Uri constructor cannot parse http://hostname:port/ when hostname is * or +

[chuacw]

Description

• The Uri constructor cannot parse http://hostname:port/ when hostname is * or +, ie, http://*:9999/ or http://+:9999 will cause an exception to be thrown.

            httpListener = new HttpListener(); 
            string url = "http://*:1234/"; 
            Uri uri = new Uri(url);  
            // do something here... then pass the url (not uri) to the httpListener 
            httpListener.Prefixes.Add(url); 

• On the "new Uri(url)" line, the following exception occurred
  System.UriFormatException
  HResult=0x80131537
  Message=Invalid URI: The hostname could not be parsed.
  Source=System.Private.Uri
  StackTrace:
  at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind)
  at System.Uri..ctor(String uriString)
  at HttpListenerSegments.Program..ctor() in K:\Development\CSharp\HttpListenerSegments\Program.cs:line 18
  at HttpListenerSegments.Program.Main(String[] args) in K:\Development\CSharp\HttpListenerSegments\Program.cs:line 79

• The Uri constructor should parse * or + into the DnsSafeHost, Host and IdnHost properties/fields (and whatever fields that currently holds the hostname).

• .NET Core 2.1

• Windows 11

• x64

[svick]

As far as I can tell, those are not valid HTTP URIs, so I think it's correct that the Uri constructor rejects them. They are valid HttpListener URI prefixes, but that's not the same thing as URIs.

Why do you think the current behavior is incorrect?

[chuacw]

I didn't say it's incorrect, I say it should parse it. While it's true that * and + are not valid in a URI, I need the Uri class to support parsing of this, so that I don't have to parse it on my own, or duplicate an entire class just to parse * and + into the host field.

[buyaa-n]

Tagging the area experts @dotnet/ncl for proper response, please move to runtime if needed

Tagging subscribers to this area: @dotnet/ncl
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

• The Uri constructor cannot parse http://hostname:port/ when hostname is * or +, ie, http://*:9999/ or http://+:9999 will cause an exception to be thrown.

            httpListener = new HttpListener(); 
            string url = "http://*:1234/"; 
            Uri uri = new Uri(url);  
            // do something here... then pass the url (not uri) to the httpListener 
            httpListener.Prefixes.Add(url); 

• On the "new Uri(url)" line, the following exception occurred
  System.UriFormatException
  HResult=0x80131537
  Message=Invalid URI: The hostname could not be parsed.
  Source=System.Private.Uri
  StackTrace:
  at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind)
  at System.Uri..ctor(String uriString)
  at HttpListenerSegments.Program..ctor() in K:\Development\CSharp\HttpListenerSegments\Program.cs:line 18
  at HttpListenerSegments.Program.Main(String[] args) in K:\Development\CSharp\HttpListenerSegments\Program.cs:line 79

• The Uri constructor should parse * or + into the DnsSafeHost, Host and IdnHost properties/fields (and whatever fields that currently holds the hostname).

• .NET Core 2.1

• Windows 11

• x64

Author:	chuacw
Assignees:	-
Labels:	area-System.Net, untriaged, Team:Libraries
Milestone:	-

Tagging subscribers to this area: @dotnet/ncl
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

• The Uri constructor cannot parse http://hostname:port/ when hostname is * or +, ie, http://*:9999/ or http://+:9999 will cause an exception to be thrown.

            httpListener = new HttpListener(); 
            string url = "http://*:1234/"; 
            Uri uri = new Uri(url);  
            // do something here... then pass the url (not uri) to the httpListener 
            httpListener.Prefixes.Add(url); 

• On the "new Uri(url)" line, the following exception occurred
  System.UriFormatException
  HResult=0x80131537
  Message=Invalid URI: The hostname could not be parsed.
  Source=System.Private.Uri
  StackTrace:
  at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind)
  at System.Uri..ctor(String uriString)
  at HttpListenerSegments.Program..ctor() in K:\Development\CSharp\HttpListenerSegments\Program.cs:line 18
  at HttpListenerSegments.Program.Main(String[] args) in K:\Development\CSharp\HttpListenerSegments\Program.cs:line 79

• The Uri constructor should parse * or + into the DnsSafeHost, Host and IdnHost properties/fields (and whatever fields that currently holds the hostname).

• .NET Core 2.1

• Windows 11

• x64

Author:	chuacw
Assignees:	-
Labels:	area-System.Net, untriaged, feature-request
Milestone:	-

[GrabYourPitchforks]

Feature request for System.Uri area owners.

[MihaZupan]

We've seen similar requests to relax the hostname parsing restrictions in the past (#36595).

It is worth noting that RFC 3986 allows such hostnames under the reg-name syntax definition, it is System.Uri that chooses to use a stricter DNS-like validation for hostnames.

We would be open to relaxing these requirements if there is enough interest in this.
Please upvote the original issue/this comment to let us gauge community interest in this and prioritize accordingly.