more shared logic for argument/header parsing

8 files changed, 380 insertions, 220 deletions

diff --git a/src/exchange/taler-exchange-httpd_deposits_get.c b/src/exchange/taler-exchange-httpd_deposits_get.c
index ebbb13e08..26c9e2618 100644
--- a/src/exchange/taler-exchange-httpd_deposits_get.c
+++ b/src/exchange/taler-exchange-httpd_deposits_get.c
@@ -65,6 +65,12 @@ struct DepositWtidContext
   struct TALER_WireTransferIdentifierRawP wtid;
 
   /**
+   * Signature by the merchant.
+   */
+  struct TALER_MerchantSignatureP merchant_sig;
+
+
+  /**
    * Set by #handle_wtid data to the coin's contribution to the wire transfer.
    */
   struct TALER_Amount coin_contribution;
@@ -275,89 +281,103 @@ handle_track_transaction_request (
 }
 
 
+/**
+ * Function called to clean up a context.
+ *
+ * @param rc request context with data to clean up
+ */
+static void
+dwc_cleaner (struct TEH_RequestContext *rc)
+{
+  struct DepositWtidContext *ctx = rc->rh_ctx;
+
+  GNUNET_free (ctx);
+}
+
+
 MHD_RESULT
 TEH_handler_deposits_get (struct TEH_RequestContext *rc,
                           const char *const args[4])
 {
-  enum GNUNET_GenericReturnValue res;
-  struct TALER_MerchantSignatureP merchant_sig;
-  struct DepositWtidContext ctx;
+  struct DepositWtidContext *ctx = rc->rh_ctx;
 
