code polishing

This commit is contained in:
giomba 2019-12-23 18:57:21 +01:00
parent 12d09f24c5
commit 11e56ac38c
4 changed files with 77 additions and 86 deletions

View File

@ -16,8 +16,6 @@ namespace coppino {
void hexdump(const char* pointer, int len);
uint16_t compute_checksum(const char* src_addr, const char* dst_addr, uint8_t next_header, const char* payload, int len);
void blink();
}

View File

@ -22,58 +22,4 @@ namespace coppino {
Serial.print('.');
}
}
uint16_t compute_checksum(const char* src_addr, const char* dst_addr, uint8_t next_header, const char* payload, int len) {
char buffer[LEN];
uint32_t total;
uint16_t* ptr;
int words;
int i = len;
memcpy(buffer, payload, len);
if (len % 2) {
buffer[len] = 0;
i++;
}
memcpy(buffer + i, src_addr, 16); i += 16;
memcpy(buffer + i, dst_addr, 16); i += 16;
memcpy(buffer + i, "\0\0", 2); i += 2;
buffer[i] = len >> 8; i += 1;
buffer[i] = len & 0xff; i += 1;
memcpy(buffer + i, "\0\0\0", 3); i += 3;
buffer[i] = next_header; i += 1;
total = 0;
ptr = (uint16_t*)buffer;
words = (i + 1) / 2;
while (words--) total += *ptr++;
while (total & 0xffff0000)
total = (total >> 16) + (total & 0xffff);
//total -= 64*256; // TODO -- this is an ugly fix, something is wrong somewhere else
return ~((uint16_t) total);
/*
uint16_t checksum = 0;
for (i = 0; i < len; i = i + 2) {
part = ((*(packet + i + 0)) << 8) + *(packet + i + 1);
checksum += part;
}
for (i = 0; i < 16; i = i + 2 ) {
part = ((*(src_addr + i + 0)) << 8) + *(src_addr + i + 1);
checksum += part;
part = ((*(dst_addr + i + 0)) << 8) + *(dst_addr + i + 1);
checksum += part;
}
checksum += (len + 58); // upper-layer packet length + next header
while (checksum >> 16)
checksum = (checksum & 0xffff) + (checksum >> 16);
*/
}
void blink() {
digitalWrite(13, !digitalRead(13));
}
}

9
ipv6.h
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@ -4,6 +4,11 @@
namespace ipv6 {
const uint8_t LEN = 128;
const uint8_t ICMP_ECHO_REQUEST_TYPE = 128;
const uint8_t ICMP_ECHO_REPLY_TYPE = 129;
const uint8_t NH_ICMP = 58;
const uint8_t NH_UDP = 17;
class IPv6Addr {
private:
@ -15,7 +20,7 @@ namespace ipv6 {
const char* serialize();
};
extern IPv6Addr ALL_NODES_ADDRESS;
extern const IPv6Addr ALL_NODES_ADDRESS;
struct ipv6_packet_header {
char field[4];
@ -43,6 +48,8 @@ namespace ipv6 {
/* Note: content of message may be changed */
void handleICMP(const char* src, const char* dst, char* message, int len);
uint16_t compute_checksum(const char* src_addr, const char* dst_addr, uint8_t next_header, const char* payload, int len);
}
#endif

