Introduce dl key to allow per-crate download links

crates/cargo-test-support/src/registry.rs

@@ -324,6 +324,7 @@ pub struct Package {
     rust_version: Option<String>,
     cargo_features: Vec<String>,
     v: Option<u32>,
+    dl: Option<String>,
 }
 
 type FeatureMap = BTreeMap<String, Vec<String>>;
@@ -561,6 +562,7 @@ impl Package {
             rust_version: None,
             cargo_features: Vec::new(),
             v: None,
+            dl: None,
         }
     }
 
@@ -709,6 +711,12 @@ impl Package {
         self
     }
 
+    /// Specifies a different download URI for the package.
+    pub fn dl(&mut self, dl: &str) -> &mut Package {
+        self.dl = Some(dl.to_string());
+        self
+    }
+
     pub fn cargo_feature(&mut self, feature: &str) -> &mut Package {
         self.cargo_features.push(feature.to_owned());
         self
@@ -788,6 +796,9 @@ impl Package {
         if let Some(v) = self.v {
             json["v"] = serde_json::json!(v);
         }
+        if let Some(dl) = &self.dl {
+            json["dl"] = serde_json::json!(dl);
+        }
         let line = json.to_string();
 
         let file = make_dep_path(&self.name, false);

crates/resolver-tests/src/lib.rs

@@ -180,6 +180,7 @@ pub fn resolve_with_config_raw(
         deps,
         &BTreeMap::new(),
         None::<&String>,
+        None,
     )
     .unwrap();
     let opts = ResolveOpts::everything();
@@ -581,6 +582,7 @@ pub fn pkg_dep<T: ToPkgId>(name: T, dep: Vec<Dependency>) -> Summary {
         dep,
         &BTreeMap::new(),
         link,
+        None,
     )
     .unwrap()
 }
@@ -609,6 +611,7 @@ pub fn pkg_loc(name: &str, loc: &str) -> Summary {
         Vec::new(),
         &BTreeMap::new(),
         link,
+        None,
     )
     .unwrap()
 }
@@ -623,6 +626,7 @@ pub fn remove_dep(sum: &Summary, ind: usize) -> Summary {
         deps,
         &BTreeMap::new(),
         sum.links().map(|a| a.as_str()),
+        None,
     )
     .unwrap()
 }

src/cargo/core/resolver/version_prefs.rs

@@ -92,7 +92,15 @@ mod test {
         let pkg_id = pkgid(name, version);
         let config = Config::default().unwrap();
         let features = BTreeMap::new();
-        Summary::new(&config, pkg_id, Vec::new(), &features, None::<&String>).unwrap()
+        Summary::new(
+            &config,
+            pkg_id,
+            Vec::new(),
+            &features,
+            None::<&String>,
+            None,
+        )
+        .unwrap()
     }
 
     fn describe(summaries: &Vec<Summary>) -> String {

src/cargo/core/summary.rs

@@ -25,6 +25,7 @@ struct Inner {
     features: Rc<FeatureMap>,
     checksum: Option<String>,
     links: Option<InternedString>,
+    dl: Option<InternedString>,
 }
 
 impl Summary {
@@ -34,6 +35,7 @@ impl Summary {
         dependencies: Vec<Dependency>,
         features: &BTreeMap<InternedString, Vec<InternedString>>,
         links: Option<impl Into<InternedString>>,
+        dl: Option<InternedString>,
     ) -> CargoResult<Summary> {
         // ****CAUTION**** If you change anything here that may raise a new
         // error, be sure to coordinate that change with either the index
@@ -55,6 +57,7 @@ impl Summary {
                 features: Rc::new(feature_map),
                 checksum: None,
                 links: links.map(|l| l.into()),
+                dl,
             }),
         })
     }
@@ -84,6 +87,9 @@ impl Summary {
     pub fn links(&self) -> Option<InternedString> {
         self.inner.links
     }
+    pub fn dl(&self) -> Option<InternedString> {
+        self.inner.dl
+    }
 
     pub fn override_id(mut self, id: PackageId) -> Summary {
         Rc::make_mut(&mut self.inner).package_id = id;

src/cargo/sources/registry/download.rs

@@ -24,6 +24,7 @@ pub(super) fn download(
     cache_path: &Filesystem,
     config: &Config,
     pkg: PackageId,
+    override_dl: Option<&str>,
     checksum: &str,
     registry_config: RegistryConfig,
 ) -> CargoResult<MaybeLock> {
@@ -44,30 +45,36 @@ pub(super) fn download(
         }
     }
 