-  if (GNUNET_OK !=
-      GNUNET_STRINGS_string_to_data (args[0],
-                                     strlen (args[0]),
-                                     &ctx.h_wire,
-                                     sizeof (ctx.h_wire)))
-  {
-    GNUNET_break_op (0);
-    return TALER_MHD_reply_with_error (rc->connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_EXCHANGE_DEPOSITS_GET_INVALID_H_WIRE,
-                                       args[0]);
-  }
-  if (GNUNET_OK !=
-      GNUNET_STRINGS_string_to_data (args[1],
-                                     strlen (args[1]),
-                                     &ctx.merchant,
-                                     sizeof (ctx.merchant)))
-  {
-    GNUNET_break_op (0);
-    return TALER_MHD_reply_with_error (rc->connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_EXCHANGE_DEPOSITS_GET_INVALID_MERCHANT_PUB,
-                                       args[1]);
-  }
-  if (GNUNET_OK !=
-      GNUNET_STRINGS_string_to_data (args[2],
-                                     strlen (args[2]),
-                                     &ctx.h_contract_terms,
-                                     sizeof (ctx.h_contract_terms)))
-  {
-    GNUNET_break_op (0);
-    return TALER_MHD_reply_with_error (rc->connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_EXCHANGE_DEPOSITS_GET_INVALID_H_CONTRACT_TERMS,
-                                       args[2]);
-  }
-  if (GNUNET_OK !=
-      GNUNET_STRINGS_string_to_data (args[3],
-                                     strlen (args[3]),
-                                     &ctx.coin_pub,
-                                     sizeof (ctx.coin_pub)))
-  {
-    GNUNET_break_op (0);
-    return TALER_MHD_reply_with_error (rc->connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_EXCHANGE_DEPOSITS_GET_INVALID_COIN_PUB,
-                                       args[3]);
-  }
-  res = TALER_MHD_parse_request_arg_data (rc->connection,
-                                          "merchant_sig",
-                                          &merchant_sig,
-                                          sizeof (merchant_sig));
-  if (GNUNET_SYSERR == res)
-    return MHD_NO; /* internal error */
-  if (GNUNET_NO == res)
-    return MHD_YES; /* parse error */
-  TEH_METRICS_num_verifications[TEH_MT_SIGNATURE_EDDSA]++;
+  if (NULL == ctx)
   {
+    ctx = GNUNET_new (struct DepositWtidContext);
+    rc->rh_ctx = ctx;
+    rc->rh_cleaner = &dwc_cleaner;
+
+    if (GNUNET_OK !=
+        GNUNET_STRINGS_string_to_data (args[0],
+                                       strlen (args[0]),
+                                       &ctx->h_wire,
+                                       sizeof (ctx->h_wire)))
+    {
+      GNUNET_break_op (0);
+      return TALER_MHD_reply_with_error (rc->connection,
+                                         MHD_HTTP_BAD_REQUEST,
+                                         TALER_EC_EXCHANGE_DEPOSITS_GET_INVALID_H_WIRE,
+                                         args[0]);
+    }
+    if (GNUNET_OK !=
+        GNUNET_STRINGS_string_to_data (args[1],
+                                       strlen (args[1]),
+                                       &ctx->merchant,
+                                       sizeof (ctx->merchant)))
+    {
+      GNUNET_break_op (0);
+      return TALER_MHD_reply_with_error (rc->connection,
+                                         MHD_HTTP_BAD_REQUEST,
+                                         TALER_EC_EXCHANGE_DEPOSITS_GET_INVALID_MERCHANT_PUB,
+                                         args[1]);
+    }
     if (GNUNET_OK !=
-        TALER_merchant_deposit_verify (&ctx.merchant,
-                                       &ctx.coin_pub,
-                                       &ctx.h_contract_terms,
-                                       &ctx.h_wire,
-                                       &merchant_sig))
+        GNUNET_STRINGS_string_to_data (args[2],
+                                       strlen (args[2]),
+                                       &ctx->h_contract_terms,
+                                       sizeof (ctx->h_contract_terms)))
     {
       GNUNET_break_op (0);
       return TALER_MHD_reply_with_error (rc->connection,
-                                         MHD_HTTP_FORBIDDEN,
-                                         TALER_EC_EXCHANGE_DEPOSITS_GET_MERCHANT_SIGNATURE_INVALID,
-                                         NULL);
+                                         MHD_HTTP_BAD_REQUEST,
+                                         TALER_EC_EXCHANGE_DEPOSITS_GET_INVALID_H_CONTRACT_TERMS,
+                                         args[2]);
+    }
+    if (GNUNET_OK !=
+        GNUNET_STRINGS_string_to_data (args[3],
+                                       strlen (args[3]),
+                                       &ctx->coin_pub,
+                                       sizeof (ctx->coin_pub)))
+    {
+      GNUNET_break_op (0);
+      return TALER_MHD_reply_with_error (rc->connection,
+                                         MHD_HTTP_BAD_REQUEST,
+                                         TALER_EC_EXCHANGE_DEPOSITS_GET_INVALID_COIN_PUB,
+                                         args[3]);
+    }
+    TALER_MHD_parse_request_arg_auto_t (rc->connection,
+                                        "merchant_sig",
+                                        &ctx->merchant_sig);
+    TEH_METRICS_num_verifications[TEH_MT_SIGNATURE_EDDSA]++;
+    {
+      if (GNUNET_OK !=
+          TALER_merchant_deposit_verify (&ctx->merchant,
+                                         &ctx->coin_pub,
+                                         &ctx->h_contract_terms,
+                                         &ctx->h_wire,
+                                         &ctx->merchant_sig))
+      {
+        GNUNET_break_op (0);
+        return TALER_MHD_reply_with_error (rc->connection,
+                                           MHD_HTTP_FORBIDDEN,
+                                           TALER_EC_EXCHANGE_DEPOSITS_GET_MERCHANT_SIGNATURE_INVALID,
+                                           NULL);
+      }
     }
   }
 
   return handle_track_transaction_request (rc->connection,
-                                           &ctx);
+                                           ctx);
 }
 
 
diff --git a/src/exchange/taler-exchange-httpd_kyc-check.c b/src/exchange/taler-exchange-httpd_kyc-check.c
index bf4e4dea1..0372573bb 100644
--- a/src/exchange/taler-exchange-httpd_kyc-check.c
+++ b/src/exchange/taler-exchange-httpd_kyc-check.c
@@ -520,34 +520,8 @@ TEH_handler_kyc_check (
                                          "usertype");
     }
 
