Imported Upstream version 0.9.2upstream/0.9.2

1 files changed, 2084 insertions, 0 deletions

diff --git a/src/fs/fs_uri.c b/src/fs/fs_uri.c
new file mode 100644
index 0000000..5dfdcb5
--- /dev/null
+++ b/src/fs/fs_uri.c
@@ -0,0 +1,2084 @@
+/*
+     This file is part of GNUnet.
+     (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Christian Grothoff (and other contributing authors)
+
+     GNUnet is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 3, or (at your
+     option) any later version.
+
+     GNUnet 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
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with GNUnet; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+*/
+
+/**
+ * @file fs/fs_uri.c
+ * @brief Parses and produces uri strings.
+ * @author Igor Wronsky, Christian Grothoff
+ *
+ * GNUnet URIs are of the general form "gnunet://MODULE/IDENTIFIER".
+ * The specific structure of "IDENTIFIER" depends on the module and
+ * maybe differenciated into additional subcategories if applicable.
+ * This module only deals with fs identifiers (MODULE = "fs").
+ * <p>
+ *
+ * This module only parses URIs for the AFS module.  The FS URIs fall
+ * into four categories, "chk", "sks", "ksk" and "loc".  The first three
+ * categories were named in analogy (!) to Freenet, but they do NOT
+ * work in exactly the same way.  They are very similar from the user's
+ * point of view (unique file identifier, subspace, keyword), but the
+ * implementation is rather different in pretty much every detail.
+ * The concrete URI formats are:
+ *
+ * <ul><li>
+ *
+ * First, there are URIs that identify a file.  They have the format
+ * "gnunet://fs/chk/HEX1.HEX2.SIZE".  These URIs can be used to
+ * download the file.  The description, filename, mime-type and other
+ * meta-data is NOT part of the file-URI since a URI uniquely
+ * identifies a resource (and the contents of the file would be the
+ * same even if it had a different description).
+ *
+ * </li><li>
+ *
+ * The second category identifies entries in a namespace.  The format
+ * is "gnunet://fs/sks/NAMESPACE/IDENTIFIER" where the namespace
+ * should be given in HEX.  Applications may allow using a nickname
+ * for the namespace if the nickname is not ambiguous.  The identifier
+ * can be either an ASCII sequence or a HEX-encoding.  If the
+ * identifier is in ASCII but the format is ambiguous and could denote
+ * a HEX-string a "/" is appended to indicate ASCII encoding.
+ *
+ * </li> <li>
+ *
+ * The third category identifies ordinary searches.  The format is
+ * "gnunet://fs/ksk/KEYWORD[+KEYWORD]*".  Using the "+" syntax
+ * it is possible to encode searches with the boolean "AND" operator.
+ * "+" is used since it indicates a commutative 'and' operation and
+ * is unlikely to be used in a keyword by itself.
+ *
+ * </li><li>
+ *
+ * The last category identifies a datum on a specific machine.  The
+ * format is "gnunet://fs/loc/HEX1.HEX2.SIZE.PEER.SIG.EXPTIME".  PEER is
+ * the BinName of the public key of the peer storing the datum.  The
+ * signature (SIG) certifies that this peer has this content.
+ * HEX1, HEX2 and SIZE correspond to a 'chk' URI.
+ *
+ * </li></ul>
+ *
+ * The encoding for hexadecimal values is defined in the hashing.c
+ * module in the gnunetutil library and discussed there.
+ * <p>
+ */
+#include "platform.h"
+#include "gnunet_fs_service.h"
+#include "gnunet_signatures.h"
+#include "fs_api.h"
+#include <unitypes.h>
+#include <unicase.h>
+#include <uniconv.h>
+#include <unistr.h>
+#include <unistdio.h>
+
+
+
+/**
+ * Get a unique key from a URI.  This is for putting URIs
+ * into HashMaps.  The key may change between FS implementations.
+ *
+ * @param uri uri to convert to a unique key
+ * @param key wherer to store the unique key
+ */
+void
+GNUNET_FS_uri_to_key (const struct GNUNET_FS_Uri *uri, GNUNET_HashCode * key)
+{
+  switch (uri->type)
+  {
+  case chk:
+    *key = uri->data.chk.chk.query;
+    return;
+  case sks:
+    GNUNET_CRYPTO_hash (uri->data.sks.identifier,
+                        strlen (uri->data.sks.identifier), key);
+    break;
+  case ksk:
+    if (uri->data.ksk.keywordCount > 0)
+      GNUNET_CRYPTO_hash (uri->data.ksk.keywords[0],
+                          strlen (uri->data.ksk.keywords[0]), key);
+    break;
+  case loc:
+    GNUNET_CRYPTO_hash (&uri->data.loc.fi,
+                        sizeof (struct FileIdentifier) +
+                        sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
+                        key);
+    break;
+  default:
+    memset (key, 0, sizeof (GNUNET_HashCode));
+    break;
+  }
+}
+
+
+/**
+ * Convert keyword URI to a human readable format
+ * (i.e. the search query that was used in the first place)
+ *
+ * @param uri ksk uri to convert to a string
+ * @return string with the keywords
+ */
+char *
+GNUNET_FS_uri_ksk_to_string_fancy (const struct GNUNET_FS_Uri *uri)
+{
+  size_t n;
+  char *ret;
+  unsigned int i;
+  const char *keyword;
+  char **keywords;
+  unsigned int keywordCount;
+
+  if ((uri == NULL) || (uri->type != ksk))
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  keywords = uri->data.ksk.keywords;
+  keywordCount = uri->data.ksk.keywordCount;
+  n = keywordCount + 1;
+  for (i = 0; i < keywordCount; i++)
+  {
+    keyword = keywords[i];
+    n += strlen (keyword) - 1;
+    if (NULL != strstr (&keyword[1], " "))
+      n += 2;
+    if (keyword[0] == '+')
+      n++;
+  }
+  ret = GNUNET_malloc (n);
+  strcpy (ret, "");
+  for (i = 0; i < keywordCount; i++)
+  {
+    keyword = keywords[i];
+    if (NULL != strstr (&keyword[1], " "))
+    {
+      strcat (ret, "\"");
+      if (keyword[0] == '+')
+        strcat (ret, keyword);
+      else
+        strcat (ret, &keyword[1]);
+      strcat (ret, "\"");
+    }
+    else
+    {
+      if (keyword[0] == '+')
+        strcat (ret, keyword);
+      else
+        strcat (ret, &keyword[1]);
+    }
+    strcat (ret, " ");
+  }
+  return ret;
+}
+
+
+/**
+ * Given a keyword with %-encoding (and possibly quotes to protect
+ * spaces), return a copy of the keyword without %-encoding and
+ * without double-quotes (%22).  Also, add a space at the beginning
+ * if there is not a '+'.
+ *
+ * @param in string with %-encoding
+ * @param emsg where to store the parser error message (if any)
+ * @return decodded string with leading space (or preserved plus)
+ */
+static char *
+percent_decode_keyword (const char *in, char **emsg)
+{
+  char *out;
+  char *ret;
+  unsigned int rpos;
+  unsigned int wpos;
+  unsigned int hx;
+
+  out = GNUNET_strdup (in);
+  rpos = 0;
+  wpos = 0;
+  while (out[rpos] != '\0')
+  {
+    if (out[rpos] == '%')
+    {
+      if (1 != sscanf (&out[rpos + 1], "%2X", &hx))
+      {
+        GNUNET_free (out);
+        *emsg = GNUNET_strdup (_("`%' must be followed by HEX number"));
+        return NULL;
+      }
+      rpos += 3;
+      if (hx == '"')
+        continue;               /* skip double quote */
+      out[wpos++] = (char) hx;
+    }
+    else
+    {
+      out[wpos++] = out[rpos++];
+    }
+  }
+  out[wpos] = '\0';
+  if (out[0] == '+')
+  {
+    ret = GNUNET_strdup (out);
+  }
+  else
+  {
+    /* need to prefix with space */
+    ret = GNUNET_malloc (strlen (out) + 2);
+    strcpy (ret, " ");
+    strcat (ret, out);
+  }
+  GNUNET_free (out);
+  return ret;
+}
+
+#define GNUNET_FS_URI_KSK_PREFIX GNUNET_FS_URI_PREFIX GNUNET_FS_URI_KSK_INFIX
+
+/**
+ * Parse a KSK URI.
