nortti
/
ethermess
1
0
Fork 0
Code Issues Pull Requests Releases 1 Wiki Activity

Check padding

This commit is contained in:
Juhani Krekelä 2019-07-09 16:22:55 +03:00
parent 1f179e8b2b
commit 43540d51bc
1 changed files with 30 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
ethermess.c
View File

@ -233,6 +233,20 @@ void read_command(void) {
}
}
bool check_padding(const unsigned char *data, size_t index, size_t data_length) {
// Valid padding is all zero bytes
assert(index <= data_length);
for (size_t i = index; i < data_length; i++) {
if (data[i] != 0) {
// Check failed
return false;
}
}
// Check succeeded
return true;
}
void handle_status(const unsigned char source_mac[6], const unsigned char *data, size_t data_length) {
if (data_length < 2) {
// Too short
@ -259,6 +273,11 @@ void handle_status(const unsigned char source_mac[6], const unsigned char *data,
unsigned char nick[256];
memcpy(nick, &data[2], nick_length);
if (!check_padding(data, 2 + nick_length, data_length)) {
// Malformed padding
return;
}
// TODO: check that nick is valid utf-8 with no control chars
char mac[18];
@ -303,6 +322,11 @@ void handle_msgid(const unsigned char source_mac[6], const unsigned char *data,
uint16_t msgid = data[0] << 8 | data[1];
if (!check_padding(data, 2, data_length)) {
// Malformed padding
return;
}
ssize_t cache_index = msgid_cache_lookup(source_mac);
if (cache_index == -1) {
// Not in the cache, so add it there
@ -375,7 +399,9 @@ void process_frame(void) {
// Process the packet based on the packet type
switch (packet_type) {
case EMT_STATUS_REQUEST:
send_status(source_mac);
if (check_padding(&frame[16], 0, packet_length - 16)) {
send_status(source_mac);
}
break;
case EMT_STATUS:
@ -383,7 +409,9 @@ void process_frame(void) {
break;
case EMT_MSGID_REQUEST:
send_msgid(source_mac);
if (check_padding(&frame[16], 0, packet_length - 16)) {
send_msgid(source_mac);
}
break;
case EMT_MSGID:
@ -393,8 +421,6 @@ void process_frame(void) {
default:
fprintf(stderr, "Ignoring packet of type %i\n", packet_type);
}
// TODO: Check that padding, if any, is all zeroes
}
void eventloop(void) {