-    {
-      const char *ts;
-
-      ts = MHD_lookup_connection_value (rc->connection,
-                                        MHD_GET_ARGUMENT_KIND,
-                                        "timeout_ms");
-      if (NULL != ts)
-      {
-        char dummy;
-        unsigned long long tms;
-
-        if (1 !=
-            sscanf (ts,
-                    "%llu%c",
-                    &tms,
-                    &dummy))
-        {
-          GNUNET_break_op (0);
-          return TALER_MHD_reply_with_error (rc->connection,
-                                             MHD_HTTP_BAD_REQUEST,
-                                             TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                             "timeout_ms");
-        }
-        kyp->timeout = GNUNET_TIME_relative_to_absolute (
-          GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS,
-                                         tms));
-      }
-    }
+    TALER_MHD_parse_request_timeout (rc->connection,
+                                     &kyp->timeout);
   }
 
   if ( (NULL == kyp->eh) &&
diff --git a/src/exchange/taler-exchange-httpd_kyc-proof.c b/src/exchange/taler-exchange-httpd_kyc-proof.c
index 6d06f0c82..9668ee54c 100644
--- a/src/exchange/taler-exchange-httpd_kyc-proof.c
+++ b/src/exchange/taler-exchange-httpd_kyc-proof.c
@@ -297,7 +297,6 @@ TEH_handler_kyc_proof (
 {
   struct KycProofContext *kpc = rc->rh_ctx;
   const char *provider_section_or_logic = args[0];
-  const char *h_payto;
 
   if (NULL == kpc)
   {
@@ -310,33 +309,13 @@ TEH_handler_kyc_proof (
                                          TALER_EC_GENERIC_ENDPOINT_UNKNOWN,
                                          "'/kyc-proof/$PROVIDER_SECTION?state=$H_PAYTO' required");
     }
-    h_payto = MHD_lookup_connection_value (rc->connection,
-                                           MHD_GET_ARGUMENT_KIND,
-                                           "state");
-    if (NULL == h_payto)
-    {
-      GNUNET_break_op (0);
-      return TALER_MHD_reply_with_error (rc->connection,
-                                         MHD_HTTP_BAD_REQUEST,
-                                         TALER_EC_GENERIC_PARAMETER_MISSING,
-                                         "h_payto");
-    }
     kpc = GNUNET_new (struct KycProofContext);
     kpc->rc = rc;
     rc->rh_ctx = kpc;
     rc->rh_cleaner = &clean_kpc;
-    if (GNUNET_OK !=
-        GNUNET_STRINGS_string_to_data (h_payto,
-                                       strlen (h_payto),
-                                       &kpc->h_payto,
-                                       sizeof (kpc->h_payto)))
-    {
-      GNUNET_break_op (0);
-      return TALER_MHD_reply_with_error (rc->connection,
-                                         MHD_HTTP_BAD_REQUEST,
-                                         TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                         "h_payto");
-    }
+    TALER_MHD_parse_request_arg_auto_t (rc->connection,
+                                        "state",
+                                        &kpc->h_payto);
     if (GNUNET_OK !=
         TALER_KYCLOGIC_lookup_logic (provider_section_or_logic,
                                      &kpc->logic,
diff --git a/src/exchange/taler-exchange-httpd_purses_delete.c b/src/exchange/taler-exchange-httpd_purses_delete.c
index 58cc78250..5bf7c24c9 100644
--- a/src/exchange/taler-exchange-httpd_purses_delete.c
+++ b/src/exchange/taler-exchange-httpd_purses_delete.c
@@ -57,29 +57,9 @@ TEH_handler_purses_delete (
                                        TALER_EC_EXCHANGE_GENERIC_PURSE_PUB_MALFORMED,
                                        args[0]);
   }
-  {
-    const char *sig;
-
-    sig = MHD_lookup_connection_value (connection,
-                                       MHD_HEADER_KIND,
-                                       "Taler-Purse-Signature");
-    if ( (NULL == sig) ||
-         (GNUNET_OK !=
-          GNUNET_STRINGS_string_to_data (sig,
-                                         strlen (sig),
-                                         &purse_sig,
-                                         sizeof (purse_sig))) )
-    {
-      GNUNET_break_op (0);
-      return TALER_MHD_reply_with_error (connection,
-                                         MHD_HTTP_BAD_REQUEST,
-                                         (NULL == sig)
-                                         ? TALER_EC_GENERIC_PARAMETER_MISSING
-                                         : TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                         "Taler-Purse-Signature");
-    }
-  }
-
+  TALER_MHD_parse_request_header_auto_t (connection,
+                                         "Taler-Purse-Signature",
+                                         &purse_sig);
   if (GNUNET_OK !=
       TALER_wallet_purse_delete_verify (&purse_pub,
                                         &purse_sig))
diff --git a/src/exchange/taler-exchange-httpd_purses_get.c b/src/exchange/taler-exchange-httpd_purses_get.c
index 434798a80..613372357 100644
--- a/src/exchange/taler-exchange-httpd_purses_get.c
+++ b/src/exchange/taler-exchange-httpd_purses_get.c
@@ -243,36 +243,8 @@ TEH_handler_purses_get (struct TEH_RequestContext *rc,
                                          args[1]);
     }
 
