#!/bin/sh

global SRC_DIR := $[pwd]

# Read the 'JOB_FACTOR' property from '.config'
global JOB_FACTOR := $[grep -i ^JOB_FACTOR .config | cut -f2 -d'=]

# Find the number of available CPU cores.
global NUM_CORES := $[grep ^processor /proc/cpuinfo | wc -l]

# Calculate the number of 'make' jobs to be used later.
global NUM_JOBS := $(NUM_CORES * JOB_FACTOR)

if test ! -d $SRC_DIR/work/glibc/glibc_prepared  {
  echo "Cannot continue - Dropbear SSH depends on GLIBC. Please buld GLIBC first."
  exit 1
}

cd work/overlay/dropbear

# Change to the Dropbear source directory which ls finds, e.g. 'dropbear-2016.73'.
cd $[ls -d dropbear-*]

echo "Preparing Dropbear work area. This may take a while..."
make clean -j $NUM_JOBS !2 >/dev/null

rm -rf ../dropbear_installed

echo "Configuring Dropbear..."
./configure \
  --prefix=$SRC_DIR/work/overlay/dropbear/dropbear_installed \
  --disable-zlib \
  --disable-loginfunc \
  CFLAGS="-Os -s -fno-stack-protector -U_FORTIFY_SOURCE"

echo "Building Dropbear..."
make -j $NUM_JOBS

echo "Installing Dropbear..."
make install -j $NUM_JOBS

mkdir -p ../dropbear_installed/lib

# Copy all dependent GLIBC libraries.
cp $SRC_DIR/work/glibc/glibc_prepared/lib/libnsl.so.1 ../dropbear_installed/lib
cp $SRC_DIR/work/glibc/glibc_prepared/lib/libnss_compat.so.2 ../dropbear_installed/lib
cp $SRC_DIR/work/glibc/glibc_prepared/lib/libutil.so.1 ../dropbear_installed/lib
cp $SRC_DIR/work/glibc/glibc_prepared/lib/libcrypt.so.1 ../dropbear_installed/lib

mkdir -p ../dropbear_installed/etc/dropbear

# Create Dropbear SSH configuration BEGIN

# Create RSA key.
../dropbear_installed/bin/dropbearkey \
  -t rsa \
  -f ../dropbear_installed/etc/dropbear/dropbear_rsa_host_key 

# Create DSS key.
../dropbear_installed/bin/dropbearkey \
  -t dss \
  -f ../dropbear_installed/etc/dropbear/dropbear_dss_host_key 

# Create ECDSA key.
../dropbear_installed/bin/dropbearkey \
  -t ecdsa \
  -f ../dropbear_installed/etc/dropbear/dropbear_ecdsa_host_key 

# Create user/group configuration files.
touch ../dropbear_installed/etc/passwd
touch ../dropbear_installed/etc/group

# Add group 0 for root.
echo "root:x:0:" \
  > ../dropbear_installed/etc/group

# Add user root with password 'toor'.
echo "root:AprZpdBUhZXss:0:0:Minimal Root,,,:/root:/bin/sh" \
  > ../dropbear_installed/etc/passwd

# Create home folder for root user.
mkdir -p ../dropbear_installed/root

# Create Dropbear SSH configuration END

echo "Reducing Dropbear size..."
strip -g \
  ../dropbear_installed/bin/* \
  ../dropbear_installed/sbin/* \
  ../dropbear_installed/lib/*

cp -r \
  ../dropbear_installed/etc \
  ../dropbear_installed/bin \
  ../dropbear_installed/sbin \
  ../dropbear_installed/lib \
  $SRC_DIR/work/src/minimal_overlay

echo "Dropbear has been installed."

