Add rustls feature

The `rustls` feature will enable building with [rustls] instead of
OpenSSL.  This will make it so the `sshca-cli` binary can be statically
linked, and thus distributable as a single file.

[rustls]: https://github.com/rustls/rustls

Cargo.lock

@@ -419,6 +419,20 @@ dependencies = [
  "want",
 ]
 
+[[package]]
+name = "hyper-rustls"
+version = "0.24.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec3efd23720e2049821a693cbc7e65ea87c72f1c58ff2f9522ff332b1491e590"
+dependencies = [
+ "futures-util",
+ "http",
+ "hyper",
+ "rustls",
+ "tokio",
+ "tokio-rustls",
+]
+
 [[package]]
 name = "hyper-tls"
 version = "0.5.0"
@@ -780,6 +794,7 @@ dependencies = [
  "http",
  "http-body",
  "hyper",
+ "hyper-rustls",
  "hyper-tls",
  "ipnet",
  "js-sys",
@@ -790,17 +805,21 @@ dependencies = [
  "once_cell",
  "percent-encoding",
  "pin-project-lite",
+ "rustls",
+ "rustls-pemfile",
  "serde",
  "serde_json",
  "serde_urlencoded",
  "system-configuration",
  "tokio",
  "tokio-native-tls",
+ "tokio-rustls",
  "tower-service",
  "url",
  "wasm-bindgen",
  "wasm-bindgen-futures",
  "web-sys",
+ "webpki-roots",
  "winreg",
 ]
 
@@ -837,6 +856,37 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "rustls"
+version = "0.21.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f9d5a6813c0759e4609cd494e8e725babae6a2ca7b62a5536a13daaec6fcb7ba"
+dependencies = [
+ "log",
+ "ring",
+ "rustls-webpki",
+ "sct",
+]
+
+[[package]]
+name = "rustls-pemfile"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1c74cae0a4cf6ccbbf5f359f08efdf8ee7e1dc532573bf0db71968cb56b1448c"
+dependencies = [
+ "base64",
+]
+
+[[package]]
+name = "rustls-webpki"
+version = "0.101.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b6275d1ee7a1cd780b64aca7726599a1dbc893b1e64144529e55c3c2f745765"
+dependencies = [
+ "ring",
+ "untrusted",
+]
+
 [[package]]
 name = "ryu"
 version = "1.0.15"
@@ -852,6 +902,16 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "sct"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da046153aa2352493d6cb7da4b6e5c0c057d8a1d0a9aa8560baffdd945acd414"
+dependencies = [
+ "ring",
+ "untrusted",
+]
+
 [[package]]
 name = "security-framework"
 version = "2.9.2"
@@ -970,7 +1030,7 @@ checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
 
 [[package]]
 name = "sshca-cli"
-version = "0.1.0"
+version = "0.1.1"
 dependencies = [
  "argh",
  "argon2",
@@ -1097,6 +1157,16 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "tokio-rustls"
+version = "0.24.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c28327cf380ac148141087fbfb9de9d7bd4e84ab5d2c28fbc911d753de8a7081"
+dependencies = [
+ "rustls",
+ "tokio",
+]
+
 [[package]]
 name = "tokio-util"
 version = "0.7.10"
@@ -1352,6 +1422,12 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "webpki-roots"
+version = "0.25.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1778a42e8b3b90bff8d0f5032bf22250792889a5cdc752aa0020c84abe3aaf10"
+
 [[package]]
 name = "winapi"
 version = "0.3.9"

Cargo.toml

@@ -12,9 +12,18 @@ argh = "0.1.12"
 argon2 = { version = "0.5.2", default-features = false, features = ["alloc"] }
 gethostname = "0.4.3"
 jsonwebtoken = { version = "9.1.0", default-features = false }
-reqwest = { version = "0.11.22", features = ["multipart"] }
+reqwest = { version = "0.11.22", default-features = false, features = ["multipart"] }
 serde = { version = "1.0.190", features = ["derive"] }
 tokio = { version = "1.33.0", features = ["rt", "macros"] }
 tracing = "0.1.40"
 tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }
 uuid = "1.5.0"
+
+[features]
+default = ["native-tls"]
+native-tls = [
+    "reqwest/default-tls",
+]
+rustls = [
+    "reqwest/rustls-tls",
+]