2 * Copyright (C) 2012 Andre Noll <maan@tuebingen.mpg.de>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file sideband.c Implementation of the sideband API. */
13 #include "portable_io.h"
17 /** Each sideband packet consists of a header and a data part. */
18 #define SIDEBAND_HEADER_SIZE 5
21 char header
[SIDEBAND_HEADER_SIZE
];
22 size_t bytes_dispatched
; /* including header */
23 sb_transformation trafo
;
31 * Prepare to receive a sideband packet.
33 * \param max_size Do not allocate more than this many bytes.
34 * \param t Optional sideband transformation.
35 * \param trafo_context Passed verbatim to \a t.
37 * \a trafo_context is ignored if \a t is \p NULL.
39 * \return An opaque sideband handle.
41 struct sb_context
*sb_new_recv(size_t max_size
, sb_transformation t
,
44 struct sb_context
*c
= para_calloc(sizeof(*c
));
46 c
->max_size
= max_size
;
48 c
->trafo_context
= trafo_context
;
53 * Prepare to write a sideband packet.
55 * \param sbb Data and meta data to send.
56 * \param dont_free Do not try to deallocate the sideband buffer.
57 * \param t See \ref sb_new_recv().
58 * \param trafo_context See \ref sb_new_recv().
60 * It's OK to supply a zero-sized buffer in \a sbb. In this case only the band
61 * designator is sent through the sideband channel. Otherwise, if \a dont_free
62 * is false, the buffer of \a sbb is freed after the data has been sent.
64 * \return See \ref sb_new_recv().
66 struct sb_context
*sb_new_send(struct sb_buffer
*sbb
, bool dont_free
,
67 sb_transformation t
, void *trafo_context
)
69 struct sb_context
*c
= para_calloc(sizeof(*c
));
70 struct iovec src
, dst
, *srcp
, *dstp
;
74 c
->trafo_context
= trafo_context
;
75 c
->dont_free
= dont_free
;
77 write_u32(c
->header
, sbb
->iov
.iov_len
);
78 write_u8(c
->header
+ 4, sbb
->band
);
81 src
= (typeof(src
)){.iov_base
= c
->header
, .iov_len
= SIDEBAND_HEADER_SIZE
};
82 t(&src
, &dst
, trafo_context
);
83 if (src
.iov_base
!= dst
.iov_base
) {
84 memcpy(c
->header
, dst
.iov_base
, SIDEBAND_HEADER_SIZE
);
87 if (!iov_valid(&sbb
->iov
))
91 t(srcp
, dstp
, trafo_context
);
92 if (srcp
->iov_base
!= dstp
->iov_base
) {
102 * Deallocate all memory associated with a sideband handle.
104 * \param c The sideband handle.
106 * \a c must point to a handle previously returned by \ref sb_new_recv() or
107 * \ref sb_new_send(). It \a c is \p NULL, the function does nothing.
109 void sb_free(struct sb_context
*c
)
114 free(c
->sbb
.iov
.iov_base
);
119 * Obtain pointer(s) to the sideband send buffer(s).
121 * \param c The sideband handle.
122 * \param iov Array of two I/O vectors.
124 * \return The number of buffers that need to be sent, either 1 or 2.
126 * This function fills out the buffers described by \a iov. The result can be
127 * passed to \ref xwritev() or similar.
129 * \sa \ref sb_get_recv_buffer().
131 int sb_get_send_buffers(struct sb_context
*c
, struct iovec iov
[2])
133 struct sb_buffer
*sbb
= &c
->sbb
;
134 size_t n
= c
->bytes_dispatched
;
136 if (n
< SIDEBAND_HEADER_SIZE
) {
137 iov
[0].iov_base
= c
->header
+ n
;
138 iov
[0].iov_len
= SIDEBAND_HEADER_SIZE
- n
;
139 if (!iov_valid(&sbb
->iov
))
144 n
-= SIDEBAND_HEADER_SIZE
;
145 assert(n
< sbb
->iov
.iov_len
);
146 iov
[0].iov_base
= sbb
->iov
.iov_base
+ n
;
147 iov
[0].iov_len
= sbb
->iov
.iov_len
- n
;
149 iov
[1].iov_base
= NULL
;
155 * Update the sideband context after data has been sent.
157 * \param c The sideband handle.
158 * \param nbytes The number of sent bytes.
160 * \return False if more data must be sent to complete the sideband transfer,
161 * true if the transfer is complete. In this case all resources are freed and
162 * the sideband handle must not be used any more.
