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HTTP3: Huffman decoding 

Add Huffman decoding from libngttp2 library (MIT licensed),
and use it in HTTP/3 to display the decoded QPACK bytes.
(HTTP/2 and HTTP/3 use the same Huffman encoding.) These
files are not part of the public libnghttp2 library but
normally internal.

Note that libnghttp3 does not supply a function to inflate
headers like nghttp2_hd_inflate_h2.

Related to #16761
This commit is contained in:
John Thacker 2023-12-10 23:34:17 -05:00 committed by AndersBroman
parent c3c0fb7263
commit 79c6e9db9d
6 changed files with 5124 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
epan/CMakeLists.txt
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@ -107,6 +107,7 @@ set(LIBWIRESHARK_PUBLIC_HEADERS
maxmind_db.h
media_params.h
next_tvb.h
nghttp2_hd_huffman.h
nlpid.h
oids.h
osi-utils.h
@ -216,6 +217,7 @@ set(LIBWIRESHARK_NONGENERATED_FILES
maxmind_db.c
media_params.c
next_tvb.c
nghttp2_hd_huffman_data.c
oids.c
osi-utils.c
packet.c
@ -253,6 +255,7 @@ set(LIBWIRESHARK_NONGENERATED_FILES
tvbuff_base64.c
tvbuff_brotli.c
tvbuff_composite.c
tvbuff_hpackhuff.c
tvbuff_real.c
tvbuff_subset.c
tvbuff_zlib.c

19
epan/dissectors/packet-http3.c
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@ -1606,6 +1606,7 @@ dissect_http3_qpack_encoder_stream(tvbuff_t *tvb, packet_info *pinfo _U_, proto_
guint remaining;
proto_item *opcode_ti;
proto_tree *opcode_tree;
tvbuff_t *decoded_tvb;
guint decoded = 0;
gint fin = 0, inc = 0;
volatile bool can_continue = true;
@ -1663,6 +1664,12 @@ dissect_http3_qpack_encoder_stream(tvbuff_t *tvb, packet_info *pinfo _U_, proto_
if (value_huffman) {
proto_tree_add_item(opcode_tree, hf_http3_qpack_encoder_opcode_insert_indexed_hval, tvb,
val_bytes_offset, (guint32)val_bytes_len, ENC_NA);
decoded_tvb = tvb_child_uncompress_hpack_huff(tvb, (int)val_bytes_offset, (int)val_bytes_len);
if (decoded_tvb) {
add_new_data_source(pinfo, decoded_tvb, "Decoded QPACK Value");
proto_tree_add_item(opcode_tree, hf_http3_qpack_encoder_opcode_insert_indexed_val, decoded_tvb,
0, tvb_captured_length(decoded_tvb), ENC_NA);
}
} else {
proto_tree_add_item(opcode_tree, hf_http3_qpack_encoder_opcode_insert_indexed_val, tvb,
val_bytes_offset, (guint32)val_bytes_len, ENC_NA);
@ -1724,6 +1731,12 @@ dissect_http3_qpack_encoder_stream(tvbuff_t *tvb, packet_info *pinfo _U_, proto_
if (name_huffman) {
proto_tree_add_item(opcode_tree, hf_http3_qpack_encoder_opcode_insert_hname, tvb, name_bytes_offset,
(guint32)name_bytes_len, ENC_NA);
decoded_tvb = tvb_child_uncompress_hpack_huff(tvb, (int)name_bytes_offset, (int)name_bytes_len);
if (decoded_tvb) {
add_new_data_source(pinfo, decoded_tvb, "Decoded QPACK Name");
proto_tree_add_item(opcode_tree, hf_http3_qpack_encoder_opcode_insert_name, decoded_tvb,
0, tvb_captured_length(decoded_tvb), ENC_NA);
}
} else {
proto_tree_add_item(opcode_tree, hf_http3_qpack_encoder_opcode_insert_name, tvb, name_bytes_offset,
(guint32)name_bytes_len, ENC_NA);
@ -1732,6 +1745,12 @@ dissect_http3_qpack_encoder_stream(tvbuff_t *tvb, packet_info *pinfo _U_, proto_
if (value_huffman) {
proto_tree_add_item(opcode_tree, hf_http3_qpack_encoder_opcode_insert_hval, tvb, val_bytes_offset,
(guint32)val_bytes_len, ENC_NA);
decoded_tvb = tvb_child_uncompress_hpack_huff(tvb, (int)val_bytes_offset, (int)val_bytes_len);
if (decoded_tvb) {
add_new_data_source(pinfo, decoded_tvb, "Decoded QPACK Value");
proto_tree_add_item(opcode_tree, hf_http3_qpack_encoder_opcode_insert_val, decoded_tvb,
0, tvb_captured_length(decoded_tvb), ENC_NA);
}
} else {
proto_tree_add_item(opcode_tree, hf_http3_qpack_encoder_opcode_insert_val, tvb, val_bytes_offset,
(guint32)val_bytes_len, ENC_NA);

