Replace plain String with SecretString for GitHub token (#509)

This commit changed the type of `lychee-lib::ClientBuilder::github_token` from
`String` to `secrecy::SecretString` to fortify the secret management within our
program.

Note that this won't affect TOML configuration of `lychee-bin` because
`serde::Deserialize` is still implemented for `SecretString`.

lychee-bin/Cargo.toml

@@ -45,6 +45,7 @@ once_cell = "1.9.0"
 dashmap = { version = "5.1.0", features = ["serde"] }
 csv = "1.1.6"
 humantime = "2.1.0"
+secrecy = { version = "0.8.0", features = ["serde"] }
 
 [dev-dependencies]
 assert_cmd = "2.0.4"

lychee-bin/src/options.rs

@@ -5,6 +5,7 @@ use const_format::{concatcp, formatcp};
 use lychee_lib::{
     Base, Input, DEFAULT_MAX_REDIRECTS, DEFAULT_MAX_RETRIES, DEFAULT_TIMEOUT, DEFAULT_USER_AGENT,
 };
+use secrecy::{ExposeSecret, SecretString};
 use serde::Deserialize;
 use structopt::StructOpt;
 
@@ -284,7 +285,7 @@ pub(crate) struct Config {
     /// GitHub API token to use when checking github.com links, to avoid rate limiting
     #[structopt(long, env = "GITHUB_TOKEN", hide_env_values = true)]
     #[serde(default)]
-    pub(crate) github_token: Option<String>,
+    pub(crate) github_token: Option<SecretString>,
 
     /// Skip missing input files (default is to error if they don't exist)
     #[structopt(long)]
@@ -364,11 +365,24 @@ impl Config {
             method: DEFAULT_METHOD;
             base: None;
             basic_auth: None;
-            github_token: None;
             skip_missing: false;
             glob_ignore_case: false;
             output: None;
             require_https: false;
         }
+
+        if self
+            .github_token
+            .as_ref()
+            .map(ExposeSecret::expose_secret)
+            .is_none()
+            && toml
+                .github_token
+                .as_ref()
+                .map(ExposeSecret::expose_secret)
+                .is_some()
+        {
+            self.github_token = toml.github_token;
+        }
     }
 }

lychee-lib/Cargo.toml

@@ -51,6 +51,7 @@ lazy_static = "1.4.0"
 html5ever = "0.25.1"
 html5gum = "0.4.0"
 octocrab = "0.15.4"
+secrecy = "0.8.0"
 
 [dependencies.par-stream]
 version = "0.10.0"

lychee-lib/src/client.rs

@@ -23,6 +23,7 @@ use http::{
 use octocrab::Octocrab;
 use regex::RegexSet;
 use reqwest::header;
+use secrecy::{ExposeSecret, SecretString};
 use tokio::time::sleep;
 use typed_builder::TypedBuilder;
 
@@ -65,7 +66,7 @@ pub struct ClientBuilder {
     ///
     /// As of Feb 2022, it's 60 per hour without GitHub token v.s.
     /// 5000 per hour with token.
-    github_token: Option<String>,
+    github_token: Option<SecretString>,
     /// Links matching this set of regular expressions are **always** checked.
     ///
     /// This has higher precedence over [`ClientBuilder::excludes`], **but**
@@ -240,9 +241,9 @@ impl ClientBuilder {
         })
         .build()?;
 
-        let github_client = match github_token {
+        let github_client = match github_token.as_ref().map(ExposeSecret::expose_secret) {
             Some(token) if !token.is_empty() => {
-                Some(Octocrab::builder().personal_token(token).build()?)
+                Some(Octocrab::builder().personal_token(token.clone()).build()?)
             }
             _ => None,
         };