-    {
-      const char *long_poll_timeout_ms;
-
-      long_poll_timeout_ms
-        = MHD_lookup_connection_value (rc->connection,
-                                       MHD_GET_ARGUMENT_KIND,
-                                       "timeout_ms");
-      if (NULL != long_poll_timeout_ms)
-      {
-        unsigned int timeout_ms;
-        char dummy;
-        struct GNUNET_TIME_Relative timeout;
-
-        if (1 != sscanf (long_poll_timeout_ms,
-                         "%u%c",
-                         &timeout_ms,
-                         &dummy))
-        {
-          GNUNET_break_op (0);
-          return TALER_MHD_reply_with_error (rc->connection,
-                                             MHD_HTTP_BAD_REQUEST,
-                                             TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                             "timeout_ms (must be non-negative number)");
-        }
-        timeout = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS,
-                                                 timeout_ms);
-        gc->timeout = GNUNET_TIME_relative_to_absolute (timeout);
-      }
-    }
-
+    TALER_MHD_parse_request_timeout (rc->connection,
+                                     &gc->timeout);
     if ( (GNUNET_TIME_absolute_is_future (gc->timeout)) &&
          (NULL == gc->eh) )
     {
diff --git a/src/exchange/taler-exchange-httpd_reserves_get.c b/src/exchange/taler-exchange-httpd_reserves_get.c
index 21c0b74aa..3ffbda293 100644
--- a/src/exchange/taler-exchange-httpd_reserves_get.c
+++ b/src/exchange/taler-exchange-httpd_reserves_get.c
@@ -178,9 +178,6 @@ TEH_handler_reserves_get (struct TEH_RequestContext *rc,
 
   if (NULL == rp)
   {
-    struct GNUNET_TIME_Relative timeout
-      = GNUNET_TIME_UNIT_ZERO;
-
     rp = GNUNET_new (struct ReservePoller);
     rp->connection = rc->connection;
     rp->rc = rc;
@@ -201,34 +198,8 @@ TEH_handler_reserves_get (struct TEH_RequestContext *rc,
                                          TALER_EC_GENERIC_RESERVE_PUB_MALFORMED,
                                          args[0]);
     }
-    {
-      const char *long_poll_timeout_ms;
-
-      long_poll_timeout_ms
-        = MHD_lookup_connection_value (rc->connection,
-                                       MHD_GET_ARGUMENT_KIND,
-                                       "timeout_ms");
-      if (NULL != long_poll_timeout_ms)
-      {
-        unsigned int timeout_ms;
-        char dummy;
-
-        if (1 != sscanf (long_poll_timeout_ms,
-                         "%u%c",
-                         &timeout_ms,
-                         &dummy))
-        {
-          GNUNET_break_op (0);
-          return TALER_MHD_reply_with_error (rc->connection,
-                                             MHD_HTTP_BAD_REQUEST,
-                                             TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                             "timeout_ms (must be non-negative number)");
-        }
-        timeout = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS,
-                                                 timeout_ms);
-      }
-    }
-    rp->timeout = GNUNET_TIME_relative_to_absolute (timeout);
+    TALER_MHD_parse_request_timeout (rc->connection,
+                                     &rp->timeout);
   }
 
   if ( (GNUNET_TIME_absolute_is_future (rp->timeout)) &&
diff --git a/src/include/taler_mhd_lib.h b/src/include/taler_mhd_lib.h
index b64231352..e2e8ecb08 100644
--- a/src/include/taler_mhd_lib.h
+++ b/src/include/taler_mhd_lib.h
@@ -437,7 +437,47 @@ TALER_MHD_parse_json_array (struct MHD_Connection *connection,
 
