Show some HTTP headers in error messages.

src/cargo/core/package.rs

@@ -26,7 +26,7 @@ use crate::core::{Dependency, Manifest, PackageId, SourceId, Target};
 use crate::core::{SourceMap, Summary, Workspace};
 use crate::ops;
 use crate::util::config::PackageCacheLock;
-use crate::util::errors::{CargoResult, HttpNotSuccessful};
+use crate::util::errors::{CargoResult, HttpNotSuccessful, DEBUG_HEADERS};
 use crate::util::interning::InternedString;
 use crate::util::network::retry::{Retry, RetryResult};
 use crate::util::network::sleep::SleepTracker;
@@ -379,6 +379,9 @@ struct Download<'cfg> {
     /// Actual downloaded data, updated throughout the lifetime of this download.
     data: RefCell<Vec<u8>>,
 
+    /// HTTP headers for debugging.
+    headers: RefCell<Vec<String>>,
+
     /// The URL that we're downloading from, cached here for error messages and
     /// reenqueuing.
     url: String,
@@ -762,6 +765,19 @@ impl<'a, 'cfg> Downloads<'a, 'cfg> {
             });
             Ok(buf.len())
         })?;
+        handle.header_function(move |data| {
+            tls::with(|downloads| {
+                if let Some(downloads) = downloads {
+                    // Headers contain trailing \r\n, trim them to make it easier
+                    // to work with.
+                    let h = String::from_utf8_lossy(data).trim().to_string();
+                    if DEBUG_HEADERS.iter().any(|p| h.starts_with(p)) {
+                        downloads.pending[&token].0.headers.borrow_mut().push(h);
+                    }
+                }
+            });
+            true
+        })?;
 
         handle.progress(true)?;
         handle.progress_function(move |dl_total, dl_cur, _, _| {
@@ -787,6 +803,7 @@ impl<'a, 'cfg> Downloads<'a, 'cfg> {
         let dl = Download {
             token,
             data: RefCell::new(Vec::new()),
+            headers: RefCell::new(Vec::new()),
             id,
             url,
             descriptor,
@@ -826,6 +843,7 @@ impl<'a, 'cfg> Downloads<'a, 'cfg> {
                 .remove(&token)
                 .expect("got a token for a non-in-progress transfer");
             let data = mem::take(&mut *dl.data.borrow_mut());
+            let headers = mem::take(&mut *dl.headers.borrow_mut());
             let mut handle = self.set.multi.remove(handle)?;
             self.pending_ids.remove(&dl.id);
 
@@ -867,6 +885,7 @@ impl<'a, 'cfg> Downloads<'a, 'cfg> {
                             code,
                             url: url.to_string(),
                             body: data,
+                            headers,
                         }
                         .into());
                     }

src/cargo/sources/registry/http_remote.rs

@@ -7,7 +7,7 @@ use crate::ops::{self};
 use crate::sources::registry::download;
 use crate::sources::registry::MaybeLock;
 use crate::sources::registry::{LoadResponse, RegistryConfig, RegistryData};
-use crate::util::errors::{CargoResult, HttpNotSuccessful};
+use crate::util::errors::{CargoResult, HttpNotSuccessful, DEBUG_HEADERS};
 use crate::util::network::retry::{Retry, RetryResult};
 use crate::util::network::sleep::SleepTracker;
 use crate::util::{auth, Config, Filesystem, IntoUrl, Progress, ProgressStyle};
@@ -142,6 +142,7 @@ struct Headers {
     last_modified: Option<String>,
     etag: Option<String>,
     www_authenticate: Vec<String>,
+    others: Vec<String>,
 }
 
 enum StatusCode {
@@ -293,6 +294,7 @@ impl<'cfg> HttpRegistry<'cfg> {
                             code,
                             url: url.to_owned(),
                             body: data,
+                            headers: download.header_map.take().others,
                         }
                         .into());
                     }
@@ -546,6 +548,7 @@ impl<'cfg> RegistryData for HttpRegistry<'cfg> {
                         code: 401,
                         body: result.data,
                         url: self.full_url(path),
+                        headers: result.header_map.others,
                     }
                     .into());
                     if self.auth_required {
@@ -665,7 +668,11 @@ impl<'cfg> RegistryData for HttpRegistry<'cfg> {
                             LAST_MODIFIED => header_map.last_modified = Some(value.to_string()),
                             ETAG => header_map.etag = Some(value.to_string()),
                             WWW_AUTHENTICATE => header_map.www_authenticate.push(value.to_string()),
-                            _ => {}
+                            _ => {
+                                if DEBUG_HEADERS.iter().any(|prefix| tag.starts_with(prefix)) {
+                                    header_map.others.push(format!("{tag}: {value}"));
+                                }
+                            }
                         }
                     }
                 });

src/cargo/util/errors.rs

@@ -8,11 +8,22 @@ use super::truncate_with_ellipsis;
 
 pub type CargoResult<T> = anyhow::Result<T>;
 
