diff --git a/rida/scm.py b/rida/scm.py
new file mode 100644
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--- /dev/null
+++ b/rida/scm.py
@@ -0,0 +1,251 @@
+# some functions kindly copied and then heavily modified from the koji sources: koji/daemon.py
+#
+# Copyright (c) 2010-2016 Red Hat, Inc.
+#
+#    This is free software; you can redistribute it and/or
+#    modify it under the terms of the GNU Lesser General Public
+#    License as published by the Free Software Foundation;
+#    version 2.1 of the License.
+#
+#    This software is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+#    Lesser General Public License for more details.
+#
+#    You should have received a copy of the GNU Lesser General Public
+#    License along with this software; if not, write to the Free Software
+#    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+# Original Authors of the koji source:
+#       Mike McLean <mikem@redhat.com>
+#       Mike Bonnet <mikeb@redhat.com>
+# Modified by:
+#       Karsten Hopp <karsten@redhat.com>
+
+
+import os
+import sys
+import time
+import traceback
+import subprocess
+import rida
+
+class SCM(object):
+    "SCM abstraction class"
+
+    types = {'GIT': ('git://', 'git+http://', 'git+https://', 'git+rsync://'),
+             'GIT+SSH': ('git+ssh://',)}
+
+    def is_scm_url(url):
+        """
+        Return True if the url appears to be a valid, accessible source location, False otherwise
+        """
+        for schemes in SCM.types.values():
+            for scheme in schemes:
+                if url.startswith(scheme):
+                    return True
+        else:
+            return False
+    is_scm_url = staticmethod(is_scm_url)
+
+    def __init__(self, url, allowed_scm):
+        """
+        Initialize the SCM object using the specified url.
+        If url is not in the list of allowed_scm, an error will be raised.
+        NOTE: only git URLs in the following formats are supported atm:
+            git://
+            git+http://
+            git+https://
+            git+rsync://
+            git+ssh://
+
+        The initialized SCM object will have the following attributes:
+        - url (the unmodified url)
+        - allowed_scm (the list of allowed scm)
+        """
+
+        for allowed in allowed_scm:
+            if url.startswith(allowed):
+                break
+            else:
+                raise RuntimeError('%s is not in the list of allowed SCMs' % url)
+
+        if not SCM.is_scm_url(url):
+            raise RuntimeError('Invalid SCM URL: %s' % url)
+
+        self.url = url
+        self.allowed_scm = allowed_scm
+
+        for scmtype, schemes in SCM.types.items():
+            if self.url.startswith(schemes):
+                self.scmtype = scmtype
+                break
+        else:
+            # should never happen
+            raise RuntimeError('Invalid SCM URL: %s' % url)
+
+    def _run(self, cmd, chdir=None):
+        numretry = 0
+        path = cmd[0]
+        args = cmd
+        pid = os.fork()
+        if not pid:
+            while numretry <= 3:
+                numretry += 1
+                try:
+                    if chdir:
+                        os.chdir(chdir)
+                    os.execvp(path, args)
+                except:   # XXX maybe switch to subprocess (python-3.5) where 
+                          # we can check for return codes and timeouts
+                    msg = ''.join(traceback.format_exception(*sys.exc_info()))
+                    print(msg)
+                    if numretry == 3:
+                        os._exit(1)
+                    time.sleep(10)
+        else:
+            while True:
+                status = os.waitpid(pid, os.WNOHANG)
+                time.sleep(1)
+
+                if status[0] != 0:
+                    return status[1]
+
+    def checkout(self, scmdir):
+        """
+        Checkout the module from SCM.  Accepts the following parameters:
+         - scmdir: the working directory
+
+        Returns the directory that the module was checked-out into (a subdirectory of scmdir)
+        """
+        # TODO: sanity check arguments
+        sourcedir = scmdir
+
+        gitrepo = self.url
+        commonrepo = os.path.dirname(gitrepo) + '/common'
+        checkout_path = os.path.basename(gitrepo)
+        if gitrepo.endswith('/.git'):
+            # If we're referring to the .git subdirectory of the main module,
+            # assume we need to do the same for the common module
+            checkout_path = os.path.basename(gitrepo[:-5])
+            commonrepo = os.path.dirname(gitrepo[:-5]) + '/common/.git'
+        elif gitrepo.endswith('.git'):
+            # If we're referring to a bare repository for the main module,
+            # assume we need to do the same for the common module
+            checkout_path = os.path.basename(gitrepo[:-4])
+            commonrepo = os.path.dirname(gitrepo[:-4]) + '/common.git'
+
+        sourcedir = '%s/%s' % (scmdir, checkout_path)
+        module_checkout_cmd = ['git', 'clone', gitrepo, sourcedir]
+
+        # perform checkouts
+        self._run(module_checkout_cmd, chdir=scmdir)
+
+        return sourcedir
+
+    def get_git_master_head_giturl(self):
+        """
+        Return the git hash of this git object's master HEAD
+        """
+        # drop git hash if url contains it:
+        gitrepo = self.url.split('?')[0]
+        (status , output) = subprocess.getstatusoutput('git ls-remote %s' % gitrepo)
+        if status != 0:
+            raise RuntimeError('can\'t get git hash of master HEAD in %s' % self.url)
+        b = output.split(os.linesep)
+        ret = ''
+        for line in b:
+            if 'refs/heads/master' in line:
+                ret = gitrepo + '?#' + line.split('\t')[0]
+                break
+        return ret
+        
+def get_fedpkg_url_git_master_head_pkgname(pkgname=None):
+    """
+    Return the complete git URL to master HEAD of the given package.
