Merge pull request #3909 from matthewbauer/readd-hashed-mirrors

Add hashed-mirrors back

2 files changed, 17 insertions, 0 deletions

diff --git a/src/libstore/builtins/fetchurl.cc b/src/libstore/builtins/fetchurl.cc
index 6585a480d..4fb5d8a06 100644
--- a/src/libstore/builtins/fetchurl.cc
+++ b/src/libstore/builtins/fetchurl.cc
@@ -58,6 +58,20 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
         }
     };
 
+    /* Try the hashed mirrors first. */
+    if (getAttr("outputHashMode") == "flat")
+        for (auto hashedMirror : settings.hashedMirrors.get())
+            try {
+                if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
+                std::optional<HashType> ht = parseHashTypeOpt(getAttr("outputHashAlgo"));
+                Hash h = newHashAllowEmpty(getAttr("outputHash"), ht);
+                fetch(hashedMirror + printHashType(h.type) + "/" + h.to_string(Base16, false));
+                return;
+            } catch (Error & e) {
+                debug(e.what());
+            }
+
+    /* Otherwise try the specified URL. */
     fetch(mainUrl);
 }
 
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 3406a9331..e3bb4cf84 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -335,6 +335,9 @@ public:
         "setuid/setgid bits or with file capabilities."};
 #endif
 
+    Setting<Strings> hashedMirrors{this, {}, "hashed-mirrors",
+        "A list of servers used by builtins.fetchurl to fetch files by hash."};
+
     Setting<uint64_t> minFree{this, 0, "min-free",
         "Automatically run the garbage collector when free disk space drops below the specified amount."};