+ *
+ * @param s an uri string
+ * @param emsg where to store the parser error message (if any)
+ * @return NULL on error, otherwise the KSK URI
+ */
+static struct GNUNET_FS_Uri *
+uri_ksk_parse (const char *s, char **emsg)
+{
+  struct GNUNET_FS_Uri *ret;
+  char **keywords;
+  unsigned int pos;
+  int max;
+  int iret;
+  int i;
+  size_t slen;
+  char *dup;
+  int saw_quote;
+
+  GNUNET_assert (s != NULL);
+  slen = strlen (s);
+  pos = strlen (GNUNET_FS_URI_KSK_PREFIX);
+  if ((slen <= pos) || (0 != strncmp (s, GNUNET_FS_URI_KSK_PREFIX, pos)))
+    return NULL;                /* not KSK URI */
+  if ((s[slen - 1] == '+') || (s[pos] == '+'))
+  {
+    *emsg =
+        GNUNET_strdup (_("Malformed KSK URI (must not begin or end with `+')"));
+    return NULL;
+  }
+  max = 1;
+  saw_quote = 0;
+  for (i = pos; i < slen; i++)
+  {
+    if ((s[i] == '%') && (&s[i] == strstr (&s[i], "%22")))
+    {
+      saw_quote = (saw_quote + 1) % 2;
+      i += 3;
+      continue;
+    }
+    if ((s[i] == '+') && (saw_quote == 0))
+    {
+      max++;
+      if (s[i - 1] == '+')
+      {
+        *emsg = GNUNET_strdup (_("`++' not allowed in KSK URI"));
+        return NULL;
+      }
+    }
+  }
+  if (saw_quote == 1)
+  {
+    *emsg = GNUNET_strdup (_("Quotes not balanced in KSK URI"));
+    return NULL;
+  }
+  iret = max;
+  dup = GNUNET_strdup (s);
+  keywords = GNUNET_malloc (max * sizeof (char *));
+  for (i = slen - 1; i >= pos; i--)
+  {
+    if ((s[i] == '%') && (&s[i] == strstr (&s[i], "%22")))
+    {
+      saw_quote = (saw_quote + 1) % 2;
+      i += 3;
+      continue;
+    }
+    if ((dup[i] == '+') && (saw_quote == 0))
+    {
+      keywords[--max] = percent_decode_keyword (&dup[i + 1], emsg);
+      if (NULL == keywords[max])
+        goto CLEANUP;
+      dup[i] = '\0';
+    }
+  }
+  keywords[--max] = percent_decode_keyword (&dup[pos], emsg);
+  if (NULL == keywords[max])
+    goto CLEANUP;
+  GNUNET_assert (max == 0);
+  GNUNET_free (dup);
+  ret = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  ret->type = ksk;
+  ret->data.ksk.keywordCount = iret;
+  ret->data.ksk.keywords = keywords;
+  return ret;
+CLEANUP:
+  for (i = 0; i < max; i++)
+    GNUNET_free_non_null (keywords[i]);
+  GNUNET_free (keywords);
+  GNUNET_free (dup);
+  return NULL;
+}
+
+
+#define GNUNET_FS_URI_SKS_PREFIX GNUNET_FS_URI_PREFIX GNUNET_FS_URI_SKS_INFIX
+
+/**
+ * Parse an SKS URI.
+ *
+ * @param s an uri string
+ * @param emsg where to store the parser error message (if any)
+ * @return NULL on error, SKS URI otherwise
+ */
+static struct GNUNET_FS_Uri *
+uri_sks_parse (const char *s, char **emsg)
+{
+  struct GNUNET_FS_Uri *ret;
+  GNUNET_HashCode namespace;
+  char *identifier;
+  unsigned int pos;
+  size_t slen;
+  char enc[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)];
+
+  GNUNET_assert (s != NULL);
+  slen = strlen (s);
+  pos = strlen (GNUNET_FS_URI_SKS_PREFIX);
+  if ((slen <= pos) || (0 != strncmp (s, GNUNET_FS_URI_SKS_PREFIX, pos)))
+    return NULL;                /* not an SKS URI */
+  if ((slen < pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)) ||
+      (s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] != '/'))
+  {
+    *emsg = GNUNET_strdup (_("Malformed SKS URI"));
+    return NULL;
+  }
+  memcpy (enc, &s[pos], sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded));
+  enc[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] = '\0';
+  if (GNUNET_OK != GNUNET_CRYPTO_hash_from_string (enc, &namespace))
+  {
+    *emsg = GNUNET_strdup (_("Malformed SKS URI"));
+    return NULL;
+  }
+  identifier =
+      GNUNET_strdup (&s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)]);
+  ret = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  ret->type = sks;
+  ret->data.sks.namespace = namespace;
+  ret->data.sks.identifier = identifier;
+  return ret;
+}
+
+#define GNUNET_FS_URI_CHK_PREFIX GNUNET_FS_URI_PREFIX GNUNET_FS_URI_CHK_INFIX
+
+
+/**
+ * Parse a CHK URI.
+ *
+ * @param s an uri string
+ * @param emsg where to store the parser error message (if any)
+ * @return NULL on error, CHK URI otherwise
+ */
+static struct GNUNET_FS_Uri *
+uri_chk_parse (const char *s, char **emsg)
+{
+  struct GNUNET_FS_Uri *ret;
+  struct FileIdentifier fi;
+  unsigned int pos;
+  unsigned long long flen;
+  size_t slen;
+  char h1[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)];
+  char h2[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)];
+
+  if (NULL == s)
+    return NULL;
+  GNUNET_assert (s != NULL);
+  slen = strlen (s);
+  pos = strlen (GNUNET_FS_URI_CHK_PREFIX);
+  if ((slen < pos + 2 * sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) + 1) ||
+      (0 != strncmp (s, GNUNET_FS_URI_CHK_PREFIX, pos)))
+    return NULL;                /* not a CHK URI */
+  if ((s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] != '.') ||
+      (s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) * 2 - 1] != '.'))
+  {
+    *emsg = GNUNET_strdup (_("Malformed CHK URI"));
+    return NULL;
+  }
+  memcpy (h1, &s[pos], sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded));
+  h1[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] = '\0';
+  memcpy (h2, &s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)],
+          sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded));
+  h2[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] = '\0';
+
+  if ((GNUNET_OK != GNUNET_CRYPTO_hash_from_string (h1, &fi.chk.key)) ||
+      (GNUNET_OK != GNUNET_CRYPTO_hash_from_string (h2, &fi.chk.query)) ||
+      (1 !=
+       SSCANF (&s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) * 2],
+               "%llu", &flen)))
+  {
+    *emsg = GNUNET_strdup (_("Malformed CHK URI"));
+    return NULL;
+  }
+  fi.file_length = GNUNET_htonll (flen);
+  ret = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  ret->type = chk;
+  ret->data.chk = fi;
+  return ret;
+}
+
+
+/**
+ * Convert a character back to the binary value
+ * that it represents (given base64-encoding).
+ *
+ * @param a character to convert
+ * @return offset in the "tbl" array
+ */
+static unsigned int
+c2v (unsigned char a)
+{
+  if ((a >= '0') && (a <= '9'))
+    return a - '0';
+  if ((a >= 'A') && (a <= 'Z'))
+    return (a - 'A' + 10);
+  if ((a >= 'a') && (a <= 'z'))
+    return (a - 'a' + 36);
+  if (a == '_')
+    return 62;
+  if (a == '=')
+    return 63;
+  return -1;
+}
+
+
+/**
+ * Convert string back to binary data.
+ *
+ * @param input '\\0'-terminated string
+ * @param data where to write binary data
+ * @param size how much data should be converted
+ * @return number of characters processed from input,
+ *        -1 on error
+ */
+static int
+enc2bin (const char *input, void *data, size_t size)
+{
+  size_t len;
+  size_t pos;
+  unsigned int bits;
+  unsigned int hbits;
+
+  len = size * 8 / 6;
+  if (((size * 8) % 6) != 0)
+    len++;
+  if (strlen (input) < len)
+    return -1;                  /* error! */
+  bits = 0;
+  hbits = 0;
+  len = 0;
+  for (pos = 0; pos < size; pos++)
+  {
+    while (hbits < 8)
+    {
+      bits |= (c2v (input[len++]) << hbits);
+      hbits += 6;
+    }
+    (((unsigned char *) data)[pos]) = (unsigned char) bits;
+    bits >>= 8;
+    hbits -= 8;
+  }
+  return len;
+}
+
+
+/**
+ * Structure that defines how the
+ * contents of a location URI must be
+ * assembled in memory to create or
+ * verify the signature of a location
+ * URI.