54
epan/nghttp2_hd_huffman.h Normal file
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@ -0,0 +1,54 @@
/* @file
* nghttp2 - HTTP/2 C Library
*
* Copyright (c) 2013 Tatsuhiro Tsujikawa
*
* SPDX-License-Identifier: MIT
*/
#ifndef NGHTTP2_HD_HUFFMAN_H
#define NGHTTP2_HD_HUFFMAN_H
#include <config.h>
#include <stdlib.h>
#include <stdint.h>
typedef enum {
/* FSA accepts this state as the end of huffman encoding
sequence. */
NGHTTP2_HUFF_ACCEPTED = 1 << 14,
/* This state emits symbol */
NGHTTP2_HUFF_SYM = 1 << 15,
} nghttp2_huff_decode_flag;
typedef struct {
/* fstate is the current huffman decoding state, which is actually
the node ID of internal huffman tree with
nghttp2_huff_decode_flag OR-ed. We have 257 leaf nodes, but they
are identical to root node other than emitting a symbol, so we
have 256 internal nodes [1..255], inclusive. The node ID 256 is
a special node and it is a terminal state that means decoding
failed. */
uint16_t fstate;
/* symbol if NGHTTP2_HUFF_SYM flag set */
uint8_t sym;
} nghttp2_huff_decode;
typedef nghttp2_huff_decode huff_decode_table_type[16];
typedef struct {
/* fstate is the current huffman decoding state. */
uint16_t fstate;
} nghttp2_hd_huff_decode_context;
typedef struct {
/* The number of bits in this code */
uint32_t nbits;
/* Huffman code aligned to LSB */
uint32_t code;
} nghttp2_huff_sym;
extern const nghttp2_huff_sym huff_sym_table[];
extern const nghttp2_huff_decode huff_decode_table[][16];
#endif /* NGHTTP2_HD_HUFFMAN_H */

4963
epan/nghttp2_hd_huffman_data.c Normal file
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File diff suppressed because it is too large Load Diff

9
epan/tvbuff.h
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@ -1226,6 +1226,15 @@ extern tvbuff_t* base64_to_tvb(tvbuff_t *parent, const char *base64);
extern tvbuff_t* base64_tvb_to_new_tvb(tvbuff_t* parent, int offset, int length);
extern tvbuff_t* base64uri_tvb_to_new_tvb(tvbuff_t* parent, int offset, int length);
/* From tvbuff_hpackhuff.c */
WS_DLL_PUBLIC wmem_strbuf_t* tvb_get_hpack_huffman_strbuf(wmem_allocator_t *scope,
tvbuff_t *tvb, const int offset, const int len);
WS_DLL_PUBLIC tvbuff_t* tvb_child_uncompress_hpack_huff(tvbuff_t *parent,
int offset, int length);
/**
* Extract a variable length integer from a tvbuff.
* Each byte in a varint, except the last byte, has the most significant bit (msb)

76
epan/tvbuff_hpackhuff.c Normal file
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@ -0,0 +1,76 @@
/* @file
* Decompression of the Huffman encoding used for HTTP fields in HPACK (HTTP/2)
* and QPACK (HTTP/3)
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/tvbuff.h>
#include <epan/nghttp2_hd_huffman.h>
static wmem_strbuf_t *
get_hpack_huffman_strbuf(wmem_allocator_t *scope, const uint8_t *ptr, size_t len)
{
wmem_strbuf_t *strbuf;
strbuf = wmem_strbuf_new_sized(scope, len + 1);
nghttp2_huff_decode node = {0, 0};
const nghttp2_huff_decode *nodep = &node;
while (len > 0) {
uint8_t ch = *ptr++;
nodep = &huff_decode_table[nodep->fstate & 0x1ff][ch >> 4];
if (nodep->fstate & NGHTTP2_HUFF_SYM) {
wmem_strbuf_append_c(strbuf, nodep->sym);
}
nodep = &huff_decode_table[nodep->fstate & 0x1ff][ch & 0xf];
if (nodep->fstate & NGHTTP2_HUFF_SYM) {
wmem_strbuf_append_c(strbuf, nodep->sym);
}
len--;
}
if (!(nodep->fstate & NGHTTP2_HUFF_ACCEPTED)) {
wmem_strbuf_destroy(strbuf);
return NULL;
}
return strbuf;
}
wmem_strbuf_t *
tvb_get_hpack_huffman_strbuf(wmem_allocator_t *scope, tvbuff_t *tvb, const int offset, const int len)
{
return get_hpack_huffman_strbuf(scope, tvb_get_ptr(tvb, offset, len), len);
}
tvbuff_t*
tvb_child_uncompress_hpack_huff(tvbuff_t* parent, int offset, int length)
{
tvbuff_t* tvb = NULL;
wmem_strbuf_t *strbuf;
char* data;
gsize len;
strbuf = tvb_get_hpack_huffman_strbuf(NULL, parent, offset, length);
if (strbuf) {
len = wmem_strbuf_get_len(strbuf);
data = wmem_strbuf_finalize(strbuf);
tvb = tvb_new_child_real_data(parent, (const guint8*)data, (guint)len, (gint)len);
tvb_set_free_cb(tvb, g_free);
}
return tvb;
}