separate util.c and url.c

1 files changed, 409 insertions, 0 deletions

diff --git a/src/util/url.c b/src/util/url.c
new file mode 100644
index 000000000..be15917b6
--- /dev/null
+++ b/src/util/url.c
@@ -0,0 +1,409 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014-2020 Taler Systems SA
+
+  TALER 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.
+
+  TALER 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
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file url.c
+ * @brief URL handling utility functions
+ * @author Florian Dold
+ */
+#include "platform.h"
+#include "taler_util.h"
+
+
+/**
+ * Check if a character is reserved and should
+ * be urlencoded.
+ *
+ * @param c character to look at
+ * @return #GNUNET_YES if @a c needs to be urlencoded,
+ *         #GNUNET_NO otherwise
+ */
+static bool
+is_reserved (char c)
+{
+  switch (c)
+  {
+  case '0': case '1': case '2': case '3': case '4':
+  case '5': case '6': case '7': case '8': case '9':
+  case 'a': case 'b': case 'c': case 'd': case 'e':
+  case 'f': case 'g': case 'h': case 'i': case 'j':
+  case 'k': case 'l': case 'm': case 'n': case 'o':
+  case 'p': case 'q': case 'r': case 's': case 't':
+  case 'u': case 'v': case 'w': case 'x': case 'y': case 'z':
+  case 'A': case 'B': case 'C': case 'D': case 'E':
+  case 'F': case 'G': case 'H': case 'I': case 'J':
+  case 'K': case 'L': case 'M': case 'N': case 'O':
+  case 'P': case 'Q': case 'R': case 'S': case 'T':
+  case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':
+  case '-': case '.': case '_': case '~':
+    return GNUNET_NO;
+  default:
+    break;
+  }
+  return GNUNET_YES;
+}
+
+
+/**
+ * Get the length of a string after it has been
+ * urlencoded.
+ *
+ * @param s the string
+ * @returns the size of the urlencoded @a s
+ */
+static size_t
+urlencode_len (const char *s)
+{
+  size_t len = 0;
+  for (; *s != '\0'; len++, s++)
+    if (GNUNET_YES == is_reserved (*s))
+      len += 2;
+  return len;
+}
+
+
+/**
+ * URL-encode a string according to rfc3986.
+ *
+ * @param buf buffer to write the result to
+ * @param s string to encode
+ */
+static void
+buffer_write_urlencode (struct GNUNET_Buffer *buf,
+                        const char *s)
+{
+  GNUNET_buffer_ensure_remaining (buf, urlencode_len (s) + 1);
+
+  for (size_t i = 0; i < strlen (s); i++)
+  {
+    if (GNUNET_YES == is_reserved (s[i]))
+      GNUNET_buffer_write_fstr (buf, "%%%02X", s[i]);
+    else
+      buf->mem[buf->position++] = s[i];
+  }
+}
+
+
+/**
+ * URL-encode a string according to rfc3986.
+ *
+ * @param s string to encode
+ * @returns the urlencoded string, the caller must free it with #GNUNET_free()
+ */
+char *
+TALER_urlencode (const char *s)
+{
+  struct GNUNET_Buffer buf = { 0 };
+
+  buffer_write_urlencode (&buf, s);
+  return GNUNET_buffer_reap_str (&buf);
+}
+
+
+/**
+ * Make an absolute URL with query parameters.
+ *
+ * @param base_url absolute base URL to use
+ * @param path path of the url
+ * @param ... NULL-terminated key-value pairs (char *) for query parameters,
+ *        the value will be url-encoded
+ * @returns the URL (must be freed with #GNUNET_free) or
+ *          NULL if an error occured.
+ */
+char *
+TALER_url_join (const char *base_url,
+                const char *path,
+                ...)
