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basics of ND with RADV

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neighbor discovery protocol basics, just for fun and for radv slaac
this is a working version, but code is not perfect,
just commit to save the checkpoint -- this isn't the master, is it?
This commit is contained in:
giomba 2019-12-24 23:00:31 +01:00
parent 9beb97fdba
commit 5c7b1ffc99
2 changed files with 94 additions and 35 deletions
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31
ipv6.h
View File

@ -6,10 +6,13 @@ namespace ipv6 {
const uint8_t LEN = 128; const uint8_t LEN = 128;
const uint8_t ICMP_ECHO_REQUEST_TYPE = 128; const uint8_t ICMP_ECHO_REQUEST_TYPE = 128;
const uint8_t ICMP_ECHO_REPLY_TYPE = 129; const uint8_t ICMP_ECHO_REPLY_TYPE = 129;
const uint8_t ICMP_RADV_TYPE = 134;
const uint8_t NH_ICMP = 58; const uint8_t NH_ICMP = 58;
const uint8_t NH_UDP = 17; const uint8_t NH_UDP = 17;
extern uint8_t HOP_LIMIT;
class IPv6Addr { class IPv6Addr {
private: private:
char address[16]; char address[16];
@ -18,6 +21,7 @@ namespace ipv6 {
IPv6Addr(const char* address); IPv6Addr(const char* address);
}; };
extern const IPv6Addr LINK_LOCAL_ADDRESS;
extern const IPv6Addr ALL_NODES_ADDRESS; extern const IPv6Addr ALL_NODES_ADDRESS;
struct ipv6_packet_header { struct ipv6_packet_header {
@ -64,6 +68,33 @@ namespace ipv6 {
const char* payload, /* IPv6 payload */ const char* payload, /* IPv6 payload */
int len /* IPv6 payload length */ int len /* IPv6 payload length */
); );
struct ICMPv6_RADV {
uint8_t type;
uint8_t code;
char checksum[2];
uint8_t cur_hop_limit;
uint8_t mo_flags;
uint16_t router_lifetime;
uint32_t reachable_time;
uint32_t retrans_time;
};
struct ICMPv6_RADV_Option {
uint8_t type;
uint8_t len;
};
struct ICMPv6_RADV_PrefixInformation {
uint8_t type;
uint8_t len;
uint8_t prefix_length;
uint8_t la_flags;
uint32_t valid_lifetime;
uint32_t preferred_lifetime;
uint32_t reserved2;
char prefix[16];
};
} }
#endif #endif

