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HTTP: Test the first header line in a PDU more 

For a PDU where we haven't seen a request, response, or
header line yet, check to see if the header name is valid
before deciding that it is a header. Prevents many false
positives on continuation data that happens to have a line
end and a colon, where we couldn't do desegmentation for
some reason.
This commit is contained in:
John Thacker 2022-08-19 21:15:21 -04:00 committed by A Wireshark GitLab Utility
parent 4915b646d0
commit d8e877f610
1 changed files with 34 additions and 25 deletions
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59
epan/dissectors/packet-http.c
View File

@ -327,6 +327,7 @@ static int is_http_request_or_reply(const gchar *data, int linelen,
*reqresp_dissector, http_conv_t *conv_data);
static guint chunked_encoding_dissector(tvbuff_t **tvb_ptr, packet_info *pinfo,
proto_tree *tree, int offset);
static gboolean valid_header_name(const guchar *line, int header_len);
static void process_header(tvbuff_t *tvb, int offset, int next_offset,
const guchar *line, int linelen, int colon_offset,
packet_info *pinfo, proto_tree *tree,
@ -1390,10 +1391,13 @@ dissect_http_message(tvbuff_t *tvb, int offset, packet_info *pinfo,
linep = (const guchar *)memchr(line, ':', linelen);
if (linep) {
/*
* Colon found, assume it is a header.
* Colon found, assume it is a header if we've seen a
* valid line before. Check a little more if not.
*/
colon_offset += (int)(linep - line);
goto is_http;
if (saw_req_resp_or_header || valid_header_name(line, (int)(linep - line))) {
colon_offset += (int)(linep - line);
goto is_http;
}
}
/*
@ -3066,6 +3070,32 @@ is_token_char(char c)
return strchr("!#$%&\\:*+-.^_`|~", c) || g_ascii_isalnum(c);
}
static gboolean
valid_header_name(const guchar *line, int header_len)
{
/*
* Validate the header name. This allows no space between the field name
* and colon (RFC 7230, Section. 3.2.4).
*/
if (header_len == 0) {
return FALSE;
}
for (int i = 0; i < header_len; i++) {
/*
* NUL is not a valid character; treat it specially
* due to C's notion that strings are NUL-terminated.
*/
if (line[i] == '\0') {
return FALSE;
}
if (!is_token_char(line[i])) {
return FALSE;
}
}
return TRUE;
}
static void
process_header(tvbuff_t *tvb, int offset, int next_offset,
const guchar *line, int linelen, int colon_offset,
@ -3092,31 +3122,10 @@ process_header(tvbuff_t *tvb, int offset, int next_offset,
line_end_offset = offset + linelen;
header_len = colon_offset - offset;
/*
* Validate the header name. This allows no space between the field name
* and colon (RFC 7230, Section. 3.2.4).
*/
gboolean valid_header_name = header_len != 0;
if (valid_header_name) {
for (i = 0; i < header_len; i++) {
/*
* NUL is not a valid character; treat it specially
* due to C's notion that strings are NUL-terminated.
*/
if (line[i] == '\0') {
valid_header_name = FALSE;
break;
}
if (!is_token_char(line[i])) {
valid_header_name = FALSE;
break;
}
}
}
/**
* Not a valid header name? Just add a line plus expert info.
*/
if (!valid_header_name) {
if (!valid_header_name(line, header_len)) {
if (http_type == HTTP_REQUEST) {
hf_index = hf_http_request_line;
} else if (http_type == HTTP_RESPONSE) {