164 bool sb_sent(struct sb_context
*c
, size_t nbytes
)
166 struct sb_buffer
*sbb
= &c
->sbb
;
167 size_t sz
= SIDEBAND_HEADER_SIZE
+ sbb
->iov
.iov_len
;
169 assert(c
->bytes_dispatched
+ nbytes
<= sz
);
170 c
->bytes_dispatched
+= nbytes
;
171 if (c
->bytes_dispatched
< sz
)
178 * Obtain a pointer to the next sideband read buffer.
180 * \param c The sideband handle.
181 * \param iov Result IO vector.
183 * This fills in \a iov to point to the buffer to which the next chunk of
184 * received data should be written.
186 void sb_get_recv_buffer(struct sb_context
*c
, struct iovec
*iov
)
188 struct sb_buffer
*sbb
= &c
->sbb
;
189 size_t n
= c
->bytes_dispatched
;
191 if (n
< SIDEBAND_HEADER_SIZE
) {
192 iov
->iov_base
= c
->header
+ n
;
193 iov
->iov_len
= SIDEBAND_HEADER_SIZE
- n
;
196 n
-= SIDEBAND_HEADER_SIZE
;
197 assert(sbb
->iov
.iov_base
);
198 assert(sbb
->iov
.iov_len
> n
);
199 iov
->iov_base
= sbb
->iov
.iov_base
+ n
;
200 iov
->iov_len
= sbb
->iov
.iov_len
- n
;
204 * Update the sideband context after data has been received.
206 * \param c The sideband handle.
207 * \param nbytes The number of bytes that have been received.
208 * \param result The received sideband packet.
210 * \return Negative on errors, zero if more data needs to be read to complete
211 * this sideband packet, one if the sideband packet has been received
214 * Only if the function returns one, the sideband buffer pointed to by \a
215 * result is set to point to the received data.
217 int sb_received(struct sb_context
*c
, size_t nbytes
, struct sb_buffer
*result
)
219 struct sb_buffer
*sbb
= &c
->sbb
;
220 size_t n
= c
->bytes_dispatched
,
221 sz
= SIDEBAND_HEADER_SIZE
+ sbb
->iov
.iov_len
;
223 assert(n
+ nbytes
<= sz
);
224 c
->bytes_dispatched
+= nbytes
;
225 if (c
->bytes_dispatched
< SIDEBAND_HEADER_SIZE
)
227 if (n
>= SIDEBAND_HEADER_SIZE
) { /* header has already been received */
228 if (c
->bytes_dispatched
< sz
) /* need to recv more body data */
230 /* received everything, decrypt and return sbb */
233 c
->trafo(&sbb
->iov
, &dst
, c
->trafo_context
);
234 if (sbb
->iov
.iov_base
!= dst
.iov_base
) {
235 free(sbb
->iov
.iov_base
);
236 sbb
->iov
.iov_base
= dst
.iov_base
;
239 ((char *)(sbb
->iov
.iov_base
))[sbb
->iov
.iov_len
] = '\0';
242 /* header has been received, decrypt and decode it */
243 if (c
->trafo
) { /* decrypt */
244 struct iovec dst
, src
= (typeof(src
)) {
245 .iov_base
= c
->header
,
246 .iov_len
= SIDEBAND_HEADER_SIZE
248 c
->trafo(&src
, &dst
, c
->trafo_context
);
249 if (src
.iov_base
!= dst
.iov_base
) {
250 memcpy(c
->header
, dst
.iov_base
,
251 SIDEBAND_HEADER_SIZE
);
255 /* Decode header, setup sbb */
256 sbb
->iov
.iov_len
= read_u32(c
->header
);
257 sbb
->band
= read_u8(c
->header
+ 4);
258 sbb
->iov
.iov_base
= NULL
;
259 if (sbb
->iov
.iov_len
== 0) /* zero-sized msg */
261 if (c
->max_size
> 0 && sbb
->iov
.iov_len
> c
->max_size
) {
262 PARA_ERROR_LOG("packet too big (is %zu, max %zu)\n",
263 sbb
->iov
.iov_len
, c
->max_size
);
264 return -E_SB_PACKET_SIZE
;
267 * We like to reserve one extra byte for the terminating NULL
268 * character. However, we must make sure the +1 below does not
271 if (sbb
->iov
.iov_len
== (size_t)-1)
272 return -E_SB_PACKET_SIZE
;
273 sbb
->iov
.iov_base
= para_malloc(sbb
->iov
.iov_len
+ 1);
274 return 0; /* ready to read body */