98
ipv6.ino
View File

@ -3,7 +3,11 @@
namespace ipv6 { namespace ipv6 {
/******** costants ********/ /******** costants ********/
const IPv6Addr ALL_NODES_ADDRESS("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"); /* ff02::1 */ const IPv6Addr ALL_NODES_ADDRESS("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"); /* ff02::1 */
const IPv6Addr LINK_LOCAL_ADDRESS("\xfe\x80\x00\x00\x00\x00\x00\x00\xde\xad\xbe\xef\x12\x34\x56\x78"); /* fe80::dead:beef:1234:5678 */ /* TODO */
/******** variables ********/
uint8_t HOP_LIMIT = 64;
/******** buffer ********/ /******** buffer ********/
IPv6Packet packetin; IPv6Packet packetin;
@ -60,7 +64,7 @@ IPv6Addr::IPv6Addr(const char* address) {
IPv6Packet::IPv6Packet() { IPv6Packet::IPv6Packet() {
memset(packet, 0, LEN); memset(packet, 0, LEN);
*(packet) = 0x60; /* IP version 6 */ *(packet) = 0x60; /* IP version 6 */
*(packet + 7) = 64; /* hop limit / ttl */ *(packet + 7) = HOP_LIMIT; /* hop limit / ttl */
} }
IPv6Packet::IPv6Packet(const char* buffer, int len) { IPv6Packet::IPv6Packet(const char* buffer, int len) {
@ -112,8 +116,11 @@ void IPv6Packet::send() {
} }
void IPv6Packet::doAction() { void IPv6Packet::doAction() {
/* if destination is my address, or destination is "all nodes" address, then... */ /* if destination is my address (global or link-local), or destination is "all nodes" address, then... */
if ((memcmp(&(ALL_NODES_ADDRESS), packet + 24, 16) == 0) || (memcmp(&(coppino::address), packet + 24, 16) == 0)) { if (
(memcmp(&(ALL_NODES_ADDRESS), packet + 24, 16) == 0) ||
(memcmp(&(LINK_LOCAL_ADDRESS), packet + 24, 16) == 0) ||
(memcmp(&(coppino::address), packet + 24, 16) == 0)) {
int ilen = this->getLen(); /* input payload length */ int ilen = this->getLen(); /* input payload length */
int olen; /* output payload length */ int olen; /* output payload length */
@ -148,41 +155,62 @@ void IPv6Packet::doAction() {
int handleICMP(char* output_buffer, const char* input_buffer, int len) { int handleICMP(char* output_buffer, const char* input_buffer, int len) {
uint8_t type = *(input_buffer); uint8_t type = *(input_buffer);
if (type == ICMP_ECHO_REQUEST_TYPE) { /* if it is ICMPv6 Echo Request, then... */ /* compute checksum, and assert validity of incoming message */
/* compute checksum, and assert validity of incoming message */ char received_checksum[2];
char received_checksum[2]; memcpy(received_checksum, input_buffer + 2, 2);
memcpy(received_checksum, input_buffer + 2, 2);
memcpy(output_buffer, input_buffer, len); memcpy(output_buffer, input_buffer, len);
memset(output_buffer + 2, 0, 2); /* zero-checksum */ memset(output_buffer + 2, 0, 2); /* zero-checksum */
uint16_t computed_checksum = compute_checksum( uint16_t computed_checksum = compute_checksum(
packetin.getSrcAddress(), packetin.getSrcAddress(),
packetin.getDstAddress(), packetin.getDstAddress(),
NH_ICMP, NH_ICMP,
len, len,
output_buffer, output_buffer,
len); len);
if (memcmp(&computed_checksum, received_checksum, 2) == 0) { /* if checksum is valid, then... */ if (memcmp(&computed_checksum, received_checksum, 2) != 0) { /* if checksum is not valid, return */
/* Build an echo reply: return -1;
* the reply has the same exact format of the request,
* except for Type and Checksum */
*(output_buffer) = ICMP_ECHO_REPLY_TYPE;
memset(output_buffer + 2, 0, 2); /* zero-checksum */
uint16_t checksum = compute_checksum(
packetin.getDstAddress(),
packetin.getSrcAddress(),
NH_ICMP,
len,
output_buffer,
len);
memcpy(output_buffer + 2, &checksum, 2);
return len;
}
} }
if (type == ICMP_ECHO_REQUEST_TYPE) { /* if it is ICMPv6 Echo Request, then... */
/* Build an echo reply:
* the reply has the same exact format of the request,
* except for Type and Checksum */
*(output_buffer) = ICMP_ECHO_REPLY_TYPE;
memset(output_buffer + 2, 0, 2); /* zero-checksum */
uint16_t checksum = compute_checksum(
packetin.getDstAddress(),
packetin.getSrcAddress(),
NH_ICMP,
len,
output_buffer,
len);
memcpy(output_buffer + 2, &checksum, 2);
return len;
} else if (type == ICMP_RADV_TYPE) { /* if it is IVMPc6 Router Advertisement, then... */
ICMPv6_RADV* radv = (ICMPv6_RADV*)input_buffer;
HOP_LIMIT = (radv->cur_hop_limit != 0) ? radv->cur_hop_limit : 64;
for (
ICMPv6_RADV_Option* option = (ICMPv6_RADV_Option*) (radv + 1);
option != input_buffer + len;
option = (ICMPv6_RADV_Option*) ( ((char*)(option)) + option->len )) {
digitalWrite(13, !digitalRead(13));
if (option->type == 3 && option->len == 4) { /* if it is a ICMPv6 Prefix Information, then... */
ICMPv6_RADV_PrefixInformation* p = (ICMPv6_RADV_PrefixInformation*) option;
if (p->prefix_length != 64) continue; /* only /64 prefix is supported */
if (! (p->la_flags & 0x40)) continue; /* only SLAAC is supported */
memcpy(&coppino::address, p->prefix, 8); /* set prefix -- leave host bits unchanged */
break;
}
}
return -1;
}
return -1; return -1;
} }