Webmentions Verification

Luis QuintanillaLuis Quintanilla

Description

Sample script that shows how to perform Webmention verification per Webmentions specification.

Usage

dotnet fsi webmention-verification.fsx

Snippet

webmention-verification.fsx

// https://www.w3.org/TR/webmention/#webmention-verification

#r "nuget:FSharp.Data"
#r "nuget: Microsoft.AspNetCore.WebUtilities, 2.2.0"


open System
open System.Net
open System.Net.Http
open System.Net.Http.Headers
open System.Collections.Generic
open Microsoft.AspNetCore.WebUtilities
open FSharp.Data


type WebmentionVerificationResult =
| TaggedMention of {| Replies: bool; Likes: bool; Reposts: bool|}
| UntaggedMention
| Error of string


let getFormContent (request:HttpRequestMessage) =
async {
let! content = request.Content.ReadAsStringAsync() |> Async.AwaitTask
let query = QueryHelpers.ParseQuery(content)
let source = query["source"] |> Seq.head
let target = query["target"] |> Seq.head


    return source,target
}



let cont =

dict [
("source","https://raw.githubusercontent.com/lqdev/fsadvent-2021-webmentions/main/reply.html")
("target","https://webmention.rocks/test/1")
]


let buildSampleRequestMessage (content:IDictionary<string,string>) =


let reqMessage = new HttpRequestMessage()
reqMessage.Content &lt;- new FormUrlEncodedContent(content)

reqMessage



let req = buildSampleRequestMessage cont


// verification


let source,target =
req
|> getFormContent
|> Async.RunSynchronously


let getMentionUsingCssSelector (doc:HtmlDocument) (selector:string) (target:string) =
doc.CssSelect(selector)
|> List.map(fun x -> x.AttributeValue("href"))
|> List.filter(fun x -> x = target)


let hasMention (mentions:string list) =
mentions |> List.isEmpty |> not


let verifyWebmentions (source:string) (target:string)=
async {
use client = new HttpClient()
let reqMessage = new HttpRequestMessage(new HttpMethod("Get"), source)
reqMessage.Headers.Accept.Clear()


    // Only accept text/html content
    reqMessage.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue(&quot;text/html&quot;))
    
    // Get document
    let! res = client.SendAsync(reqMessage) |&gt; Async.AwaitTask
    
    // Verify webmention
    let webmentions = 
        match res.IsSuccessStatusCode with 
        | true -&gt;
            // Get document contents
            let body = 
                async {
                    return! res.Content.ReadAsStringAsync() |&gt; Async.AwaitTask
                } |&gt; Async.RunSynchronously

            // Parse document
            let doc = HtmlDocument.Parse(body)

            // Get links tagged as replies using microformats
            let replies = 
                getMentionUsingCssSelector doc &quot;.u-in-reply-to&quot; target

            // Get links tagged as likes using microformats
            let likes = 
                getMentionUsingCssSelector doc &quot;.u-in-like-of&quot; target

            // Get links tagged as repost using microformats
            let shares = 
                getMentionUsingCssSelector doc &quot;.u-in-repost-of&quot; target

            // Get untagged mentions
            let mentions = 
                getMentionUsingCssSelector doc &quot;a&quot; target

            // Collect all tagged mentions
            let knownInteractions = 
                [replies;likes;shares] 
                |&gt; List.collect(id)

            // Choose tagged mentions before untagged mentions
            match knownInteractions.IsEmpty,mentions.IsEmpty with 
            | true,true -&gt; Error &quot;Target not mentioned&quot;
            | true,false | false,false -&gt; 
                TaggedMention 
                    {|
                        Replies = hasMention replies 
                        Likes = hasMention likes
                        Reposts = hasMention shares
                    |}
            | false,true -&gt; UntaggedMention 

        | false -&gt; 
            Error &quot;Unable to get source&quot;
    return webmentions            
}



verifyWebmentions source target
|> Async.RunSynchronously

Sample Output

Interactions { 
    Likes = false
    Replies = true
    Shares = false }