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haproxy/src/hpack-dec.c

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/*
* HPACK decompressor (RFC7541)
*
* Copyright (C) 2014-2017 Willy Tarreau <willy@haproxy.org>
* Copyright (C) 2017 HAProxy Technologies
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <import/ist.h>
#include <haproxy/chunk.h>
#include <haproxy/global.h>
#include <haproxy/h2.h>
#include <haproxy/hpack-dec.h>
#include <haproxy/hpack-huff.h>
#include <haproxy/hpack-tbl.h>
#include <haproxy/tools.h>
#if defined(DEBUG_HPACK)
#define hpack_debug_printf printf
#define hpack_debug_hexdump debug_hexdump
#else
#define hpack_debug_printf(...) do { } while (0)
#define hpack_debug_hexdump(...) do { } while (0)
#endif
/* reads a varint from <raw>'s lowest <b> bits and <len> bytes max (raw included).
* returns the 32-bit value on success after updating raw_in and len_in. Forces
* len_in to (uint32_t)-1 on truncated input.
*/
static uint32_t get_var_int(const uint8_t **raw_in, uint32_t *len_in, int b)
{
uint32_t ret = 0;
int len = *len_in;
const uint8_t *raw = *raw_in;
uint8_t shift = 0;
len--;
ret = *(raw++) & ((1 << b) - 1);
if (ret != (uint32_t)((1 << b) - 1))
goto end;
while (len && (*raw & 128)) {
ret += ((uint32_t)(*raw++) & 127) << shift;
shift += 7;
len--;
}
/* last 7 bits */
if (!len)
goto too_short;
len--;
ret += ((uint32_t)(*raw++) & 127) << shift;
end:
*raw_in = raw;
*len_in = len;
return ret;
too_short:
*len_in = (uint32_t)-1;
return 0;
}
/* returns the pseudo-header <idx> corresponds to among the following values :
* - 0 = unknown, the header's string needs to be used instead
* - 1 = ":authority"
* - 2 = ":method"
* - 3 = ":path"
* - 4 = ":scheme"
* - 5 = ":status"
*/
static inline int hpack_idx_to_phdr(uint32_t idx)
{
if (idx > 14)
return 0;
idx >>= 1;
idx <<= 2;
return (0x55554321U >> idx) & 0xF;
}
/* If <idx> designates a static header, returns <in>. Otherwise allocates some
* room from chunk <store> to duplicate <in> into it and returns the string
* allocated there. In case of allocation failure, returns a string whose
* pointer is NULL.
*/
static inline struct ist hpack_alloc_string(struct buffer *store, uint32_t idx,
struct ist in)
{
struct ist out;
if (idx < HPACK_SHT_SIZE)
return in;
out.len = in.len;
out.ptr = chunk_newstr(store);
if (unlikely(!isttest(out)))
return out;
if (unlikely(store->data + out.len > store->size)) {
out.ptr = NULL;
return out;
}
store->data += out.len;
memcpy(out.ptr, in.ptr, out.len);
return out;
}
/* decode an HPACK frame starting at <raw> for <len> bytes, using the dynamic
* headers table <dht>, produces the output into list <list> of <list_size>
* entries max, and uses pre-allocated buffer <tmp> for temporary storage (some
* list elements will point to it). Some <list> name entries may be made of a
* NULL pointer and a len, in which case they will designate a pseudo header
* index according to the values returned by hpack_idx_to_phdr() above. The
* number of <list> entries used is returned on success, or <0 on failure, with
* the opposite one of the HPACK_ERR_* codes. A last element is always zeroed
* and is not counted in the number of returned entries. This way the caller
* can use list[].n.len == 0 as a marker for the end of list.