+{
+  unsigned int iparam = 0;
+  va_list args;
+  struct GNUNET_Buffer buf = { 0 };
+  size_t len;
+
+  GNUNET_assert (NULL != base_url);
+  GNUNET_assert (NULL != path);
+  if (0 == strlen (base_url))
+  {
+    /* base URL can't be empty */
+    GNUNET_break (0);
+    return NULL;
+  }
+  if ('/' != base_url[strlen (base_url) - 1])
+  {
+    /* Must be an actual base URL! */
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Base URL `%s' does not end with '/'\n",
+                base_url);
+    return NULL;
+  }
+  if ('/' == path[0])
+  {
+    /* The path must be relative. */
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Path `%s' is not relative\n",
+                path);
+    return NULL;
+  }
+
+  /* 1st pass: compute length */
+  len = strlen (base_url) + strlen (path) + 1;
+
+  va_start (args, path);
+  while (1)
+  {
+    char *key;
+    char *value;
+    key = va_arg (args, char *);
+    if (NULL == key)
+      break;
+    value = va_arg (args, char *);
+    if (NULL == value)
+      continue;
+    len += urlencode_len (value) + strlen (key) + 2;
+  }
+  va_end (args);
+
+  GNUNET_buffer_prealloc (&buf, len);
+  GNUNET_buffer_write_str (&buf, base_url);
+  GNUNET_buffer_write_str (&buf, path);
+
+  va_start (args, path);
+  while (1)
+  {
+    char *key;
+    char *value;
+
+    key = va_arg (args, char *);
+    if (NULL == key)
+      break;
+    value = va_arg (args, char *);
+    if (NULL == value)
+      continue;
+    GNUNET_buffer_write_str (&buf, (0 == iparam) ? "?" : "&");
+    iparam++;
+    GNUNET_buffer_write_str (&buf, key);
+    GNUNET_buffer_write_str (&buf, "=");
+    buffer_write_urlencode (&buf, value);
+  }
+  va_end (args);
+
+  return GNUNET_buffer_reap_str (&buf);
+}
+
+
+/**
+ * Make an absolute URL for the given parameters.
+ *
+ * @param proto protocol for the URL (typically https)
+ * @param host hostname for the URL
+ * @param prefix prefix for the URL
+ * @param path path for the URL
+ * @param args NULL-terminated key-value pairs (char *) for query parameters,
+ *        the value will be url-encoded
+ * @returns the URL, must be freed with #GNUNET_free
+ */
+char *
+TALER_url_absolute_raw_va (const char *proto,
+                           const char *host,
+                           const char *prefix,
+                           const char *path,
+                           va_list args)
+{
+  struct GNUNET_Buffer buf = { 0 };
+  unsigned int iparam = 0;
+  size_t len = 0;
+  va_list args2;
+
+  len += strlen (proto) + strlen ("://") + strlen (host);
+  len += strlen (prefix) + strlen (path);
+
+  va_copy (args2, args);
+  while (1)
+  {
+    char *key;
+    char *value;
+    key = va_arg (args2, char *);
+    if (NULL == key)
+      break;
+    value = va_arg (args2, char *);
+    if (NULL == value)
+      continue;
+    len += urlencode_len (value) + strlen (key) + 2;
+  }
+  va_end (args2);
+
+  GNUNET_buffer_prealloc (&buf, len);
+
+  GNUNET_buffer_write_str (&buf, proto);
+  GNUNET_buffer_write_str (&buf, "://");
+  GNUNET_buffer_write_str (&buf, host);
+
+  GNUNET_buffer_write_path (&buf, prefix);
+  GNUNET_buffer_write_path (&buf, path);
+
+  va_copy (args2, args);
+  while (1)
+  {
+    char *key;
+    char *value;
+    key = va_arg (args, char *);
+    if (NULL == key)
+      break;
+    value = va_arg (args, char *);
+    if (NULL == value)
+      continue;
+    GNUNET_buffer_write_str (&buf, (0 == iparam) ? "?" : "&");
+    iparam++;
+    GNUNET_buffer_write_str (&buf, key);
+    GNUNET_buffer_write_str (&buf, "=");
+    buffer_write_urlencode (&buf, value);
+  }
+  va_end (args2);
+
+  return GNUNET_buffer_reap_str (&buf);
+}
+
+
+/**
+ * Make an absolute URL for the given parameters.
