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Code Issues Releases Wiki Activity

Moved PDU::pseudoheader_checksum and PDU::do_checksum to Utils namespace.

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This commit is contained in:
Matias Fontanini
2011-09-07 09:52:58 -03:00
parent a216cf8401
commit f30f404632
7 changed files with 51 additions and 52 deletions
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21
include/pdu.h
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@@ -260,27 +260,6 @@ namespace Tins {
* \param parent The PDU that's one level below this one on the stack. Might be 0.
*/
virtual void write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *parent) = 0;
/** \brief Does the 16 bits sum of all 2 bytes elements between start and end.
*
* This is the checksum used by IP, UDP and TCP. If there's and odd number of
* bytes, the last one is padded and added to the checksum. The checksum is performed
* using network endiannes.
* \param start The pointer to the start of the buffer.
* \param end The pointer to the end of the buffer(excluding the last element).
* \return Returns the checksum between start and end(non inclusive).
*/
static uint32_t do_checksum(uint8_t *start, uint8_t *end);
/** \brief Performs the pseudo header checksum used in TCP and UDP PDUs.
*
* \param source_ip The source ip address.
* \param dest_ip The destination ip address.
* \param len The length to be included in the pseudo header.
* \param flag The flag to use in the protocol field of the pseudo header.
* \return The pseudo header checksum.
*/
static uint32_t pseudoheader_checksum(uint32_t source_ip, uint32_t dest_ip, uint32_t len, uint32_t flag);
private:
uint32_t _flag;
PDU *_inner_pdu;

21
include/utils.h
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@@ -177,6 +177,27 @@ namespace Tins {
*/
uint16_t channel_to_mhz(uint16_t channel);
/** \brief Does the 16 bits sum of all 2 bytes elements between start and end.
*
* This is the checksum used by IP, UDP and TCP. If there's and odd number of
* bytes, the last one is padded and added to the checksum. The checksum is performed
* using network endiannes.
* \param start The pointer to the start of the buffer.
* \param end The pointer to the end of the buffer(excluding the last element).
* \return Returns the checksum between start and end(non inclusive).
*/
uint32_t do_checksum(uint8_t *start, uint8_t *end);
/** \brief Performs the pseudo header checksum used in TCP and UDP PDUs.
*
* \param source_ip The source ip address.
* \param dest_ip The destination ip address.
* \param len The length to be included in the pseudo header.
* \param flag The flag to use in the protocol field of the pseudo header.
* \return The pseudo header checksum.
*/
uint32_t pseudoheader_checksum(uint32_t source_ip, uint32_t dest_ip, uint32_t len, uint32_t flag);
/** \brief Generic function to iterate through interface and collect
* data.
*

3
src/icmp.cpp
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@@ -177,7 +177,8 @@ void Tins::ICMP::set_redirect(uint8_t icode, uint32_t address) {
void Tins::ICMP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *) {
assert(total_sz >= sizeof(icmphdr));
if(!_icmp.check) {
uint32_t checksum = PDU::do_checksum(buffer + sizeof(icmphdr), buffer + total_sz) + PDU::do_checksum((uint8_t*)&_icmp, ((uint8_t*)&_icmp) + sizeof(icmphdr));
uint32_t checksum = Utils::do_checksum(buffer + sizeof(icmphdr), buffer + total_sz) +
Utils::do_checksum((uint8_t*)&_icmp, ((uint8_t*)&_icmp) + sizeof(icmphdr));
while (checksum >> 16)
checksum = (checksum & 0xffff) + (checksum >> 16);
_icmp.check = Utils::net_to_host_s(~checksum);

2
src/ip.cpp
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@@ -301,7 +301,7 @@ void Tins::IP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU
memset(buffer + sizeof(iphdr) + this->_options_size, 0, this->_padded_options_size - this->_options_size);
if (parent && !_ip.check) {
uint32_t checksum = PDU::do_checksum(buffer, buffer + sizeof(iphdr) + _padded_options_size);
uint32_t checksum = Utils::do_checksum(buffer, buffer + sizeof(iphdr) + _padded_options_size);
while (checksum >> 16)
checksum = (checksum & 0xffff) + (checksum >> 16);
((iphdr*)buffer)->check = Utils::net_to_host_s(~checksum);