+    Accepts the following parameters:
+    - pkgname: the package name
+    """
+    pkghash = get_hash_of_git_master_head_pkgname(pkgname)
+    if pkghash is not '':
+        return 'git://pkgs.fedoraproject.org/rpms/' + pkgname + '?#' + pkghash
+    else:
+        return ''
+
+def get_hash_of_git_master_head_pkgname(pkgname=None):
+    """
+    Return the git hash of master HEAD
+    Accepts the following parameters:
+         - pkgname: the package name
+    """
+    if not isinstance(pkgname, str):
+        raise RuntimeError('pkgname needs to be a string')
+    gitrepo = 'git://pkgs.fedoraproject.org/rpms/' + pkgname
+    (status , output) = subprocess.getstatusoutput('git ls-remote %s' % gitrepo)
+    if status != 0:
+        raise RuntimeError('can\'t get git hash of master HEAD in %s' % gitrepo)
+    b = output.split(os.linesep)
+    ret = ''
+    for line in b:
+        if 'refs/heads/master' in line:
+            ret = line.split('\t')[0]
+            break
+    return ret
+
+def check_giturl_syntax(giturl=None):
+    """
+    dist-pkg giturls are of the form 
+    git://pkgs.fedoraproject.org/rpms/ed?#abc0235d4923930745ef05d873646f361a365457
+    Returns True if giturl has this format, False otherwise.
+    """
+    if not isinstance(giturl, str):
+        return False
+    if giturl[:6] != 'git://':
+        return False
+    if giturl[6:34] != 'pkgs.fedoraproject.org/rpms/' and giturl[6:38] != 'pkgs.stg.fedoraproject.org/rpms/':
+        return False
+    if not '?#' in giturl.split('/')[-1]:
+        return False
+    return True
+
+def convert_giturl_to_cgiturl(giturl=None):
+    """
+    dist-pkg giturls are of the form 
+    git://pkgs.fedoraproject.org/rpms/ed?#abc0235d4923930745ef05d873646f361a365457
+    cgit urls look like this:
+     http://pkgs.fedoraproject.org/cgit/rpms/ed.git/commit/?id=abc0235d4923930745ef05d873646f361a365457
+    This function takes a string with a dist-git url as parameter and returns a cgit url
+    Accepts the following parameters:
+         - giturl - dist-git url ('fedpkg giturl')
+    """
+    try:
+        url = giturl[giturl.index('://')+3:]
+    except:
+        raise RuntimeError('%s is not a dist-git URL' % giturl)
+    url = url.replace('/rpms/','/cgit/rpms/')
+    url = url.replace('?#','.git/commit/?id=')
+    return 'http://' + url
+    
+def check_if_remote_gitcommit_exists(giturl=None):
+    """
+    Instead of checking out a git repo and then looking through all the 
+    git hashes, this function uses http to connect to cgit and checks
+    for availability of p.e. 
+    http://pkgs.fedoraproject.org/cgit/rpms/ed.git/commit/?id=abc0235d4923930745ef05d873646f361a365457
+    Accepts the following parameters:
+         - giturl - dist-git url ('fedpkg giturl')
+    """
+    if not check_giturl_syntax(giturl):
+        return False
+    import http.client
+    import os
+    cgiturl = convert_giturl_to_cgiturl(giturl)
+    urlpath = cgiturl[cgiturl.index('://')+3:]
+    urlpath = urlpath[urlpath.index('/'):]
+    http_obj = http.client.HTTPConnection('pkgs.fedoraproject.org')
+    http_obj.request('HEAD',urlpath)
+    res = http_obj.getresponse()
+    if res.status == 200:
+        return True
+    else:
+        return False