-    let mut url = registry_config.dl;
-    if !url.contains(CRATE_TEMPLATE)
-        && !url.contains(VERSION_TEMPLATE)
-        && !url.contains(PREFIX_TEMPLATE)
-        && !url.contains(LOWER_PREFIX_TEMPLATE)
-        && !url.contains(CHECKSUM_TEMPLATE)
-    {
-        // Original format before customizing the download URL was supported.
-        write!(
-            url,
-            "/{}/{}/download",
-            pkg.name(),
-            pkg.version().to_string()
-        )
-        .unwrap();
-    } else {
-        let prefix = make_dep_prefix(&*pkg.name());
-        url = url
-            .replace(CRATE_TEMPLATE, &*pkg.name())
-            .replace(VERSION_TEMPLATE, &pkg.version().to_string())
-            .replace(PREFIX_TEMPLATE, &prefix)
-            .replace(LOWER_PREFIX_TEMPLATE, &prefix.to_lowercase())
-            .replace(CHECKSUM_TEMPLATE, checksum);
-    }
+    let url = override_dl.map_or_else(
+        || {
+            let mut url = registry_config.dl;
+            if !url.contains(CRATE_TEMPLATE)
+                && !url.contains(VERSION_TEMPLATE)
+                && !url.contains(PREFIX_TEMPLATE)
+                && !url.contains(LOWER_PREFIX_TEMPLATE)
+                && !url.contains(CHECKSUM_TEMPLATE)
+            {
+                // Original format before customizing the download URL was supported.
+                write!(
+                    url,
+                    "/{}/{}/download",
+                    pkg.name(),
+                    pkg.version().to_string()
+                )
+                .unwrap();
+            } else {
+                let prefix = make_dep_prefix(&*pkg.name());
+                url = url
+                    .replace(CRATE_TEMPLATE, &*pkg.name())
+                    .replace(VERSION_TEMPLATE, &pkg.version().to_string())
+                    .replace(PREFIX_TEMPLATE, &prefix)
+                    .replace(LOWER_PREFIX_TEMPLATE, &prefix.to_lowercase())
+                    .replace(CHECKSUM_TEMPLATE, checksum);
+            }
+            url
+        },
+        ToString::to_string,
+    );
 
     Ok(MaybeLock::Download {
         url,

src/cargo/sources/registry/http_remote.rs

@@ -548,7 +548,12 @@ impl<'cfg> RegistryData for HttpRegistry<'cfg> {
         self.requested_update = true;
     }
 
-    fn download(&mut self, pkg: PackageId, checksum: &str) -> CargoResult<MaybeLock> {
+    fn download(
+        &mut self,
+        pkg: PackageId,
+        override_dl: Option<&str>,
+        checksum: &str,
+    ) -> CargoResult<MaybeLock> {
         let registry_config = loop {
             match self.config()? {
                 Poll::Pending => self.block_until_ready()?,
@@ -559,6 +564,7 @@ impl<'cfg> RegistryData for HttpRegistry<'cfg> {
             &self.cache_path,
             &self.config,
             pkg,
+            override_dl,
             checksum,
             registry_config,
         )

src/cargo/sources/registry/index.rs

@@ -265,19 +265,21 @@ impl<'cfg> RegistryIndex<'cfg> {
         }
     }
 
-    /// Returns the hash listed for a specified `PackageId`.
-    pub fn hash(&mut self, pkg: PackageId, load: &mut dyn RegistryData) -> Poll<CargoResult<&str>> {
+    /// Returns the package summary for a specified `PackageId`.
+    pub fn summary(
+        &mut self,
+        pkg: PackageId,
+        load: &mut dyn RegistryData,
+    ) -> Poll<CargoResult<&IndexSummary>> {
         let req = OptVersionReq::exact(pkg.version());
         let summary = self.summaries(pkg.name(), &req, load)?;
         let summary = match summary {
             Poll::Ready(mut summary) => summary.next(),
             Poll::Pending => return Poll::Pending,
         };
-        Poll::Ready(Ok(summary
-            .ok_or_else(|| internal(format!("no hash listed for {}", pkg)))?
-            .summary
-            .checksum()
-            .ok_or_else(|| internal(format!("no hash listed for {}", pkg)))?))
+        Poll::Ready(Ok(
+            summary.ok_or_else(|| internal(format!("no summary for {}", pkg)))?
+        ))
     }
 
     /// Load a list of summaries for `name` package in this registry which
@@ -854,6 +856,7 @@ impl IndexSummary {
             yanked,
             links,
             v,
+            dl,
         } = serde_json::from_slice(line)?;
         let v = v.unwrap_or(1);
         log::trace!("json parsed registry {}/{}", name, vers);
@@ -867,7 +870,7 @@ impl IndexSummary {
                 features.entry(name).or_default().extend(values);
             }
         }
-        let mut summary = Summary::new(config, pkgid, deps, &features, links)?;
+        let mut summary = Summary::new(config, pkgid, deps, &features, links, dl)?;
         summary.set_checksum(cksum);
         Ok(IndexSummary {
             summary,

src/cargo/sources/registry/local.rs

@@ -99,7 +99,12 @@ impl<'cfg> RegistryData for LocalRegistry<'cfg> {
         self.updated
     }
 
-    fn download(&mut self, pkg: PackageId, checksum: &str) -> CargoResult<MaybeLock> {
+    fn download(
+        &mut self,
+        pkg: PackageId,
+        _override_dl: Option<&str>,
+        checksum: &str,
+    ) -> CargoResult<MaybeLock> {
         let crate_file = format!("{}-{}.crate", pkg.name(), pkg.version());
 
