This improves error messages when the file is too short or too long.
Also rewrite the test for SaveECDSA because LoadECDSA has its own
test now.

Co-authored-by: Felix Lange <fjl@twurst.com>

This removes a bunch of weird code around the counter overflow check in
concatKDF and makes it actually work for different hash output sizes.

The overflow check worked as follows: concatKDF applies the hash function N
times, where N is roundup(kdLen, hashsize) / hashsize. N should not
overflow 32 bits because that would lead to a repetition in the KDF output.

A couple issues with the overflow check:

- It used the hash.BlockSize, which is wrong because the
  block size is about the input of the hash function. Luckily, all standard
  hash functions have a block size that's greater than the output size, so
  concatKDF didn't crash, it just generated too much key material.
- The check used big.Int to compare against 2^32-1.
- The calculation could still overflow before reaching the check.

The new code in concatKDF doesn't check for overflow. Instead, there is a
new check on ECIESParams which ensures that params.KeyLen is < 512. This
removes any possibility of overflow.

There are a couple of miscellaneous improvements bundled in with this
change:

- The key buffer is pre-allocated instead of appending the hash output
  to an initially empty slice.
- The code that uses concatKDF to derive keys is now shared between Encrypt
  and Decrypt.
- There was a redundant invocation of IsOnCurve in Decrypt. This is now removed
  because elliptic.Unmarshal already checks whether the input is a valid curve
  point since Go 1.5.

Co-authored-by: Felix Lange <fjl@twurst.com>

* build: use golangci-lint

This changes build/ci.go to download and run golangci-lint instead
of gometalinter.

* core/state: fix unnecessary conversion

* p2p/simulations: fix lock copying (found by go vet)

* signer/core: fix unnecessary conversions

* crypto/ecies: remove unused function cmpPublic

* core/rawdb: remove unused function print

* core/state: remove unused function xTestFuzzCutter

* core/vm: disable TestWriteExpectedValues in a different way

* core/forkid: remove unused function checksum

* les: remove unused type proofsData

* cmd/utils: remove unused functions prefixedNames, prefixFor

* crypto/bn256: run goimports

* p2p/nat: fix goimports lint issue

* cmd/clef: avoid using unkeyed struct fields

* les: cancel context in testRequest

* rlp: delete unreachable code

* core: gofmt

* internal/build: simplify DownloadFile for Go 1.11 compatibility

* build: remove go test --short flag

* .travis.yml: disable build cache

* whisper/whisperv6: fix ineffectual assignment in TestWhisperIdentityManagement

* .golangci.yml: enable goconst and ineffassign linters

* build: print message when there are no lint issues

* internal/build: refactor download a bit

Most of these changes are related to the Go 1.13 changes to test binary
flag handling. 

* cmd/geth: make attach tests more reliable

This makes the test wait for the endpoint to come up by polling
it instead of waiting for two seconds.

* tests: fix test binary flags for Go 1.13

Calling flag.Parse during package initialization is prohibited
as of Go 1.13 and causes test failures. Call it in TestMain instead.

* crypto/ecies: remove useless -dump flag in tests

* p2p/simulations: fix test binary flags for Go 1.13

Calling flag.Parse during package initialization is prohibited
as of Go 1.13 and causes test failures. Call it in TestMain instead.

* build: remove workaround for ./... vendor matching

This workaround was necessary for Go 1.8. The Go 1.9 release changed
the expansion rules to exclude vendored packages.

* Makefile: use relative path for GOBIN

This makes the "Run ./build/bin/..." line look nicer.

* les: fix test binary flags for Go 1.13

Calling flag.Parse during package initialization is prohibited
as of Go 1.13 and causes test failures. Call it in TestMain instead.

Original change by @jpeletier 

The precompile at 0x09 wraps the BLAKE2b F compression function:
https://tools.ietf.org/html/rfc7693#section-3.2

The precompile requires 6 inputs tightly encoded, taking exactly 213
bytes, as explained below.

