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inashivb wants to merge 3 commits into from
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Ftp issues/v2 #8963

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124057a
ftp: separate truncated line markers
inashivb Jun 5, 2023
c362487
ftp: mark LF found per line
inashivb Jun 5, 2023
5d6942d
ftp: remove unnecessary code
inashivb Jun 5, 2023
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49 changes: 24 additions & 25 deletions src/app-layer-ftp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -340,7 +340,8 @@ typedef struct FtpInput_ {
int32_t orig_len;
} FtpInput;

static AppLayerResult FTPGetLineForDirection(FtpState *state, FtpLineState *line, FtpInput *input)
static AppLayerResult FTPGetLineForDirection(
FtpState *state, FtpLineState *line, FtpInput *input, bool *current_line_truncated)
{
SCEnter();

Expand All @@ -351,18 +352,18 @@ static AppLayerResult FTPGetLineForDirection(FtpState *state, FtpLineState *line
uint8_t *lf_idx = memchr(input->buf + input->consumed, 0x0a, input->len);

if (lf_idx == NULL) {
if (!state->current_line_truncated && (uint32_t)input->len >= ftp_max_line_len) {
state->current_line_truncated = true;
if (!(*current_line_truncated) && (uint32_t)input->len >= ftp_max_line_len) {
*current_line_truncated = true;
line->buf = input->buf;
line->len = ftp_max_line_len;
line->delim_len = 0;
input->len = 0;
SCReturnStruct(APP_LAYER_OK);
}
SCReturnStruct(APP_LAYER_INCOMPLETE(input->consumed, input->len + 1));
} else if (state->current_line_truncated) {
} else if (*current_line_truncated) {
// Whatever came in with first LF should also get discarded
state->current_line_truncated = false;
*current_line_truncated = false;
line->len = 0;
line->delim_len = 0;
input->len = 0;
Expand All @@ -372,26 +373,18 @@ static AppLayerResult FTPGetLineForDirection(FtpState *state, FtpLineState *line
// e.g. input_len = 5077
// lf_idx = 5010
// max_line_len = 4096
if (!state->current_line_truncated && (uint32_t)input->len >= ftp_max_line_len) {
state->current_line_truncated = true;
line->buf = input->buf;
line->len = ftp_max_line_len;
if (input->consumed >= 2 && input->buf[input->consumed - 2] == 0x0D) {
line->delim_len = 2;
line->len -= 2;
} else {
line->delim_len = 1;
line->len -= 1;
}
input->len = 0;
SCReturnStruct(APP_LAYER_OK);
}
uint32_t o_consumed = input->consumed;
input->consumed = lf_idx - input->buf + 1;
line->len = input->consumed - o_consumed;
input->len -= line->len;
line->lf_found = true;
DEBUG_VALIDATE_BUG_ON((input->consumed + input->len) != input->orig_len);
line->buf = input->buf + o_consumed;
if (line->len >= ftp_max_line_len) {
*current_line_truncated = true;
line->len = ftp_max_line_len;
SCReturnStruct(APP_LAYER_OK);
}
if (input->consumed >= 2 && input->buf[input->consumed - 2] == 0x0D) {
line->delim_len = 2;
line->len -= 2;
Expand Down Expand Up @@ -505,12 +498,12 @@ static AppLayerResult FTPParseRequest(Flow *f, void *ftp_state, AppLayerParserSt
}

FtpInput ftpi = { .buf = input, .len = input_len, .orig_len = input_len, .consumed = 0 };
FtpLineState line = { .buf = NULL, .len = 0, .delim_len = 0 };
FtpLineState line = { .buf = NULL, .len = 0, .delim_len = 0, .lf_found = false };

uint8_t direction = STREAM_TOSERVER;
AppLayerResult res;
while (1) {
res = FTPGetLineForDirection(state, &line, &ftpi);
res = FTPGetLineForDirection(state, &line, &ftpi, &state->current_line_truncated_ts);
if (res.status == 1) {
return res;
} else if (res.status == -1) {
Expand All @@ -531,8 +524,11 @@ static AppLayerResult FTPParseRequest(Flow *f, void *ftp_state, AppLayerParserSt

tx->command_descriptor = cmd_descriptor;
tx->request_length = CopyCommandLine(&tx->request, &line);
tx->request_truncated = state->current_line_truncated;
tx->request_truncated = state->current_line_truncated_ts;

if (line.lf_found) {
state->current_line_truncated_ts = false;
}
if (tx->request_truncated) {
AppLayerDecoderEventsSetEventRaw(&tx->tx_data.events, FtpEventRequestCommandTooLong);
}
Expand Down Expand Up @@ -695,12 +691,12 @@ static AppLayerResult FTPParseResponse(Flow *f, void *ftp_state, AppLayerParserS
SCReturnStruct(APP_LAYER_OK);
}
FtpInput ftpi = { .buf = input, .len = input_len, .orig_len = input_len, .consumed = 0 };
FtpLineState line = { .buf = NULL, .len = 0, .delim_len = 0 };
FtpLineState line = { .buf = NULL, .len = 0, .delim_len = 0, .lf_found = false };

FTPTransaction *lasttx = TAILQ_FIRST(&state->tx_list);
AppLayerResult res;
while (1) {
res = FTPGetLineForDirection(state, &line, &ftpi);
res = FTPGetLineForDirection(state, &line, &ftpi, &state->current_line_truncated_tc);
if (res.status == 1) {
return res;
} else if (res.status == -1) {
Expand Down Expand Up @@ -771,11 +767,14 @@ static AppLayerResult FTPParseResponse(Flow *f, void *ftp_state, AppLayerParserS
FTPString *response = FTPStringAlloc();
if (likely(response)) {
response->len = CopyCommandLine(&response->str, &line);
response->truncated = state->current_line_truncated;
response->truncated = state->current_line_truncated_tc;
if (response->truncated) {
AppLayerDecoderEventsSetEventRaw(
&tx->tx_data.events, FtpEventResponseCommandTooLong);
}
if (line.lf_found) {
state->current_line_truncated_tc = false;
}
TAILQ_INSERT_TAIL(&tx->response_list, response, next);
}
}
Expand Down
4 changes: 3 additions & 1 deletion src/app-layer-ftp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,7 @@ typedef struct FtpLineState_ {
const uint8_t *buf;
uint32_t len;
uint8_t delim_len;
bool lf_found;
} FtpLineState;

typedef struct FTPString_ {
Expand Down Expand Up @@ -148,7 +149,8 @@ typedef struct FtpState_ {
TAILQ_HEAD(, FTPTransaction_) tx_list; /**< transaction list */
uint64_t tx_cnt;

bool current_line_truncated;
bool current_line_truncated_ts;
bool current_line_truncated_tc;

FtpRequestCommand command;
FtpRequestCommandArgOfs arg_offset;
Expand Down