1 /***************************************************************************
2 * Copyright (c) 2024 Microsoft Corporation
3 *
4 * This program and the accompanying materials are made available under the
5 * terms of the MIT License which is available at
6 * https://opensource.org/licenses/MIT.
7 *
8 * SPDX-License-Identifier: MIT
9 **************************************************************************/
10
11
12 /**************************************************************************/
13 /**************************************************************************/
14 /** */
15 /** NetX Component */
16 /** */
17 /** Internet Protocol (IP) */
18 /** */
19 /**************************************************************************/
20 /**************************************************************************/
21
22 #define NX_SOURCE_CODE
23
24
25 /* Include necessary system files. */
26
27 #include "nx_api.h"
28 #include "nx_packet.h"
29
30
31 /**************************************************************************/
32 /* */
33 /* FUNCTION RELEASE */
34 /* */
35 /* _nx_packet_data_extract_offset PORTABLE C */
36 /* 6.1 */
37 /* AUTHOR */
38 /* */
39 /* Yuxin Zhou, Microsoft Corporation */
40 /* */
41 /* DESCRIPTION */
42 /* */
43 /* This function copies data from a NetX packet (or packet chain) into */
44 /* the supplied user buffer. If an empty packet (no data) is */
45 /* received, zero bytes are copied, and the function returns without */
46 /* errors. */
47 /* */
48 /* Note that this function extracts data from a packet into user */
49 /* supplied buffer. It does not modify packet internal state */
50 /* information. The data being extracted is still available in the */
51 /* original packet for consumption again. */
52 /* */
53 /* INPUT */
54 /* */
55 /* packet_ptr Pointer to the source packet */
56 /* offset Offset from start of data */
57 /* buffer_start Pointer to destination data area */
58 /* buffer_length Size in bytes */
59 /* bytes_copied Number of bytes copied */
60 /* */
61 /* OUTPUT */
62 /* */
63 /* status Completion status */
64 /* */
65 /* CALLS */
66 /* */
67 /* None */
68 /* */
69 /* CALLED BY */
70 /* */
71 /* Application Code */
72 /* */
73 /* RELEASE HISTORY */
74 /* */
75 /* DATE NAME DESCRIPTION */
76 /* */
77 /* 05-19-2020 Yuxin Zhou Initial Version 6.0 */
78 /* 09-30-2020 Yuxin Zhou Modified comment(s), and */
79 /* verified memcpy use cases, */
80 /* resulting in version 6.1 */
81 /* */
82 /**************************************************************************/
_nx_packet_data_extract_offset(NX_PACKET * packet_ptr,ULONG offset,VOID * buffer_start,ULONG buffer_length,ULONG * bytes_copied)83 UINT _nx_packet_data_extract_offset(NX_PACKET *packet_ptr, ULONG offset, VOID *buffer_start, ULONG buffer_length, ULONG *bytes_copied)
84 {
85
86 ULONG remaining_bytes;
87 UCHAR *source_ptr;
88 UCHAR *destination_ptr;
89 ULONG offset_bytes;
90 #ifndef NX_DISABLE_PACKET_CHAIN
91 ULONG packet_fragment_length;
92 #endif /* NX_DISABLE_PACKET_CHAIN */
93 ULONG bytes_to_copy;
94 NX_PACKET *working_packet_ptr;
95
96
97 working_packet_ptr = packet_ptr;
98
99 /* Check for an invalid offset or packet length. */
100 if (offset >= working_packet_ptr -> nx_packet_length)
101 {
102
103 /* Note: A zero offset with a packet of zero length is ok. */
104 if (offset == 0)
105 {
106
107 *bytes_copied = 0;