+ */
+struct LocUriAssembly
+{
+  struct GNUNET_CRYPTO_RsaSignaturePurpose purpose;
+
+  struct GNUNET_TIME_AbsoluteNBO exptime;
+
+  struct FileIdentifier fi;
+
+  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded peer;
+
+};
+
+
+#define GNUNET_FS_URI_LOC_PREFIX GNUNET_FS_URI_PREFIX GNUNET_FS_URI_LOC_INFIX
+
+/**
+ * Parse a LOC URI.
+ * Also verifies validity of the location URI.
+ *
+ * @param s an uri string
+ * @param emsg where to store the parser error message (if any)
+ * @return NULL on error, valid LOC URI otherwise
+ */
+static struct GNUNET_FS_Uri *
+uri_loc_parse (const char *s, char **emsg)
+{
+  struct GNUNET_FS_Uri *uri;
+  char h1[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)];
+  char h2[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)];
+  unsigned int pos;
+  unsigned int npos;
+  unsigned long long exptime;
+  unsigned long long flen;
+  struct GNUNET_TIME_Absolute et;
+  struct GNUNET_CRYPTO_RsaSignature sig;
+  struct LocUriAssembly ass;
+  int ret;
+  size_t slen;
+
+  GNUNET_assert (s != NULL);
+  slen = strlen (s);
+  pos = strlen (GNUNET_FS_URI_LOC_PREFIX);
+  if ((slen < pos + 2 * sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) + 1) ||
+      (0 != strncmp (s, GNUNET_FS_URI_LOC_PREFIX, pos)))
+    return NULL;                /* not an SKS URI */
+  if ((s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] != '.') ||
+      (s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) * 2 - 1] != '.'))
+  {
+    *emsg = GNUNET_strdup (_("SKS URI malformed"));
+    return NULL;
+  }
+  memcpy (h1, &s[pos], sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded));
+  h1[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] = '\0';
+  memcpy (h2, &s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded)],
+          sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded));
+  h2[sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) - 1] = '\0';
+
+  if ((GNUNET_OK != GNUNET_CRYPTO_hash_from_string (h1, &ass.fi.chk.key)) ||
+      (GNUNET_OK != GNUNET_CRYPTO_hash_from_string (h2, &ass.fi.chk.query)) ||
+      (1 !=
+       SSCANF (&s[pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) * 2],
+               "%llu", &flen)))
+  {
+    *emsg = GNUNET_strdup (_("SKS URI malformed"));
+    return NULL;
+  }
+  ass.fi.file_length = GNUNET_htonll (flen);
+
+  npos = pos + sizeof (struct GNUNET_CRYPTO_HashAsciiEncoded) * 2;
+  while ((s[npos] != '\0') && (s[npos] != '.'))
+    npos++;
+  if (s[npos] == '\0')
+  {
+    *emsg = GNUNET_strdup (_("SKS URI malformed"));
+    goto ERR;
+  }
+  npos++;
+  ret =
+      enc2bin (&s[npos], &ass.peer,
+               sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded));
+  if (ret == -1)
+  {
+    *emsg =
+        GNUNET_strdup (_("SKS URI malformed (could not decode public key)"));
+    goto ERR;
+  }
+  npos += ret;
+  if (s[npos++] != '.')
+  {
+    *emsg = GNUNET_strdup (_("SKS URI malformed (could not find signature)"));
+    goto ERR;
+  }
+  ret = enc2bin (&s[npos], &sig, sizeof (struct GNUNET_CRYPTO_RsaSignature));
+  if (ret == -1)
+  {
+    *emsg = GNUNET_strdup (_("SKS URI malformed (could not decode signature)"));
+    goto ERR;
+  }
+  npos += ret;
+  if (s[npos++] != '.')
+  {
+    *emsg = GNUNET_strdup (_("SKS URI malformed"));
+    goto ERR;
+  }
+  if (1 != SSCANF (&s[npos], "%llu", &exptime))
+  {
+    *emsg =
+        GNUNET_strdup (_
+                       ("SKS URI malformed (could not parse expiration time)"));
+    goto ERR;
+  }
+  ass.purpose.size = htonl (sizeof (struct LocUriAssembly));
+  ass.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_PEER_PLACEMENT);
+  et.abs_value = exptime;
+  ass.exptime = GNUNET_TIME_absolute_hton (et);
+  if (GNUNET_OK !=
+      GNUNET_CRYPTO_rsa_verify (GNUNET_SIGNATURE_PURPOSE_PEER_PLACEMENT,
+                                &ass.purpose, &sig, &ass.peer))
+  {
+    *emsg =
+        GNUNET_strdup (_("SKS URI malformed (signature failed validation)"));
+    goto ERR;
+  }
+  uri = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  uri->type = loc;
+  uri->data.loc.fi = ass.fi;
+  uri->data.loc.peer = ass.peer;
+  uri->data.loc.expirationTime = et;
+  uri->data.loc.contentSignature = sig;
+
+  return uri;
+ERR:
+  return NULL;
+}
+
+
+/**
+ * Convert a UTF-8 String to a URI.
+ *
+ * @param uri string to parse
+ * @param emsg where to store the parser error message (if any)
+ * @return NULL on error
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_parse (const char *uri, char **emsg)
+{
+  struct GNUNET_FS_Uri *ret;
+  char *msg;
+
+  if (NULL == emsg)
+    emsg = &msg;
+  *emsg = NULL;
+  if ((NULL != (ret = uri_chk_parse (uri, emsg))) ||
+      (NULL != (ret = uri_ksk_parse (uri, emsg))) ||
+      (NULL != (ret = uri_sks_parse (uri, emsg))) ||
+      (NULL != (ret = uri_loc_parse (uri, emsg))))
+    return ret;
+  if (NULL == *emsg)
+    *emsg = GNUNET_strdup (_("Unrecognized URI type"));
+  if (emsg == &msg)
+    GNUNET_free (msg);
+  return NULL;
+}
+
+
+/**
+ * Free URI.
+ *
+ * @param uri uri to free
+ */
+void
+GNUNET_FS_uri_destroy (struct GNUNET_FS_Uri *uri)
+{
+  unsigned int i;
+
+  GNUNET_assert (uri != NULL);
+  switch (uri->type)
+  {
+  case ksk:
+    for (i = 0; i < uri->data.ksk.keywordCount; i++)
+      GNUNET_free (uri->data.ksk.keywords[i]);
+    GNUNET_array_grow (uri->data.ksk.keywords, uri->data.ksk.keywordCount, 0);
+    break;
+  case sks:
+    GNUNET_free (uri->data.sks.identifier);
+    break;
+  case loc:
+    break;
+  default:
+    /* do nothing */
+    break;
+  }
+  GNUNET_free (uri);
+}
+
+/**
+ * How many keywords are ANDed in this keyword URI?
+ *
+ * @param uri ksk uri to get the number of keywords from
+ * @return 0 if this is not a keyword URI
+ */
+unsigned int
+GNUNET_FS_uri_ksk_get_keyword_count (const struct GNUNET_FS_Uri *uri)
+{
+  if (uri->type != ksk)
+    return 0;
+  return uri->data.ksk.keywordCount;
+}
+
+
+/**
+ * Iterate over all keywords in this keyword URI.
+ *
+ * @param uri ksk uri to get the keywords from
+ * @param iterator function to call on each keyword
+ * @param iterator_cls closure for iterator
+ * @return -1 if this is not a keyword URI, otherwise number of
+ *   keywords iterated over until iterator aborted
+ */
+int
+GNUNET_FS_uri_ksk_get_keywords (const struct GNUNET_FS_Uri *uri,
+                                GNUNET_FS_KeywordIterator iterator,
+                                void *iterator_cls)
+{
+  unsigned int i;
+  char *keyword;
+
+  if (uri->type != ksk)
+    return -1;
+  if (iterator == NULL)
+    return uri->data.ksk.keywordCount;
+  for (i = 0; i < uri->data.ksk.keywordCount; i++)
+  {
+    keyword = uri->data.ksk.keywords[i];
+    /* first character of keyword indicates
+     * if it is mandatory or not */
+    if (GNUNET_OK != iterator (iterator_cls, &keyword[1], keyword[0] == '+'))
+      return i;
+  }
+  return i;
+}
+
+
+/**
+ * Add the given keyword to the set of keywords represented by the URI.
+ * Does nothing if the keyword is already present.