+/// These are headers that are included in error messages to help with
+/// diagnosing issues.
+pub const DEBUG_HEADERS: &[&str] = &[
+    "x-amz-cf-id",
+    "x-amz-cf-pop",
+    "x-amz-id-2",
+    "x-cache",
+    "x-served-by",
+];
+
 #[derive(Debug)]
 pub struct HttpNotSuccessful {
     pub code: u32,
     pub url: String,
     pub body: Vec<u8>,
+    pub headers: Vec<String>,
 }
 
 impl fmt::Display for HttpNotSuccessful {
@@ -23,9 +34,13 @@ impl fmt::Display for HttpNotSuccessful {
 
         write!(
             f,
-            "failed to get successful HTTP response from `{}`, got {}\nbody:\n{body}",
+            "failed to get successful HTTP response from `{}`, got {}\n",
-            self.url, self.code
+            self.url, self.code,
-        )
+        )?;
+        if !self.headers.is_empty() {
+            write!(f, "debug headers:\n{}\n", self.headers.join("\n"))?;
+        }
+        write!(f, "body:\n{body}",)
     }
 }
 

src/cargo/util/network/retry.rs

@@ -151,12 +151,14 @@ fn with_retry_repeats_the_call_then_works() {
         code: 501,
         url: "Uri".to_string(),
         body: Vec::new(),
+        headers: Vec::new(),
     }
     .into();
     let error2 = HttpNotSuccessful {
         code: 502,
         url: "Uri".to_string(),
         body: Vec::new(),
+        headers: Vec::new(),
     }
     .into();
     let mut results: Vec<CargoResult<()>> = vec![Ok(()), Err(error1), Err(error2)];
@@ -176,12 +178,14 @@ fn with_retry_finds_nested_spurious_errors() {
         code: 501,
         url: "Uri".to_string(),
         body: Vec::new(),
+        headers: Vec::new(),
     });
     let error1 = anyhow::Error::from(error1.context("A non-spurious wrapping err"));
     let error2 = anyhow::Error::from(HttpNotSuccessful {
         code: 502,
         url: "Uri".to_string(),
         body: Vec::new(),
+        headers: Vec::new(),
     });
     let error2 = anyhow::Error::from(error2.context("A second chained error"));
     let mut results: Vec<CargoResult<()>> = vec![Ok(()), Err(error1), Err(error2)];
@@ -200,6 +204,7 @@ fn default_retry_schedule() {
             code: 500,
             url: "Uri".to_string(),
             body: Vec::new(),
+            headers: Vec::new(),
         }))
     };
     let config = Config::default().unwrap();

