1 /*
2  * ngtcp2
3  *
4  * Copyright (c) 2017 ngtcp2 contributors
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining
7  * a copy of this software and associated documentation files (the
8  * "Software"), to deal in the Software without restriction, including
9  * without limitation the rights to use, copy, modify, merge, publish,
10  * distribute, sublicense, and/or sell copies of the Software, and to
11  * permit persons to whom the Software is furnished to do so, subject to
12  * the following conditions:
13  *
14  * The above copyright notice and this permission notice shall be
15  * included in all copies or substantial portions of the Software.
16  *
17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
21  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
22  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
23  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
24  */
25 #ifndef NGTCP2_PPE_H
26 #define NGTCP2_PPE_H
27 
28 #ifdef HAVE_CONFIG_H
29 #  include <config.h>
30 #endif /* HAVE_CONFIG_H */
31 
32 #include <ngtcp2/ngtcp2.h>
33 
34 #include "ngtcp2_pkt.h"
35 #include "ngtcp2_buf.h"
36 #include "ngtcp2_crypto.h"
37 
38 /*
39  * ngtcp2_ppe is the Protected Packet Encoder.
40  */
41 typedef struct ngtcp2_ppe {
42   ngtcp2_buf buf;
43   ngtcp2_crypto_cc *cc;
44   /* hdlen is the number of bytes for packet header written in buf. */
45   size_t hdlen;
46   /* len_offset is the offset to Length field. */
47   size_t len_offset;
48   /* pkt_num_offset is the offset to packet number field. */
49   size_t pkt_num_offset;
50   /* pkt_numlen is the number of bytes used to encode a packet
51      number */
52   size_t pkt_numlen;
53   /* sample_offset is the offset to sample for packet number
54      encryption. */
55   size_t sample_offset;
56   /* pkt_num is the packet number written in buf. */
57   int64_t pkt_num;
58   /* nonce is the buffer to store nonce.  It should be equal or longer
59      than then length of IV. */
60   uint8_t nonce[32];
61 } ngtcp2_ppe;
62 
63 /*
64  * ngtcp2_ppe_init initializes |ppe| with the given buffer.
65  */
66 void ngtcp2_ppe_init(ngtcp2_ppe *ppe, uint8_t *out, size_t outlen,
67                      ngtcp2_crypto_cc *cc);
68 
69 /*
70  * ngtcp2_ppe_encode_hd encodes |hd|.
71  *
72  * This function returns 0 if it succeeds, or one of the following
73  * negative error codes:
74  *
75  * NGTCP2_ERR_NOBUF
76  *     The buffer is too small.
77  */
78 int ngtcp2_ppe_encode_hd(ngtcp2_ppe *ppe, const ngtcp2_pkt_hd *hd);
79 
80 /*
81  * ngtcp2_ppe_encode_frame encodes |fr|.
82  *
83  * This function returns 0 if it succeeds, or one of the following
84  * negative error codes:
85  *
86  * NGTCP2_ERR_NOBUF
87  *     The buffer is too small.
88  */
89 int ngtcp2_ppe_encode_frame(ngtcp2_ppe *ppe, ngtcp2_frame *fr);
90 
91 /*
92  * ngtcp2_ppe_final encrypts QUIC packet payload.  If |**ppkt| is not
93  * NULL, the pointer to the packet is assigned to it.
94  *
95  * This function returns the length of QUIC packet, including header,
96  * and payload if it succeeds, or one of the following negative error
97  * codes:
98  *
99  * NGTCP2_ERR_CALLBACK_FAILURE
100  *     User-defined callback function failed.
101  */
102 ngtcp2_ssize ngtcp2_ppe_final(ngtcp2_ppe *ppe, const uint8_t **ppkt);
103 
104 /*
105  * ngtcp2_ppe_left returns the number of bytes left to write
106  * additional frames.  This does not count AEAD overhead.
107  */
108 size_t ngtcp2_ppe_left(ngtcp2_ppe *ppe);
109 
110 /*
111  * ngtcp2_ppe_pktlen returns the provisional packet length.  It
112  * includes AEAD overhead.
113  */
114 size_t ngtcp2_ppe_pktlen(ngtcp2_ppe *ppe);
115 
116 /**
117  * @function
118  *
119  * `ngtcp2_ppe_padding` encodes PADDING frames to the end of the
120  * buffer.  This function returns the number of bytes padded.
121  */
122 size_t ngtcp2_ppe_padding(ngtcp2_ppe *ppe);
123 
124 /*
125  * ngtcp2_ppe_padding_hp_sample adds PADDING frame if the current
126  * payload does not have enough space for header protection sample.
127  * This function should be called just before calling
128  * ngtcp2_ppe_final().
129  *
130  * This function returns the number of bytes added as padding.
131  */
132 size_t ngtcp2_ppe_padding_hp_sample(ngtcp2_ppe *ppe);
133 
134 /*
135  * ngtcp2_ppe_padding_size adds PADDING frame so that the size of QUIC
136  * packet is at least |n| bytes long.  If it is unable to add PADDING
137  * in that way, this function still adds PADDING frame as much as
138  * possible.  This function should be called just before calling
139  * ngtcp2_ppe_final().  For Short packet, this function should be
140  * called instead of ngtcp2_ppe_padding_hp_sample.
141  *
142  * This function returns the number of bytes added as padding.
143  */
144 size_t ngtcp2_ppe_padding_size(ngtcp2_ppe *ppe, size_t n);
145 
146 /*
147  * ngtcp2_ppe_ensure_hp_sample returns nonzero if the buffer has
148  * enough space for header protection sample.  This should be called
149  * right after packet header is written.
150  */
151 int ngtcp2_ppe_ensure_hp_sample(ngtcp2_ppe *ppe);
152 
153 #endif /* NGTCP2_PPE_H */
154