+ *
+ * @param uri ksk uri to modify
+ * @param keyword keyword to add
+ * @param is_mandatory is this keyword mandatory?
+ */
+void
+GNUNET_FS_uri_ksk_add_keyword (struct GNUNET_FS_Uri *uri, const char *keyword,
+                               int is_mandatory)
+{
+  unsigned int i;
+  const char *old;
+  char *n;
+
+  GNUNET_assert (uri->type == ksk);
+  for (i = 0; i < uri->data.ksk.keywordCount; i++)
+  {
+    old = uri->data.ksk.keywords[i];
+    if (0 == strcmp (&old[1], keyword))
+      return;
+  }
+  GNUNET_asprintf (&n, is_mandatory ? "+%s" : " %s", keyword);
+  GNUNET_array_append (uri->data.ksk.keywords, uri->data.ksk.keywordCount, n);
+}
+
+
+/**
+ * Remove the given keyword from the set of keywords represented by the URI.
+ * Does nothing if the keyword is not present.
+ *
+ * @param uri ksk uri to modify
+ * @param keyword keyword to add
+ */
+void
+GNUNET_FS_uri_ksk_remove_keyword (struct GNUNET_FS_Uri *uri,
+                                  const char *keyword)
+{
+  unsigned int i;
+  char *old;
+
+  GNUNET_assert (uri->type == ksk);
+  for (i = 0; i < uri->data.ksk.keywordCount; i++)
+  {
+    old = uri->data.ksk.keywords[i];
+    if (0 == strcmp (&old[1], keyword))
+    {
+      uri->data.ksk.keywords[i] =
+          uri->data.ksk.keywords[uri->data.ksk.keywordCount - 1];
+      GNUNET_array_grow (uri->data.ksk.keywords, uri->data.ksk.keywordCount,
+                         uri->data.ksk.keywordCount - 1);
+      GNUNET_free (old);
+      return;
+    }
+  }
+}
+
+
+/**
+ * Obtain the identity of the peer offering the data
+ *
+ * @param uri the location URI to inspect
+ * @param peer where to store the identify of the peer (presumably) offering the content
+ * @return GNUNET_SYSERR if this is not a location URI, otherwise GNUNET_OK
+ */
+int
+GNUNET_FS_uri_loc_get_peer_identity (const struct GNUNET_FS_Uri *uri,
+                                     struct GNUNET_PeerIdentity *peer)
+{
+  if (uri->type != loc)
+    return GNUNET_SYSERR;
+  GNUNET_CRYPTO_hash (&uri->data.loc.peer,
+                      sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded),
+                      &peer->hashPubKey);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Obtain the expiration of the LOC URI.
+ *
+ * @param uri location URI to get the expiration from
+ * @return expiration time of the URI
+ */
+struct GNUNET_TIME_Absolute
+GNUNET_FS_uri_loc_get_expiration (const struct GNUNET_FS_Uri *uri)
+{
+  GNUNET_assert (uri->type == loc);
+  return uri->data.loc.expirationTime;
+}
+
+
+
+/**
+ * Obtain the URI of the content itself.
+ *
+ * @param uri location URI to get the content URI from
+ * @return NULL if argument is not a location URI
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_loc_get_uri (const struct GNUNET_FS_Uri *uri)
+{
+  struct GNUNET_FS_Uri *ret;
+
+  if (uri->type != loc)
+    return NULL;
+  ret = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  ret->type = chk;
+  ret->data.chk = uri->data.loc.fi;
+  return ret;
+}
+
+
+/**
+ * Construct a location URI (this peer will be used for the location).
+ *
+ * @param baseUri content offered by the sender
+ * @param cfg configuration information (used to find our hostkey)
+ * @param expiration_time how long will the content be offered?
+ * @return the location URI, NULL on error
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_loc_create (const struct GNUNET_FS_Uri *baseUri,
+                          const struct GNUNET_CONFIGURATION_Handle *cfg,
+                          struct GNUNET_TIME_Absolute expiration_time)
+{
+  struct GNUNET_FS_Uri *uri;
+  struct GNUNET_CRYPTO_RsaPrivateKey *my_private_key;
+  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded my_public_key;
+  char *keyfile;
+  struct LocUriAssembly ass;
+
+  if (baseUri->type != chk)
+    return NULL;
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_filename (cfg, "GNUNETD", "HOSTKEY",
+                                               &keyfile))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                _("Lacking key configuration settings.\n"));
+    return NULL;
+  }
+  my_private_key = GNUNET_CRYPTO_rsa_key_create_from_file (keyfile);
+  if (my_private_key == NULL)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                _("Could not access hostkey file `%s'.\n"), keyfile);
+    GNUNET_free (keyfile);
+    return NULL;
+  }
+  GNUNET_free (keyfile);
+  GNUNET_CRYPTO_rsa_key_get_public (my_private_key, &my_public_key);
+  ass.purpose.size = htonl (sizeof (struct LocUriAssembly));
+  ass.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_PEER_PLACEMENT);
+  ass.exptime = GNUNET_TIME_absolute_hton (expiration_time);
+  ass.fi = baseUri->data.chk;
+  ass.peer = my_public_key;
+  uri = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  uri->type = loc;
+  uri->data.loc.fi = baseUri->data.chk;
+  uri->data.loc.expirationTime = expiration_time;
+  uri->data.loc.peer = my_public_key;
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CRYPTO_rsa_sign (my_private_key, &ass.purpose,
+                                         &uri->data.loc.contentSignature));
+  GNUNET_CRYPTO_rsa_key_free (my_private_key);
+  return uri;
+}
+
+
+/**
+ * Create an SKS URI from a namespace and an identifier.
+ *
+ * @param ns namespace
+ * @param id identifier
+ * @param emsg where to store an error message
+ * @return an FS URI for the given namespace and identifier
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_sks_create (struct GNUNET_FS_Namespace *ns, const char *id,
+                          char **emsg)
+{
+  struct GNUNET_FS_Uri *ns_uri;
+  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded pk;
+
+  ns_uri = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  ns_uri->type = sks;
+  GNUNET_CRYPTO_rsa_key_get_public (ns->key, &pk);
+  GNUNET_CRYPTO_hash (&pk, sizeof (pk), &ns_uri->data.sks.namespace);
+  ns_uri->data.sks.identifier = GNUNET_strdup (id);
+  return ns_uri;
+}
+
+
+/**
+ * Create an SKS URI from a namespace ID and an identifier.
+ *
+ * @param nsid namespace ID
+ * @param id identifier
+ * @return an FS URI for the given namespace and identifier
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_sks_create_from_nsid (GNUNET_HashCode * nsid, const char *id)
+{
+  struct GNUNET_FS_Uri *ns_uri;
+
+  ns_uri = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  ns_uri->type = sks;
+  ns_uri->data.sks.namespace = *nsid;
+  ns_uri->data.sks.identifier = GNUNET_strdup (id);
+  return ns_uri;
+}
+
+
+/**
+ * Merge the sets of keywords from two KSK URIs.
+ * (useful for merging the canonicalized keywords with
+ * the original keywords for sharing).
+ *
+ * @param u1 first uri
+ * @param u2 second uri
+ * @return merged URI, NULL on error
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_ksk_merge (const struct GNUNET_FS_Uri *u1,
+                         const struct GNUNET_FS_Uri *u2)
+{
+  struct GNUNET_FS_Uri *ret;
+  unsigned int kc;
+  unsigned int i;
+  unsigned int j;
+  int found;
+  const char *kp;
+  char **kl;
+
+  if ((u1 == NULL) && (u2 == NULL))
+    return NULL;
+  if (u1 == NULL)
+    return GNUNET_FS_uri_dup (u2);
+  if (u2 == NULL)
+    return GNUNET_FS_uri_dup (u1);
+  if ((u1->type != ksk) || (u2->type != ksk))
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  kc = u1->data.ksk.keywordCount;
+  kl = GNUNET_malloc ((kc + u2->data.ksk.keywordCount) * sizeof (char *));
+  for (i = 0; i < u1->data.ksk.keywordCount; i++)
+    kl[i] = GNUNET_strdup (u1->data.ksk.keywords[i]);
+  for (i = 0; i < u2->data.ksk.keywordCount; i++)
+  {
+    kp = u2->data.ksk.keywords[i];
+    found = 0;
+    for (j = 0; j < u1->data.ksk.keywordCount; j++)
+      if (0 == strcmp (kp + 1, kl[j] + 1))
+      {
+        found = 1;
+        if (kp[0] == '+')
+          kl[j][0] = '+';
+        break;
+      }
+    if (0 == found)
+      kl[kc++] = GNUNET_strdup (kp);
+  }
+  ret = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  ret->type = ksk;
+  ret->data.ksk.keywordCount = kc;
+  ret->data.ksk.keywords = kl;
+  return ret;
+}
+
+
+/**
+ * Duplicate URI.