*/
int hpack_decode_frame(struct hpack_dht *dht, const uint8_t *raw, uint32_t len,
struct http_hdr *list, int list_size,
struct buffer *tmp)
{
uint32_t idx;
uint32_t nlen;
uint32_t vlen;
uint8_t huff;
struct ist name;
struct ist value;
int must_index;
int ret;
hpack_debug_hexdump(stderr, "[HPACK-DEC] ", (const char *)raw, 0, len);
chunk_reset(tmp);
ret = 0;
while (len) {
int __maybe_unused code = *raw; /* first byte, only for debugging */
must_index = 0;
if (*raw >= 0x80) {
/* indexed header field */
if (*raw == 0x80) {
hpack_debug_printf("unhandled code 0x%02x (raw=%p, len=%u)\n", *raw, raw, len);
ret = -HPACK_ERR_UNKNOWN_OPCODE;
goto leave;
}
hpack_debug_printf("%02x: p14: indexed header field : ", code);
idx = get_var_int(&raw, &len, 7);
if (len == (uint32_t)-1) { // truncated
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TRUNCATED;
goto leave;
}
hpack_debug_printf(" idx=%u ", idx);
if (!hpack_valid_idx(dht, idx)) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
value = hpack_alloc_string(tmp, idx, hpack_idx_to_value(dht, idx));
if (!isttest(value)) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
/* here we don't index so we can always keep the pseudo header number */
name = ist2(NULL, hpack_idx_to_phdr(idx));
if (!name.len) {
name = hpack_alloc_string(tmp, idx, hpack_idx_to_name(dht, idx));
if (!isttest(name)) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
}
/* <name> and <value> are now set and point to stable values */
}
else if (*raw >= 0x20 && *raw <= 0x3f) {
/* max dyn table size change */
hpack_debug_printf("%02x: p18: dynamic table size update : ", code);
if (ret) {
/* 7541#4.2.1 : DHT size update must only be at the beginning */
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
idx = get_var_int(&raw, &len, 5);
if (len == (uint32_t)-1) { // truncated
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TRUNCATED;
goto leave;
}
hpack_debug_printf(" new len=%u\n", idx);
if (idx > dht->size) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_INVALID_ARGUMENT;
goto leave;
}
continue;
}
else if (!(*raw & (*raw - 0x10))) {
/* 0x00, 0x10, and 0x40 (0x20 and 0x80 were already handled above) */
/* literal header field without/never/with incremental indexing -- literal name */
if (*raw == 0x00)
hpack_debug_printf("%02x: p17: literal without indexing : ", code);
else if (*raw == 0x10)
hpack_debug_printf("%02x: p18: literal never indexed : ", code);
else if (*raw == 0x40)
hpack_debug_printf("%02x: p16: literal with indexing : ", code);
if (*raw == 0x40)
must_index = 1;
raw++; len--;
/* retrieve name */
if (!len) { // truncated
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TRUNCATED;
goto leave;
}
huff = *raw & 0x80;
nlen = get_var_int(&raw, &len, 7);
if (len == (uint32_t)-1 || len < nlen) { // truncated
hpack_debug_printf("##ERR@%d## (truncated): nlen=%d len=%d\n",
__LINE__, (int)nlen, (int)len);
ret = -HPACK_ERR_TRUNCATED;
goto leave;
}
name = ist2(raw, nlen);
raw += nlen;
len -= nlen;
if (huff) {
char *ntrash = chunk_newstr(tmp);
if (!ntrash) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
nlen = huff_dec((const uint8_t *)name.ptr, name.len, ntrash,
tmp->size - tmp->data);
if (nlen == (uint32_t)-1) {
hpack_debug_printf("2: can't decode huffman.\n");
ret = -HPACK_ERR_HUFFMAN;
goto leave;
}
hpack_debug_printf(" [name huff %d->%d] ", (int)name.len, (int)nlen);
tmp->data += nlen; // make room for the value
name = ist2(ntrash, nlen);
}
/* retrieve value */
if (!len) { // truncated
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TRUNCATED;
goto leave;
}
huff = *raw & 0x80;
vlen = get_var_int(&raw, &len, 7);
if (len == (uint32_t)-1 || len < vlen) { // truncated
hpack_debug_printf("##ERR@%d## : vlen=%d len=%d\n",
__LINE__, (int)vlen, (int)len);
ret = -HPACK_ERR_TRUNCATED;
goto leave;
}
value = ist2(raw, vlen);
raw += vlen;
len -= vlen;
if (huff) {
char *vtrash = chunk_newstr(tmp);