 
 /**
- * Extract fixed-size base32crockford encoded data from request.
+ * Extract optional "timeout_ms" argument from request.
+ *
+ * @param connection the MHD connection
+ * @param[out] expiration set to #GNUNET_TIME_UNIT_ZERO_ABS if there was no timeout,
+ *         the current time plus the value given under "timeout_ms" otherwise
+ * @return #GNUNET_OK on success, #GNUNET_NO if an
+ *     error was returned on @a connection (caller should return #MHD_YES) and
+ *     #GNUNET_SYSERR if we failed to return an error (caller should return #MHD_NO)
+ */
+enum GNUNET_GenericReturnValue
+TALER_MHD_parse_request_arg_timeout (struct MHD_Connection *connection,
+                                     struct GNUNET_TIME_Absolute *expiration);
+
+
+/**
+ * Extract optional "timeout_ms" argument from request.
+ * Macro that *returns* #MHD_YES/#MHD_NO if the "timeout_ms"
+ * argument existed but failed to parse.
+ *
+ * @param connection the MHD connection
+ * @param[out] expiration set to #GNUNET_TIME_UNIT_ZERO_ABS if there was no timeout,
+ *         the current time plus the value given under "timeout_ms" otherwise
+ */
+#define TALER_MHD_parse_request_timeout(connection,expiration) \
+  do {                                                         \
+    switch (TALER_MHD_parse_request_arg_timeout (connection,   \
+                                                 expiration))  \
+    {                      \
+    case GNUNET_SYSERR:    \
+      GNUNET_break (0);    \
+      return MHD_NO;       \
+    case GNUNET_NO:        \
+      GNUNET_break_op (0); \
+    case GNUNET_OK:        \
+      break;               \
+    }                      \
+  } while (0)
+
+
+/**
+ * Extract fixed-size base32crockford encoded data from request argument.
  *
  * Queues an error response to the connection if the parameter is missing or
  * invalid.
@@ -446,16 +486,152 @@ TALER_MHD_parse_json_array (struct MHD_Connection *connection,
  * @param param_name the name of the parameter with the key
  * @param[out] out_data pointer to store the result
  * @param out_size expected size of @a out_data
+ * @param[out] present set to true if argument was found
  * @return
  *   #GNUNET_YES if the the argument is present
- *   #GNUNET_NO if the argument is absent or malformed
+ *   #GNUNET_NO if the argument is malformed
  *   #GNUNET_SYSERR on internal error (error response could not be sent)
  */
 enum GNUNET_GenericReturnValue
 TALER_MHD_parse_request_arg_data (struct MHD_Connection *connection,
                                   const char *param_name,
                                   void *out_data,
-                                  size_t out_size);
+                                  size_t out_size,
+                                  bool *present);
+
+
+/**
+ * Extract fixed-size base32crockford encoded data from request header.
+ *
+ * Queues an error response to the connection if the parameter is missing or
+ * invalid.
+ *
+ * @param connection the MHD connection
+ * @param header_name the name of the HTTP header with the value
+ * @param[out] out_data pointer to store the result
+ * @param out_size expected size of @a out_data
+ * @param[out] present set to true if argument was found
+ * @return
+ *   #GNUNET_YES if the the argument is present
+ *   #GNUNET_NO if the argument is malformed
+ *   #GNUNET_SYSERR on internal error (error response could not be sent)
+ */
+enum GNUNET_GenericReturnValue
+TALER_MHD_parse_request_header_data (struct MHD_Connection *connection,
+                                     const char *header_name,
+                                     void *out_data,
+                                     size_t out_size,
+                                     bool *present);
+
+/**
+ * Extract fixed-size base32crockford encoded data from request.
+ *
+ * @param connection the MHD connection
+ * @param name the name of the parameter with the key
+ * @param[out] out_data pointer to store the result, type must determine size
+ * @param[in,out] required pass true to require presence of this argument; if 'false'
+ *                         set to true if the argument was found
+ * @return
+ *   #GNUNET_YES if the the argument is present