+ *
+ * @param uri the URI to duplicate
+ * @return copy of the URI
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_dup (const struct GNUNET_FS_Uri *uri)
+{
+  struct GNUNET_FS_Uri *ret;
+  unsigned int i;
+
+  if (uri == NULL)
+    return NULL;
+  ret = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  memcpy (ret, uri, sizeof (struct GNUNET_FS_Uri));
+  switch (ret->type)
+  {
+  case ksk:
+    if (ret->data.ksk.keywordCount >=
+        GNUNET_MAX_MALLOC_CHECKED / sizeof (char *))
+    {
+      GNUNET_break (0);
+      GNUNET_free (ret);
+      return NULL;
+    }
+    if (ret->data.ksk.keywordCount > 0)
+    {
+      ret->data.ksk.keywords =
+          GNUNET_malloc (ret->data.ksk.keywordCount * sizeof (char *));
+      for (i = 0; i < ret->data.ksk.keywordCount; i++)
+        ret->data.ksk.keywords[i] = GNUNET_strdup (uri->data.ksk.keywords[i]);
+    }
+    else
+      ret->data.ksk.keywords = NULL;    /* just to be sure */
+    break;
+  case sks:
+    ret->data.sks.identifier = GNUNET_strdup (uri->data.sks.identifier);
+    break;
+  case loc:
+    break;
+  default:
+    break;
+  }
+  return ret;
+}
+
+
+/**
+ * Create an FS URI from a single user-supplied string of keywords.
+ * The string is broken up at spaces into individual keywords.
+ * Keywords that start with "+" are mandatory.  Double-quotes can
+ * be used to prevent breaking up strings at spaces (and also
+ * to specify non-mandatory keywords starting with "+").
+ *
+ * Keywords must contain a balanced number of double quotes and
+ * double quotes can not be used in the actual keywords (for
+ * example, the string '""foo bar""' will be turned into two
+ * "OR"ed keywords 'foo' and 'bar', not into '"foo bar"'.
+ *
+ * @param keywords the keyword string
+ * @param emsg where to store an error message
+ * @return an FS URI for the given keywords, NULL
+ *  if keywords is not legal (i.e. empty).
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_ksk_create (const char *keywords, char **emsg)
+{
+  char **keywordarr;
+  unsigned int num_Words;
+  int inWord;
+  char *pos;
+  struct GNUNET_FS_Uri *uri;
+  char *searchString;
+  int saw_quote;
+
+  if (keywords == NULL)
+  {
+    *emsg = GNUNET_strdup (_("No keywords specified!\n"));
+    GNUNET_break (0);
+    return NULL;
+  }
+  searchString = GNUNET_strdup (keywords);
+  num_Words = 0;
+  inWord = 0;
+  saw_quote = 0;
+  pos = searchString;
+  while ('\0' != *pos)
+  {
+    if ((saw_quote == 0) && (isspace ((unsigned char) *pos)))
+    {
+      inWord = 0;
+    }
+    else if (0 == inWord)
+    {
+      inWord = 1;
+      ++num_Words;
+    }
+    if ('"' == *pos)
+      saw_quote = (saw_quote + 1) % 2;
+    pos++;
+  }
+  if (num_Words == 0)
+  {
+    GNUNET_free (searchString);
+    *emsg = GNUNET_strdup (_("No keywords specified!\n"));
+    return NULL;
+  }
+  if (saw_quote != 0)
+  {
+    GNUNET_free (searchString);
+    *emsg = GNUNET_strdup (_("Number of double-quotes not balanced!\n"));
+    return NULL;
+  }
+  keywordarr = GNUNET_malloc (num_Words * sizeof (char *));
+  num_Words = 0;
+  inWord = 0;
+  pos = searchString;
+  while ('\0' != *pos)
+  {
+    if ((saw_quote == 0) && (isspace ((unsigned char) *pos)))
+    {
+      inWord = 0;
+      *pos = '\0';
+    }
+    else if (0 == inWord)
+    {
+      keywordarr[num_Words] = pos;
+      inWord = 1;
+      ++num_Words;
+    }
+    if ('"' == *pos)
+      saw_quote = (saw_quote + 1) % 2;
+    pos++;
+  }
+  uri =
+      GNUNET_FS_uri_ksk_create_from_args (num_Words,
+                                          (const char **) keywordarr);
+  GNUNET_free (keywordarr);
+  GNUNET_free (searchString);
+  return uri;
+}
+
+
+/**
+ * Create an FS URI from a user-supplied command line of keywords.
+ * Arguments should start with "+" to indicate mandatory
+ * keywords.
+ *
+ * @param argc number of keywords
+ * @param argv keywords (double quotes are not required for
+ *             keywords containing spaces; however, double
+ *             quotes are required for keywords starting with
+ *             "+"); there is no mechanism for having double
+ *             quotes in the actual keywords (if the user
+ *             did specifically specify double quotes, the
+ *             caller should convert each double quote
+ *             into two single quotes).
+ * @return an FS URI for the given keywords, NULL
+ *  if keywords is not legal (i.e. empty).
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_ksk_create_from_args (unsigned int argc, const char **argv)
+{
+  unsigned int i;
+  struct GNUNET_FS_Uri *uri;
+  const char *keyword;
+  char *val;
+  const char *r;
+  char *w;
+  char *emsg;
+
+  if (argc == 0)
+    return NULL;
+  /* allow URI to be given as one and only keyword and
+   * handle accordingly */
+  emsg = NULL;
+  if ((argc == 1) && (strlen (argv[0]) > strlen (GNUNET_FS_URI_PREFIX)) &&
+      (0 ==
+       strncmp (argv[0], GNUNET_FS_URI_PREFIX, strlen (GNUNET_FS_URI_PREFIX)))
+      && (NULL != (uri = GNUNET_FS_uri_parse (argv[0], &emsg))))
+    return uri;
+  GNUNET_free_non_null (emsg);
+  uri = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  uri->type = ksk;
+  uri->data.ksk.keywordCount = argc;
+  uri->data.ksk.keywords = GNUNET_malloc (argc * sizeof (char *));
+  for (i = 0; i < argc; i++)
+  {
+    keyword = argv[i];
+    if (keyword[0] == '+')
+      val = GNUNET_strdup (keyword);
+    else
+      GNUNET_asprintf (&val, " %s", keyword);
+    r = val;
+    w = val;
+    while ('\0' != *r)
+    {
+      if ('"' == *r)
+        r++;
+      else
+        *(w++) = *(r++);
+    }
+    *w = '\0';
+    uri->data.ksk.keywords[i] = val;
+  }
+  return uri;
+}
+
+
+/**
+ * Test if two URIs are equal.
+ *
+ * @param u1 one of the URIs
+ * @param u2 the other URI
+ * @return GNUNET_YES if the URIs are equal
+ */
+int
+GNUNET_FS_uri_test_equal (const struct GNUNET_FS_Uri *u1,
+                          const struct GNUNET_FS_Uri *u2)
+{
+  int ret;
+  unsigned int i;
+  unsigned int j;
+
+  GNUNET_assert (u1 != NULL);
+  GNUNET_assert (u2 != NULL);
+  if (u1->type != u2->type)
+    return GNUNET_NO;
+  switch (u1->type)
+  {
+  case chk:
+    if (0 ==
+        memcmp (&u1->data.chk, &u2->data.chk, sizeof (struct FileIdentifier)))
+      return GNUNET_YES;
+    return GNUNET_NO;
+  case sks:
+    if ((0 ==
+         memcmp (&u1->data.sks.namespace, &u2->data.sks.namespace,
+                 sizeof (GNUNET_HashCode))) &&
+        (0 == strcmp (u1->data.sks.identifier, u2->data.sks.identifier)))
+
+      return GNUNET_YES;
+    return GNUNET_NO;
+  case ksk:
+    if (u1->data.ksk.keywordCount != u2->data.ksk.keywordCount)
+      return GNUNET_NO;
+    for (i = 0; i < u1->data.ksk.keywordCount; i++)
+    {
+      ret = GNUNET_NO;
+      for (j = 0; j < u2->data.ksk.keywordCount; j++)
+      {
+        if (0 == strcmp (u1->data.ksk.keywords[i], u2->data.ksk.keywords[j]))
+        {
+          ret = GNUNET_YES;
+          break;
+        }
+      }
+      if (ret == GNUNET_NO)
+        return GNUNET_NO;
+    }
+    return GNUNET_YES;
+  case loc:
+    if (memcmp
+        (&u1->data.loc, &u2->data.loc,
+         sizeof (struct FileIdentifier) +
+         sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded) +
+         sizeof (struct GNUNET_TIME_Absolute) + sizeof (unsigned short) +
+         sizeof (unsigned short)) != 0)
+      return GNUNET_NO;
+    return GNUNET_YES;
+  default:
+    return GNUNET_NO;
+  }
+}
+
+
+/**
+ * Is this a namespace URI?