27
src/pdu.cpp
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@@ -102,30 +102,3 @@ Tins::PDU *Tins::PDU::clone_packet() const {
}
return ret;
}
/* Static methods */
uint32_t Tins::PDU::do_checksum(uint8_t *start, uint8_t *end) {
uint32_t checksum(0);
uint16_t *ptr = (uint16_t*)start, *last = (uint16_t*)end, padding(0);
if(((end - start) & 1) == 1) {
last = (uint16_t*)end - 1;
padding = *(end - 1) << 8;
}
while(ptr < last)
checksum += Utils::net_to_host_s(*(ptr++));
return checksum + padding;
}
uint32_t Tins::PDU::pseudoheader_checksum(uint32_t source_ip, uint32_t dest_ip, uint32_t len, uint32_t flag) {
uint32_t checksum(0);
source_ip = Utils::net_to_host_l(source_ip);
dest_ip = Utils::net_to_host_l(dest_ip);
uint16_t *ptr = (uint16_t*)&source_ip;
checksum += (uint32_t)(*ptr) + (uint32_t)(*(ptr+1));
ptr = (uint16_t*)&dest_ip;
checksum += (uint32_t)(*ptr) + (uint32_t)(*(ptr+1));
checksum += flag + len;
return checksum;
}

4
src/udp.cpp
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@@ -83,8 +83,8 @@ void Tins::UDP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PD
length(sizeof(udphdr) + inner_pdu()->size());
std::memcpy(buffer, &_udp, sizeof(udphdr));
if(!_udp.check && ip_packet) {
uint32_t checksum = PDU::pseudoheader_checksum(ip_packet->src_addr(), ip_packet->dst_addr(), size(), IPPROTO_UDP) +
PDU::do_checksum(buffer, buffer + total_sz);
uint32_t checksum = Utils::pseudoheader_checksum(ip_packet->src_addr(), ip_packet->dst_addr(), size(), IPPROTO_UDP) +
Utils::do_checksum(buffer, buffer + total_sz);
while (checksum >> 16)
checksum = (checksum & 0xffff)+(checksum >> 16);
((udphdr*)buffer)->check = Utils::net_to_host_s(~checksum);

25
src/utils.cpp
View File

@@ -252,6 +252,31 @@ uint16_t Tins::Utils::channel_to_mhz(uint16_t channel) {
return 2407 + (channel * 5);
}
uint32_t Tins::Utils::do_checksum(uint8_t *start, uint8_t *end) {
uint32_t checksum(0);
uint16_t *ptr = (uint16_t*)start, *last = (uint16_t*)end, padding(0);
if(((end - start) & 1) == 1) {
last = (uint16_t*)end - 1;
padding = *(end - 1) << 8;
}
while(ptr < last)
checksum += Utils::net_to_host_s(*(ptr++));
return checksum + padding;
}
uint32_t Tins::Utils::pseudoheader_checksum(uint32_t source_ip, uint32_t dest_ip, uint32_t len, uint32_t flag) {
uint32_t checksum(0);
source_ip = Utils::net_to_host_l(source_ip);
dest_ip = Utils::net_to_host_l(dest_ip);
uint16_t *ptr = (uint16_t*)&source_ip;
checksum += (uint32_t)(*ptr) + (uint32_t)(*(ptr+1));
ptr = (uint16_t*)&dest_ip;
checksum += (uint32_t)(*ptr) + (uint32_t)(*(ptr+1));
checksum += flag + len;
return checksum;
}
uint32_t Tins::Utils::crc32(uint8_t* data, uint32_t data_size) {
uint32_t i, crc = 0;
static uint32_t crc_table[] = {