1 /* SPDX-License-Identifier: GPL-2.0+ */
5  * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
18  * struct msgbuf - Buffer struct to construct SSH messages.
19  * @begin: Pointer to the beginning of the allocated buffer space.
20  * @end:   Pointer to the end (one past last element) of the allocated buffer
22  * @ptr:   Pointer to the first free element in the buffer.
31  * msgb_init() - Initialize the given message buffer struct.
32  * @msgb: The buffer struct to initialize
33  * @ptr:  Pointer to the underlying memory by which the buffer will be backed.
36  * Initialize the given message buffer struct using the provided memory as
41 	msgb->begin = ptr;  in msgb_init()
42 	msgb->end = ptr + cap;  in msgb_init()
43 	msgb->ptr = ptr;  in msgb_init()
47  * msgb_bytes_used() - Return the current number of bytes used in the buffer.
48  * @msgb: The message buffer.
52 	return msgb->ptr - msgb->begin;  in msgb_bytes_used()
57 	*msgb->ptr = value;  in __msgb_push_u8()
58 	msgb->ptr += sizeof(u8);  in __msgb_push_u8()
63 	put_unaligned_le16(value, msgb->ptr);  in __msgb_push_u16()
64 	msgb->ptr += sizeof(u16);  in __msgb_push_u16()
68  * msgb_push_u16() - Push a u16 value to the buffer.
69  * @msgb:  The message buffer.
70  * @value: The value to push to the buffer.
74 	if (WARN_ON(msgb->ptr + sizeof(u16) > msgb->end))  in msgb_push_u16()
81  * msgb_push_syn() - Push SSH SYN bytes to the buffer.
82  * @msgb: The message buffer.
90  * msgb_push_buf() - Push raw data to the buffer.
91  * @msgb: The message buffer.
92  * @buf:  The data to push to the buffer.
93  * @len:  The length of the data to push to the buffer.
97 	msgb->ptr = memcpy(msgb->ptr, buf, len) + len;  in msgb_push_buf()
101  * msgb_push_crc() - Compute CRC and push it to the buffer.
102  * @msgb: The message buffer.
112  * msgb_push_frame() - Push a SSH message frame header to the buffer.
113  * @msgb: The message buffer
114  * @ty:   The type of the frame.
115  * @len:  The length of the payload of the frame.
116  * @seq:  The sequence ID of the frame/packet.
120 	u8 *const begin = msgb->ptr;  in msgb_push_frame()
122 	if (WARN_ON(msgb->ptr + sizeof(struct ssh_frame) > msgb->end))  in msgb_push_frame()
125 	__msgb_push_u8(msgb, ty);	/* Frame type. */  in msgb_push_frame()
126 	__msgb_push_u16(msgb, len);	/* Frame payload length. */  in msgb_push_frame()
127 	__msgb_push_u8(msgb, seq);	/* Frame sequence ID. */  in msgb_push_frame()
129 	msgb_push_crc(msgb, begin, msgb->ptr - begin);  in msgb_push_frame()
133  * msgb_push_ack() - Push a SSH ACK frame to the buffer.
134  * @msgb: The message buffer
135  * @seq:  The sequence ID of the frame/packet to be ACKed.
142 	/* ACK-type frame + CRC. */  in msgb_push_ack()
145 	/* Payload CRC (ACK-type frames do not have a payload). */  in msgb_push_ack()
146 	msgb_push_crc(msgb, msgb->ptr, 0);  in msgb_push_ack()
150  * msgb_push_nak() - Push a SSH NAK frame to the buffer.
151  * @msgb: The message buffer
158 	/* NAK-type frame + CRC. */  in msgb_push_nak()
161 	/* Payload CRC (ACK-type frames do not have a payload). */  in msgb_push_nak()
162 	msgb_push_crc(msgb, msgb->ptr, 0);  in msgb_push_nak()
166  * msgb_push_cmd() - Push a SSH command frame with payload to the buffer.
167  * @msgb: The message buffer.
168  * @seq:  The sequence ID (SEQ) of the frame/packet.
169  * @rqid: The request ID (RQID) of the request contained in the frame.
170  * @rqst: The request to wrap in the frame.
181 	/* Command frame + CRC. */  in msgb_push_cmd()
182 	msgb_push_frame(msgb, type, sizeof(struct ssh_command) + rqst->length, seq);  in msgb_push_cmd()
184 	/* Frame payload: Command struct + payload. */  in msgb_push_cmd()
185 	if (WARN_ON(msgb->ptr + sizeof(struct ssh_command) > msgb->end))  in msgb_push_cmd()
188 	cmd = msgb->ptr;  in msgb_push_cmd()
191 	__msgb_push_u8(msgb, rqst->target_category);	/* Target category. */  in msgb_push_cmd()
192 	__msgb_push_u8(msgb, rqst->target_id);		/* Target ID. */  in msgb_push_cmd()
194 	__msgb_push_u8(msgb, rqst->instance_id);	/* Instance ID. */  in msgb_push_cmd()
196 	__msgb_push_u8(msgb, rqst->command_id);		/* Command ID. */  in msgb_push_cmd()
199 	msgb_push_buf(msgb, rqst->payload, rqst->length);  in msgb_push_cmd()
202 	msgb_push_crc(msgb, cmd, msgb->ptr - cmd);  in msgb_push_cmd()