lsquic_packet_out.h revision c7d81ce1 
1/* Copyright (c) 2017 - 2019 LiteSpeed Technologies Inc.  See LICENSE. */
2/*
3 * lsquic_packet_out.h -- Structure and routines dealing with packet_out
4 */
5
6#ifndef LSQUIC_PACKET_OUT_H
7#define LSQUIC_PACKET_OUT_H 1
8
9#include <sys/queue.h>
10
11struct malo;
12struct lsquic_conn;
13struct lsquic_engine_public;
14struct lsquic_mm;
15struct lsquic_stream;
16struct parse_funcs;
17
18/* Each stream_rec is associated with one packet_out.  packet_out can have
19 * zero or more stream_rec structures.  stream_rec keeps a pointer to a stream
20 * that has STREAM or RST_STREAM frames inside packet_out.  `sr_frame_type'
21 * specifies the type of the frame; if this value is zero, values of the
22 * other struct members are not valid.  `sr_off' indicates where inside
23 * packet_out->po_data the frame begins and `sr_len' is its length.
24 *
25 * We need this information for three reasons:
26 *   1. A stream is not destroyed until all of its STREAM and RST_STREAM
27 *      frames are acknowledged.  This is to make sure that we do not exceed
28 *      maximum allowed number of streams.
29 *   2. When a packet is resubmitted, STREAM frames for a stream that has
30 *      been reset are not to be resubmitted.
31 *   3. A buffered packet may have to be split before it is scheduled (this
32 *      occurs if we guessed incorrectly the number of bytes required to
33 *      encode the packet number and the actual number would make packet
34 *      larger than the max).
35 *
36 */
37struct stream_rec {
38    struct lsquic_stream    *sr_stream;
39    unsigned short           sr_off,
40                             sr_len;
41    enum quic_frame_type     sr_frame_type:16;
42};
43
44#define srec_taken(srec) ((srec)->sr_frame_type)
45
46struct stream_rec_arr {
47    TAILQ_ENTRY(stream_rec_arr)     next_stream_rec_arr;
48    struct stream_rec               srecs[
49      ( 64                              /* Efficient size for malo allocator */
50      - sizeof(TAILQ_ENTRY(stream_rec)) /* next_stream_rec_arr */
51      ) / sizeof(struct stream_rec)
52    ];
53};
54
55TAILQ_HEAD(stream_rec_arr_tailq, stream_rec_arr);
56
57typedef struct lsquic_packet_out
58{
59    /* `po_next' is used for packets_out, unacked_packets and expired_packets
60     * lists.
61     */
62    TAILQ_ENTRY(lsquic_packet_out)
63                       po_next;
64    lsquic_time_t      po_sent;       /* Time sent */
65    lsquic_packno_t    po_packno;
66
67    enum packet_out_flags {
68        PO_HELLO    = (1 << 1),         /* Packet contains SHLO or CHLO data */
69        PO_ENCRYPTED= (1 << 3),         /* po_enc_data has encrypted data */
70        PO_SREC_ARR = (1 << 4),
71#define POBIT_SHIFT 5
72        PO_BITS_0   = (1 << 5),         /* PO_BITS_0 and PO_BITS_1 encode the */
73        PO_BITS_1   = (1 << 6),         /*   packet number length.  See macros below. */
74        PO_NONCE    = (1 << 7),         /* Use value in `po_nonce' to generate header */
75        PO_VERSION  = (1 << 8),         /* Use value in `po_ver_tag' to generate header */
76        PO_CONN_ID  = (1 << 9),         /* Include connection ID in public header */
77        PO_REPACKNO = (1 <<10),         /* Regenerate packet number */
78        PO_NOENCRYPT= (1 <<11),         /* Do not encrypt data in po_data */
79        PO_VERNEG   = (1 <<12),         /* Version negotiation packet. */
80        PO_STREAM_END
81                    = (1 <<13),         /* STREAM frame reaches the end of the packet: no
82                                         * further writes are allowed.
