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porting dhcp additions to ndpi 4.2 stable #5

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merged 1 commit into from
Sep 27, 2022
Merged

porting dhcp additions to ndpi 4.2 stable #5

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16 changes: 14 additions & 2 deletions src/include/ndpi_typedefs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1286,8 +1286,20 @@ struct ndpi_flow_struct {
} bittorrent;

struct {
char fingerprint[48];
char class_ident[48];
u_int32_t xid;
u_int32_t yiaddr;
u_int32_t siaddr;
u_int8_t chaddr[6];
/* DHCP Options */
char domain_name[256]; /* option 15 limited to 255 chars see RFC 1035 */
u_int32_t requested_ip; /* option 50 */
u_int32_t lease_time; /* option 51 */
u_int8_t msg_type; /* option 53 */
u_int8_t valid; /* signifies valid dhcp resp */
ndpi_ip_addr_t server_ident; /* option 54 */
char fingerprint[48]; /* option 55 */
u_int32_t renew_time; /* option 58 */
char class_ident[48]; /* option 60 */
} dhcp;
} protos;

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32 changes: 31 additions & 1 deletion src/lib/protocols/dhcp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -101,6 +101,7 @@ void ndpi_search_dhcp_udp(struct ndpi_detection_module_struct *ndpi_struct, stru

if(msg_type <= 8) {
foundValidMsgType = 1;
flow->protos.dhcp.valid = 1;
break;
}
}
Expand All @@ -120,6 +121,13 @@ void ndpi_search_dhcp_udp(struct ndpi_detection_module_struct *ndpi_struct, stru
NDPI_LOG_INFO(ndpi_struct, "found DHCP\n");
ndpi_int_dhcp_add_connection(ndpi_struct, flow);

/* Assign basic dhcp information to flow structure */
flow->protos.dhcp.msg_type = msg_type; /* option 53 msg_type */
flow->protos.dhcp.xid = dhcp->xid;
flow->protos.dhcp.siaddr = dhcp->siaddr;
flow->protos.dhcp.yiaddr = dhcp->yiaddr;
memcpy(flow->protos.dhcp.chaddr, dhcp->chaddr, sizeof(dhcp->chaddr));

/* Second iteration: parse the interesting options */
while(i + 1 /* for the len */ < dhcp_options_size) {
u_int8_t id = dhcp->options[i];
Expand Down Expand Up @@ -166,8 +174,30 @@ void ndpi_search_dhcp_udp(struct ndpi_detection_module_struct *ndpi_struct, stru
// while(j < len) { printf( "%c", name[j]); j++; }; printf("\n");
#endif
ndpi_hostname_sni_set(flow, name, len);
}
} else if(id == 15 /* Domain Name */) {
char *name = (char*)&dhcp->options[i+2];
int j = 0;

j = ndpi_min(len, sizeof(flow->protos.dhcp.domain_name)-1);
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Is there a reason ndpi_min was used here, but if (len > ...) checks are used in the rest of the code below? I think the code would be clearer if the same approach was used, either:

if (len > sizeof(buf)) len = sizeof(buf);

or

len = ndpi_min(len, sizeof(buf));

I think both should achieve the same thing, and the code will be easier to read because it will be more consistent.

strncpy((char*)flow->protos.dhcp.domain_name, name, j);
flow->protos.dhcp.domain_name[j] = '\0';
} else if(id == 50) /* Requested IP */ {
if (len > sizeof(flow->protos.dhcp.requested_ip))
len = sizeof(flow->protos.dhcp.requested_ip);
memcpy(&flow->protos.dhcp.requested_ip, (char*)&dhcp->options[i+2], len);
} else if(id == 51) /* Lease Time */ {
if (len > sizeof(flow->protos.dhcp.lease_time))
len = sizeof(flow->protos.dhcp.lease_time);
memcpy(&flow->protos.dhcp.lease_time, (char*)&dhcp->options[i+2], len);
} else if(id == 54) /* Server Identifier */ {
if (len > sizeof(flow->protos.dhcp.server_ident))
len = sizeof(flow->protos.dhcp.server_ident);
memcpy(&flow->protos.dhcp.server_ident, (char*)&dhcp->options[i+2], len);
} else if(id == 58) /* Renewal Time */ {
if (len > sizeof(flow->protos.dhcp.renew_time))
len = sizeof(flow->protos.dhcp.renew_time);
memcpy(&flow->protos.dhcp.renew_time, (char*)&dhcp->options[i+2], len);
}
i += len + 2;
}
}
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