1 /* Copyright (C) 2012 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
3 /** \file sideband.c Implementation of the sideband API. */
9 #include "portable_io.h"
13 /** Each sideband packet consists of a header and a data part. */
14 #define SIDEBAND_HEADER_SIZE 5
17 char header
[SIDEBAND_HEADER_SIZE
];
18 size_t bytes_dispatched
; /* including header */
19 sb_transformation trafo
;
27 * Prepare to receive a sideband packet.
29 * \param max_size Do not allocate more than this many bytes.
30 * \param t Optional sideband transformation.
31 * \param trafo_context Passed verbatim to \a t.
33 * \a trafo_context is ignored if \a t is \p NULL.
35 * \return An opaque sideband handle.
37 struct sb_context
*sb_new_recv(size_t max_size
, sb_transformation t
,
40 struct sb_context
*c
= para_calloc(sizeof(*c
));
42 c
->max_size
= max_size
;
44 c
->trafo_context
= trafo_context
;
49 * Prepare to write a sideband packet.
51 * \param sbb Data and meta data to send.
52 * \param dont_free Do not try to deallocate the sideband buffer.
53 * \param t See \ref sb_new_recv().
54 * \param trafo_context See \ref sb_new_recv().
56 * It's OK to supply a zero-sized buffer in \a sbb. In this case only the band
57 * designator is sent through the sideband channel. Otherwise, if \a dont_free
58 * is false, the buffer of \a sbb is freed after the data has been sent.
60 * \return See \ref sb_new_recv().
62 struct sb_context
*sb_new_send(struct sb_buffer
*sbb
, bool dont_free
,
63 sb_transformation t
, void *trafo_context
)
65 struct sb_context
*c
= para_calloc(sizeof(*c
));
66 struct iovec src
, dst
, *srcp
, *dstp
;
70 c
->trafo_context
= trafo_context
;
71 c
->dont_free
= dont_free
;
73 write_u32(c
->header
, sbb
->iov
.iov_len
);
74 write_u8(c
->header
+ 4, sbb
->band
);
77 src
= (typeof(src
)){.iov_base
= c
->header
, .iov_len
= SIDEBAND_HEADER_SIZE
};
78 t(&src
, &dst
, trafo_context
);
79 if (src
.iov_base
!= dst
.iov_base
) {
80 memcpy(c
->header
, dst
.iov_base
, SIDEBAND_HEADER_SIZE
);
83 if (!iov_valid(&sbb
->iov
))
87 t(srcp
, dstp
, trafo_context
);
88 if (srcp
->iov_base
!= dstp
->iov_base
) {
98 * Deallocate all memory associated with a sideband handle.
100 * \param c The sideband handle.
102 * \a c must point to a handle previously returned by \ref sb_new_recv() or
103 * \ref sb_new_send(). It \a c is \p NULL, the function does nothing.
105 void sb_free(struct sb_context
*c
)
110 free(c
->sbb
.iov
.iov_base
);
115 * Obtain pointer(s) to the sideband send buffer(s).
117 * \param c The sideband handle.
118 * \param iov Array of two I/O vectors.
120 * \return The number of buffers that need to be sent, either 1 or 2.
122 * This function fills out the buffers described by \a iov. The result can be
123 * passed to \ref xwritev() or similar.
125 * \sa \ref sb_get_recv_buffer().
127 int sb_get_send_buffers(struct sb_context
*c
, struct iovec iov
[2])
129 struct sb_buffer
*sbb
= &c
->sbb
;
130 size_t n
= c
->bytes_dispatched
;
132 if (n
< SIDEBAND_HEADER_SIZE
) {
133 iov
[0].iov_base
= c
->header
+ n
;
134 iov
[0].iov_len
= SIDEBAND_HEADER_SIZE
- n
;
135 if (!iov_valid(&sbb
->iov
))
140 n
-= SIDEBAND_HEADER_SIZE
;
141 assert(n
< sbb
->iov
.iov_len
);
142 iov
[0].iov_base
= sbb
->iov
.iov_base
+ n
;
143 iov
[0].iov_len
= sbb
->iov
.iov_len
- n
;
145 iov
[1].iov_base
= NULL
;
151 * Update the sideband context after data has been sent.
153 * \param c The sideband handle.
154 * \param nbytes The number of sent bytes.
156 * \return False if more data must be sent to complete the sideband transfer,
157 * true if the transfer is complete. In this case all resources are freed and
158 * the sideband handle must not be used any more.
