make zero-sized value counting more fine grained #516
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crusso
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Jan 26, 2024
| fn dec_zero_sized_value(&mut self) -> Result<()> { | ||
| //eprintln!("{}", self.zero_sized_values); | ||
| if self.zero_sized_values == 0 { | ||
| return Err(Error::msg("Too many zero sized values")); |
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Suggested change
| return Err(Error::msg("Too many zero sized values")); | |
| return Err(Error::msg("Too many zero sized values")); |
Suggested change
| return Err(Error::msg("Too many zero sized values")); | |
| return Err(Error::msg("Too many zero-sized values")); |
crusso
approved these changes
Jan 26, 2024
mraszyk
reviewed
Jan 28, 2024
| }), | ||
| _ => false, | ||
| fn dec_zero_sized_value(&mut self) -> Result<()> { | ||
| //eprintln!("{}", self.zero_sized_values); |
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should this comment be dropped?
mraszyk
reviewed
Jan 28, 2024
spec/Candid.md
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| @@ -1255,7 +1255,7 @@ M(id(v*) : principal) = i8(1) M(v* : vec nat8) | |||
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| Note: | |||
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| * Since `null`, `reserved`, `record {}`, and records of such values, take no space, to prevent unbounded sized message, we limit the total vector length of such zero-sized values in a messagev (on the wire) to be 2,000,000 elements. For example, if a message contains two vectors, one at type `vec null` and one at type `vec record {}`, then the length of both vectors combined cannot exceed 2,000,000 elements. | |||
| * Since `null`, `reserved` and `record {}` take no space, to prevent unbounded sized message, we limit the total number of such zero-sized values in a message (on the wire) to be 2,000,000 elements. For example, a value of type `record { null; reserved; record { record {} } }` contains 3 zero-sized values; a value of type `vec opt record { null; null }` with length 100 contains at most 200 zero-sized values (it is 200 when the vector contains no `null` values); if a message contains two vectors, one at type `vec null` and one at type `vec record {}`, then the length of both vectors combined cannot exceed 2,000,000 elements. | |||
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a value of type
record { null; reserved; record { record {} } }contains 3 zero-sized values
Could you please list the zero-sized values explicitly? I believe to have counter 4:
nullreservedrecord {}record { record {} }
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And in fact also the entire record { null; reserved; record { record {} } } is a 5th zero-sized value there.
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I will try to rephrase the spec. We only count the occurrences of null, reserved and record {} to simulate the effect that if these values were not zero sized. record { record {} } would not be zero sized, if record {} weren't zero sized.
mraszyk
reviewed
Jan 28, 2024
| @@ -337,16 +334,13 @@ impl<'de> Deserializer<'de> { | |||
| } | |||
| Ok(()) | |||
| } | |||
| fn is_zero_sized_type(&self, t: &Type) -> bool { | |||
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Conceptually, we should check this condition for every (nested) value and limit all such (nested) zero-sized values at 2M in total.
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See above. That would be overcounting, e.g., record { null; null } would be counted as 3 instead of 2.
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Update spec to limit the number of zero-sized values in a message, instead of the sum length of
vec {zero-sized value}.