if (!vtrash) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
vlen = huff_dec((const uint8_t *)value.ptr, value.len, vtrash,
tmp->size - tmp->data);
if (vlen == (uint32_t)-1) {
hpack_debug_printf("3: can't decode huffman.\n");
ret = -HPACK_ERR_HUFFMAN;
goto leave;
}
hpack_debug_printf(" [value huff %d->%d] ", (int)value.len, (int)vlen);
tmp->data += vlen; // make room for the value
value = ist2(vtrash, vlen);
}
/* <name> and <value> are correctly filled here */
}
else {
/* 0x01..0x0f : literal header field without indexing -- indexed name */
/* 0x11..0x1f : literal header field never indexed -- indexed name */
/* 0x41..0x7f : literal header field with incremental indexing -- indexed name */
if (*raw <= 0x0f)
hpack_debug_printf("%02x: p16: literal without indexing -- indexed name : ", code);
else if (*raw >= 0x41)
hpack_debug_printf("%02x: p15: literal with indexing -- indexed name : ", code);
else
hpack_debug_printf("%02x: p16: literal never indexed -- indexed name : ", code);
/* retrieve name index */
if (*raw >= 0x41) {
must_index = 1;
idx = get_var_int(&raw, &len, 6);
}
else
idx = get_var_int(&raw, &len, 4);
hpack_debug_printf(" idx=%u ", idx);
if (len == (uint32_t)-1 || !len) { // truncated
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TRUNCATED;
goto leave;
}
if (!hpack_valid_idx(dht, idx)) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
/* retrieve value */
huff = *raw & 0x80;
vlen = get_var_int(&raw, &len, 7);
if (len == (uint32_t)-1 || len < vlen) { // truncated
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TRUNCATED;
goto leave;
}
value = ist2(raw, vlen);
raw += vlen;
len -= vlen;
if (huff) {
char *vtrash = chunk_newstr(tmp);
if (!vtrash) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
vlen = huff_dec((const uint8_t *)value.ptr, value.len, vtrash,
tmp->size - tmp->data);
if (vlen == (uint32_t)-1) {
hpack_debug_printf("##ERR@%d## can't decode huffman : ilen=%d osize=%d\n",
__LINE__, (int)value.len,
(int)(tmp->size - tmp->data));
hpack_debug_hexdump(stderr, "[HUFFMAN] ", value.ptr, 0, value.len);
ret = -HPACK_ERR_HUFFMAN;
goto leave;
}
tmp->data += vlen; // make room for the value
value = ist2(vtrash, vlen);
}
name = IST_NULL;
if (!must_index)
name.len = hpack_idx_to_phdr(idx);
if (!name.len) {
name = hpack_alloc_string(tmp, idx, hpack_idx_to_name(dht, idx));
if (!isttest(name)) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
}
/* <name> and <value> are correctly filled here */
}
/* We must not accept empty header names (forbidden by the spec and used
* as a list termination).
*/
if (!name.len) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_INVALID_ARGUMENT;
goto leave;
}
/* here's what we have here :
* - name.len > 0
* - value is filled with either const data or data allocated from tmp
* - name.ptr == NULL && !must_index : known pseudo-header #name.len
* - name.ptr != NULL || must_index : general header, unknown pseudo-header or index needed
*/
if (ret >= list_size) {
hpack_debug_printf("##ERR@%d##\n", __LINE__);
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
list[ret].n = name;
list[ret].v = value;
ret++;
if (must_index && hpack_dht_insert(dht, name, value) < 0) {
hpack_debug_printf("failed to find some room in the dynamic table\n");
ret = -HPACK_ERR_DHT_INSERT_FAIL;
goto leave;
}
hpack_debug_printf("\e[1;34m%s\e[0m: ",
isttest(name) ? istpad(trash.area, name).ptr : h2_phdr_to_str(name.len));
hpack_debug_printf("\e[1;35m%s\e[0m [mustidx=%d, used=%d] [n=(%p,%d) v=(%p,%d)]\n",
istpad(trash.area, value).ptr, must_index,
dht->used,
name.ptr, (int)name.len, value.ptr, (int)value.len);
}
if (ret >= list_size) {
ret = -HPACK_ERR_TOO_LARGE;
goto leave;
}
/* put an end marker */
list[ret].n = list[ret].v = IST_NULL;
ret++;
leave:
hpack_debug_printf("-- done: ret=%d list_size=%d --\n", (int)ret, (int)list_size);
return ret;
}
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