surveyor: add basic implementation

Author: nmattia

infra/surveyor/LICENSE

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+Copyright (c) 2017 Nicolas Mattia
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

infra/surveyor/Makefile

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+surveyor.so: surveyor.c
+	gcc -Wall -nostartfiles -fpic -shared surveyor.c -o surveyor.so -ldl -D_GNU_SOURCE

infra/surveyor/README.md

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+# Surveyor - Re-map ports and IP addresses
+

infra/surveyor/default.nix

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+let pkgs = import ./nix {}; in
+
+with rec
+{
+  runTest = test: pkgs.runCommand "test"
+    { buildInputs = [ pkgs.netcat pkgs.curl pkgs.haskellPackages.wai-app-static ] ;}
+    test;
+
+  runPort = port:
+    ''
+    trap 'echo $SRV_TEST_PIDS | xargs kill -9' EXIT
+    SRV_TEST_PIDS="''${SRV_TEST_PIDS:-""}"
+    warp -d ${apiPort port} -p ${builtins.toString port} &
+    SRV_TEST_PIDS="$SRV_TEST_PIDS $!"
+    while ! nc -z 127.0.0.1 ${builtins.toString port}; do
+      echo waiting for port ${builtins.toString port}
+      sleep 1
+    done
+    '';
+
+  apiPort = port: pkgs.writeTextFile
+    { text = builtins.toString port ;
+      name = "someAPI";
+    };
+};
+
+let tests =
+{
+  # Accessing localhost on port 80 reroutes to port 1234
+  test_portMap =
+    ''
+      ${runPort 1234}
+
+      SRV_MAP="*:80:*:1234" \
+        LD_PRELOAD="${pkgs.surveyor}/lib/surveyor.so" \
+         curl localhost | grep -q '1234'
+
+      touch $out
+    '';
+
+  # Accessing 127.0.0.2 reroutes to 127.0.0.1
+  test_addrMap =
+    ''
+      ${runPort 1234}
+
+      SRV_MAP="127.0.0.2:*:127.0.0.1:*" \
+        LD_PRELOAD="${pkgs.surveyor}/lib/surveyor.so" \
+         curl 127.0.0.2:1234 | grep -q '1234'
+
+      touch $out
+    '';
+
+  # Accessing anything on port 1234 reroutes to 1235 and
+  # accessing anything on port 1235 reroutes to 1234
+  test_swapPorts =
+    ''
+      ${runPort 1234}
+      ${runPort 1235}
+
+      export SRV_MAP="*:1234:*:1235 *:1235:*:1234"
+
+      LD_PRELOAD="${pkgs.surveyor}/lib/surveyor.so" \
+          curl localhost:1234 | grep -q '1235'
+      LD_PRELOAD="${pkgs.surveyor}/lib/surveyor.so" \
+          curl localhost:1235 | grep -q '1234'
+
+      touch $out
+    '';
+}; in
+
+{ inherit (pkgs) surveyor;
+  inherit test_portMap;
+} // (builtins.mapAttrs (k: v: runTest v) tests)

infra/surveyor/nix/default.nix

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+{ sources ? import ./sources.nix }:
+with
+  { overlay = _: pkgs:
+      { inherit (import sources.niv {}) niv;
+        surveyor = pkgs.stdenv.mkDerivation
+        { name = "surveyor";
+          src = pkgs.lib.sourceByRegex ../.
+            [ "^Makefile$"
+              "^surveyor.c"
+            ];
+          installPhase = "mkdir -p $out/lib && cp surveyor.so $out/lib";
+          } ;
+      };
+  };
+import sources.nixpkgs
+  { overlays = [ overlay ] ; config = {}; }

infra/surveyor/nix/sources.json

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+{
+    "nixpkgs": {
+        "url": "https://github.com/NixOS/nixpkgs-channels/archive/15f08994517a695efa5e9b216c5caaf497a10019.tar.gz",
+        "owner": "NixOS",
+        "branch": "nixos-18.09",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz",
+        "repo": "nixpkgs-channels",
+        "type": "tarball",
+        "sha256": "04y5car353rwnx5hysdc6i5j04hp7bbxnc228fa6r332iiwrj2zg",
+        "description": "Nixpkgs/NixOS branches that track the Nixpkgs/NixOS channels",
+        "rev": "15f08994517a695efa5e9b216c5caaf497a10019"
+    },
+    "niv": {
+        "homepage": "https://github.com/nmattia/niv",
+        "url": "https://github.com/nmattia/niv/archive/c2698b0780b783880e0b1a520723948fe3b5c26a.tar.gz",
+        "owner": "nmattia",
+        "branch": "master",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz",
+        "repo": "niv",
+        "type": "tarball",
+        "sha256": "0v68x0h9si6kjqg5fcjrgsbsf4x18m32a786yvjmrdkrki9qwmcq",
+        "description": "Easy dependency management for Nix projects",
+        "rev": "c2698b0780b783880e0b1a520723948fe3b5c26a"
+    }
+}

infra/surveyor/nix/sources.nix

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+# This file has been generated by Niv.
+
+# A record, from name to path, of the third-party packages
+with rec
+{
+  pkgs = import <nixpkgs> {};
+
+  sources = builtins.fromJSON (builtins.readFile ./sources.json);
+
+  mapAttrs = builtins.mapAttrs or
+    (f: set: with builtins;
+      listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set)));
+
+  getFetcher = spec:
+    let fetcherName =
+      if builtins.hasAttr "type" spec
+      then builtins.getAttr "type" spec
+      else "tarball";
+    in builtins.getAttr fetcherName {
+      "tarball" = pkgs.fetchzip;
+      "file" = pkgs.fetchurl;
+    };
+};
+# NOTE: spec must _not_ have an "outPath" attribute
+mapAttrs (_: spec:
+  if builtins.hasAttr "outPath" spec
+  then abort
+    "The values in sources.json should not have an 'outPath' attribute"
+  else
+    if builtins.hasAttr "url" spec && builtins.hasAttr "sha256" spec
+    then
+      spec //
+      { outPath = getFetcher spec { inherit (spec) url sha256; } ; }
+    else spec
+  ) sources