Move bitcoin/p2p into p2p

Moves all of the content from `bitcoin/p2p` into `p2p`.

`TryFrom<Network>` must be implemented for `Network -> Magic` now that
`Network` is a foreign, non-exhaustive type. Ser/de test is updated
accordingly, as well as the `Magic::from_network` constructor, which I
have opted to return an `Option<Self>`. The `TryFrom` implementation
uses a new `UnknownNetworkError(Network)` that mirrors the `Magic ->
Network` error.

The example handshake does not generate a random nonce for the version
message, as there is no `rand` dependency in this crate and the program
only makes a single, user-defined connection.

It appears we can do better than copying and pasting the consensus
encoding macros and functions from `bitcoin` without doing weird
cross-crate macros that require some special knowledge of the crate to
know when they will compile.

Author: rustaceanrob

Cargo-minimal.lock

@@ -77,6 +77,7 @@ name = "bitcoin-fuzz"
 version = "0.0.1"
 dependencies = [
  "bitcoin",
+ "bitcoin-p2p-messages",
  "honggfuzz",
  "serde",
  "serde_json",
@@ -109,6 +110,15 @@ dependencies = [
 [[package]]
 name = "bitcoin-p2p-messages"
 version = "0.1.0"
+dependencies = [
+ "bitcoin",
+ "bitcoin-internals",
+ "bitcoin-io 0.2.0",
+ "bitcoin-units",
+ "bitcoin_hashes 0.16.0",
+ "hex-conservative 0.3.0",
+ "hex_lit",
+]
 
 [[package]]
 name = "bitcoin-primitives"

Cargo-recent.lock

@@ -76,6 +76,7 @@ name = "bitcoin-fuzz"
 version = "0.0.1"
 dependencies = [
  "bitcoin",
+ "bitcoin-p2p-messages",
  "honggfuzz",
  "serde",
  "serde_json",
@@ -108,6 +109,15 @@ dependencies = [
 [[package]]
 name = "bitcoin-p2p-messages"
 version = "0.1.0"
+dependencies = [
+ "bitcoin",
+ "bitcoin-internals",
+ "bitcoin-io 0.2.0",
+ "bitcoin-units",
+ "bitcoin_hashes 0.16.0",
+ "hex-conservative 0.3.0",
+ "hex_lit",
+]
 
 [[package]]
 name = "bitcoin-primitives"

bitcoin/Cargo.toml

@@ -56,10 +56,6 @@ rustdoc-args = ["--cfg", "docsrs"]
 [[example]]
 name = "bip32"
 
-[[example]]
-name = "handshake"
-required-features = ["rand-std"]
-
 [[example]]
 name = "ecdsa-psbt"
 required-features = ["std", "bitcoinconsensus"]

bitcoin/src/lib.rs

@@ -94,7 +94,6 @@ extern crate serde;
 mod internal_macros;
 
 #[macro_use]
-pub mod p2p;
 pub mod address;
 pub mod bip152;
 pub mod bip158;