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/*
* fastcgi.c
*
* Copyright (C) 2022-23 - ntop.org
*
* nDPI is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* nDPI is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with nDPI. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "ndpi_protocol_ids.h"
#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_FASTCGI
#include "ndpi_api.h"
#include "ndpi_private.h"
/* Reference: http://www.mit.edu/~yandros/doc/specs/fcgi-spec.html */
PACK_ON
struct FCGI_Header {
u_int8_t version;
u_int8_t type;
u_int16_t requestId;
u_int16_t contentLength;
u_int8_t paddingLength;
u_int8_t reserved;
} PACK_OFF;
enum FCGI_Type {
FCGI_MIN = 1,
FCGI_BEGIN_REQUEST = 1,
FCGI_ABORT_REQUEST = 2,
FCGI_END_REQUEST = 3,
FCGI_PARAMS = 4,
FCGI_STDIN = 5,
FCGI_STDOUT = 6,
FCGI_STDERR = 7,
FCGI_DATA = 8,
FCGI_GET_VALUES = 9,
FCGI_GET_VALUES_RESULT = 10,
FCGI_UNKNOWN_TYPE = 11,
FCGI_MAX = 11
};
PACK_ON
struct FCGI_Params {
u_int8_t key_length;
u_int8_t value_length;
} PACK_OFF;
struct fcgi_one_line_mapping {
char const * const key;
struct ndpi_int_one_line_struct * const value;
};
static int ndpi_search_fastcgi_extra(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow);
static void ndpi_int_fastcgi_add_connection(struct ndpi_detection_module_struct * const ndpi_struct,
struct ndpi_flow_struct * const flow,
ndpi_protocol_match_result * const match)
{
NDPI_LOG_INFO(ndpi_struct, "found fastcgi\n");
ndpi_set_detected_protocol(ndpi_struct, flow,
NDPI_PROTOCOL_FASTCGI,
(match != NULL ? match->protocol_id : NDPI_PROTOCOL_UNKNOWN),
NDPI_CONFIDENCE_DPI);
if (flow->extra_packets_func == NULL)
{
flow->max_extra_packets_to_check = 5;
flow->extra_packets_func = ndpi_search_fastcgi_extra;
}
}
static int fcgi_parse_params(struct ndpi_flow_struct * const flow,
struct ndpi_packet_struct * const packet)
{
size_t i, j;
struct fcgi_one_line_mapping mappings[] = {
{ "SCRIPT_URL", &packet->http_url_name },
{ "HTTP_HOST", &packet->host_line },
{ "HTTP_ACCEPT", &packet->accept_line },
{ "HTTP_USER_AGENT", &packet->user_agent_line },
{ "SERVER_SOFTWARE", &packet->server_line },
{ "REQUEST_METHOD", &packet->http_method }
};
i = sizeof(struct FCGI_Header);
while (i + sizeof(struct FCGI_Params) < packet->payload_packet_len)
{
struct FCGI_Params const * const params = (struct FCGI_Params const *)&packet->payload[i];
i += sizeof(*params);
if (i + params->key_length + params->value_length > packet->payload_packet_len)
{
return 1;
}
for (j = 0; j < NDPI_ARRAY_LENGTH(mappings); ++j)
{
if (strlen(mappings[j].key) == params->key_length &&
strncmp((char const *)&packet->payload[i], mappings[j].key, params->key_length) == 0)
{
mappings[j].value->ptr = &packet->payload[i + params->key_length];
mappings[j].value->len = params->value_length;
if (packet->parsed_lines < NDPI_MAX_PARSE_LINES_PER_PACKET)
{
packet->line[packet->parsed_lines].ptr = &packet->payload[i + params->key_length];
packet->line[packet->parsed_lines].len = params->value_length;
packet->parsed_lines++;
}
break;
}
}
i += params->key_length + params->value_length;
};
if (i != packet->payload_packet_len)
{
return 1;
}
flow->http.method = ndpi_http_str2method((const char*)packet->http_method.ptr,
(u_int16_t)packet->http_method.len);
ndpi_hostname_sni_set(flow, packet->host_line.ptr, packet->host_line.len, NDPI_HOSTNAME_NORM_ALL);
ndpi_user_agent_set(flow, packet->user_agent_line.ptr, packet->user_agent_line.len);
if (flow->http.url == NULL && packet->http_url_name.len > 0)
{
flow->http.url = ndpi_malloc(packet->http_url_name.len + 1);
if (flow->http.url != NULL)
{
strncpy(flow->http.url, (char const *)packet->http_url_name.ptr, packet->http_url_name.len);
flow->http.url[packet->http_url_name.len] = '\0';
}
}
return 0;
}
static void ndpi_search_fastcgi(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct * const packet = &ndpi_struct->packet;
struct FCGI_Header const * fcgi_hdr;
enum FCGI_Type fcgi_type;
u_int16_t content_len;
ndpi_protocol_match_result ret_match;
NDPI_LOG_DBG(ndpi_struct, "search fastcgi\n");
if (packet->payload_packet_len < sizeof(struct FCGI_Header))
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
fcgi_hdr = (struct FCGI_Header const *)&packet->payload[0];
if (fcgi_hdr->version != 0x01)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
fcgi_type = (enum FCGI_Type)fcgi_hdr->type;
if (fcgi_type < FCGI_MIN || fcgi_type > FCGI_MAX)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
content_len = ntohs(fcgi_hdr->contentLength);
if (packet->payload_packet_len != sizeof(*fcgi_hdr) + content_len + fcgi_hdr->paddingLength)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
if (fcgi_type == FCGI_PARAMS)
{
if (content_len == 0)
{
flow->max_extra_packets_to_check = 0;
flow->extra_packets_func = NULL;
return;
}
if (fcgi_parse_params(flow, packet) != 0)
{
ndpi_set_risk(flow, NDPI_MALFORMED_PACKET, "Invalid FastCGI PARAMS header");
ndpi_int_fastcgi_add_connection(ndpi_struct, flow, NULL);
} else {
ndpi_match_host_subprotocol(ndpi_struct, flow,
flow->host_server_name,
strlen(flow->host_server_name),
&ret_match, NDPI_PROTOCOL_FASTCGI);
ndpi_check_dga_name(ndpi_struct, flow,
flow->host_server_name, 1, 0);
if(ndpi_is_valid_hostname((char *)packet->host_line.ptr,
packet->host_line.len) == 0) {
char str[128];
snprintf(str, sizeof(str), "Invalid host %s", flow->host_server_name);
ndpi_set_risk(flow, NDPI_INVALID_CHARACTERS, str);
/* This looks like an attack */
ndpi_set_risk(flow, NDPI_POSSIBLE_EXPLOIT, "Suspicious hostname: attack ?");
}
ndpi_int_fastcgi_add_connection(ndpi_struct, flow, &ret_match);
}
return;
}
if (flow->packet_counter > 2)
{
ndpi_int_fastcgi_add_connection(ndpi_struct, flow, NULL);
}
}
static int ndpi_search_fastcgi_extra(struct ndpi_detection_module_struct * ndpi_struct,
struct ndpi_flow_struct * flow)
{
ndpi_search_fastcgi(ndpi_struct, flow);
return flow->extra_packets_func != NULL;
}
void init_fastcgi_dissector(struct ndpi_detection_module_struct *ndpi_struct,
u_int32_t *id)
{
ndpi_set_bitmask_protocol_detection("FastCGI", ndpi_struct, *id,
NDPI_PROTOCOL_FASTCGI,
ndpi_search_fastcgi,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK
);
*id += 1;
}
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