83                                         */
84        PO_SCHED    = (1 <<14),         /* On scheduled queue */
85        PO_SENT_SZ  = (1 <<15),
86        PO_LONGHEAD = (1 <<16),
87        PO_GQUIC    = (1 <<17),         /* Used for logging */
88#define POLEV_SHIFT 18
89        PO_BITS_2   = (1 <<18),         /* PO_BITS_2 and PO_BITS_3 encode the */
90        PO_BITS_3   = (1 <<19),         /*   crypto level.  Used for logging. */
91#define POIPv6_SHIFT 20
92        PO_IPv6     = (1 <<20),         /* Set if pmi_allocate was passed is_ipv6=1,
93                                         *   otherwise unset.
94                                         */
95        PO_LIMITED  = (1 <<21),         /* Used to credit sc_next_limit if needed. */
96    }                  po_flags;
97    enum quic_ft_bit   po_frame_types:16; /* Bitmask of QUIC_FRAME_* */
98    unsigned short     po_data_sz;      /* Number of usable bytes in data */
99    unsigned short     po_enc_data_sz;  /* Number of usable bytes in data */
100    unsigned short     po_sent_sz;      /* If PO_SENT_SZ is set, real size of sent buffer. */
101    unsigned short     po_regen_sz;     /* Number of bytes at the beginning
102                                         * of data containing bytes that are
103                                         * not to be retransmitted, e.g. ACK
104                                         * frames.
105                                         */
106    unsigned short     po_n_alloc;      /* Total number of bytes allocated in po_data */
107    enum header_type   po_header_type:8;
108    unsigned char     *po_data;
109    lsquic_packno_t    po_ack2ed;       /* If packet has ACK frame, value of
110                                         * largest acked in it.
111                                         */
112
113    /* A lot of packets contain data belonging to only one stream.  Thus,
114     * `one' is used first.  If this is not enough, any number of
115     * stream_rec_arr structures can be allocated to handle more stream
116     * records.
117     */
118    union {
119        struct stream_rec               one;
120        struct stream_rec_arr_tailq     arr;
121    }                  po_srecs;
122
123    /* If PO_ENCRYPTED is set, this points to the buffer that holds encrypted
124     * data.
125     */
126    unsigned char     *po_enc_data;
127
128    lsquic_ver_tag_t   po_ver_tag;      /* Set if PO_VERSION is set */
129    unsigned char     *po_nonce;        /* Use to generate header if PO_NONCE is set */
130} lsquic_packet_out_t;
131
132/* The size of lsquic_packet_out_t could be further reduced:
133 *
134 * po_ver_tag could be encoded as a few bits representing enum lsquic_version
135 * in po_flags.  The cost is a bit of complexity.  This will save us four bytes.