108 return(NX_SUCCESS);
109 }
110
111 /* Otherwise, this is an invalid offset or packet length. */
112 return(NX_PACKET_OFFSET_ERROR);
113 }
114
115
116 /* Initialize the source pointer to NULL. */
117 source_ptr = NX_NULL;
118
119 /* Traverse packet chain to offset. */
120 offset_bytes = offset;
121 #ifndef NX_DISABLE_PACKET_CHAIN
122 while (working_packet_ptr)
123 {
124
125 /*lint -e{946} -e{947} suppress pointer subtraction, since it is necessary. */
126 packet_fragment_length = (ULONG)((working_packet_ptr -> nx_packet_append_ptr - working_packet_ptr -> nx_packet_prepend_ptr));
127
128 /* Determine if we are at the offset location fragment in the packet chain */
129 if (packet_fragment_length > offset_bytes)
130 {
131
132 /* Setup loop to copy from this packet. */
133 source_ptr = working_packet_ptr -> nx_packet_prepend_ptr + offset_bytes;
134
135 /* Yes, get out of this loop. */
136 break;
137 }
138
139
140 /* Decrement the remaining offset bytes*/
141 offset_bytes = offset_bytes - packet_fragment_length;
142
143 /* Move to next packet. */
144 working_packet_ptr = working_packet_ptr -> nx_packet_next;
145 }
146 #else /* NX_DISABLE_PACKET_CHAIN */
147 /* Setup loop to copy from this packet. */
148 source_ptr = working_packet_ptr -> nx_packet_prepend_ptr + offset_bytes;
149
150 #endif /* NX_DISABLE_PACKET_CHAIN */
151
152 /* Check for a valid source pointer. */
153 if (source_ptr == NX_NULL)
154 {
155 return(NX_PACKET_OFFSET_ERROR);
156 }
157
158 /* Setup the destination pointer. */
159 destination_ptr = buffer_start;
160 bytes_to_copy = (packet_ptr -> nx_packet_length - offset);
161
162 /* Pickup the amount of bytes to copy. */
163 if (bytes_to_copy < buffer_length)
164 {
165 *bytes_copied = bytes_to_copy; /* the amount of bytes returned to the caller */
166 remaining_bytes = bytes_to_copy; /* for use in the copy loop */
167 }
168 else
169 {
170 *bytes_copied = buffer_length;
171 remaining_bytes = buffer_length;
172 }
173
174 #ifndef NX_DISABLE_PACKET_CHAIN
175 /* Loop to copy bytes from packet(s). */
176 while (working_packet_ptr && remaining_bytes)
177 {
178 #endif /* NX_DISABLE_PACKET_CHAIN */
179
180 /* Calculate bytes to copy. */
181 /*lint -e{946} -e{947} suppress pointer subtraction, since it is necessary. */
182 bytes_to_copy = (ULONG)(working_packet_ptr -> nx_packet_append_ptr - source_ptr);
183 if (remaining_bytes < bytes_to_copy)
184 {
185 bytes_to_copy = remaining_bytes;
186 }
187
188 /* Copy data from this packet. */
189 memcpy(destination_ptr, source_ptr, bytes_to_copy); /* Use case of memcpy is verified. lgtm[cpp/banned-api-usage-required-any] */
190
191 /* Update the pointers. */
192 destination_ptr += bytes_to_copy;
193 remaining_bytes -= bytes_to_copy;
194
195 #ifndef NX_DISABLE_PACKET_CHAIN
196 /* Move to next packet. */
197 working_packet_ptr = working_packet_ptr -> nx_packet_next;
198
199 /* Check for a next packet. */
200 if (working_packet_ptr)
201 {
202
203 /* Setup new source pointer. */
204 source_ptr = working_packet_ptr -> nx_packet_prepend_ptr;
205 }
206 }
207 #endif /* NX_DISABLE_PACKET_CHAIN */
208
209 /* If trace is enabled, insert this event into the trace buffer. */
210 NX_TRACE_IN_LINE_INSERT(NX_TRACE_PACKET_DATA_EXTRACT_OFFSET, packet_ptr, buffer_length, *bytes_copied, 0, NX_TRACE_PACKET_EVENTS, 0, 0);
211
212 /* Return successful completion. */
213 return(NX_SUCCESS);
214 }
215
216