+ *
+ * @param uri the uri to check
+ * @return GNUNET_YES if this is an SKS uri
+ */
+int
+GNUNET_FS_uri_test_sks (const struct GNUNET_FS_Uri *uri)
+{
+  return uri->type == sks;
+}
+
+
+/**
+ * Get the ID of a namespace from the given
+ * namespace URI.
+ *
+ * @param uri the uri to get the namespace ID from
+ * @param nsid where to store the ID of the namespace
+ * @return GNUNET_OK on success
+ */
+int
+GNUNET_FS_uri_sks_get_namespace (const struct GNUNET_FS_Uri *uri,
+                                 GNUNET_HashCode * nsid)
+{
+  if (!GNUNET_FS_uri_test_sks (uri))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  *nsid = uri->data.sks.namespace;
+  return GNUNET_OK;
+}
+
+
+/**
+ * Get the content identifier of an SKS URI.
+ *
+ * @param uri the sks uri
+ * @return NULL on error (not a valid SKS URI)
+ */
+char *
+GNUNET_FS_uri_sks_get_content_id (const struct GNUNET_FS_Uri *uri)
+{
+  if (!GNUNET_FS_uri_test_sks (uri))
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  return GNUNET_strdup (uri->data.sks.identifier);
+}
+
+
+/**
+ * Convert namespace URI to a human readable format
+ * (using the namespace description, if available).
+ *
+ * @param cfg configuration to use
+ * @param uri SKS uri to convert
+ * @return NULL on error (not an SKS URI)
+ */
+char *
+GNUNET_FS_uri_sks_to_string_fancy (struct GNUNET_CONFIGURATION_Handle *cfg,
+                                   const struct GNUNET_FS_Uri *uri)
+{
+  char *ret;
+  char *name;
+
+  if (uri->type != sks)
+    return NULL;
+  name = GNUNET_PSEUDONYM_id_to_name (cfg, &uri->data.sks.namespace);
+  if (name == NULL)
+    return GNUNET_FS_uri_to_string (uri);
+  GNUNET_asprintf (&ret, "%s: %s", name, uri->data.sks.identifier);
+  GNUNET_free (name);
+  return ret;
+}
+
+
+/**
+ * Is this a keyword URI?
+ *
+ * @param uri the uri
+ * @return GNUNET_YES if this is a KSK uri
+ */
+int
+GNUNET_FS_uri_test_ksk (const struct GNUNET_FS_Uri *uri)
+{
+#if EXTRA_CHECKS
+  unsigned int i;
+
+  if (uri->type == ksk)
+  {
+    for (i=0;i < uri->data.ksk.keywordCount; i++)
+      GNUNET_assert (uri->data.ksk.keywords[i] != NULL);
+  }
+#endif
+  return uri->type == ksk;
+}
+
+
+/**
+ * Is this a file (or directory) URI?
+ *
+ * @param uri the uri to check
+ * @return GNUNET_YES if this is a CHK uri
+ */
+int
+GNUNET_FS_uri_test_chk (const struct GNUNET_FS_Uri *uri)
+{
+  return uri->type == chk;
+}
+
+
+/**
+ * What is the size of the file that this URI
+ * refers to?
+ *
+ * @param uri the CHK URI to inspect
+ * @return size of the file as specified in the CHK URI
+ */
+uint64_t
+GNUNET_FS_uri_chk_get_file_size (const struct GNUNET_FS_Uri * uri)
+{
+  switch (uri->type)
+  {
+  case chk:
+    return GNUNET_ntohll (uri->data.chk.file_length);
+  case loc:
+    return GNUNET_ntohll (uri->data.loc.fi.file_length);
+  default:
+    GNUNET_assert (0);
+  }
+  return 0;                     /* unreachable */
+}
+
+
+/**
+ * Is this a location URI?
+ *
+ * @param uri the uri to check
+ * @return GNUNET_YES if this is a LOC uri
+ */
+int
+GNUNET_FS_uri_test_loc (const struct GNUNET_FS_Uri *uri)
+{
+  return uri->type == loc;
+}
+
+
+/**
+ * Add a keyword as non-mandatory (with ' '-prefix) to the
+ * given keyword list at offset 'index'.  The array is
+ * guaranteed to be long enough.
+ * 
+ * @param s keyword to add
+ * @param array array to add the keyword to
+ * @param index offset where to add the keyword
+ */
+static void
+insert_non_mandatory_keyword (const char *s, char **array, int index)
+{
+  char *nkword;
+  GNUNET_asprintf (&nkword, " %s", /* space to mark as 'non mandatory' */ s);
+  array[index] = nkword;
+}
+
+
+/**
+ * Test if the given keyword 's' is already present in the 
+ * given array, ignoring the '+'-mandatory prefix in the array.
+ *
+ * @param s keyword to test
+ * @param array keywords to test against, with ' ' or '+' prefix to ignore
+ * @param array_length length of the array
+ * @return GNUNET_YES if the keyword exists, GNUNET_NO if not
+ */ 
+static int
+find_duplicate (const char *s, const char **array, int array_length)
+{
+  int j;
+
+  for (j = array_length - 1; j >= 0; j--)
+    if (0 == strcmp (&array[j][1], s))
+      return GNUNET_YES;
+  return GNUNET_NO;
+}
+
+static char *
+normalize_metadata (enum EXTRACTOR_MetaFormat format, const char *data,
+    size_t data_len)
+{
+  uint8_t *free_str = NULL;
+  uint8_t *str_to_normalize = (uint8_t *) data;
+  uint8_t *normalized;
+  size_t r_len;
+  if (str_to_normalize == NULL)
+    return NULL;
+  /* Don't trust libextractor */
+  if (format == EXTRACTOR_METAFORMAT_UTF8)
+  {
+    free_str = (uint8_t *) u8_check ((const uint8_t *) data, data_len);
+    if (free_str == NULL)
+      free_str = NULL;
+    else
+      format = EXTRACTOR_METAFORMAT_C_STRING;
+  }
+  if (format == EXTRACTOR_METAFORMAT_C_STRING)
+  {
+    free_str = u8_strconv_from_encoding (data, locale_charset (), iconveh_escape_sequence);
+    if (free_str == NULL)
+      return NULL;
+  }
+
+  normalized = u8_tolower (str_to_normalize, strlen ((char *) str_to_normalize), NULL, UNINORM_NFD, NULL, &r_len);
+  /* free_str is allocated by libunistring internally, use free() */
+  if (free_str != NULL)
+    free (free_str);
+  if (normalized != NULL)
+  {
+    /* u8_tolower allocates a non-NULL-terminated string! */
+    free_str = GNUNET_malloc (r_len + 1);
+    memcpy (free_str, normalized, r_len);
+    free_str[r_len] = '\0';
+    free (normalized);
+    normalized = free_str;
+  }
+  return (char *) normalized;
+}
+
+/**
+ * Counts the number of UTF-8 characters (not bytes) in the string,
+ * returns that count.
+ */
+static size_t
+u8_strcount (const uint8_t *s)
+{
+  size_t count;
+  ucs4_t c;
+  GNUNET_assert (s != NULL);
+  if (s[0] == 0)
+    return 0;
+  for (count = 0; s != NULL; count++)
+    s = u8_next (&c, s);
+  return count - 1;
+}
+
+
+/**
+ * Break the filename up by matching [], () and {} pairs to make
+ * keywords. In case of nesting parentheses only the inner pair counts.
+ * You can't escape parentheses to scan something like "[blah\{foo]" to
+ * make a "blah{foo" keyword, this function is only a heuristic!
+ *
+ * @param s string to break down.
+ * @param array array to fill with enclosed tokens. If NULL, then tokens
+ *        are only counted.
+ * @param index index at which to start filling the array (entries prior
+ *        to it are used to check for duplicates). ignored if array == NULL.
