From b46aad6df449445a9fc4aa7b32bd40005438e3f7 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 13 Apr 2024 14:18:05 +0200 Subject: Adding upstream version 2.9.5. Signed-off-by: Daniel Baumann --- dev/hpack/gen-enc.c | 205 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 205 insertions(+) create mode 100644 dev/hpack/gen-enc.c (limited to 'dev/hpack/gen-enc.c') diff --git a/dev/hpack/gen-enc.c b/dev/hpack/gen-enc.c new file mode 100644 index 0000000..3fc5ef9 --- /dev/null +++ b/dev/hpack/gen-enc.c @@ -0,0 +1,205 @@ +/* + * HPACK encoding table generator. It produces a stream of + * and a table pointing to the first of each series. + * The end of the stream is marked by =0. In parallel, a length-indexed + * table is built to access the first entry of each length. + * + * Build like this : + * gcc -I../../include -o gen-enc gen-enc.c + */ +#define HPACK_STANDALONE + +#include +#include +#include +#include +#include +#include +#include +#include "../../src/hpack-tbl.c" + +struct idxhdr { + const char *ptr; + int len; + int idx; +}; + +struct idxhdr idxhdr[HPACK_SHT_SIZE]; +static int positions[32]; +static char known_hdr[1024]; + +/* preferred ordering of headers of similar size. Those not mentioned will be + * less prioritized. + */ +const struct { + const char *name; + const int rank; +} ranks[] = { + { .name = "age", .rank = 1 }, + { .name = "via", .rank = 2 }, + + { .name = "date", .rank = 1 }, + { .name = "host", .rank = 2 }, + + { .name = "accept", .rank = 1 }, + { .name = "server", .rank = 2 }, + { .name = "cookie", .rank = 3 }, + + { .name = "referer", .rank = 1 }, + { .name = "expires", .rank = 2 }, + + { .name = "location", .rank = 1 }, + + { .name = "user-agent", .rank = 1 }, + { .name = "set-cookie", .rank = 2 }, + + { .name = "content-type", .rank = 1 }, + + { .name = "cache-control", .rank = 1 }, + { .name = "last-modified", .rank = 2 }, + { .name = "accept-ranges", .rank = 3 }, + { .name = "if-none-match", .rank = 4 }, + + { .name = "content-length", .rank = 1 }, + + { .name = "accept-encoding", .rank = 1 }, + { .name = "accept-language", .rank = 2 }, + + { .name = "content-encoding", .rank = 1 }, + + { .name = "transfer-encoding", .rank = 1 }, + { .name = "if-modified-since", .rank = 2 }, + + { .name = "content-disposition", .rank = 1 }, +}; + +/* returns the rank of header or 255 if not found */ +int get_hdr_rank(const char *name) +{ + int i; + + for (i = 0; i < sizeof(ranks) / sizeof(ranks[0]); i++) { + if (strcmp(ranks[i].name, name) == 0) + return ranks[i].rank; + } + return 255; +} + +/* sorts first on the length, second on the name, and third on the idx, so that + * headers which appear with multiple occurrences are always met first. + */ +int cmp_idx(const void *l, const void *r) +{ + const struct idxhdr *a = l, *b = r; + int ranka, rankb; + int ret; + + if (a->len < b->len) + return -1; + else if (a->len > b->len) + return 1; + + ranka = get_hdr_rank(a->ptr); + rankb = get_hdr_rank(b->ptr); + + if (ranka < rankb) + return -1; + else if (ranka > rankb) + return 1; + + /* same rank, check for duplicates and use index */ + ret = strcmp(a->ptr, b->ptr); + if (ret != 0) + return ret; + + if (a->idx < b->idx) + return -1; + else if (a->idx > b->idx) + return 1; + else + return 0; +} + +int main(int argc, char **argv) +{ + int pos; + int prev; + int len; + int i; + + for (len = 0; len < 32; len++) + positions[len] = -1; + + for (i = 0; i < HPACK_SHT_SIZE; i++) { + idxhdr[i].ptr = hpack_sht[i].n.ptr; + idxhdr[i].len = hpack_sht[i].n.len; + idxhdr[i].idx = i; + } + + /* sorts all header names by length first, then by name, and finally by + * idx so that we meet smaller headers first, that within a length they + * appear in frequency order, and that multiple occurrences appear with + * the smallest index first. + */ + qsort(&idxhdr[1], HPACK_SHT_SIZE - 1, sizeof(idxhdr[0]), cmp_idx); + + pos = 0; + prev = -1; + for (i = 1; i < HPACK_SHT_SIZE; i++) { + len = idxhdr[i].len; + if (len > 31) { + //printf("skipping %s (len=%d)\n", idxhdr[i].ptr, idxhdr[i].len); + continue; + } + + /* first occurrence of this length? */ + if (positions[len] == -1) + positions[len] = pos; + else if (prev >= 0 && + memcmp(&known_hdr[prev] + 2, idxhdr[i].ptr, len) == 0) { + /* duplicate header field */ + continue; + } + + /* store in the output array */ + + if (pos + 1 + len + 2 >= sizeof(known_hdr)) + abort(); + + prev = pos; + known_hdr[pos++] = len; + known_hdr[pos++] = idxhdr[i].idx; + memcpy(&known_hdr[pos], idxhdr[i].ptr, len); + pos += len; + //printf("%d %d %s\n", len, idxhdr[i].idx, idxhdr[i].ptr); + } + + if (pos + 1 >= sizeof(known_hdr)) + abort(); + known_hdr[pos++] = 0; // size zero ends the stream + + printf("const char hpack_enc_stream[%d] = {\n", pos); + for (i = 0; i < pos; i++) { + if ((i & 7) == 0) + printf("\t /* % 4d: */", i); + + printf(" 0x%02x,", known_hdr[i]); + + if ((i & 7) == 7 || (i == pos - 1)) + putchar('\n'); + } + printf("};\n\n"); + + printf("const signed short hpack_pos_len[32] = {\n"); + for (i = 0; i < 32; i++) { + if ((i & 7) == 0) + printf("\t /* % 4d: */", i); + + printf(" % 4d,", positions[i]); + + if ((i & 7) == 7 || (i == pos - 1)) + putchar('\n'); + } + printf("};\n\n"); + return 0; +} -- cgit v1.2.3