136 */
137
138#define lsquic_packet_out_avail(p) ((unsigned short) \
139                                        ((p)->po_n_alloc - (p)->po_data_sz))
140
141#define lsquic_packet_out_packno_bits(p) (((p)->po_flags >> POBIT_SHIFT) & 0x3)
142
143#define lsquic_packet_out_set_packno_bits(p, b) do {                    \
144    (p)->po_flags &= ~(0x3 << POBIT_SHIFT);                             \
145    (p)->po_flags |= ((b) & 0x3) << POBIT_SHIFT;                        \
146} while (0)
147
148#define lsquic_packet_out_ipv6(p) ((int)(((p)->po_flags >> POIPv6_SHIFT) & 1))
149
150#define lsquic_packet_out_set_ipv6(p, b) do {                           \
151    (p)->po_flags &= ~(1 << POIPv6_SHIFT);                              \
152    (p)->po_flags |= ((b) & 1) << POIPv6_SHIFT;                         \
153} while (0)
154
155#define lsquic_po_header_length(lconn, po_flags) ( \
156    lconn->cn_pf->pf_packout_header_size(lconn, po_flags))
157
158#define lsquic_packet_out_total_sz(lconn, p) (\
159    lconn->cn_pf->pf_packout_size(lconn, p))
160
161#if __GNUC__
162#if LSQUIC_EXTRA_CHECKS
163#define lsquic_packet_out_sent_sz(lconn, p) (                               \
164        __builtin_expect(((p)->po_flags & PO_SENT_SZ), 1) ?                 \
165        (assert((p)->po_sent_sz == lsquic_packet_out_total_sz(lconn, p)),   \
166            (p)->po_sent_sz) : lsquic_packet_out_total_sz(lconn, p))
167#   else
168#define lsquic_packet_out_sent_sz(lconn, p) (                               \
169        __builtin_expect(((p)->po_flags & PO_SENT_SZ), 1) ?                 \
170        (p)->po_sent_sz : lsquic_packet_out_total_sz(lconn, p))
171#endif
172#else
173#   define lsquic_packet_out_sent_sz(lconn, p) (                            \
174        (p)->po_flags & PO_SENT_SZ ?                                        \
175        (p)->po_sent_sz : lsquic_packet_out_total_sz(lconn, p))
176#endif
177
178#define lsquic_packet_out_verneg(p) \
179    (((p)->po_flags & (PO_NOENCRYPT|PO_VERNEG)) == (PO_NOENCRYPT|PO_VERNEG))
180
181#define lsquic_packet_out_pubres(p) \
182    (((p)->po_flags & (PO_NOENCRYPT|PO_VERNEG)) ==  PO_NOENCRYPT           )
183
184#define lsquic_packet_out_set_enc_level(p, level) do {                      \
185    (p)->po_flags &= ~(3 << POLEV_SHIFT);                                   \
186    (p)->po_flags |= level << POLEV_SHIFT;                                  \
187} while (0)
188
189#define lsquic_packet_out_enc_level(p)  (((p)->po_flags >> POLEV_SHIFT) & 3)
190
191struct packet_out_srec_iter {
192    lsquic_packet_out_t         *packet_out;
193    struct stream_rec_arr       *cur_srec_arr;
194    unsigned                     srec_idx;
195    int                          impl_idx;
196};
197
198struct stream_rec *
199posi_first (struct packet_out_srec_iter *posi, lsquic_packet_out_t *);
200
201struct stream_rec *
202posi_next (struct packet_out_srec_iter *posi);
203
204lsquic_packet_out_t *
205lsquic_packet_out_new (struct lsquic_mm *, struct malo *, int use_cid,
206                       const struct lsquic_conn *, enum packno_bits,
207                       const lsquic_ver_tag_t *, const unsigned char *nonce);
208
209void
210lsquic_packet_out_destroy (lsquic_packet_out_t *,
211                        struct lsquic_engine_public *, void *peer_ctx);
212
213int
214lsquic_packet_out_add_stream (lsquic_packet_out_t *packet_out,
215                              struct lsquic_mm *mm,
216                              struct lsquic_stream *new_stream,
217                              enum quic_frame_type,
218                              unsigned short off, unsigned short len);
219
220unsigned
221lsquic_packet_out_elide_reset_stream_frames (lsquic_packet_out_t *, uint32_t);
222
223int
224lsquic_packet_out_split_in_two (struct lsquic_mm *, lsquic_packet_out_t *,
225    lsquic_packet_out_t *, const struct parse_funcs *, unsigned excess_bytes);
226
227void
228lsquic_packet_out_chop_regen (lsquic_packet_out_t *);
229
230void
231lsquic_packet_out_ack_streams (struct lsquic_packet_out *);
232
233void
234lsquic_packet_out_zero_pad (struct lsquic_packet_out *);
235
236size_t
237lsquic_packet_out_mem_used (const struct lsquic_packet_out *);
238
239int
240lsquic_packet_out_turn_on_fin (struct lsquic_packet_out *,
241                   const struct parse_funcs *, const struct lsquic_stream *);
242
243#endif
244