+ * @return number of tokens counted (including duplicates), or number of
+ *         tokens extracted (excluding duplicates). 0 if there are no
+ *         matching parens in the string (when counting), or when all tokens 
+ *         were duplicates (when extracting).
+ */
+static int
+get_keywords_from_parens (const char *s, char **array, int index)
+{
+  int count = 0;
+  char *open_paren;
+  char *close_paren;
+  char *ss;
+  char tmp;
+
+  if (NULL == s)
+    return 0;
+  ss = GNUNET_strdup (s);
+  open_paren = ss - 1;
+  while (NULL != (open_paren = strpbrk (open_paren + 1, "[{(")))
+  {
+    int match = 0;
+
+    close_paren = strpbrk (open_paren + 1, "]})");
+    if (NULL == close_paren)
+      continue;
+    switch (open_paren[0])
+    {
+    case '[':
+      if (']' == close_paren[0])
+        match = 1;
+      break;
+    case '{':
+      if ('}' == close_paren[0])
+        match = 1;
+      break;
+    case '(':
+      if (')' == close_paren[0])
+        match = 1;
+      break;
+    default:
+      break;
+    }
+    if (match && (close_paren - open_paren > 1))
+    {
+      tmp = close_paren[0];
+      close_paren[0] = '\0';
+      /* Keywords must be at least 3 characters long */
+      if (u8_strcount ((const uint8_t *) &open_paren[1]) <= 2)
+      {
+        close_paren[0] = tmp;
+        continue;
+      }
+      if (NULL != array)
+      {
+        char *normalized;
+        if (GNUNET_NO == find_duplicate ((const char *) &open_paren[1],
+            (const char **) array, index + count))
+        {
+	  insert_non_mandatory_keyword ((const char *) &open_paren[1], array,
+					index + count);
+          count++;
+        }
+        normalized = normalize_metadata (EXTRACTOR_METAFORMAT_UTF8,
+            &open_paren[1], close_paren - &open_paren[1]);
+        if (normalized != NULL)
+        {
+          if (GNUNET_NO == find_duplicate ((const char *) normalized,
+              (const char **) array, index + count))
+          {
+	    insert_non_mandatory_keyword ((const char *) normalized, array,
+					  index + count);
+            count++;
+          }
+          GNUNET_free (normalized);
+        }
+      }
+      else
+	count++;
+      close_paren[0] = tmp;
+    }   
+  }
+  GNUNET_free (ss);
+  return count;
+}
+
+
+/**
+ * Where to break up keywords
+ */
+#define TOKENS "_. /-!?#&+@\"\'\\;:,"
+
+/**
+ * Break the filename up by TOKENS to make
+ * keywords.
+ *
+ * @param s string to break down.
+ * @param array array to fill with tokens. If NULL, then tokens are only
+ *        counted.
+ * @param index index at which to start filling the array (entries prior
+ *        to it are used to check for duplicates). ignored if array == NULL.
+ * @return number of tokens (>1) counted (including duplicates), or number of
+ *         tokens extracted (excluding duplicates). 0 if there are no
+ *         separators in the string (when counting), or when all tokens were
+ *         duplicates (when extracting).
+ */
+static int
+get_keywords_from_tokens (const char *s, char **array, int index)
+{
+  char *p;
+  char *ss;
+  int seps = 0;
+
+  ss = GNUNET_strdup (s);
+  for (p = strtok (ss, TOKENS); p != NULL; p = strtok (NULL, TOKENS))
+  {
+    /* Keywords must be at least 3 characters long */
+    if (u8_strcount ((const uint8_t *) p) <= 2)
+      continue;
+    if (NULL != array)
+    {
+      char *normalized;
+      if (GNUNET_NO == find_duplicate (p, (const char **) array, index + seps))
+      {
+        insert_non_mandatory_keyword (p, array,
+				      index + seps);
+	seps++;
+      }
+      normalized = normalize_metadata (EXTRACTOR_METAFORMAT_UTF8,
+          p, strlen (p));
+      if (normalized != NULL)
+      {
+        if (GNUNET_NO == find_duplicate ((const char *) normalized,
+            (const char **) array, index + seps))
+        {
+          insert_non_mandatory_keyword ((const char *) normalized, array,
+				  index + seps);
+          seps++;
+        }
+        GNUNET_free (normalized);
+      }
+    }
+    else
+      seps++;
+  }
+  GNUNET_free (ss);
+  return seps;
+}
+#undef TOKENS
+
+/**
+ * Function called on each value in the meta data.
+ * Adds it to the URI.
+ *
+ * @param cls URI to update
+ * @param plugin_name name of the plugin that produced this value;
+ *        special values can be used (i.e. '&lt;zlib&gt;' for zlib being
+ *        used in the main libextractor library and yielding
+ *        meta data).
+ * @param type libextractor-type describing the meta data
+ * @param format basic format information about data
+ * @param data_mime_type mime-type of data (not of the original file);
+ *        can be NULL (if mime-type is not known)
+ * @param data actual meta-data found
+ * @param data_len number of bytes in data
+ * @return 0 (always)
+ */
+static int
+gather_uri_data (void *cls, const char *plugin_name,
+                 enum EXTRACTOR_MetaType type, enum EXTRACTOR_MetaFormat format,
+                 const char *data_mime_type, const char *data, size_t data_len)
+{
+  struct GNUNET_FS_Uri *uri = cls;
+  char *normalized_data;
+
+  if ((format != EXTRACTOR_METAFORMAT_UTF8) &&
+      (format != EXTRACTOR_METAFORMAT_C_STRING))
+    return 0;
+  /* Keywords must be at least 3 characters long
+   * If given non-utf8 string it will, most likely, find it to be invalid,
+   * and will return the length of its valid part, skipping the keyword.
+   * If it does - fix the extractor, not this check!
+   */
+  if (u8_strcount ((const uint8_t *) data) <= 2)
+  {
+    return 0;
+  }
+  normalized_data = normalize_metadata (format, data, data_len);
+  if (!find_duplicate (data, (const char **) uri->data.ksk.keywords, uri->data.ksk.keywordCount))
+  {
+    insert_non_mandatory_keyword (data,
+				  uri->data.ksk.keywords, uri->data.ksk.keywordCount);
+    uri->data.ksk.keywordCount++;
+  }
+  if (normalized_data != NULL)
+  {
+    if (!find_duplicate (normalized_data, (const char **) uri->data.ksk.keywords, uri->data.ksk.keywordCount))
+    {
+      insert_non_mandatory_keyword (normalized_data,
+				    uri->data.ksk.keywords, uri->data.ksk.keywordCount);
+      uri->data.ksk.keywordCount++;
+    }
+    GNUNET_free (normalized_data);
+  }
+  return 0;
+}
+
+
+/**
+ * Construct a keyword-URI from meta-data (take all entries
+ * in the meta-data and construct one large keyword URI
+ * that lists all keywords that can be found in the meta-data).
+ *
+ * @param md metadata to use
+ * @return NULL on error, otherwise a KSK URI
+ */
+struct GNUNET_FS_Uri *
+GNUNET_FS_uri_ksk_create_from_meta_data (const struct GNUNET_CONTAINER_MetaData
+                                         *md)
+{
+  struct GNUNET_FS_Uri *ret;
+  char *filename;
+  char *full_name = NULL;
+  char *ss;
+  int ent;
+  int tok_keywords = 0;
+  int paren_keywords = 0;
+
+  if (md == NULL)
+    return NULL;
+  ret = GNUNET_malloc (sizeof (struct GNUNET_FS_Uri));
+  ret->type = ksk;
+  ent = GNUNET_CONTAINER_meta_data_iterate (md, NULL, NULL);
+  if (ent > 0)
+  {
+    full_name = GNUNET_CONTAINER_meta_data_get_first_by_types (md,
+        EXTRACTOR_METATYPE_GNUNET_ORIGINAL_FILENAME, -1);
+    if (NULL != full_name)
+    {
+      filename = full_name;
+      while (NULL != (ss = strstr (filename, DIR_SEPARATOR_STR)))
+        filename = ss + 1;
+      tok_keywords = get_keywords_from_tokens (filename, NULL, 0);
+      paren_keywords = get_keywords_from_parens (filename, NULL, 0);
+    }
+    /* x2 because there might be a normalized variant of every keyword */
+    ret->data.ksk.keywords = GNUNET_malloc (sizeof (char *) * (ent
+        + tok_keywords + paren_keywords) * 2);
+    GNUNET_CONTAINER_meta_data_iterate (md, &gather_uri_data, ret);
+  }
+  if (tok_keywords > 0)
+    ret->data.ksk.keywordCount += get_keywords_from_tokens (filename,
+        ret->data.ksk.keywords,
+        ret->data.ksk.keywordCount);
+  if (paren_keywords > 0)
+    ret->data.ksk.keywordCount += get_keywords_from_parens (filename,
+        ret->data.ksk.keywords,
+        ret->data.ksk.keywordCount);
+  if (ent > 0)
+    GNUNET_free_non_null (full_name);
+  return ret;
+}
+
+
+/**
+ * In URI-encoding, does the given character
+ * need to be encoded using %-encoding?
