dash/doc/build-unix.md

UNIX BUILD NOTES
====================
Some notes on how to build Dash Core in Unix.

(for OpenBSD specific instructions, see [build-openbsd.md](build-openbsd.md))

Note
---------------------
Always use absolute paths to configure and compile Dash Core and the dependencies.
For example, when specifying the path of the dependency:

	../dist/configure --enable-cxx --disable-shared --with-pic --prefix=$BDB_PREFIX

Here BDB_PREFIX must be an absolute path - it is defined using $(pwd) which ensures
the usage of the absolute path.

To Build
---------------------

```bash
./autogen.sh
./configure
make
make install # optional
```

This will build dash-qt as well, if the dependencies are met.

Dependencies
---------------------

These dependencies are required:

 Library     | Purpose          | Description
 ------------|------------------|----------------------
 libboost    | Utility          | Library for threading, data structures, etc
 libevent    | Networking       | OS independent asynchronous networking

Optional dependencies:

 Library     | Purpose          | Description
 ------------|------------------|----------------------
 gmp         | Optimized math routines | Arbitrary precision arithmetic library
 miniupnpc   | UPnP Support     | Firewall-jumping support
 libnatpmp   | NAT-PMP Support  | Firewall-jumping support
 libdb4.8    | Berkeley DB      | Wallet storage (only needed when wallet enabled)
 qt          | GUI              | GUI toolkit (only needed when GUI enabled)
 libqrencode | QR codes in GUI  | Optional for generating QR codes (only needed when GUI enabled)
 univalue    | Utility          | JSON parsing and encoding (bundled version will be used unless --with-system-univalue passed to configure)
 libzmq3     | ZMQ notification | Optional, allows generating ZMQ notifications (requires ZMQ version >= 4.0.0)
 sqlite3     | SQLite DB        | Wallet storage (only needed when wallet enabled)

For the versions used, see [dependencies.md](dependencies.md)

Memory Requirements
--------------------

C++ compilers are memory-hungry. It is recommended to have at least 1.5 GB of
memory available when compiling Dash Core. On systems with less, gcc can be
tuned to conserve memory with additional CXXFLAGS:


    ./configure CXXFLAGS="--param ggc-min-expand=1 --param ggc-min-heapsize=32768"

Dependency Build Instructions: Ubuntu & Debian
----------------------------------------------
Build requirements:

    sudo apt-get install build-essential libtool autotools-dev automake pkg-config libevent-dev bsdmainutils bison python3

Options when installing required Boost library files:

1. On at least Ubuntu 14.04+ and Debian 7+ there are generic names for the
individual boost development packages, so the following can be used to only
install necessary parts of boost:

        sudo apt-get install libboost-system-dev libboost-filesystem-dev libboost-test-dev libboost-thread-dev

2. If that doesn't work, you can install all boost development packages with:

        sudo apt-get install libboost-all-dev

BerkeleyDB is required for the wallet.

**For Ubuntu only:** db4.8 packages are available [here](https://launchpad.net/~bitcoin/+archive/bitcoin).
You can add the repository and install using the following commands:

    sudo apt-get install software-properties-common
    sudo add-apt-repository ppa:bitcoin/bitcoin
    sudo apt-get update
    sudo apt-get install libdb4.8-dev libdb4.8++-dev

Ubuntu and Debian have their own `libdb-dev` and `libdb++-dev` packages, but these will install
BerkeleyDB 5.1 or later. This will break binary wallet compatibility with the distributed executables, which
are based on BerkeleyDB 4.8. If you do not care about wallet compatibility,
pass `--with-incompatible-bdb` to configure.

SQLite is required for the wallet:

    sudo apt install libsqlite3-dev

To build Dash Core without wallet, see [*Disable-wallet mode*](/doc/build-unix.md#disable-wallet-mode)

Optional port mapping libraries (see: `--with-miniupnpc`, `--enable-upnp-default`, and `--with-natpmp`, `--enable-natpmp-default`):

    sudo apt install libminiupnpc-dev libnatpmp-dev

ZMQ dependencies (provides ZMQ API):

    sudo apt-get install libzmq3-dev

GMP dependencies (provides platform-optimized routines):

   sudo apt-get install libgmp-dev

Dependencies for the GUI: Ubuntu & Debian
-----------------------------------------

If you want to build dash-qt, make sure that the required packages for Qt development
are installed. Qt 5 is necessary to build the GUI.
To build without GUI pass `--without-gui`.

