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akslip.c
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akslip.c
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// src/aksl/akslip.c 2017-10-25 Alan U. Kennington.
/*-----------------------------------------------------------------------------
Copyright (C) 1989-2018, Alan U. Kennington.
You may distribute this software under the terms of Alan U. Kennington's
modified Artistic Licence, as specified in the accompanying LICENCE file.
-----------------------------------------------------------------------------*/
// This module contains simple atomic IP actions without event-handling.
// For event-handling software, see module selector.[ch].
/*------------------------------------------------------------------------------
Functions in this file:
print
hostname2ip
sendto
sendto
udp_open
udp_open
tcp_open
tcp_open
tcp_reopen
reset_ip_src_dst
reset_tcp_src_dst
accept_in
tcp_packet::
print
ip_packet::
ip_packet
decode_options
decode
print
nbytes_from::
recvfrom
udp_port_set::
open
ip_map_table::
insert_map
clear_map
print_maps
ip_switch::
smap
dmap
tcp_mirror
send_to_switch
print
------------------------------------------------------------------------------*/
// AKSL header files:
#include "aksl/akslip.h"
#ifndef AKSL_NUMPRINT_H
#include "aksl/numprint.h"
#endif
// System header files:
#if defined(SOLARIS) || defined(linux)
// For FIONBIO:
#ifndef AKSL_X_FCNTL_H
#define AKSL_X_FCNTL_H
#include <fcntl.h>
#endif
// For perror():
#ifndef AKSL_X_STDIO_H
#define AKSL_X_STDIO_H
#include <stdio.h>
#endif
#elif !defined(WIN32)
// For FIONBIO:
#ifndef AKSL_X_SYS_IOCTL_H
#define AKSL_X_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#endif
#ifdef WIN32
#ifndef AKSL_X_WINIOCTL_H
#define AKSL_X_WINIOCTL_H
#include <winioctl.h>
#endif
#else
#ifndef AKSL_X_ARPA_INET_H
#define AKSL_X_ARPA_INET_H
#include <arpa/inet.h>
#endif
#endif
#ifndef AKSL_X_ERRNO_H
#define AKSL_X_ERRNO_H
#include <errno.h>
#endif
static const char* ip_protocol_string[256] = {
"ip", "icmp", "igmp", "ggp", "?", "?", "tcp", "?", // 0
"egp", "?", "?", "?", "pup", "?", "?", "?", // 8
"?", "udp", "?", "?", "?", "?", "idp", "?", // 16
"?", "?", "?", "?", "?", "?", "?", "?", // 24
"?", "?", "?", "?", "?", "?", "?", "?", // 32
"?", "?", "?", "?", "?", "?", "?", "?", // 40
"?", "?", "?", "?", "?", "?", "?", "?", // 48
"?", "?", "?", "?", "?", "?", "?", "hello", // 56
"?", "?", "?", "?", "?", "?", "?", "?", // 64
"?", "?", "?", "?", "?", "nd", "?", "?", // 72
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "?",
"?", "?", "?", "?", "?", "?", "?", "raw"
};
/*------------------------------------------------------------------------------
Print a "hostent" structure, which is the structure returned by a
gethostbyname() call. It describes the contents of an entry in the /etc/hosts
file.
------------------------------------------------------------------------------*/
//----------------------//
// print //
//----------------------//
void print(hostent* pe, ostream& os) {
if (!pe) {
os << "Null hostent pointer." << endl;
return;
}
if (!pe->h_name)
os << "official host name = null pointer\n";
else
os << "official host name = \"" << pe->h_name << "\"\n";
for (char** ppc = pe->h_aliases; *ppc; ++ppc)
os << "host name alias = \"" << *ppc << "\"\n";
os << "host address type = " << pe->h_addrtype << NL;
os << "host address length = " << pe->h_length << NL;
for (FOR_DECL(char**) ppc = pe->h_addr_list; *ppc; ++ppc) {
os << "host IP address = ";
for (int i = 0; i < pe->h_length; ++i) {
if (i > 0)
os << ".";
os << (int)(0xff & (*ppc)[i]);
}
os << NL;
}
os << flush;
} // End of function print.
/*------------------------------------------------------------------------------
This returns a 32-bit address (in host byte order) for the given string.
If any error occurs, then 0 is returned.
Warning: unfortunately, INADDR_ANY == 0 !!!!
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Note: this function should cache IP addresses, because the DNS look-ups are very
costly.
------------------------------------------------------------------------------*/
//----------------------//
// hostname2ip //
//----------------------//
uint32 hostname2ip(const char* hostname) {
if (nullstr(hostname))
return INADDR_ANY; // The default local host IP address.
