code polishing
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12d09f24c5
commit
11e56ac38c
@ -16,8 +16,6 @@ namespace coppino {
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void hexdump(const char* pointer, int len);
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uint16_t compute_checksum(const char* src_addr, const char* dst_addr, uint8_t next_header, const char* payload, int len);
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void blink();
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}
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54
coppino.ino
54
coppino.ino
@ -22,58 +22,4 @@ namespace coppino {
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Serial.print('.');
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}
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}
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uint16_t compute_checksum(const char* src_addr, const char* dst_addr, uint8_t next_header, const char* payload, int len) {
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char buffer[LEN];
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uint32_t total;
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uint16_t* ptr;
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int words;
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int i = len;
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memcpy(buffer, payload, len);
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if (len % 2) {
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buffer[len] = 0;
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i++;
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}
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memcpy(buffer + i, src_addr, 16); i += 16;
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memcpy(buffer + i, dst_addr, 16); i += 16;
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memcpy(buffer + i, "\0\0", 2); i += 2;
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buffer[i] = len >> 8; i += 1;
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buffer[i] = len & 0xff; i += 1;
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memcpy(buffer + i, "\0\0\0", 3); i += 3;
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buffer[i] = next_header; i += 1;
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total = 0;
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ptr = (uint16_t*)buffer;
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words = (i + 1) / 2;
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while (words--) total += *ptr++;
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while (total & 0xffff0000)
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total = (total >> 16) + (total & 0xffff);
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//total -= 64*256; // TODO -- this is an ugly fix, something is wrong somewhere else
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return ~((uint16_t) total);
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/*
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uint16_t checksum = 0;
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for (i = 0; i < len; i = i + 2) {
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part = ((*(packet + i + 0)) << 8) + *(packet + i + 1);
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checksum += part;
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}
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for (i = 0; i < 16; i = i + 2 ) {
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part = ((*(src_addr + i + 0)) << 8) + *(src_addr + i + 1);
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checksum += part;
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part = ((*(dst_addr + i + 0)) << 8) + *(dst_addr + i + 1);
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checksum += part;
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}
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checksum += (len + 58); // upper-layer packet length + next header
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while (checksum >> 16)
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checksum = (checksum & 0xffff) + (checksum >> 16);
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*/
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}
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void blink() {
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digitalWrite(13, !digitalRead(13));
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}
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}
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9
ipv6.h
9
ipv6.h
@ -4,6 +4,11 @@
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namespace ipv6 {
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const uint8_t LEN = 128;
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const uint8_t ICMP_ECHO_REQUEST_TYPE = 128;
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const uint8_t ICMP_ECHO_REPLY_TYPE = 129;
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const uint8_t NH_ICMP = 58;
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const uint8_t NH_UDP = 17;
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class IPv6Addr {
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private:
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@ -15,7 +20,7 @@ namespace ipv6 {
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const char* serialize();
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};
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extern IPv6Addr ALL_NODES_ADDRESS;
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extern const IPv6Addr ALL_NODES_ADDRESS;
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struct ipv6_packet_header {
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char field[4];
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@ -43,6 +48,8 @@ namespace ipv6 {
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/* Note: content of message may be changed */
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void handleICMP(const char* src, const char* dst, char* message, int len);
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uint16_t compute_checksum(const char* src_addr, const char* dst_addr, uint8_t next_header, const char* payload, int len);
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}
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#endif
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98
ipv6.ino
98
ipv6.ino
@ -2,7 +2,47 @@
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namespace ipv6 {
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/******** costants ********/
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IPv6Addr ALL_NODES_ADDRESS("\xff\x02\x00\x00\x00\x00\x00\x00\x01"); /* ff02::1 */
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const IPv6Addr ALL_NODES_ADDRESS("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"); /* ff02::1 */
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/******** FUNCTIONS *******/
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uint16_t compute_checksum(const char* src_addr, const char* dst_addr, uint8_t next_header, const char* payload, int len) {
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char buffer[LEN];
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uint32_t total;
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uint16_t* ptr;
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int words;
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int i = len;
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/* prepare buffer with all data to checksum:
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- the actual payload
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- the pseudo ipv6 header
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*/
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/* actual payload */