View File

@ -2,7 +2,47 @@
namespace ipv6 {
/******** costants ********/
IPv6Addr ALL_NODES_ADDRESS("\xff\x02\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\x01"); /* ff02::1 */
/******** FUNCTIONS *******/
uint16_t compute_checksum(const char* src_addr, const char* dst_addr, uint8_t next_header, const char* payload, int len) {
char buffer[LEN];
uint32_t total;
uint16_t* ptr;
int words;
int i = len;
/* prepare buffer with all data to checksum:
- the actual payload
- the pseudo ipv6 header
*/
/* actual payload */
memcpy(buffer, payload, len);
if (len % 2) { /* pad with 0 if length is odd */
buffer[len] = 0;
i++;
}
/* pseudo ipv6 header -- see RFC 2460, Section 8.1 */
memcpy(buffer + i, src_addr, 16); i += 16;
memcpy(buffer + i, dst_addr, 16); i += 16;
memset(buffer + i, 0, 3); i+= 3; /* first 3 bytes always 0, because len always < 256 */
buffer[i] = len & 0xff; i += 1;
memset(buffer + i, 0, 3); i += 3; /* zero, as per-standard */
buffer[i] = next_header; i += 1;
/* do computation */
total = 0;
ptr = (uint16_t*)buffer;
words = (i + 1) / 2;
while (words--) total += *ptr++;
while (total & 0xffff0000) {
total = (total >> 16) + (total & 0xffff);
}
return ~((uint16_t) total);
}
/******** IPv6Addr ********/
IPv6Addr::IPv6Addr() {;}
@ -57,10 +97,10 @@ void IPv6Packet::setPayload(char* payload, uint8_t len) {
int len = ((*(packet + 4)) << 8) + (*(packet + 5));
switch(*(packet + 6)) { /* next header */
case 58:
case NH_ICMP:
handleICMP(packet + 8, packet + 24, packet + 40, len);
break;
case 17:
case NH_UDP:
// handleUDP(packet + 40, len);
break;
default:
@ -72,36 +112,36 @@ void IPv6Packet::setPayload(char* payload, uint8_t len) {
void handleICMP(const char* src_addr, const char* dst_addr, char* packet, int len) {
uint8_t type = *(packet);
uint32_t checksum = ((*(packet + 2)) << 8) + (*(packet + 3));
uint16_t part;
IPv6Addr dst;
int i;
switch (type) {
case 128:
/* TODO compute checksum, and assert validity of incoming message */
/* then... */
if (type == ICMP_ECHO_REQUEST_TYPE) { /* if it is ICMPv6 Echo Request, then... */
/* compute checksum, and assert validity of incoming message */
char received_checksum[2];
memcpy(received_checksum, packet + 2, 2);
/* Build an echo reply:
* the reply has the same exact format of the request,
* except for Type and Checksum */
*(packet) = 129; /* echo reply type */
*(packet + 2) = *(packet + 3) = 0; /* zero-checksum */
memset(packet + 2, 0, 2); /* zero-checksum */
uint16_t computed_checksum = compute_checksum(src_addr, dst_addr, NH_ICMP, packet, len);
checksum = coppino::compute_checksum(src_addr, dst_addr, 58, packet, len);
memcpy(packet + 2, &checksum, 2);
if (memcmp(&computed_checksum, received_checksum, 2) == 0) { /* if checksum is valid, then... */
/* Build an echo reply:
* the reply has the same exact format of the request,
* except for Type and Checksum */
*(packet) = ICMP_ECHO_REPLY_TYPE;
memset(packet + 2, 0, 2); /* zero-checksum */
IPv6Packet reply_packet;
reply_packet.setPayload(packet, len);
reply_packet.setSrcAddress(coppino::address);
dst.deserialize(src_addr);
reply_packet.setDstAddress(dst);
reply_packet.setNextHeader(58); // ICMPv6
slip::send((void*)&reply_packet, 40 + len);
break;
default:
/* no other types have been implemented */
break;
uint16_t checksum = compute_checksum(src_addr, dst_addr, NH_ICMP, packet, len);
memcpy(packet + 2, &checksum, 2);
IPv6Packet reply_packet;
reply_packet.setPayload(packet, len);
IPv6Addr tmp_addr;
tmp_addr.deserialize(dst_addr);
reply_packet.setSrcAddress(tmp_addr);
tmp_addr.deserialize(src_addr);
reply_packet.setDstAddress(tmp_addr);
reply_packet.setNextHeader(NH_ICMP);
slip::send((void*)&reply_packet, 40 + len);
}
}
return;
}