+ *
+ * @param proto protocol for the URL (typically https)
+ * @param host hostname for the URL
+ * @param prefix prefix for the URL
+ * @param path path for the URL
+ * @param ... NULL-terminated key-value pairs (char *) for query parameters,
+ *        the value will be url-encoded
+ * @returns the URL, must be freed with #GNUNET_free
+ */
+char *
+TALER_url_absolute_raw (const char *proto,
+                        const char *host,
+                        const char *prefix,
+                        const char *path,
+                        ...)
+{
+  char *result;
+  va_list args;
+
+  va_start (args, path);
+  result = TALER_url_absolute_raw_va (proto, host, prefix, path, args);
+  va_end (args);
+  return result;
+}
+
+
+/**
+ * Find out if an MHD connection is using HTTPS (either
+ * directly or via proxy).
+ *
+ * @param connection MHD connection
+ * @returns GNUNET_YES if the MHD connection is using https,
+ *          GNUNET_NO if the MHD connection is using http,
+ *          GNUNET_SYSERR if the connection type couldn't be determined
+ */
+int
+TALER_mhd_is_https (struct MHD_Connection *connection)
+{
+  const union MHD_ConnectionInfo *ci;
+  const union MHD_DaemonInfo *di;
+  const char *forwarded_proto = MHD_lookup_connection_value (connection,
+                                                             MHD_HEADER_KIND,
+                                                             "X-Forwarded-Proto");
+
+  if (NULL != forwarded_proto)
+  {
+    if (0 == strcmp (forwarded_proto, "https"))
+      return GNUNET_YES;
+    if (0 == strcmp (forwarded_proto, "http"))
+      return GNUNET_NO;
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  /* likely not reverse proxy, figure out if we are
+     http by asking MHD */
+  ci = MHD_get_connection_info (connection,
+                                MHD_CONNECTION_INFO_DAEMON);
+  if (NULL == ci)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  di = MHD_get_daemon_info (ci->daemon,
+                            MHD_DAEMON_INFO_FLAGS);
+  if (NULL == di)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  if (0 != (di->flags & MHD_USE_TLS))
+    return GNUNET_YES;
+  return GNUNET_NO;
+}
+
+
+/**
+ * Make an absolute URL for a given MHD connection.
+ *
+ * @param connection the connection to get the URL for
+ * @param path path of the url
+ * @param ... NULL-terminated key-value pairs (char *) for query parameters,
+ *        the value will be url-encoded
+ * @returns the URL, must be freed with #GNUNET_free
+ */
+char *
+TALER_url_absolute_mhd (struct MHD_Connection *connection,
+                        const char *path,
+                        ...)
+{
+  /* By default we assume we're running under HTTPS */
+  const char *proto;
+  const char *host;
+  const char *forwarded_host;
+  const char *prefix;
+  va_list args;
+  char *result;
+
+  if (GNUNET_YES == TALER_mhd_is_https (connection))
+    proto = "https";
+  else
+    proto = "http";
+
+  host = MHD_lookup_connection_value (connection, MHD_HEADER_KIND, "Host");
+  forwarded_host = MHD_lookup_connection_value (connection, MHD_HEADER_KIND,
+                                                "X-Forwarded-Host");
+
+  prefix = MHD_lookup_connection_value (connection, MHD_HEADER_KIND,
+                                        "X-Forwarded-Prefix");
+  if (NULL == prefix)
+    prefix = "";
+
+  if (NULL != forwarded_host)
+    host = forwarded_host;
+
+  if (NULL == host)
+  {
+    /* Should never happen, at last the host header should be defined */
+    GNUNET_break (0);
+    return NULL;
+  }
+
+  va_start (args, path);
+  result = TALER_url_absolute_raw_va (proto, host, prefix, path, args);
+  va_end (args);
+  return result;
+}
+
+
+/* end of url.c */