cd $SRC_DIR

(CommandList
  children: [
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:SRC_DIR)
          op: Equal
          rhs: 
            {
              (CommandSubPart
                command_list: (CommandList children:[(C {(pwd)})])
                left_token: <Left_CommandSub "$(">
                spids: [5 7]
              )
            }
          spids: [4]
        )
      ]
      spids: [4]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:JOB_FACTOR)
          op: Equal
          rhs: 
            {
              (DQ 
                (CommandSubPart
                  command_list: 
                    (CommandList
                      children: [
                        (Pipeline
                          children: [
                            (C {(grep)} {(-i)} {(Lit_Other "^") (JOB_FACTOR)} {(.config)})
                            (C {(cut)} {(-f2)} {(-d) (SQ <"=">)})
                          ]
                          negated: False
                        )
                      ]
                    )
                  left_token: <Left_CommandSub "$(">
                  spids: [15 35]
                )
              )
            }
          spids: [13]
        )
      ]
      spids: [13]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:NUM_CORES)
          op: Equal
          rhs: 
            {
              (CommandSubPart
                command_list: 
                  (CommandList
                    children: [
                      (Pipeline
                        children: [
                          (C {(grep)} {(Lit_Other "^") (processor)} {(/proc/cpuinfo)})
                          (C {(wc)} {(-l)})
                        ]
                        negated: False
                      )
                    ]
                  )
                left_token: <Left_CommandSub "$(">
                spids: [43 56]
              )
            }
          spids: [42]
        )
      ]
      spids: [42]
    )
    (Assignment
      keyword: Assign_None
      pairs: [
        (assign_pair
          lhs: (LhsName name:NUM_JOBS)
          op: Equal
          rhs: 
            {
              (ArithSubPart
                anode: 
                  (ArithBinary
                    op_id: Arith_Star
                    left: (ArithVarRef name:NUM_CORES)
                    right: (ArithVarRef name:JOB_FACTOR)
                  )
                spids: [63 70]
              )
            }
          spids: [62]
        )
      ]
      spids: [62]
    )
    (If
      arms: [
        (if_arm
          cond: [
            (Sentence
              child: 
                (C {(Lit_Other "[")} {(KW_Bang "!")} {(-d)} 
                  {($ VSub_Name "$SRC_DIR") (/work/glibc/glibc_prepared)} {(Lit_Other "]")}
                )
              terminator: <Op_Semi ";">
            )
          ]
          action: [
            (C {(echo)} 
              {(DQ ("Cannot continue - Dropbear SSH depends on GLIBC. Please buld GLIBC first."))}
            )
            (C {(exit)} {(1)})
          ]
          spids: [-1 88]
        )
      ]
      spids: [-1 102]
    )
    (C {(cd)} {(work/overlay/dropbear)})
    (C {(cd)} 
      {
        (CommandSubPart
          command_list: (CommandList children:[(C {(ls)} {(-d)} {(dropbear-) (Lit_Other "*")})])
          left_token: <Left_CommandSub "$(">
          spids: [115 122]
        )
      }
    )
    (C {(echo)} {(DQ ("Preparing Dropbear work area. This may take a while..."))})
    (SimpleCommand
      words: [{(make)} {(clean)} {(-j)} {($ VSub_Name "$NUM_JOBS")}]
      redirects: [(Redir op_id:Redir_Great fd:2 arg_word:{(/dev/null)} spids:[139])]
    )
    (C {(rm)} {(-rf)} {(../dropbear_installed)})
    (C {(echo)} {(DQ ("Configuring Dropbear..."))})
    (C {(./configure)} 
      {(--prefix) (Lit_Other "=") ($ VSub_Name "$SRC_DIR") (/work/overlay/dropbear/dropbear_installed)} {(--disable-zlib)} {(--disable-loginfunc)} 
      {(Lit_VarLike "CFLAGS=") (DQ ("-Os -s -fno-stack-protector -U_FORTIFY_SOURCE"))}
    )
    (C {(echo)} {(DQ ("Building Dropbear..."))})
    (C {(make)} {(-j)} {($ VSub_Name "$NUM_JOBS")})
    (C {(echo)} {(DQ ("Installing Dropbear..."))})
    (C {(make)} {(install)} {(-j)} {($ VSub_Name "$NUM_JOBS")})
    (C {(mkdir)} {(-p)} {(../dropbear_installed/lib)})
    (C {(cp)} {($ VSub_Name "$SRC_DIR") (/work/glibc/glibc_prepared/lib/libnsl.so.1)} 
      {(../dropbear_installed/lib)}
    )
    (C {(cp)} {($ VSub_Name "$SRC_DIR") (/work/glibc/glibc_prepared/lib/libnss_compat.so.2)} 
      {(../dropbear_installed/lib)}
    )
    (C {(cp)} {($ VSub_Name "$SRC_DIR") (/work/glibc/glibc_prepared/lib/libutil.so.1)} 
      {(../dropbear_installed/lib)}
    )
    (C {(cp)} {($ VSub_Name "$SRC_DIR") (/work/glibc/glibc_prepared/lib/libcrypt.so.1)} 
      {(../dropbear_installed/lib)}
    )
    (C {(mkdir)} {(-p)} {(../dropbear_installed/etc/dropbear)})
    (C {(../dropbear_installed/bin/dropbearkey)} {(-t)} {(rsa)} {(-f)} 
      {(../dropbear_installed/etc/dropbear/dropbear_rsa_host_key)}
    )
    (C {(../dropbear_installed/bin/dropbearkey)} {(-t)} {(dss)} {(-f)} 
      {(../dropbear_installed/etc/dropbear/dropbear_dss_host_key)}
    )
    (C {(../dropbear_installed/bin/dropbearkey)} {(-t)} {(ecdsa)} {(-f)} 
      {(../dropbear_installed/etc/dropbear/dropbear_ecdsa_host_key)}
    )
    (C {(touch)} {(../dropbear_installed/etc/passwd)})
    (C {(touch)} {(../dropbear_installed/etc/group)})
    (SimpleCommand
      words: [{(echo)} {(DQ ("root:x:0:"))}]
      redirects: [
        (Redir
          op_id: Redir_Great
          fd: -1
          arg_word: {(../dropbear_installed/etc/group)}
          spids: [339]
        )
      ]
    )
    (SimpleCommand
      words: [{(echo)} {(DQ ("root:AprZpdBUhZXss:0:0:Minimal Root,,,:/root:/bin/sh"))}]
      redirects: [
        (Redir
          op_id: Redir_Great
          fd: -1
          arg_word: {(../dropbear_installed/etc/passwd)}
          spids: [355]
        )
      ]
    )
    (C {(mkdir)} {(-p)} {(../dropbear_installed/root)})
    (C {(echo)} {(DQ ("Reducing Dropbear size..."))})
    (C {(strip)} {(-g)} {(../dropbear_installed/bin/) (Lit_Other "*")} 
      {(../dropbear_installed/sbin/) (Lit_Other "*")} {(../dropbear_installed/lib/) (Lit_Other "*")}
    )
    (C {(cp)} {(-r)} {(../dropbear_installed/etc)} {(../dropbear_installed/bin)} 
      {(../dropbear_installed/sbin)} {(../dropbear_installed/lib)} {($ VSub_Name "$SRC_DIR") (/work/src/minimal_overlay)}
    )
    (C {(echo)} {(DQ ("Dropbear has been installed."))})
    (C {(cd)} {($ VSub_Name "$SRC_DIR")})
  ]
)