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Potential Backwards Indexing #5

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Tracked by #6
rcgoodfellow opened this issue Aug 30, 2022 · 1 comment · Fixed by #12
Closed
Tracked by #6

Potential Backwards Indexing #5

rcgoodfellow opened this issue Aug 30, 2022 · 1 comment · Fixed by #12
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rcgoodfellow commented Aug 30, 2022 •
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See:

p4/test/src/p4/sidecar-lite.p4

Lines 397 to 399 in c53f861

//TODO this is backwards should be?
//if(hdr.ipv6.dst[127:112] == ll) {
if(hdr.ipv6.dst[15:0] == ll) {

@rcgoodfellow rcgoodfellow mentioned this issue Aug 30, 2022
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@rcgoodfellow rcgoodfellow self-assigned this Aug 30, 2022
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The crux of the issue is this statement from section 13.8 from the P4-16 specification

When extracting data into a bit-string or integer, the first packet bit is extracted to the most significant bit of the integer.

Currently, we're doing the arguably more intuitive thing of extracting the first packet bit to the first bit of a bit<N> header field.

rcgoodfellow added a commit that referenced this issue Nov 10, 2022
@rcgoodfellow
implement confused-endian semantics
9d14237 
The p4 spec states that the first bit from a packet extracts into the
last bit of bit-string types, this means that we go from protocol-endian
to p4-endian and then back to protocol-endian on the way out.

Fixes #5.
@rcgoodfellow rcgoodfellow mentioned this issue Nov 10, 2022
Merged
rcgoodfellow added a commit that referenced this issue Nov 10, 2022
@rcgoodfellow
implement confused-endian semantics
8df8f6d 
The p4 spec states that the first bit from a packet extracts into the
last bit of bit-string types, this means that we go from protocol-endian
to p4-endian and then back to protocol-endian on the way out.

Fixes #5.
rcgoodfellow added a commit that referenced this issue Nov 10, 2022
@rcgoodfellow
implement confused-endian semantics
14b5443 
The p4 spec states that the first bit from a packet extracts into the
last bit of bit-string types, this means that we go from protocol-endian
to p4-endian and then back to protocol-endian on the way out.

Fixes #5.
rcgoodfellow added a commit that referenced this issue Nov 10, 2022
@rcgoodfellow
implement confused-endian semantics
2b0fb58 
The p4 spec states that the first bit from a packet extracts into the
last bit of bit-string types, this means that we go from protocol-endian
to p4-endian and then back to protocol-endian on the way out.

Fixes #5.
rcgoodfellow added a commit that referenced this issue Nov 10, 2022
@rcgoodfellow
implement confused-endian semantics
0a134f8 
The p4 spec states that the first bit from a packet extracts into the
last bit of bit-string types, this means that we go from protocol-endian
to p4-endian and then back to protocol-endian on the way out.

Fixes #5.
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implement confused-endian semantics oxidecomputer/p4
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