network timeout configuration doesn't always work

[ehuss]

Problem
Cargo seems to mostly ignore the http.timeout configuration.

The problem is that progress function that handles timeouts is not called when there is no network traffic. According to https://curl.haxx.se/libcurl/c/CURLOPT_PROGRESSFUNCTION.html, when using the multi interface the progress won't get called during idleness "unless you call the appropriate libcurl function that performs transfers" whatever that means.

Steps

1. Start a network transfer (cargo fetch).
2. Pull the network cord.
3. Wait. Cargo's timeout will not match the value in http.timeout. Typically it seems to time out after 2.5 minutes on Linux and macOS. Windows was a little more confusing (I couldn't really get a good reading).

Possible Solution(s)
Uncertain if there is some way to force libcurl to call the progress function with the multi interface?

Notes

cargo 1.46.0-nightly (4f74d9b2a 2020-07-08)

[alexcrichton]

Can you test to see if this diff fixes the issue for you?

diff --git a/src/cargo/core/package.rs b/src/cargo/core/package.rs
index 1187def1d..07d50041e 100644
--- a/src/cargo/core/package.rs
+++ b/src/cargo/core/package.rs
@@ -899,11 +899,9 @@ impl<'a, 'cfg> Downloads<'a, 'cfg> {
                 break Ok(pair);
             }
             assert!(!self.pending.is_empty());
-            let timeout = self
-                .set
-                .multi
-                .get_timeout()?
-                .unwrap_or_else(|| Duration::new(5, 0));
+            let min_timeout = Duration::new(1, 0);
+            let timeout = self.set.multi.get_timeout()?.unwrap_or(min_timeout);
+            let timeout = timeout.min(min_timeout);
             self.set
                 .multi
                 .wait(&mut [], timeout)