tests/testsuite/registry.rs

@@ -3274,3 +3274,148 @@ or use environment variable CARGO_REGISTRY_TOKEN
         .with_status(101)
         .run();
 }
+
+const SAMPLE_HEADERS: &[&str] = &[
+    "x-amz-cf-pop: SFO53-P2",
+    "x-amz-cf-id: vEc3osJrCAXVaciNnF4Vev-hZFgnYwmNZtxMKRJ5bF6h9FTOtbTMnA==",
+    "x-cache: Hit from cloudfront",
+    "server: AmazonS3",
+    "x-amz-version-id: pvsJYY_JGsWiSETZvLJKb7DeEW5wWq1W",
+    "x-amz-server-side-encryption: AES256",
+    "content-type: text/plain",
+    "via: 1.1 bcbc5b46216015493e082cfbcf77ef10.cloudfront.net (CloudFront)",
+];
+
+#[cargo_test]
+fn debug_header_message_index() {
+    // The error message should include some headers for debugging purposes.
+    let _server = RegistryBuilder::new()
+        .http_index()
+        .add_responder("/index/3/b/bar", |_, _| Response {
+            code: 503,
+            headers: SAMPLE_HEADERS.iter().map(|s| s.to_string()).collect(),
+            body: b"Please slow down".to_vec(),
+        })
+        .build();
+    Package::new("bar", "1.0.0").publish();
+
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+                version = "0.1.0"
+
+                [dependencies]
+                bar = "1.0"
+            "#,
+        )
+        .file("src/lib.rs", "")
+        .build();
+    p.cargo("fetch").with_status(101).with_stderr("\
+[UPDATING] `dummy-registry` index
+warning: spurious network error (3 tries remaining): failed to get successful HTTP response from `http://127.0.0.1:[..]/index/3/b/bar`, got 503
+debug headers:
+x-amz-cf-pop: SFO53-P2
+x-amz-cf-id: vEc3osJrCAXVaciNnF4Vev-hZFgnYwmNZtxMKRJ5bF6h9FTOtbTMnA==
+x-cache: Hit from cloudfront
+body:
+Please slow down
+warning: spurious network error (2 tries remaining): failed to get successful HTTP response from `http://127.0.0.1:[..]/index/3/b/bar`, got 503
+debug headers:
+x-amz-cf-pop: SFO53-P2
+x-amz-cf-id: vEc3osJrCAXVaciNnF4Vev-hZFgnYwmNZtxMKRJ5bF6h9FTOtbTMnA==
+x-cache: Hit from cloudfront
+body:
+Please slow down
+warning: spurious network error (1 tries remaining): failed to get successful HTTP response from `http://127.0.0.1:[..]/index/3/b/bar`, got 503
+debug headers:
+x-amz-cf-pop: SFO53-P2
+x-amz-cf-id: vEc3osJrCAXVaciNnF4Vev-hZFgnYwmNZtxMKRJ5bF6h9FTOtbTMnA==
+x-cache: Hit from cloudfront
+body:
+Please slow down
+error: failed to get `bar` as a dependency of package `foo v0.1.0 ([ROOT]/foo)`
+
+Caused by:
+  failed to query replaced source registry `crates-io`
+
+Caused by:
+  download of 3/b/bar failed
+
+Caused by:
+  failed to get successful HTTP response from `http://127.0.0.1:[..]/index/3/b/bar`, got 503
+  debug headers:
+  x-amz-cf-pop: SFO53-P2
+  x-amz-cf-id: vEc3osJrCAXVaciNnF4Vev-hZFgnYwmNZtxMKRJ5bF6h9FTOtbTMnA==
+  x-cache: Hit from cloudfront
+  body:
+  Please slow down
+").run();
+}
+
+#[cargo_test]
+fn debug_header_message_dl() {
+    // Same as debug_header_message_index, but for the dl endpoint which goes
+    // through a completely different code path.
+    let _server = RegistryBuilder::new()
+        .http_index()
+        .add_responder("/dl/bar/1.0.0/download", |_, _| Response {
+            code: 503,
+            headers: SAMPLE_HEADERS.iter().map(|s| s.to_string()).collect(),
+            body: b"Please slow down".to_vec(),
+        })
+        .build();
+    Package::new("bar", "1.0.0").publish();
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+                version = "0.1.0"
+
+                [dependencies]
+                bar = "1.0"
+            "#,
+        )
+        .file("src/lib.rs", "")
+        .build();
+
+    p.cargo("fetch").with_status(101).with_stderr("\
+[UPDATING] `dummy-registry` index
+[DOWNLOADING] crates ...
+warning: spurious network error (3 tries remaining): failed to get successful HTTP response from `http://127.0.0.1:[..]/dl/bar/1.0.0/download`, got 503
+debug headers:
+x-amz-cf-pop: SFO53-P2
+x-amz-cf-id: vEc3osJrCAXVaciNnF4Vev-hZFgnYwmNZtxMKRJ5bF6h9FTOtbTMnA==
+x-cache: Hit from cloudfront
+body:
+Please slow down
+warning: spurious network error (2 tries remaining): failed to get successful HTTP response from `http://127.0.0.1:[..]/dl/bar/1.0.0/download`, got 503
+debug headers:
+x-amz-cf-pop: SFO53-P2
+x-amz-cf-id: vEc3osJrCAXVaciNnF4Vev-hZFgnYwmNZtxMKRJ5bF6h9FTOtbTMnA==
+x-cache: Hit from cloudfront
+body:
+Please slow down
+warning: spurious network error (1 tries remaining): failed to get successful HTTP response from `http://127.0.0.1:[..]/dl/bar/1.0.0/download`, got 503
+debug headers:
+x-amz-cf-pop: SFO53-P2
+x-amz-cf-id: vEc3osJrCAXVaciNnF4Vev-hZFgnYwmNZtxMKRJ5bF6h9FTOtbTMnA==
+x-cache: Hit from cloudfront
+body:
+Please slow down
+error: failed to download from `http://127.0.0.1:[..]/dl/bar/1.0.0/download`
+
+Caused by:
+  failed to get successful HTTP response from `http://127.0.0.1:[..]/dl/bar/1.0.0/download`, got 503
+  debug headers:
+  x-amz-cf-pop: SFO53-P2
+  x-amz-cf-id: vEc3osJrCAXVaciNnF4Vev-hZFgnYwmNZtxMKRJ5bF6h9FTOtbTMnA==
+  x-cache: Hit from cloudfront
+  body:
+  Please slow down
+").run();
+}