+   fileData.resize(chunkSize);
+
+   while (bytesRead < streamSize)
+   {
+      const std::size_t bytesRemaining = streamSize - bytesRead;
+      const std::size_t readSize       = std::min(chunkSize, bytesRemaining);
+
+      is.read(fileData.data(), readSize);
+
+      if (!is.good() || !EVP_DigestUpdate(mdctx, fileData.data(), readSize))
+      {
+         logger_->error("Message digest update failed");
+         EVP_MD_CTX_free(mdctx);
+         return false;
+      }
+
+      bytesRead += readSize;
+   }
+
+   digest.resize(mdsize);
+
+   if (!EVP_DigestFinal_ex(mdctx, digest.data(), nullptr))
+   {
+      logger_->error("Message digest finalization failed");
+      EVP_MD_CTX_free(mdctx);
+      digest.clear();
+      return false;
+   }
+
+   EVP_MD_CTX_free(mdctx);
+
+   return true;
+}
+
+} // namespace util
+} // namespace scwx

wxdata/wxdata.cmake

@@ -67,7 +67,8 @@ set(SRC_PROVIDER source/scwx/provider/aws_level2_data_provider.cpp
                  source/scwx/provider/nexrad_data_provider.cpp
                  source/scwx/provider/nexrad_data_provider_factory.cpp
                  source/scwx/provider/warnings_provider.cpp)
-set(HDR_UTIL include/scwx/util/enum.hpp
+set(HDR_UTIL include/scwx/util/digest.hpp
+             include/scwx/util/enum.hpp
              include/scwx/util/environment.hpp
              include/scwx/util/float.hpp
              include/scwx/util/hash.hpp
@@ -80,7 +81,8 @@ set(HDR_UTIL include/scwx/util/enum.hpp
              include/scwx/util/threads.hpp
              include/scwx/util/time.hpp
              include/scwx/util/vectorbuf.hpp)
-set(SRC_UTIL source/scwx/util/environment.cpp
+set(SRC_UTIL source/scwx/util/digest.cpp
+             source/scwx/util/environment.cpp
              source/scwx/util/float.cpp
              source/scwx/util/hash.cpp
              source/scwx/util/logger.cpp