diff options
Diffstat (limited to 'bittorrent/bittorrent/libs/mbtbe/src/decode.c')
| -rw-r--r-- | bittorrent/bittorrent/libs/mbtbe/src/decode.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/bittorrent/bittorrent/libs/mbtbe/src/decode.c b/bittorrent/bittorrent/libs/mbtbe/src/decode.c new file mode 100644 index 0000000..875f0db --- /dev/null +++ b/bittorrent/bittorrent/libs/mbtbe/src/decode.c @@ -0,0 +1,220 @@ +#include <mbt/be/bencode.h> +#include <mbt/utils/utils.h> +#include <mbt/utils/view.h> + +// libc +#include <ctype.h> +#include <stdlib.h> + +#define MBT_INT64_MAX_ULL 9223372036854775807LLU + +static inline bool mbt_be_consume(struct mbt_cview *buf, char expected); +static inline bool mbt_be_parse_u64(struct mbt_cview *buf, uint64_t *val, + char end); +static inline bool mbt_be_parse_i64(struct mbt_cview *buf, int64_t *val); +static inline bool mbt_be_parse_str(struct mbt_cview *buf, struct mbt_str *str); +static inline struct mbt_be_node *mbt_be_decode_rec(struct mbt_cview *buf); +static inline struct mbt_be_node *mbt_be_decode_num(struct mbt_cview *buf); +static inline struct mbt_be_node *mbt_be_decode_str(struct mbt_cview *buf); +static inline struct mbt_be_node *mbt_be_decode_list(struct mbt_cview *buf); +static inline struct mbt_be_node *mbt_be_decode_dict(struct mbt_cview *buf); + +struct mbt_be_node *mbt_be_decode(struct mbt_cview *buf) +{ + struct mbt_cview copy = *buf; + struct mbt_be_node *res = mbt_be_decode_rec(©); + if (!res) + return NULL; + *buf = copy; + return res; +} + +static inline bool mbt_be_consume(struct mbt_cview *buf, char expected) +{ + if (!buf->size || *buf->data != expected) + return false; + *buf = MBT_CVIEW_SUB(*buf, 1); + return true; +} + +static inline bool mbt_be_parse_u64(struct mbt_cview *buf, uint64_t *val, + char end) +{ + uint64_t v = 0; + if (!buf->size || *buf->data == end + || (*buf->data == '0' && (buf->size == 1 || buf->data[1] != end))) + return false; + for (; !mbt_be_consume(buf, end); *buf = MBT_CVIEW_SUB(*buf, 1)) + { + if (!buf->size || !isdigit(*buf->data)) + return false; + if (__builtin_mul_overflow(v, 10, &v)) + return false; + unsigned char c = *buf->data - '0'; + if (__builtin_add_overflow(v, c, &v)) + return false; + } + *val = v; + return true; +} + +static inline bool mbt_be_parse_i64(struct mbt_cview *buf, int64_t *val) +{ + bool neg = mbt_be_consume(buf, '-'); + uint64_t v; + if (!mbt_be_parse_u64(buf, &v, 'e')) + return false; + if ((v == 0 && neg) || v > MBT_INT64_MAX_ULL + (neg ? 1ull : 0ull)) + return false; + if (v == MBT_INT64_MAX_ULL + 1ull) + *val = INT64_MIN; + else if (neg) + *val = -v; + else + *val = v; + return true; +} + +static inline bool mbt_be_parse_str(struct mbt_cview *buf, struct mbt_str *str) +{ + uint64_t len; + if (!mbt_be_parse_u64(buf, &len, ':')) + return false; + + if (!mbt_str_pushcv(str, MBT_CVIEW(buf->data, len))) + return false; + + *buf = MBT_CVIEW_SUB(*buf, len); + return true; +} + +static inline struct mbt_be_node *mbt_be_decode_rec(struct mbt_cview *buf) +{ + if (!buf->size) + return NULL; + switch (*buf->data) + { + case 'i': + *buf = MBT_CVIEW_SUB(*buf, 1); + return mbt_be_decode_num(buf); + case 'd': + *buf = MBT_CVIEW_SUB(*buf, 1); + return mbt_be_decode_dict(buf); + case 'l': + *buf = MBT_CVIEW_SUB(*buf, 1); + return mbt_be_decode_list(buf); + default: + return mbt_be_decode_str(buf); + } +} + +static inline struct mbt_be_node *mbt_be_decode_num(struct mbt_cview *buf) +{ + int64_t val; + if (!mbt_be_parse_i64(buf, &val)) + return NULL; + + return mbt_be_num_init(val); +} + +static inline struct mbt_be_node *mbt_be_decode_str(struct mbt_cview *buf) +{ + struct mbt_be_node *bn = mbt_be_str_init(MBT_CVIEW(NULL, 0)); + if (!bn) + return NULL; + + if (!mbt_be_parse_str(buf, &bn->v.str)) + { + mbt_be_free(bn); + return NULL; + } + + return bn; +} + +static inline struct mbt_be_node *mbt_be_decode_list(struct mbt_cview *buf) +{ + struct mbt_be_node *bn = mbt_be_list_init(NULL); + if (!bn) + return NULL; + size_t nb_elements = 0; + bn->v.list = calloc(1, sizeof(struct mbt_be_node *)); + if (!bn->v.list) + { + free(bn); + return NULL; + } + + for (; !mbt_be_consume(buf, 'e'); ++nb_elements) + { + struct mbt_be_node **ptr = realloc( + bn->v.list, (nb_elements + 2) * sizeof(struct mbt_be_node *)); + if (!bn->v.list) + { + mbt_be_free(bn); + return NULL; + } + bn->v.list = ptr; + bn->v.list[nb_elements + 1] = NULL; + + bn->v.list[nb_elements] = mbt_be_decode_rec(buf); + if (!bn->v.list[nb_elements]) + { + mbt_be_free(bn); + return NULL; + } + } + + bn->v.list[nb_elements] = NULL; + return bn; +} + +static inline struct mbt_be_node *mbt_be_decode_dict(struct mbt_cview *buf) +{ + struct mbt_be_node *bn = mbt_be_dict_init(NULL); + if (!bn) + return NULL; + + size_t nb_elements = 0; + bn->v.dict = calloc(1, sizeof(struct mbt_be_pair *)); + if (!bn->v.dict) + { + free(bn); + return NULL; + } + + for (; !mbt_be_consume(buf, 'e'); ++nb_elements) + { + struct mbt_be_pair **ptr = realloc( + bn->v.dict, (nb_elements + 2) * sizeof(struct mbt_be_pair *)); + if (!ptr) + { + mbt_be_free(bn); + return NULL; + } + bn->v.dict = ptr; + bn->v.dict[nb_elements + 1] = NULL; + + bn->v.dict[nb_elements] = calloc(1, sizeof(**ptr)); + if (!bn->v.dict[nb_elements]) + { + mbt_be_free(bn); + return NULL; + } + + if (!mbt_be_parse_str(buf, &bn->v.dict[nb_elements]->key)) + { + mbt_be_free(bn); + return NULL; + } + + bn->v.dict[nb_elements]->val = mbt_be_decode_rec(buf); + if (!bn->v.dict[nb_elements]->val) + { + mbt_be_free(bn); + return NULL; + } + } + + return bn; +} |