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memcpy(buffer, payload, len);
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if (len % 2) { /* pad with 0 if length is odd */
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buffer[len] = 0;
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i++;
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}
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/* pseudo ipv6 header -- see RFC 2460, Section 8.1 */
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memcpy(buffer + i, src_addr, 16); i += 16;
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memcpy(buffer + i, dst_addr, 16); i += 16;
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memset(buffer + i, 0, 3); i+= 3; /* first 3 bytes always 0, because len always < 256 */
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buffer[i] = len & 0xff; i += 1;
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memset(buffer + i, 0, 3); i += 3; /* zero, as per-standard */
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buffer[i] = next_header; i += 1;
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/* do computation */
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total = 0;
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ptr = (uint16_t*)buffer;
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words = (i + 1) / 2;
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while (words--) total += *ptr++;
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while (total & 0xffff0000) {
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total = (total >> 16) + (total & 0xffff);
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}
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return ~((uint16_t) total);
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}
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/******** IPv6Addr ********/
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IPv6Addr::IPv6Addr() {;}
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@ -57,10 +97,10 @@ void IPv6Packet::setPayload(char* payload, uint8_t len) {
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int len = ((*(packet + 4)) << 8) + (*(packet + 5));
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switch(*(packet + 6)) { /* next header */
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case 58:
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case NH_ICMP:
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handleICMP(packet + 8, packet + 24, packet + 40, len);
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break;
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case 17:
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case NH_UDP:
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// handleUDP(packet + 40, len);
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break;
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default:
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@ -72,36 +112,36 @@ void IPv6Packet::setPayload(char* payload, uint8_t len) {
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void handleICMP(const char* src_addr, const char* dst_addr, char* packet, int len) {
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uint8_t type = *(packet);
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uint32_t checksum = ((*(packet + 2)) << 8) + (*(packet + 3));
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uint16_t part;
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IPv6Addr dst;
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int i;
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switch (type) {
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case 128:
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/* TODO compute checksum, and assert validity of incoming message */
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/* then... */
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if (type == ICMP_ECHO_REQUEST_TYPE) { /* if it is ICMPv6 Echo Request, then... */
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/* compute checksum, and assert validity of incoming message */
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char received_checksum[2];
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memcpy(received_checksum, packet + 2, 2);
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/* Build an echo reply:
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* the reply has the same exact format of the request,
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* except for Type and Checksum */
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*(packet) = 129; /* echo reply type */
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*(packet + 2) = *(packet + 3) = 0; /* zero-checksum */
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memset(packet + 2, 0, 2); /* zero-checksum */
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uint16_t computed_checksum = compute_checksum(src_addr, dst_addr, NH_ICMP, packet, len);
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checksum = coppino::compute_checksum(src_addr, dst_addr, 58, packet, len);
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memcpy(packet + 2, &checksum, 2);
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if (memcmp(&computed_checksum, received_checksum, 2) == 0) { /* if checksum is valid, then... */
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/* Build an echo reply:
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* the reply has the same exact format of the request,
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* except for Type and Checksum */
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*(packet) = ICMP_ECHO_REPLY_TYPE;
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memset(packet + 2, 0, 2); /* zero-checksum */
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IPv6Packet reply_packet;
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reply_packet.setPayload(packet, len);
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reply_packet.setSrcAddress(coppino::address);
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dst.deserialize(src_addr);
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reply_packet.setDstAddress(dst);
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reply_packet.setNextHeader(58); // ICMPv6
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slip::send((void*)&reply_packet, 40 + len);
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break;
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default:
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/* no other types have been implemented */
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break;
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uint16_t checksum = compute_checksum(src_addr, dst_addr, NH_ICMP, packet, len);
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memcpy(packet + 2, &checksum, 2);
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IPv6Packet reply_packet;
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reply_packet.setPayload(packet, len);
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IPv6Addr tmp_addr;
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tmp_addr.deserialize(dst_addr);
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reply_packet.setSrcAddress(tmp_addr);
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tmp_addr.deserialize(src_addr);
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reply_packet.setDstAddress(tmp_addr);
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reply_packet.setNextHeader(NH_ICMP);
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slip::send((void*)&reply_packet, 40 + len);
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}
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}
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return;
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}
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