Add an insecure_disable_tls_host_verification command line option

When set, this disables the host verification of all HTTP requests. Available
for both the fetch and serve mode.

Also introduced an App.Config, for future command line options which need to
be passed more deeply into the code.

src/http/client.zig

@@ -45,9 +45,13 @@ pub const Client = struct {
     allocator: Allocator,
     state_pool: StatePool,
     root_ca: tls.config.CertBundle,
+    tls_verify_host: bool = true,
 
-    // we only allow passing in a root_ca for testing
-    pub fn init(allocator: Allocator, max_concurrent: usize) !Client {
+    const Opts = struct {
+        tls_verify_host: bool = true,
+    };
+
+    pub fn init(allocator: Allocator, max_concurrent: usize, opts: Opts) !Client {
         var root_ca = try tls.config.CertBundle.fromSystem(allocator);
         errdefer root_ca.deinit(allocator);
 
@@ -58,6 +62,7 @@ pub const Client = struct {
             .root_ca = root_ca,
             .allocator = allocator,
             .state_pool = state_pool,
+            .tls_verify_host = opts.tls_verify_host,
         };
     }
 
@@ -123,7 +128,7 @@ pub const Request = struct {
     _has_host_header: bool,
 
     // Whether or not we should verify that the host matches the certificate CN
-    _tls_verify_host: bool = true,
+    _tls_verify_host: bool,
 
     pub const Method = enum {
         GET,
@@ -167,6 +172,7 @@ pub const Request = struct {
             ._client = client,
             ._redirect_count = 0,
             ._has_host_header = false,
+            ._tls_verify_host = client.tls_verify_host,
         };
     }
 
@@ -205,11 +211,13 @@ pub const Request = struct {
 
     // TODO timeout
     const SendSyncOpts = struct {
-        tls_verify_host: bool = true,
+        tls_verify_host: ?bool = null,
     };
     // Makes an synchronous request
     pub fn sendSync(self: *Request, opts: SendSyncOpts) anyerror!Response {
-        self._tls_verify_host = opts.tls_verify_host;
+        if (opts.tls_verify_host) |override| {
+            self._tls_verify_host = override;
+        }
         try self.prepareInitialSend();
         return self.doSendSync();
     }
@@ -230,11 +238,13 @@ pub const Request = struct {
     }
 
     const SendAsyncOpts = struct {
-        tls_verify_host: bool = true,
+        tls_verify_host: ?bool = null,
     };
     // Makes an asynchronous request
     pub fn sendAsync(self: *Request, loop: anytype, handler: anytype, opts: SendAsyncOpts) !void {
-        self._tls_verify_host = opts.tls_verify_host;
+        if (opts.tls_verify_host) |override| {
+            self._tls_verify_host = override;
+        }
         try self.prepareInitialSend();
         return self.doSendAsync(loop, handler);
     }
@@ -2176,5 +2186,5 @@ fn testReader(state: *State, res: *TestResponse, data: []const u8) !void {
 }
 
 fn testClient() !Client {
-    return try Client.init(testing.allocator, 1);
+    return try Client.init(testing.allocator, 1, .{});
 }