- `rounds` - the number of rounds - 32-bit unsigned big-endian word
- `h` - the state vector - 8 unsigned 64-bit little-endian words
- `m` - the message block vector - 16 unsigned 64-bit little-endian words
- `t_0, t_1` - offset counters - 2 unsigned 64-bit little-endian words
- `f` - the final block indicator flag - 8-bit word

[4 bytes for rounds][64 bytes for h][128 bytes for m][8 bytes for t_0]
[8 bytes for t_1][1 byte for f]

The boolean `f` parameter is considered as `true` if set to `1`.
The boolean `f` parameter is considered as `false` if set to `0`.
All other values yield an invalid encoding of `f` error.

The precompile should compute the F function as specified in the RFC
(https://tools.ietf.org/html/rfc7693#section-3.2) and return the updated
state vector `h` with unchanged encoding (little-endian).

See EIP-152 for details.

* Removed comment section referring to Cloudflare's bn curve parameters

* Added comment to clarify the nature of the parameters

* Changed value of xi to i+9

* Added checks for nil pointers in Marshal functions

* Set nil pointer to identity in GT before marshaling

Package crypto works with or without cgo, which is great. However, to make it
work without cgo required setting the build tag `nocgo`. It's common to disable
cgo by instead just setting the environment variable `CGO_ENABLED=0`. Setting
this environment variable does _not_ implicitly set the build tag `nocgo`. So
projects that try to build the crypto package with `CGO_ENABLED=0` will fail. I
have done this myself several times. Until today, I had just assumed that this
meant that this package requires cgo.

But a small build tag change will make this case work. Instead of using `nocgo`
and `!nocgo`, we can use `!cgo` and `cgo`, respectively. The `cgo` build tag is
automatically set if cgo is enabled, and unset if it is disabled.

* core/vm/runtim: benchmark create/create2

* core/vm: do less hashing in CREATE2

* core/vm: avoid storing jumpdest analysis for initcode

* core/vm: avoid unneccesary lookups, remove unused fields

* core/vm: go formatting tests

* core/vm: save jumpdest analysis locally

* core/vm: use common.Hash instead of nil, fix review comments

* core/vm: removed type destinations

* core/vm: correct check for empty hash

* eth: more elegant api_tracer

* core/vm: address review concerns

`(void)data;` may cause link error on Windows.

* core, crypto, params: implement CREATE2 evm instrction

* core/vm: add opcode to string mapping

* core: remove past fork checking

* core, crypto: use option2 to generate new address

Our original wrapper code had two parts. One taken from a third
party repository (who took it from upstream Go) licensed under
BSD-3. The second written by Jeff, Felix and Gustav, licensed
under LGPL. This made this package problematic to use from the
outside.

With the agreement of the original copyright holders, this commit
changes the license of the LGPL portions of the code to BSD-3:

---
I agree changing from LGPL to a BSD style license.

Jeff
---
Hey guys,

My preference would be to relicense to GNUBL, but I'm also OK with BSD.

Cheers,
Gustav
---
Felix Lange (fjl):
I would approve anything that makes our licensing less complicated
---

ToECDSAPub was unsafe because it returned a non-nil key with nil X, Y in
case of invalid input. This change replaces ToECDSAPub with
UnmarshalPubkey across the codebase.

The parameter `rand` is unused in `PrivateKey.Decrypt`. Decryption in
the ECIES encryption scheme is deterministic, so randomness isn't
needed.

* crypto/bn256: full switchover to cloudflare's code

* crypto/bn256: only use cloudflare for optimized architectures

* crypto/bn256: upstream fallback for non-optimized code

* .travis, build: drop support for Go 1.8 (need type aliases)

* crypto/bn256/cloudflare: enable curve mul lattice optimization

* core/vm, crypto/bn256: switch over to cloudflare library

* crypto/bn256: unmarshal constraint + start pure go impl

* crypto/bn256: combo cloudflare and google lib

* travis: drop 386 test job

Fixes #15744