From e854b8a3e75e134d77c659c90bbca23ecca1cc3d Mon Sep 17 00:00:00 2001
From: Paul Tax <paultax@gmail.com>
Date: Fri, 13 Jan 2012 14:26:52 +0100
Subject: Initial commit

---
 awsauth.py | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 awsauth.py

(limited to 'awsauth.py')

diff --git a/awsauth.py b/awsauth.py
new file mode 100644
index 0000000..7ddac4f
--- /dev/null
+++ b/awsauth.py
@@ -0,0 +1,94 @@
+import base64
+import hmac
+import urllib
+from hashlib import sha1 as sha
+from urlparse import urlparse
+from email.utils import formatdate
+from requests.auth import AuthBase
+
+class S3Auth(AuthBase):
+    # List of Query String Arguments of Interest
+    special_params = ['acl', 'location', 'logging', 'partNumber', 'policy',
+                       'requestPayment', 'torrent', 'versioning', 'versionId',
+                       'versions', 'website', 'uploads', 'uploadId',
+                       'response-content-type', 'response-content-language',
+                       'response-expires', 'reponse-cache-control',
+                       'response-content-disposition',
+                       'response-content-encoding']
+
+
+    """Attaches AWS Authentication to the given Request object."""
+    def __init__(self, access_key, secret_key):
+        self.access_key = str(access_key)
+        self.secret_key = str(secret_key)
+
+    def __call__(self, r):
+        #Create date header if it is not created yet
+        if not r.headers.has_key('date') and not r.headers.has_key('x-amz-date'):
+            r.headers['date'] = formatdate(timeval=None, localtime=False, usegmt=True)
+        r.headers['Authorization'] = 'AWS %s:%s'%(self.access_key, self.get_signature(r))
+        return r
+
+    def get_signature(self, r):   
+        h = hmac.new(self.secret_key, self.get_canonical_string(r), digestmod=sha)
+        return base64.encodestring(h.digest()).strip()
+
+    def get_canonical_string(self, r):
+        parsedurl = urlparse(r.url)
+        objectkey = parsedurl.path[1:]
+        query_args = parsedurl.query.split('&')
+        #Sort alphabetical
+        query_args.sort()
+        bucket = ''
+        if len(parsedurl.netloc.split('.')) == 4:
+            bucket = parsedurl.netloc.split('.')[0]
+        if len(parsedurl.netloc.split('.')) == 3 and parsedurl.netloc.split('.')[0].lower() != 's3':
+            bucket = parsedurl.netloc.split('.')[0]
+        
+        interesting_headers = {}
+        for key in r.headers:
+            lk = key.lower()
+            if r.headers[key] != None and (lk in ['content-md5', 'content-type', 'date'] or
+                                         lk.startswith('x-amz-')):
+                interesting_headers[lk] = r.headers[key].strip()
+    
+        # these keys get empty strings if they don't exist
+        if not interesting_headers.has_key('content-type'):
+            interesting_headers['content-type'] = ''
+        if not interesting_headers.has_key('content-md5'):
+            interesting_headers['content-md5'] = ''
+    
+        # If x-amz-date is used it supersedes the date header.
+        if interesting_headers.has_key('x-amz-date'):
+            interesting_headers['date'] = ''
+                    
+        sorted_header_keys = interesting_headers.keys()
+        sorted_header_keys.sort()
+    
+        buf = "%s\n" % r.method
+        for key in sorted_header_keys:
+            val = interesting_headers[key]
+            if key.startswith('x-amz-'):
+                buf += "%s:%s\n" % (key, val)
+            else:
+                buf += "%s\n" % val
+    
+        # append the bucket if it exists
+        if bucket != "":
+            buf += "/%s" % bucket
+    
+        # add the objectkey.  even if it doesn't exist, add the slash
+        buf += "/%s" % urllib.quote_plus(objectkey)
+    
+        params_found = False
+        # handle special query string arguments
+        for q in query_args:
+            k = q.split('=')[0]
+            if k in self.special_params:
+                if params_found:
+                    buf += "&%s"%q
+                else:    
+                    buf += "?%s"%q
+                params_found = True              
+        return buf       
+
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