1 files changed, 27 insertions, 0 deletions
diff --git a/src/hashFFI.cc b/src/hashFFI.cc
index ab20030..f349ba4 100644
--- a/src/hashFFI.cc
+++ b/src/hashFFI.cc
@@ -18,6 +18,7 @@
 #include <cstdio>
 
 #include <openssl/md5.h>
+#include <openssl/sha.h>
 extern "C" {
 #include <urweb/urweb_cpp.h>
 }
@@ -70,3 +71,29 @@ uw_Basis_string uw_HashFFI_md5(uw_context* const context,
          "failed to properly terminate digest");
   return result;
 }
+
+uw_Basis_string uw_HashFFI_sha1(uw_context* const context,
+                               const uw_Basis_blob input) {
+  using Digest = std::array<unsigned char, SHA_DIGEST_LENGTH>;
+  // Perform the SHA-1 operation.
+  Digest raw_result;
+  SHA1(reinterpret_cast<unsigned char*>(input.data), input.size,
+      raw_result.data());
+  // Convert it to a hex string.  This will be twice as large (two hex digits
+  // per byte), plus an additional byte for the null terminator.
+  const auto result_length = 2 * raw_result.size() + 1;
+  uw_Basis_string result =
+      reinterpret_cast<uw_Basis_string>(uw_malloc(context, result_length));
+  Assert(context, result, BOUNDED_RETRY,
+         "unable to allocate memory for digest");
+  for (Digest::size_type i = 0; i < raw_result.size(); i++) {
+    sprintf(result + 2 * i, "%02x", raw_result[i]);
+  }
+  // Make sure the string is properly terminated.
+  for (std::size_t i = 0; i < result_length - 2; i++) {
+    Assert(context, result[i] != '\0', "null byte in digest");
+  }
+  Assert(context, result[result_length - 1] == '\0',
+         "failed to properly terminate digest");
+  return result;
+}