+ *   #GNUNET_NO if the argument is absent or malformed
+ *   #GNUNET_SYSERR on internal error (error response could not be sent)
+ */
+#define TALER_MHD_parse_request_arg_auto(connection,name,val,required) \
+  do {                                                                 \
+    bool p;                                                            \
+    switch (TALER_MHD_parse_request_arg_data (connection, name,        \
+                                              val, sizeof (*val), &p)) \
+    {                      \
+    case GNUNET_SYSERR:    \
+      GNUNET_break (0);    \
+      return MHD_NO;       \
+    case GNUNET_NO:        \
+      GNUNET_break_op (0); \
+      return MHD_YES;      \
+    case GNUNET_OK:        \
+      if (required & (! p)) \
+      return TALER_MHD_reply_with_error (   \
+        connection,                         \
+        MHD_HTTP_BAD_REQUEST,               \
+        TALER_EC_GENERIC_PARAMETER_MISSING, \
+        name);                              \
+      required = p;                         \
+      break;               \
+    }                      \
+  } while (0)
+
+
+/**
+ * Extract required fixed-size base32crockford encoded data from request.
+ *
+ * @param connection the MHD connection
+ * @param name the name of the parameter with the key
+ * @param[out] out_data pointer to store the result, type must determine size
+ * @return
+ *   #GNUNET_YES if the the argument is present
+ *   #GNUNET_NO if the argument is absent or malformed
+ *   #GNUNET_SYSERR on internal error (error response could not be sent)
+ */
+#define TALER_MHD_parse_request_arg_auto_t(connection,name,val) \
+  do {                                                          \
+    bool b = true;                                              \
+    TALER_MHD_parse_request_arg_auto (connection,name,val,b);   \
+  } while (0)
+
+/**
+ * Extract fixed-size base32crockford encoded data from request.
+ *
+ * @param connection the MHD connection
+ * @param name the name of the header with the key
+ * @param[out] out_data pointer to store the result, type must determine size
+ * @param[in,out] required pass true to require presence of this argument; if 'false'
+ *                         set to true if the argument was found
+ * @return
+ *   #GNUNET_YES if the the argument is present
+ *   #GNUNET_NO if the argument is absent or malformed
+ *   #GNUNET_SYSERR on internal error (error response could not be sent)
+ */
+#define TALER_MHD_parse_request_header_auto(connection,name,val,required) \
+  do {                                                                    \
+    bool p;                                                               \
+    switch (TALER_MHD_parse_request_header_data (connection, name,        \
+                                                 val, sizeof (*val), &p)) \
+    {                      \
+    case GNUNET_SYSERR:    \
+      GNUNET_break (0);    \
+      return MHD_NO;       \
+    case GNUNET_NO:        \
+      GNUNET_break_op (0); \
+      return MHD_YES;      \
+    case GNUNET_OK:        \
+      if (required & (! p)) \
+      return TALER_MHD_reply_with_error (   \
+        connection,                         \
+        MHD_HTTP_BAD_REQUEST,               \
+        TALER_EC_GENERIC_PARAMETER_MISSING, \
+        name);                              \
+      required = p;                         \
+      break;               \
+    }                      \
+  } while (0)
+
+
+/**
+ * Extract required fixed-size base32crockford encoded data from request.
+ *
+ * @param connection the MHD connection
+ * @param name the name of the header with the key
+ * @param[out] out_data pointer to store the result, type must determine size
+ * @return
+ *   #GNUNET_YES if the the argument is present
+ *   #GNUNET_NO if the argument is absent or malformed
+ *   #GNUNET_SYSERR on internal error (error response could not be sent)
+ */
+#define TALER_MHD_parse_request_header_auto_t(connection,name,val) \
+  do {                                                             \
+    bool b = true;                                                 \
+    TALER_MHD_parse_request_header_auto (connection,name,val,b);   \
+  } while (0)
 
