Services won't deserialize properly if functions aren't in alphabetical order

Developers Rust
1

I have a the following canister:

ic_cdk::export::candid::define_service!(
    UnsortedService : {
        "b" : ic_cdk::export::candid::func!(() -> (bool) query);
        "a" : ic_cdk::export::candid::func!(() -> (bool) query)
    }
);

ic_cdk::export::candid::define_service!(
    SortedService : {
        "a" : ic_cdk::export::candid::func!(() -> (bool) query);
        "b" : ic_cdk::export::candid::func!(() -> (bool) query)
    }
);

#[ic_cdk_macros::query]
fn check_sorted_service(service: SortedService) -> SortedService {
    service
}

#[ic_cdk_macros::query]
fn check_unsorted_service(service: UnsortedService) -> UnsortedService {
    service
}

There are two services defined. One that has the functions in alphabetical order and one out of order.
I have one function for each of these services that simple takes the corresponding service as a parameter and returns it.
Everything is compiling fine, but when I try to call check_unsorted_service

dcc service_canister check_unsorted_service '(service "r7inp-6aaaa-aaaaa-aaabq-cai")'

I get the following error:

Error deserializing blob 0x4449444c0269020162010161016a00017e01010100010a00000000000000030101
Error: Failed to deserialize idl blob: Invalid data.
Caused by: Failed to deserialize idl blob: Invalid data.
  Cannot parse header 4449444c0269020162010161016a00017e01010100010a00000000000000030101
    Invalid table entry 0: Service(ServType { len: 2, meths: [Meths { len: 1, name: "b", ty: IndexType { index: 1 } }, Meths { len: 1, name: "a", ty: IndexType { index: 1 } }] })
      method name a duplicate or not sorted

If I call the other method it works just fine

$ dcc service_canister check_sorted_service '(service "r7inp-6aaaa-aaaaa-aaabq-cai")'

(service "r7inp-6aaaa-aaaaa-aaabq-cai")

The other canister looks like this

#[ic_cdk_macros::query]
fn a() -> bool {
    return true;
}

#[ic_cdk_macros::query]
fn b() -> bool {
    return false
}

Any thoughts on why this is happening?

1 Like
2

I am seeing this on both DFX 0.13.1 and 0.14.1
Here are my dependencies

[dependencies]
candid = "=0.9.0-beta.3"
ic-cdk = "=0.8.0-beta.0"
ic-cdk-macros = "0.6.10"
serde = "1.0.137"
1 Like
3

Thanks for reporting this. This is a bug, I will fix it. The macro expansion should sort the methods.

4 Likes
4

Thank you for looking into it!

1 Like
5

Awesome thanks! Good luck

6

Is there an issue or PR for this?

7

I found this merged PR: sort define_service by chenyan-dfinity · Pull Request #441 · dfinity/candid · GitHub.

Recent released candid should include the fix.

1 Like
8

Do you know if dfx has this fix integrated yet?

9

We are running into this issue again, we’re still debugging, but it seems like the problem is arising from dfx itself when trying to deserialize a Candid service that we return from an Azle canister.

Is it possible the dfx dependencies haven’t been updated to include this fix?

Here’s the error:

$ dfx canister call service serviceParam '(service "aaaaa-aa")'Error deserializing blob 0x4449444c036a000171006a00017e01016902077570646174653100067175657279310101020100Error: Failed to deserialize idl blob: Invalid data.Caused by: Failed to deserialize idl blob: Invalid data.  Cannot parse header 4449444c036a000171006a00017e01016902077570646174653100067175657279310101020100    Invalid table entry 2: Service(ServType { len: 2, meths: [Meths { len: 7, name: "update1", ty: IndexType { index: 0 } }, Meths { len: 6, name: "query1", ty: IndexType { index: 1 } }] })      method name query1 duplicate or not sorted

Here’s a slightly simplified version of the Azle method that was called:

class extends Service {
    @query([], bool)
    query1(): bool {
        return true;
    }

    @update([], text)
    update1(): text {
        return 'SomeService update1';
    }
}

@query([SomeService], SomeService)
serviceParam(someService: SomeService): SomeService {
    return someService;
}
10

I’m thinking this is a problem with @dfinity/candid, I think the same fix for candid in Rust needs to be done for @dfinity/candid. @kpeacock

11

It is indeed a problem in @dfinity/candid. Debugging we found a quick fix. Notice we changed the sort function in the constructor:

export class ServiceClass extends ConstructType {
    constructor(fields) {
        super();
        // this._fields = Object.entries(fields).sort((a, b) => idlLabelToId(a[0]) - idlLabelToId(b[0]));
        this._fields = Object.entries(fields).sort((a, b) => {
            if (a[0] < b[0]) {
                return -1;
            }

            if (a[0] > b[0]) {
                return 1;
            }

            return 0;
        });
    }
    accept(v, d) {
        return v.visitService(this, d);
    }
    covariant(x) {
        if (x && x._isPrincipal)
            return true;
        throw new Error(`Invalid ${this.display()} argument: ${toReadableString(x)}`);
    }
    encodeValue(x) {
        const buf = x.toUint8Array();
        const len = lebEncode(buf.length);
        return concat(new Uint8Array([1]), len, buf);
    }
    _buildTypeTableImpl(T) {
        this._fields.forEach(([_, func]) => func.buildTypeTable(T));
        const opCode = slebEncode(-23 /* IDLTypeIds.Service */);
        const len = lebEncode(this._fields.length);
        const meths = this._fields.map(([label, func]) => {
            const labelBuf = new TextEncoder().encode(label);
            const labelLen = lebEncode(labelBuf.length);
            return concat(labelLen, labelBuf, func.encodeType(T));
        });
        T.add(this, concat(opCode, len, ...meths));
    }
    decodeValue(b) {
        return decodePrincipalId(b);
    }
    get name() {
        const fields = this._fields.map(([key, value]) => key + ':' + value.name);
        return `service {${fields.join('; ')}}`;
    }
    valueToString(x) {
        return `service "${x.toText()}"`;
    }
}
12

You are right. That’s a bug on the agent-js side. The sorting function should be alphabet, not based on the IDL hash.

1 Like
13

Do you have an ETA on when this bug could be fixed? We’re trying to decide if we should maintain a fork or not.

14

There’s a similar issue in @dfinity/agent v0.19.3.

Update: Looks like a fix was recently merged so the JS agent part should be resolved in the next release

See fix: service ordering must be alphabetical by lastmjs · Pull Request #781 · dfinity/agent-js · GitHub