         // Note that the usage of `into_path_unlocked` here is because the local

src/cargo/sources/registry/mod.rs

@@ -176,8 +176,10 @@ use tar::Archive;
 use crate::core::dependency::{DepKind, Dependency};
 use crate::core::source::MaybePackage;
 use crate::core::{Package, PackageId, Source, SourceId, Summary};
+use crate::sources::registry::index::IndexSummary;
 use crate::sources::PathSource;
 use crate::util::hex;
+use crate::util::internal;
 use crate::util::interning::InternedString;
 use crate::util::into_url::IntoUrl;
 use crate::util::network::PollExt;
@@ -277,6 +279,8 @@ pub struct RegistryPackage<'a> {
     /// Added early 2018 (see <https://github.com/rust-lang/cargo/pull/4978>),
     /// can be `None` if published before then.
     links: Option<InternedString>,
+    /// Allows overriding the registry's global `dl` link for this package only.
+    dl: Option<InternedString>,
     /// The schema version for this entry.
     ///
     /// If this is None, it defaults to version 1. Entries with unknown
@@ -481,7 +485,12 @@ pub trait RegistryData {
     /// `finish_download`. For already downloaded `.crate` files, it does not
     /// validate the checksum, assuming the filesystem does not suffer from
     /// corruption or manipulation.
-    fn download(&mut self, pkg: PackageId, checksum: &str) -> CargoResult<MaybeLock>;
+    fn download(
+        &mut self,
+        pkg: PackageId,
+        override_dl: Option<&str>,
+        checksum: &str,
+    ) -> CargoResult<MaybeLock>;
 
     /// Finish a download by saving a `.crate` file to disk.
     ///
@@ -764,13 +773,20 @@ impl<'cfg> Source for RegistrySource<'cfg> {
     }
 
     fn download(&mut self, package: PackageId) -> CargoResult<MaybePackage> {
-        let hash = loop {
-            match self.index.hash(package, &mut *self.ops)? {
+        let (hash, override_dl) = loop {
+            match self.index.summary(package, &mut *self.ops)? {
                 Poll::Pending => self.block_until_ready()?,
-                Poll::Ready(hash) => break hash,
+                Poll::Ready(IndexSummary { ref summary, .. }) => {
+                    break (
+                        summary
+                            .checksum()
+                            .ok_or_else(|| internal(format!("no hash listed for {}", package)))?,
+                        summary.dl(),
+                    )
+                }
             }
         };
-        match self.ops.download(package, hash)? {
+        match self.ops.download(package, override_dl.as_deref(), hash)? {
             MaybeLock::Ready(file) => self.get_pkg(package, &file).map(MaybePackage::Ready),
             MaybeLock::Download { url, descriptor } => {
                 Ok(MaybePackage::Download { url, descriptor })
@@ -780,9 +796,13 @@ impl<'cfg> Source for RegistrySource<'cfg> {
 
     fn finish_download(&mut self, package: PackageId, data: Vec<u8>) -> CargoResult<Package> {
         let hash = loop {
-            match self.index.hash(package, &mut *self.ops)? {
+            match self.index.summary(package, &mut *self.ops)? {
                 Poll::Pending => self.block_until_ready()?,
-                Poll::Ready(hash) => break hash,
+                Poll::Ready(IndexSummary { ref summary, .. }) => {
+                    break summary
+                        .checksum()
+                        .ok_or_else(|| internal(format!("no hash listed for {}", package)))?
+                }
             }
         };
         let file = self.ops.finish_download(package, hash, &data)?;

src/cargo/sources/registry/remote.rs

@@ -296,7 +296,12 @@ impl<'cfg> RegistryData for RemoteRegistry<'cfg> {
         self.updated
     }
 
-    fn download(&mut self, pkg: PackageId, checksum: &str) -> CargoResult<MaybeLock> {
+    fn download(
+        &mut self,
+        pkg: PackageId,
+        override_dl: Option<&str>,
+        checksum: &str,
+    ) -> CargoResult<MaybeLock> {
         let registry_config = loop {
             match self.config()? {
                 Poll::Pending => self.block_until_ready()?,
@@ -308,6 +313,7 @@ impl<'cfg> RegistryData for RemoteRegistry<'cfg> {
             &self.cache_path,
             &self.config,
             pkg,
+            override_dl,
             checksum,
             registry_config,
         )

src/cargo/util/toml/mod.rs

@@ -1627,6 +1627,7 @@ impl TomlManifest {
             deps,
             me.features.as_ref().unwrap_or(&empty_features),
             project.links.as_deref(),
+            None,
         )?;
 
         let metadata = ManifestMetadata {

src/doc/src/reference/registries.md

@@ -264,6 +264,11 @@ explaining the format of the entry.
     // The `links` string value from the package's manifest, or null if not
     // specified. This field is optional and defaults to null.
     "links": null,
+    // This optional field specifies the download link for this package
+    // only, overriding the global `dl` link declared in the registry's
+    // `config.toml`. The `{crate}` markers et al. are not interpolated
+    // in this context.
+    "dl": "https://crates.io/api/v1/crates/foo/0.1.0/download"
     // An unsigned 32-bit integer value indicating the schema version of this
     // entry.
     //