+ */
+static int
+needs_percent (char c)
+{
+  return (!
+          ((isalnum ((unsigned char) c)) || (c == '-') || (c == '_') ||
+           (c == '.') || (c == '~')));
+}
+
+
+/**
+ * Convert a KSK URI to a string.
+ *
+ * @param uri the URI to convert
+ * @return NULL on error (i.e. keywordCount == 0)
+ */
+static char *
+uri_ksk_to_string (const struct GNUNET_FS_Uri *uri)
+{
+  char **keywords;
+  unsigned int keywordCount;
+  size_t n;
+  char *ret;
+  unsigned int i;
+  unsigned int j;
+  unsigned int wpos;
+  size_t slen;
+  const char *keyword;
+
+  if (uri->type != ksk)
+    return NULL;
+  keywords = uri->data.ksk.keywords;
+  keywordCount = uri->data.ksk.keywordCount;
+  n = keywordCount + strlen (GNUNET_FS_URI_PREFIX) +
+      strlen (GNUNET_FS_URI_KSK_INFIX) + 1;
+  for (i = 0; i < keywordCount; i++)
+  {
+    keyword = keywords[i];
+    slen = strlen (keyword);
+    n += slen;
+    for (j = 0; j < slen; j++)
+    {
+      if ((j == 0) && (keyword[j] == ' '))
+      {
+        n--;
+        continue;               /* skip leading space */
+      }
+      if (needs_percent (keyword[j]))
+        n += 2;                 /* will use %-encoding */
+    }
+  }
+  ret = GNUNET_malloc (n);
+  strcpy (ret, GNUNET_FS_URI_PREFIX);
+  strcat (ret, GNUNET_FS_URI_KSK_INFIX);
+  wpos = strlen (ret);
+  for (i = 0; i < keywordCount; i++)
+  {
+    keyword = keywords[i];
+    slen = strlen (keyword);
+    for (j = 0; j < slen; j++)
+    {
+      if ((j == 0) && (keyword[j] == ' '))
+        continue;               /* skip leading space */
+      if (needs_percent (keyword[j]))
+      {
+        sprintf (&ret[wpos], "%%%02X", keyword[j]);
+        wpos += 3;
+      }
+      else
+      {
+        ret[wpos++] = keyword[j];
+      }
+    }
+    if (i != keywordCount - 1)
+      ret[wpos++] = '+';
+  }
+  return ret;
+}
+
+
+/**
+ * Convert SKS URI to a string.
+ *
+ * @param uri sks uri to convert
+ * @return NULL on error
+ */
+static char *
+uri_sks_to_string (const struct GNUNET_FS_Uri *uri)
+{
+  const GNUNET_HashCode *namespace;
+  const char *identifier;
+  char *ret;
+  struct GNUNET_CRYPTO_HashAsciiEncoded ns;
+
+  if (uri->type != sks)
+    return NULL;
+  namespace = &uri->data.sks.namespace;
+  identifier = uri->data.sks.identifier;
+  GNUNET_CRYPTO_hash_to_enc (namespace, &ns);
+  GNUNET_asprintf (&ret, "%s%s%s/%s", GNUNET_FS_URI_PREFIX,
+                   GNUNET_FS_URI_SKS_INFIX, (const char *) &ns, identifier);
+  return ret;
+}
+
+
+/**
+ * Convert a CHK URI to a string.
+ *
+ * @param uri chk uri to convert
+ * @return NULL on error
+ */
+static char *
+uri_chk_to_string (const struct GNUNET_FS_Uri *uri)
+{
+  const struct FileIdentifier *fi;
+  char *ret;
+  struct GNUNET_CRYPTO_HashAsciiEncoded keyhash;
+  struct GNUNET_CRYPTO_HashAsciiEncoded queryhash;
+
+  if (uri->type != chk)
+    return NULL;
+  fi = &uri->data.chk;
+  GNUNET_CRYPTO_hash_to_enc (&fi->chk.key, &keyhash);
+  GNUNET_CRYPTO_hash_to_enc (&fi->chk.query, &queryhash);
+
+  GNUNET_asprintf (&ret, "%s%s%s.%s.%llu", GNUNET_FS_URI_PREFIX,
+                   GNUNET_FS_URI_CHK_INFIX, (const char *) &keyhash,
+                   (const char *) &queryhash, GNUNET_ntohll (fi->file_length));
+  return ret;
+}
+
+/**
+ * Convert binary data to a string.
+ *
+ * @param data binary data to convert
+ * @param size number of bytes in data
+ * @return converted data
+ */
+static char *
+bin2enc (const void *data, size_t size)
+{
+  /**
+   * 64 characters for encoding, 6 bits per character
+   */
+  static char *tbl =
+      "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_=";
+
+  size_t len;
+  size_t pos;
+  unsigned int bits;
+  unsigned int hbits;
+  char *ret;
+
+  GNUNET_assert (strlen (tbl) == 64);
+  len = size * 8 / 6;
+  if (((size * 8) % 6) != 0)
+    len++;
+  ret = GNUNET_malloc (len + 1);
+  ret[len] = '\0';
+  len = 0;
+  bits = 0;
+  hbits = 0;
+  for (pos = 0; pos < size; pos++)
+  {
+    bits |= ((((const unsigned char *) data)[pos]) << hbits);
+    hbits += 8;
+    while (hbits >= 6)
+    {
+      ret[len++] = tbl[bits & 63];
+      bits >>= 6;
+      hbits -= 6;
+    }
+  }
+  if (hbits > 0)
+    ret[len] = tbl[bits & 63];
+  return ret;
+}
+
+
+/**
+ * Convert a LOC URI to a string.
+ *
+ * @param uri loc uri to convert
+ * @return NULL on error
+ */
+static char *
+uri_loc_to_string (const struct GNUNET_FS_Uri *uri)
+{
+  char *ret;
+  struct GNUNET_CRYPTO_HashAsciiEncoded keyhash;
+  struct GNUNET_CRYPTO_HashAsciiEncoded queryhash;
+  char *peerId;
+  char *peerSig;
+
+  GNUNET_CRYPTO_hash_to_enc (&uri->data.loc.fi.chk.key, &keyhash);
+  GNUNET_CRYPTO_hash_to_enc (&uri->data.loc.fi.chk.query, &queryhash);
+  peerId =
+      bin2enc (&uri->data.loc.peer,
+               sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded));
+  peerSig =
+      bin2enc (&uri->data.loc.contentSignature,
+               sizeof (struct GNUNET_CRYPTO_RsaSignature));
+  GNUNET_asprintf (&ret, "%s%s%s.%s.%llu.%s.%s.%llu", GNUNET_FS_URI_PREFIX,
+                   GNUNET_FS_URI_LOC_INFIX, (const char *) &keyhash,
+                   (const char *) &queryhash,
+                   (unsigned long long) GNUNET_ntohll (uri->data.loc.
+                                                       fi.file_length), peerId,
+                   peerSig,
+                   (unsigned long long) uri->data.loc.expirationTime.abs_value);
+  GNUNET_free (peerSig);
+  GNUNET_free (peerId);
+  return ret;
+}
+
+
+/**
+ * Convert a URI to a UTF-8 String.
+ *
+ * @param uri uri to convert to a string
+ * @return the UTF-8 string
+ */
+char *
+GNUNET_FS_uri_to_string (const struct GNUNET_FS_Uri *uri)
+{
+  if (uri == NULL)
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  switch (uri->type)
+  {
+  case ksk:
+    return uri_ksk_to_string (uri);
+  case sks:
+    return uri_sks_to_string (uri);
+  case chk:
+    return uri_chk_to_string (uri);
+  case loc:
+    return uri_loc_to_string (uri);
+  default:
+    GNUNET_break (0);
+    return NULL;
+  }
+}
+
+/* end of fs_uri.c */