To build with Qt 5 you need the following:

    sudo apt-get install libqt5gui5 libqt5core5a libqt5dbus5 qttools5-dev qttools5-dev-tools

libqrencode (optional) can be installed with:

    sudo apt-get install libqrencode-dev

Once these are installed, they will be found by configure and a dash-qt executable will be
built by default.


Dependency Build Instructions: Fedora
-------------------------------------
Build requirements:

    sudo dnf install gcc-c++ libtool make autoconf automake libevent-devel boost-devel libdb4-devel libdb4-cxx-devel python3

Optional port mapping libraries (see: `--with-miniupnpc`, `--enable-upnp-default`, and `--with-natpmp`, `--enable-natpmp-default`):

    sudo dnf install miniupnpc-devel libnatpmp-devel

ZMQ dependencies (provides ZMQ API):

    sudo dnf install zeromq-devel

GMP dependencies (provides platform-optimized routines):

    sudo dnf install gmp-devel

GUI dependencies:

If you want to build dash-qt, make sure that the required packages for Qt development
are installed. Qt 5 is necessary to build the GUI.
To build without GUI pass `--without-gui`.

To build with Qt 5 you need the following:

    sudo dnf install qt5-qttools-devel qt5-qtbase-devel

libqrencode (optional) can be installed with:

    sudo dnf install qrencode-devel

SQLite can be installed with:

    sudo dnf install sqlite-devel

Notes
-----
The release is built with GCC and then "strip dashd" to strip the debug
symbols, which reduces the executable size by about 90%.


miniupnpc
---------

[miniupnpc](https://miniupnp.tuxfamily.org) may be used for UPnP port mapping.  It can be downloaded from [here](
https://miniupnp.tuxfamily.org/files/).  UPnP support is compiled in and
turned off by default.  See the configure options for upnp behavior desired:

	--without-miniupnpc      No UPnP support miniupnp not required
	--disable-upnp-default   (the default) UPnP support turned off by default at runtime
	--enable-upnp-default    UPnP support turned on by default at runtime

libnatpmp
---------

[libnatpmp](https://miniupnp.tuxfamily.org/libnatpmp.html) may be used for NAT-PMP port mapping. It can be downloaded
from [here](https://miniupnp.tuxfamily.org/files/). NAT-PMP support is compiled in and
turned off by default. See the configure options for NAT-PMP behavior desired:

	--without-natpmp          No NAT-PMP support, libnatpmp not required
	--disable-natpmp-default  (the default) NAT-PMP support turned off by default at runtime
	--enable-natpmp-default   NAT-PMP support turned on by default at runtime

Berkeley DB
-----------
It is recommended to use Berkeley DB 4.8. If you have to build it yourself:

```bash
DASH_ROOT=$(pwd)

# Pick some path to install BDB to, here we create a directory within the dash directory
BDB_PREFIX="${DASH_ROOT}/db4"
mkdir -p $BDB_PREFIX

# Fetch the source and verify that it is not tampered with
wget 'http://download.oracle.com/berkeley-db/db-4.8.30.NC.tar.gz'
echo '12edc0df75bf9abd7f82f821795bcee50f42cb2e5f76a6a281b85732798364ef  db-4.8.30.NC.tar.gz' | sha256sum -c
# -> db-4.8.30.NC.tar.gz: OK
tar -xzvf db-4.8.30.NC.tar.gz

# Build the library and install to our prefix
cd db-4.8.30.NC/build_unix/
#  Note: Do a static build so that it can be embedded into the executable, instead of having to find a .so at runtime
../dist/configure --enable-cxx --disable-shared --with-pic --prefix=$BDB_PREFIX
make install

# Configure Dash Core to use our own-built instance of BDB
cd $DASH_ROOT
./autogen.sh
./configure LDFLAGS="-L${BDB_PREFIX}/lib/" CPPFLAGS="-I${BDB_PREFIX}/include/" # (other args...)
```

Boost
-----
If you need to build Boost yourself:

	sudo su
	./bootstrap.sh
	./bjam install


Security
--------
To help make your Dash Core installation more secure by making certain attacks impossible to
exploit even if a vulnerability is found, binaries are hardened by default.
This can be disabled with:

Hardening Flags:

	./configure --enable-hardening
	./configure --disable-hardening


Hardening enables the following features:
* _Position Independent Executable_: Build position independent code to take advantage of Address Space Layout Randomization
    offered by some kernels. Attackers who can cause execution of code at an arbitrary memory
    location are thwarted if they don't know where anything useful is located.
    The stack and heap are randomly located by default, but this allows the code section to be
    randomly located as well.

