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Don't put knowledge about the "is this pcapng" test in the block-reading code. 

Have pcapng_read_section_header_block(),
pcapng_read_section_header_block(), and pcapng_read_block() just return
errors when they get errors or get a non-SHB block; let pcap_open() turn
EOF, short read, and "bad file" into "not a pcapng file" rather than
"read error".

Change-Id: If018d21ffe3de3fe7eb1f8f2973f80f685c89274
Reviewed-on: https://code.wireshark.org/review/25601
Reviewed-by: Guy Harris <guy@alum.mit.edu>
This commit is contained in:
Guy Harris 2018-02-04 14:16:37 -08:00
parent d447467eb5
commit bb2680d9b4
1 changed files with 20 additions and 43 deletions
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63
wiretap/pcapng.c
View File

@ -499,7 +499,6 @@ pcapng_read_option(FILE_T fh, pcapng_t *pn, pcapng_option_header_t *oh,
typedef enum {
PCAPNG_BLOCK_OK,
PCAPNG_BLOCK_NOT_SHB,
PCAPNG_BLOCK_ERROR
} block_return_val;
@ -521,22 +520,8 @@ pcapng_read_section_header_block(FILE_T fh, pcapng_block_header_t *bh,
guint8 *option_content = NULL; /* Allocate as large as the options block */
/* read fixed-length part of the block */
if (!wtap_read_bytes(fh, &shb, sizeof shb, err, err_info)) {
if (*err == WTAP_ERR_SHORT_READ) {
/*
* This block is too short to be an SHB.
*
* If we're reading this as part of an open,
* the file is too short to be a pcapng file.
*
* If we're not, we treat PCAPNG_BLOCK_NOT_SHB and
* PCAPNG_BLOCK_ERROR the same, so we can just return
* PCAPNG_BLOCK_NOT_SHB in both cases.
*/
return PCAPNG_BLOCK_NOT_SHB;
}
if (!wtap_read_bytes(fh, &shb, sizeof shb, err, err_info))
return PCAPNG_BLOCK_ERROR;
}
/* is the magic number one we expect? */
switch (shb.magic) {
@ -565,11 +550,7 @@ pcapng_read_section_header_block(FILE_T fh, pcapng_block_header_t *bh,
/* Not a "pcapng" magic number we know about. */
*err = WTAP_ERR_BAD_FILE;
*err_info = g_strdup_printf("pcapng_read_section_header_block: unknown byte-order magic number 0x%08x", shb.magic);
/*
* See above comment about PCAPNG_BLOCK_NOT_SHB.
*/
return PCAPNG_BLOCK_NOT_SHB;
return PCAPNG_BLOCK_ERROR;
}
/*
@ -2348,19 +2329,6 @@ pcapng_read_block(wtap *wth, FILE_T fh, pcapng_t *pn, wtapng_block_t *wblock, in
/* Try to read the (next) block header */
if (!wtap_read_bytes_or_eof(fh, &bh, sizeof bh, err, err_info)) {
pcapng_debug("pcapng_read_block: wtap_read_bytes_or_eof() failed, err = %d.", *err);
if (*err == 0 || *err == WTAP_ERR_SHORT_READ) {
/*
* Short read or EOF.
*
* If we're reading this as part of an open,
* the file is too short to be a pcapng file.
*
* If we're not, we treat PCAPNG_BLOCK_NOT_SHB and
* PCAPNG_BLOCK_ERROR the same, so we can just return
* PCAPNG_BLOCK_NOT_SHB in both cases.
*/
return PCAPNG_BLOCK_NOT_SHB;
}
return PCAPNG_BLOCK_ERROR;
}
@ -2399,10 +2367,11 @@ pcapng_read_block(wtap *wth, FILE_T fh, pcapng_t *pn, wtapng_block_t *wblock, in
* No SHB seen yet, so we're trying to read the first block
* during an open, to see whether it's an SHB; if what we
* read doesn't look like an SHB, this isn't a pcapng file.
* Report it as a "bad file" error.
*/
*err = 0;
*err = WTAP_ERR_BAD_FILE;
*err_info = NULL;
return PCAPNG_BLOCK_NOT_SHB;
return PCAPNG_BLOCK_ERROR;
}
switch (bh.block_type) {
case(BLOCK_TYPE_IDB):
@ -2517,14 +2486,22 @@ pcapng_open(wtap *wth, int *err, gchar **err_info)
/* No problem */
break;
case PCAPNG_BLOCK_NOT_SHB:
/* An error indicating that this isn't a pcapng file. */
wtap_block_free(wblock.block);
*err = 0;
*err_info = NULL;
return WTAP_OPEN_NOT_MINE;
case PCAPNG_BLOCK_ERROR:
if (*err == 0 || *err == WTAP_ERR_SHORT_READ ||
*err == WTAP_ERR_BAD_FILE) {
/*
* This is an EOF or a short read, in which case this is
* either a pcapng file that's been cut short or a file
* that's not a pcapng file, or it's not a valid pcapng
* file. It's probably not a pcapng file, so treat it
* as such, so we can try other file types.
*/
wtap_block_free(wblock.block);
*err = 0;
g_free(*err_info);
*err_info = NULL;
return WTAP_OPEN_NOT_MINE;
}
/* An I/O error, or this probably *is* a pcapng file but not a valid one. */
wtap_block_free(wblock.block);
return WTAP_OPEN_ERROR;