This commit checks that the size of the bech32 encoded invoice is not
greater than 7092 bytes, which is the maximum number of bytes that can
fit into a QR code. This mitigates a potential DoS vector where an attacker
could craft a very large bech32 invoice string containing an absurd amount
of route and/or hop hints. If sent to an application that processes
payment requests, this would allocate a burdensome amount of memory
due to the public key parsing for each route/hop hint.
For a 1.7MB payment request, this yielded about 38MB in allocations
from just parsing public keys:
```
45.51MB 7.31% 92.07% 45.51MB 7.31% math/big.nat.make
25.50MB 4.09% 96.16% 25.50MB 4.09% github.com/lightningnetwork/lnd/zpay32.bech32VerifyChecksum
1MB 0.16% 96.32% 39.50MB 6.34% github.com/lightningnetwork/lnd/zpay32.parseRouteHint
1MB 0.16% 96.48% 33.50MB 5.38% github.com/btcsuite/btcd/btcec.decompressPoint
0.50MB 0.08% 96.56% 7.50MB 1.20% crypto/elliptic.(*CurveParams).doubleJacobian
0.50MB 0.08% 96.64% 38MB 6.10% github.com/btcsuite/btcd/btcec.ParsePubKey
0 0% 96.64% 12MB 1.93% crypto/ecdsa.Verify
0 0% 96.64% 8MB 1.28% crypto/elliptic.(*CurveParams).ScalarBaseMult
0 0% 96.64% 12MB 1.93% crypto/elliptic.(*CurveParams).ScalarMult
```
With this change, memory usage will be far lower as decoding will exit
early with an error if the invoice is too large.
Before this commit, if an invoice encoded multiple `r` fields, we would
decode them as one single route. We fix this by allowing an invoice to
store multiple routes.
In this commit, we fix a logic error in our routine for converting a
uint64 to/from base32. Before this commit, we assumed that the max
number of groups was 12. However, the math.MaxUint64 (1<<64 - 1) can
actually consume more than 12 groups with an extra set of bits. Before
this commit, we would panic when attempting to parse an invoice
generated like so:
* addinvoice --amt 1337000 --expiry 99999999999999999
To fix this issue, we modify our logic to expect at most 13 groups.
Additionally, we've added a new test that would panic before applying
this commit.
Fixes#972.
This change fixes a bug when an invoice is decoded for a network
whose bech32 segwit prefix is longer than 2 characters. The length
of the Bech32HRPSegwit network parameter is used to determine
where in the human-readable portion of the invoice the amount
begins, rather than assuming it begins after the first four
characters.
Decode() now throws an error when the encoded invoice does
not match the active network.
Changes the minimum hrp length check to >= 3 instead of >= 4.
Also removes a redundant "if ...; err != nil check" that was raising
a warning in invoice.go.
When accessing a value from a byte slice, the value is returned as a
byte, which is just a uint8. When the first byte takes more than 3 bits
of space, shifting 5 bits left results in data loss.
This commit allows parseRoutingInfo to return an error when parsing a
routing info field whose length is not a multiple of 51 bytes, rather
than crash.
This commit refactors parsing each of the tagged fields of an invoice
into their own method. This makes the code easier to read and will allow
us to introduce unit tests for each parsing method.
This commit renames the invoice field Expiry to expiry, and changes
the type from time.Time to time.Duration. Getting the value of the
field will now have to be done using the getter Expiry(), which
will also return the default invoice expiry (3600s) if it is not set
explicitly by the the invoice.
