How do some canisters handle http requests

paulyoung · December 29, 2021, 11:36am

Canisters can implement http_request.

I gave a trivial example in Motoko here:

github.com/dfinity/agent-rs

feat: upgrade HTTP request calls from query to update upon canister's request

dfinity:main ← paulyoung:paulyoung/http-request

opened 01:45AM - 28 May 21 UTC

paulyoung

+86 -18

Edit: the code in this PR no longer infers when to make an update call, it does …it upon the canister’s request. *** This is a first pass at inferring when to make an update call instead of a query call based on HTTP request methods. It's based on [this discussion thread](https://forum.dfinity.org/t/feature-request-map-appropriate-http-request-methods-to-update-calls/4303?u=paulyoung) in the developer forum. Thanks to @nomeata for some feedback and help getting to this point. I think this could be made a lot more configurable (perhaps via a file that is read when `icx-proxy` starts which maps methods/routes to functions) but what's here suits my needs for now so I thought I'd share it in case there's any interest in merging. Thanks in advance for considering this change. *** ```typescript import Text "mo:base/Text"; actor { type HeaderField = (Text, Text); type Token = {}; type StreamingCallbackHttpResponse = { body : Blob; token : Token; }; type StreamingStrategy = { #Callback : { callback : shared Token -> async StreamingCallbackHttpResponse; token : Token; }; }; type HttpRequest = { method : Text; url : Text; headers : [HeaderField]; body : Blob; }; type HttpResponse = { status_code : Nat16; headers : [HeaderField]; body : Blob; streaming_strategy : ?StreamingStrategy; }; public query func http_request(request : HttpRequest) : async HttpResponse { { status_code = 200; headers = []; body = Text.encodeUtf8("Response to " # request.method # " request (query)"); streaming_strategy = null; }; }; public shared func http_request_update(request : HttpRequest) : async HttpResponse { { status_code = 200; headers = []; body = Text.encodeUtf8("Response to " # request.method # " request (update)"); streaming_strategy = null; }; }; }; ``` ``` $ icx-proxy --fetch-root-key version: 0.2.1 May 27 18:24:15.771 INFO Log Level: INFO May 27 18:24:15.797 INFO Starting server. Listening on http://127.0.0.1:3000/ ``` ``` $ curl -v -X GET -H "Content-type: application/json" -H "Accept: application/json" -d '{}' 'http://localhost:3000?canisterId=rrkah-fqaaa-aaaaa-aaaaq-cai' * Trying 127.0.0.1... * TCP_NODELAY set * Connected to localhost (127.0.0.1) port 3000 (#0) > GET /?canisterId=rrkah-fqaaa-aaaaa-aaaaq-cai HTTP/1.1 > Host: localhost:3000 > User-Agent: curl/7.64.1 > Content-type: application/json > Accept: application/json > Content-Length: 61 > * upload completely sent off: 61 out of 61 bytes < HTTP/1.1 200 OK < content-length: 31 < date: Fri, 28 May 2021 01:27:24 GMT < * Connection #0 to host localhost left intact Response to GET request (query)* Closing connection 0 ``` ``` $ curl -v -X POST -H "Content-type: application/json" -H "Accept: application/json" -d '{}' 'http://localhost:3000?canisterId=rrkah-fqaaa-aaaaa-aaaaq-cai' Note: Unnecessary use of -X or --request, POST is already inferred. * Trying 127.0.0.1... * TCP_NODELAY set * Connected to localhost (127.0.0.1) port 3000 (#0) > POST /?canisterId=rrkah-fqaaa-aaaaa-aaaaq-cai HTTP/1.1 > Host: localhost:3000 > User-Agent: curl/7.64.1 > Content-type: application/json > Accept: application/json > Content-Length: 61 > * upload completely sent off: 61 out of 61 bytes < HTTP/1.1 200 OK < content-length: 33 < date: Fri, 28 May 2021 01:27:41 GMT < * Connection #0 to host localhost left intact Response to POST request (update)* Closing connection 0 ```

There’s another here:

github.com

dfinity/motoko-playground/blob/782b2514373aa470e6363c814b0b1de5a573b746/service/pool/Main.mo#L148-L163


      
          public query func http_request(req: Metrics.HttpRequest): async Metrics.HttpResponse {
              if (req.url == "/metrics") {
                  let body = Metrics.metrics(stats);
                  {
                      status_code = 200;
                      headers = [("Content-Type", "text/plain; version=0.0.4"), ("Content-Length", Nat.toText(body.size()))];
                      body = body;
                  }
              } else {
                  {
                      status_code = 404;
                      headers = [];
                      body = Text.encodeUtf8("Not supported");
                  }
              }
          };

You can also do the same in Rust:

github.com

dfinity/cycles-wallet/blob/0f4e6c9f243f2a19caef7f7c552c9adc6ad43140/wallet/src/lib.rs#L162-L187


      
          #[query]
          fn http_request(req: HttpRequest) -> HttpResponse {
              let parts: Vec<&str> = req.url.split('?').collect();
              let asset = parts[0];
              let assets = storage::get::<Assets>();
              let certificate_header = make_asset_certificate_header(&assets.hashes, asset);
              match assets.contents.get(asset) {
                  Some((headers, value)) => {
                      let mut headers = headers.clone();
                      headers.push(certificate_header);
          
                      HttpResponse {
                          status_code: 200,
                          headers,
                          body: Cow::Borrowed(Bytes::new(value)),
                          streaming_strategy: None,
                      }
                  }
                  None => HttpResponse {
                      status_code: 404,

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github.com

dfinity/internet-identity/blob/06aca96a86779a3a197ffbb0d08199ecb2d7167c/src/internet_identity/src/main.rs#L741-L887


      
          #[query]
          fn http_request(req: HttpRequest) -> HttpResponse {
              let parts: Vec<&str> = req.url.split('?').collect();
              match parts[0] {
                  "/metrics" => {
                      let mut writer = MetricsEncoder::new(vec![], time() as i64 / 1_000_000);
                      match encode_metrics(&mut writer) {
                          Ok(()) => {
                              let body = writer.into_inner();
                              let mut headers = vec![
                                  (
                                      "Content-Type".to_string(),
                                      "text/plain; version=0.0.4".to_string(),
                                  ),
                                  ("Content-Length".to_string(), body.len().to_string()),
                              ];
                              headers.append(&mut security_headers());
                              HttpResponse {
                                  status_code: 200,
                                  headers,

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How do some canisters handle http requests

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