160 bool sb_sent(struct sb_context
*c
, size_t nbytes
)
162 struct sb_buffer
*sbb
= &c
->sbb
;
163 size_t sz
= SIDEBAND_HEADER_SIZE
+ sbb
->iov
.iov_len
;
165 assert(c
->bytes_dispatched
+ nbytes
<= sz
);
166 c
->bytes_dispatched
+= nbytes
;
167 if (c
->bytes_dispatched
< sz
)
174 * Obtain a pointer to the next sideband read buffer.
176 * \param c The sideband handle.
177 * \param iov Result IO vector.
179 * This fills in \a iov to point to the buffer to which the next chunk of
180 * received data should be written.
182 void sb_get_recv_buffer(struct sb_context
*c
, struct iovec
*iov
)
184 struct sb_buffer
*sbb
= &c
->sbb
;
185 size_t n
= c
->bytes_dispatched
;
187 if (n
< SIDEBAND_HEADER_SIZE
) {
188 iov
->iov_base
= c
->header
+ n
;
189 iov
->iov_len
= SIDEBAND_HEADER_SIZE
- n
;
192 n
-= SIDEBAND_HEADER_SIZE
;
193 assert(sbb
->iov
.iov_base
);
194 assert(sbb
->iov
.iov_len
> n
);
195 iov
->iov_base
= sbb
->iov
.iov_base
+ n
;
196 iov
->iov_len
= sbb
->iov
.iov_len
- n
;
200 * Update the sideband context after data has been received.
202 * \param c The sideband handle.
203 * \param nbytes The number of bytes that have been received.
204 * \param result The received sideband packet.
206 * \return Negative on errors, zero if more data needs to be read to complete
207 * this sideband packet, one if the sideband packet has been received
210 * Only if the function returns one, the sideband buffer pointed to by \a
211 * result is set to point to the received data.
213 int sb_received(struct sb_context
*c
, size_t nbytes
, struct sb_buffer
*result
)
215 struct sb_buffer
*sbb
= &c
->sbb
;
216 size_t n
= c
->bytes_dispatched
,
217 sz
= SIDEBAND_HEADER_SIZE
+ sbb
->iov
.iov_len
;
219 assert(n
+ nbytes
<= sz
);
220 c
->bytes_dispatched
+= nbytes
;
221 if (c
->bytes_dispatched
< SIDEBAND_HEADER_SIZE
)
223 if (n
>= SIDEBAND_HEADER_SIZE
) { /* header has already been received */
224 if (c
->bytes_dispatched
< sz
) /* need to recv more body data */
226 /* received everything, decrypt and return sbb */
229 c
->trafo(&sbb
->iov
, &dst
, c
->trafo_context
);
230 if (sbb
->iov
.iov_base
!= dst
.iov_base
) {
231 free(sbb
->iov
.iov_base
);
232 sbb
->iov
.iov_base
= dst
.iov_base
;
235 ((char *)(sbb
->iov
.iov_base
))[sbb
->iov
.iov_len
] = '\0';
238 /* header has been received, decrypt and decode it */
239 if (c
->trafo
) { /* decrypt */
240 struct iovec dst
, src
= (typeof(src
)) {
241 .iov_base
= c
->header
,
242 .iov_len
= SIDEBAND_HEADER_SIZE
244 c
->trafo(&src
, &dst
, c
->trafo_context
);
245 if (src
.iov_base
!= dst
.iov_base
) {
246 memcpy(c
->header
, dst
.iov_base
,
247 SIDEBAND_HEADER_SIZE
);
251 /* Decode header, setup sbb */
252 sbb
->iov
.iov_len
= read_u32(c
->header
);
253 sbb
->band
= read_u8(c
->header
+ 4);
254 sbb
->iov
.iov_base
= NULL
;
255 if (sbb
->iov
.iov_len
== 0) /* zero-sized msg */
257 if (c
->max_size
> 0 && sbb
->iov
.iov_len
> c
->max_size
) {
258 PARA_ERROR_LOG("packet too big (is %zu, max %zu)\n",
259 sbb
->iov
.iov_len
, c
->max_size
);
260 return -E_SB_PACKET_SIZE
;
263 * We like to reserve one extra byte for the terminating NULL
264 * character. However, we must make sure the +1 below does not
267 if (sbb
->iov
.iov_len
== (size_t)-1)
268 return -E_SB_PACKET_SIZE
;
269 sbb
->iov
.iov_base
= para_malloc(sbb
->iov
.iov_len
+ 1);
270 return 0; /* ready to read body */