http: handle auth challenge for non-proxy auth

src/Net.zig

@@ -377,6 +377,10 @@ pub const Connection = struct {
         try libcurl.curl_easy_setopt(self.easy, .proxy_user_pwd, creds.ptr);
     }
 
+    pub fn setCredentials(self: *const Connection, creds: [:0]const u8) !void {
+        try libcurl.curl_easy_setopt(self.easy, .user_pwd, creds.ptr);
+    }
+
     pub fn setCallbacks(
         self: *const Connection,
         comptime header_cb: libcurl.CurlHeaderFunction,

src/http/Client.zig

@@ -718,7 +718,11 @@ fn makeRequest(self: *Client, conn: *Net.Connection, transfer: *Transfer) anyerr
 
         // add credentials
         if (req.credentials) |creds| {
-            try conn.setProxyCredentials(creds);
+            if (transfer._auth_challenge != null and transfer._auth_challenge.?.source == .proxy) {
+                try conn.setProxyCredentials(creds);
+            } else {
+                try conn.setCredentials(creds);
+            }
         }
     }
 

src/sys/libcurl.zig

@@ -148,6 +148,7 @@ pub const CurlOption = enum(c.CURLoption) {
     cookie = c.CURLOPT_COOKIE,
     private = c.CURLOPT_PRIVATE,
     proxy_user_pwd = c.CURLOPT_PROXYUSERPWD,
+    user_pwd = c.CURLOPT_USERPWD,
     header_data = c.CURLOPT_HEADERDATA,
     header_function = c.CURLOPT_HEADERFUNCTION,
     write_data = c.CURLOPT_WRITEDATA,
@@ -512,6 +513,7 @@ pub fn curl_easy_setopt(easy: *Curl, comptime option: CurlOption, value: anytype
         .accept_encoding,
         .custom_request,
         .cookie,
+        .user_pwd,
         .proxy_user_pwd,
         .copy_post_fields,
         => blk: {