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wireshark/epan/tvbuff_base64.c

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/* tvbuff_base64.c
* Base-64 tvbuff implementation (based on real tvb)
*
* 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 <glib.h>
#include <epan/tvbuff.h>
#include "proto.h"
/* Copy of glib function modified for base64uri */
static const unsigned char mime_base64uri_rank[256] = {
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255, 255,255,63,255,255,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61,255,255,255, 0,255,255,
255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,255,255,255,255, 63,
255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
};
/**
* Copy of glib function modified for base64uri
* g_base64uri_decode_step: (skip)
* @in: (array length=len) (element-type guint8): binary input data
* @len: max length of @in data to decode
* @out: (out caller-allocates) (array) (element-type guint8): output buffer
* @state: (inout): Saved state between steps, initialize to 0
* @save: (inout): Saved state between steps, initialize to 0
*
* Incrementally decode a sequence of binary data from its Base-64 stringified
* representation. By calling this function multiple times you can convert
* data in chunks to avoid having to have the full encoded data in memory.
*
* The output buffer must be large enough to fit all the data that will
* be written to it. Since base64 encodes 3 bytes in 4 chars you need
* at least: (@len / 4) * 3 + 3 bytes (+ 3 may be needed in case of non-zero
* state).
*
* Returns: The number of bytes of output that was written
*
* Since: 2.12
**/
static gsize
g_base64uri_decode_step(const gchar* in,
gsize len,
guchar* out,
gint* state,
guint* save)
{
const guchar* inptr;
guchar* outptr;
const guchar* inend;
guchar c, rank;
guchar last[2];
unsigned int v;
int i;
g_return_val_if_fail(in != NULL || len == 0, 0);
g_return_val_if_fail(out != NULL, 0);
g_return_val_if_fail(state != NULL, 0);
g_return_val_if_fail(save != NULL, 0);
if (len == 0)
return 0;
inend = (const guchar*)in + len;
outptr = out;
/* convert 4 base64 bytes to 3 normal bytes */
v = *save;
i = *state;
last[0] = last[1] = 0;
/* we use the sign in the state to determine if we got a padding character
in the previous sequence */
if (i < 0)
{
i = -i;
last[0] = '=';
}
inptr = (const guchar*)in;
while (inptr < inend)
{
c = *inptr++;
rank = mime_base64uri_rank[c];
if (rank != 0xff)
{
last[1] = last[0];
last[0] = c;
v = (v << 6) | rank;
i++;
if (i == 4)
{
*outptr++ = v >> 16;
if (last[1] != '=')
*outptr++ = v >> 8;
if (last[0] != '=')
*outptr++ = v;
i = 0;
}
}
}
*save = v;
*state = last[0] == '=' ? -i : i;
return outptr - out;
}
/**
* Copy of glib function modified for base64uri
* g_base64uri_decode:
* @text: (not nullable): zero-terminated string with base64 text to decode
* @out_len: (out): The length of the decoded data is written here
*
* Decode a sequence of Base-64 encoded text into binary data. Note
* that the returned binary data is not necessarily zero-terminated,
* so it should not be used as a character string.
*
* Returns: (transfer full) (array length=out_len) (element-type guint8):
* newly allocated buffer containing the binary data
* that @text represents. The returned buffer must
* be freed with g_free().
*
* Since: 2.12
*/
static guchar*
g_base64uri_decode(const gchar* text,
gsize* out_len)
{
guchar* ret;
gsize input_length;
gint state = 0;
guint save = 0;
g_return_val_if_fail(text != NULL, NULL);
g_return_val_if_fail(out_len != NULL, NULL);
input_length = strlen(text);
/* We can use a smaller limit here, since we know the saved state is 0,
+1 used to avoid calling g_malloc0(0), and hence returning NULL */
ret = (guchar * )g_malloc0((input_length / 4) * 3 + 1);
*out_len = g_base64uri_decode_step(text, input_length, ret, &state, &save);
return ret;
}
tvbuff_t *
base64_to_tvb(tvbuff_t *parent, const char *base64)
{
tvbuff_t *tvb;
char *data;
gsize len;
data = g_base64_decode(base64, &len);
tvb = tvb_new_child_real_data(parent, (const guint8 *)data, (gint)len, (gint)len);
tvb_set_free_cb(tvb, g_free);
return tvb;
}
tvbuff_t*
base64_tvb_to_new_tvb(tvbuff_t* parent, int offset, int length)
{
tvbuff_t* tvb;
char* data;
gsize len;
data = g_base64_decode(tvb_get_string_enc(wmem_packet_scope(), parent, offset, length, ENC_ASCII), &len);
tvb = tvb_new_child_real_data(parent, (const guint8*)data, (gint)len, (gint)len);
tvb_set_free_cb(tvb, g_free);
return tvb;
}
tvbuff_t*
base64uri_tvb_to_new_tvb(tvbuff_t* parent, int offset, int length)
{
tvbuff_t* tvb;
char* data;
gsize len = 0;
data = g_base64uri_decode(tvb_get_string_enc(wmem_packet_scope(), parent, offset, length, ENC_ASCII), &len);
tvb = tvb_new_child_real_data(parent, (const guint8*)data, (gint)len, (gint)len);
tvb_set_free_cb(tvb, g_free);
return tvb;
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local Variables:
* c-basic-offset: 2
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=2 tabstop=8 expandtab:
* :indentSize=2:tabSize=8:noTabs=true:
*/
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