 
 /**
diff --git a/src/mhd/mhd_parsing.c b/src/mhd/mhd_parsing.c
index ee647f4b7..e76450831 100644
--- a/src/mhd/mhd_parsing.c
+++ b/src/mhd/mhd_parsing.c
@@ -86,25 +86,40 @@ TALER_MHD_parse_post_cleanup_callback (void *con_cls)
 }
 
 
-enum GNUNET_GenericReturnValue
-TALER_MHD_parse_request_arg_data (struct MHD_Connection *connection,
-                                  const char *param_name,
-                                  void *out_data,
-                                  size_t out_size)
+/**
+ * Extract fixed-size base32crockford encoded data from request.
+ *
+ * Queues an error response to the connection if the parameter is missing or
+ * invalid.
+ *
+ * @param connection the MHD connection
+ * @param param_name the name of the HTTP key with the value
+ * @param kind whether to extract from header, argument or footer
+ * @param[out] out_data pointer to store the result
+ * @param out_size expected size of @a out_data
+ * @param[out] present set to true if argument was found
+ * @return
+ *   #GNUNET_YES if the the argument is present
+ *   #GNUNET_NO if the argument is absent or malformed
+ *   #GNUNET_SYSERR on internal error (error response could not be sent)
+ */
+static enum GNUNET_GenericReturnValue
+parse_request_data (struct MHD_Connection *connection,
+                    const char *param_name,
+                    enum MHD_ValueKind kind,
+                    void *out_data,
+                    size_t out_size,
+                    bool *present)
 {
   const char *str;
 
   str = MHD_lookup_connection_value (connection,
-                                     MHD_GET_ARGUMENT_KIND,
+                                     kind,
                                      param_name);
   if (NULL == str)
   {
-    return (MHD_NO ==
-            TALER_MHD_reply_with_error (connection,
-                                        MHD_HTTP_BAD_REQUEST,
-                                        TALER_EC_GENERIC_PARAMETER_MISSING,
-                                        param_name))
-           ? GNUNET_SYSERR : GNUNET_NO;
+    *present = false;
+    return GNUNET_OK;
   }
   if (GNUNET_OK !=
       GNUNET_STRINGS_string_to_data (str,
@@ -117,6 +132,79 @@ TALER_MHD_parse_request_arg_data (struct MHD_Connection *connection,
                                         TALER_EC_GENERIC_PARAMETER_MALFORMED,
                                         param_name))
            ? GNUNET_SYSERR : GNUNET_NO;
+  *present = true;
+  return GNUNET_OK;
+}
+
+
+enum GNUNET_GenericReturnValue
+TALER_MHD_parse_request_arg_data (struct MHD_Connection *connection,
+                                  const char *param_name,
+                                  void *out_data,
+                                  size_t out_size,
+                                  bool *present)
+{
+  return parse_request_data (connection,
+                             param_name,
+                             MHD_GET_ARGUMENT_KIND,
+                             out_data,
+                             out_size,
+                             present);
+}
+
+
+enum GNUNET_GenericReturnValue
+TALER_MHD_parse_request_header_data (struct MHD_Connection *connection,
+                                     const char *header_name,
+                                     void *out_data,
+                                     size_t out_size,
+                                     bool *present)
+{
+  return parse_request_data (connection,
+                             header_name,
+                             MHD_HEADER_KIND,
+                             out_data,
+                             out_size,
+                             present);
+}
+
+
+enum GNUNET_GenericReturnValue
+TALER_MHD_parse_request_arg_timeout (struct MHD_Connection *connection,
+                                     struct GNUNET_TIME_Absolute *expiration)
+{
+  const char *ts;
+  char dummy;
+  unsigned long long tms;
+
+  ts = MHD_lookup_connection_value (connection,
+                                    MHD_GET_ARGUMENT_KIND,
+                                    "timeout_ms");
+  if (NULL == ts)
+  {
+    *expiration = GNUNET_TIME_UNIT_ZERO_ABS;
+    return GNUNET_OK;
+  }
+  if (1 !=
+      sscanf (ts,
+              "%llu%c",
+              &tms,
+              &dummy))
+  {
+    MHD_RESULT mret;
+
+    GNUNET_break_op (0);
+    mret = TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_BAD_REQUEST,
+                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                       "timeout_ms");
+    return (MHD_YES == mret)
+      ? GNUNET_NO
+      : GNUNET_SYSERR;
+  }
+  *expiration = GNUNET_TIME_relative_to_absolute (
+    GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS,
+                                   tms));
   return GNUNET_OK;
 }