    On an AMD64 processor where a library was not compiled with -fPIC, this will cause an error
    such as: "relocation R_X86_64_32 against `......' can not be used when making a shared object;"

    To test that you have built PIE executable, install scanelf, part of paxutils, and use:

    	scanelf -e ./dashd

    The output should contain:

     TYPE
    ET_DYN

* _Non-executable Stack_: If the stack is executable then trivial stack-based buffer overflow exploits are possible if
    vulnerable buffers are found. By default, Dash Core should be built with a non-executable stack,
    but if one of the libraries it uses asks for an executable stack or someone makes a mistake
    and uses a compiler extension which requires an executable stack, it will silently build an
    executable without the non-executable stack protection.

    To verify that the stack is non-executable after compiling use:
    `scanelf -e ./dashd`

    The output should contain:
	STK/REL/PTL
	RW- R-- RW-

    The STK RW- means that the stack is readable and writeable but not executable.

Disable-wallet mode
--------------------
When the intention is to run only a P2P node without a wallet, Dash Core may be compiled in
disable-wallet mode with:

    ./configure --disable-wallet

In this case there is no dependency on Berkeley DB 4.8 and SQLite.

Mining is also possible in disable-wallet mode using the `getblocktemplate` RPC call.

Additional Configure Flags
--------------------------
A list of additional configure flags can be displayed with:

    ./configure --help


Setup and Build Example: Arch Linux
-----------------------------------
This example lists the steps necessary to setup and build a command line only, non-wallet distribution of the latest changes on Arch Linux:

    pacman -S git base-devel boost libevent python
    git clone https://github.com/dashpay/dash.git
    cd dash/
    ./autogen.sh
    ./configure --disable-wallet --without-gui --without-miniupnpc
    make check

Note:
Enabling wallet support requires either compiling against a Berkeley DB newer than 4.8 (package `db`) using `--with-incompatible-bdb`,
or building and depending on a local version of Berkeley DB 4.8. The readily available Arch Linux packages are currently built using
`--with-incompatible-bdb` according to the [PKGBUILD](https://projects.archlinux.org/svntogit/community.git/tree/bitcoin/trunk/PKGBUILD).
As mentioned above, when maintaining portability of the wallet between the standard Dash Core distributions and independently built
node software is desired, Berkeley DB 4.8 must be used.


ARM Cross-compilation
-------------------
These steps can be performed on, for example, an Ubuntu VM. The depends system
will also work on other Linux distributions, however the commands for
installing the toolchain will be different.

Make sure you install the build requirements mentioned above.
Then, install the toolchain and curl:

    sudo apt-get install g++-arm-linux-gnueabihf curl

To build executables for ARM:

    cd depends
    make HOST=arm-linux-gnueabihf NO_QT=1
    cd ..
    ./configure --prefix=$PWD/depends/arm-linux-gnueabihf --enable-glibc-back-compat --enable-reduce-exports LDFLAGS=-static-libstdc++
    make


For further documentation on the depends system see [README.md](../depends/README.md) in the depends directory.

Building on FreeBSD
--------------------

(Updated as of FreeBSD 11.0)

Clang is installed by default as `cc` compiler, this makes it easier to get
started than on [OpenBSD](build-openbsd.md). Installing dependencies:

    pkg install autoconf automake libtool pkgconf
    pkg install boost-libs libevent
    pkg install gmake

You need to use GNU make (`gmake`) instead of `make`.

For the wallet (optional):

    pkg install db5

This will give a warning "configure: WARNING: Found Berkeley DB other
than 4.8; wallets opened by this build will not be portable!", but as FreeBSD never
had a binary release, this may not matter. If backwards compatibility
with 4.8-built Dash Core is needed follow the steps under "Berkeley DB" above.

Then build using:

    ./autogen.sh
    ./configure --with-incompatible-bdb BDB_CFLAGS="-I/usr/local/include/db5" BDB_LIBS="-L/usr/local/lib -ldb_cxx-5"
    gmake

*Note on debugging*: The version of `gdb` installed by default is [ancient and considered harmful](https://wiki.freebsd.org/GdbRetirement).
It is not suitable for debugging a multi-threaded C++ program, not even for getting backtraces. Please install the package `gdb` and
use the versioned gdb command e.g. `gdb7111`.