arm_uc_socket_help.c

00001 // ----------------------------------------------------------------------------
00002 // Copyright 2016-2017 ARM Ltd.
00003 //
00004 // SPDX-License-Identifier: Apache-2.0
00005 //
00006 // Licensed under the Apache License, Version 2.0 (the "License");
00007 // you may not use this file except in compliance with the License.
00008 // You may obtain a copy of the License at
00009 //
00010 //     http://www.apache.org/licenses/LICENSE-2.0
00011 //
00012 // Unless required by applicable law or agreed to in writing, software
00013 // distributed under the License is distributed on an "AS IS" BASIS,
00014 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00015 // See the License for the specific language governing permissions and
00016 // limitations under the License.
00017 // ----------------------------------------------------------------------------
00018 
00019 #include "arm_uc_socket_help.h"
00020 
00021 #include <string.h>
00022 
00023 /**
00024  * @brief Helper function for picking out values from an HTTP header.
00025  * @details The buffer is searched for the tag provided tag and if found the
00026  *          remainder of that line is MOVED to the front of the buffer and the
00027  *          size is shrunk to only include the detected value.
00028  *
00029  * @param buffer Pointer to an arm_uc_buffer_t.
00030  * @param tag_buffer Pointer to tag (a string).
00031  * @param tag_size Length of the tag.
00032  * @return True if tag was found. False otherwise.
00033  */
00034 bool arm_uc_socket_trim_value(arm_uc_buffer_t* buffer,
00035                               const char* tag_buffer,
00036                               uint32_t tag_size)
00037 {
00038     /* default return value */
00039     bool result = false;
00040 
00041     /* check for NULL pointers */
00042     if (buffer && buffer->ptr && tag_buffer)
00043     {
00044         /* search for the tag */
00045         uint32_t start = arm_uc_strnstrn(buffer->ptr,
00046                                          buffer->size,
00047                                          (const uint8_t*) tag_buffer,
00048                                          tag_size);
00049 
00050         /* check if index is within bounds */
00051         if (start < buffer->size)
00052         {
00053             /* remove tag */
00054             start += tag_size;
00055 
00056             /* remove ": " between tag and value */
00057             start += 2;
00058 
00059             /* search for the end of the line */
00060             uint32_t length = arm_uc_strnstrn(&(buffer->ptr[start]),
00061                                               buffer->size - start,
00062                                               (const uint8_t*) "\r",
00063                                               1);
00064 
00065             /* move value to front of buffer if all indices are within bounds */
00066             if ((start + length) < buffer->size)
00067             {
00068                 /* memmove handles overlapping regions */
00069                 memmove(buffer->ptr, &(buffer->ptr[start]), length);
00070 
00071                 /* resize buffer */
00072                 buffer->size = length;
00073 
00074                 /* set return value to success */
00075                 result = true;
00076             }
00077         }
00078     }
00079 
00080     return result;
00081 }