// Try to decode address as a dotted address:
uint32 addr_net = inet_addr(hostname);
uint32 addr = ntohl(addr_net); // Convert to host order.
// If not a dotted address, try the /etc/hosts file etc.:
if (addr_net == u_long(-1)) {
// The gethostbyname() call seems to require two TCP connections!
hostent* pe = gethostbyname(hostname);
if (pe && *pe->h_addr_list)
addr = ntohl(*(uint32*)*pe->h_addr_list);
else
addr = 0;
}
return addr;
} // End of function hostname2ip.
/*------------------------------------------------------------------------------
Function to interface to the Unix sendto function.
------------------------------------------------------------------------------*/
//----------------------//
// sendto //
//----------------------//
int sendto(int fd_udp, const char* bytes, int n_bytes,
uint32 host, uint16 port) {
if (fd_udp < 0 || !bytes || n_bytes < 0)
return -1;
sockaddr_in to;
set_in(to, host, port);
// Transmit the UDP packet:
int flags = 0;
return sendto(fd_udp, bytes, n_bytes, flags, (sockaddr*)&to, sizeof(to));
} // End of function sendto.
/*------------------------------------------------------------------------------
Function to interface to the Unix sendto function.
This does not permit sending of empty UDP packets.
------------------------------------------------------------------------------*/
//----------------------//
// sendto //
//----------------------//
int sendto(int fd_udp, const nbytes& buf, const sockaddr_in& to) {
if (fd_udp < 0 || buf.empty())
return -1;
// Transmit the UDP packet:
int flags = 0;
return sendto(fd_udp, buf.bytes(), buf.n_bytes(), flags,
(sockaddr*)&to, sizeof(to));
} // End of function sendto.
/*------------------------------------------------------------------------------
This function opens a UDP port for listening.
The UDP port numbers from port1 to (port1 + n_tries - 1) are tried
until one of them can successfully be opened and put into non-blocking mode.
port1 is assumed to be in host byte-order.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Return value:
>= 0 fd of successfully opened UDP port.
eBAD_ARGUMENT erroneous argument
eSOCKET_FAILED could not open UDP socket;
eBIND_FAILED could not bind any of the n_tries sockets;
eNONBLOCKING_FAILED could not put port into non-blocking mode.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Returned value of port1:
unchanged any error condition
changed successful opening of port: the opened port number.
------------------------------------------------------------------------------*/
//----------------------//
// udp_open //
//----------------------//
int udp_open(uint16& port1, int n_tries, uint32 loc_ip) {
if (n_tries <= 0)
return eBAD_ARGUMENT;
// Create a UDP socket:
int fd = socket(PF_INET, SOCK_DGRAM, 0);
if (fd < 0) {
cout << "udp_open(): Could not open UDP socket." << endl;
perror("socket");
return eSOCKET_FAILED;
}
// Choose the input address:
struct sockaddr_in bname;
set_in(bname, loc_ip, port1);
bool_enum found_port = false;
uint16 i = 0;
for (i = 0; i < n_tries; ++i) {
// Set the address for input:
bname.sin_port = htons((short)(port1 + i));
int err = bind_in(fd, bname);
if (err >= 0) {
found_port = true;
break;
}
if (err < 0) {
cout << "udp_open(): could not bind UDP port "
<< (port1 + i) << endl;
perror("bind");
}
}
if (!found_port) {
::close(fd);
return eBIND_FAILED;
}
// Put socket into non-blocking mode:
#if defined(SOLARIS) || defined(linux)
int ret = fcntl(fd, F_SETFL, (fcntl(fd, F_GETFL, 0) | O_NONBLOCK));
if (ret < 0) {
cout << "udp_open(): Error while calling fcntl to set non-blocking."
<< endl;
perror("fcntl");
::close(fd);
return eNONBLOCKING_FAILED;
}
#elif defined(WIN32)
unsigned long x = true;
if (ioctlsocket(fd, FIONBIO, &x) < 0) {
cout << "udp_open(): Error while calling ioctl to set non-blocking."
<< endl;
perror("ioctlsocket");
::close(fd);
return eNONBLOCKING_FAILED;
}
#else
int x = true;
if (ioctl(fd, FIONBIO, &x) < 0) {
cout << "udp_open(): Error while calling ioctl to set non-blocking."
<< endl;
perror("ioctl");
::close(fd);
return eNONBLOCKING_FAILED;
}
#endif
port1 += i;
return fd;
} // End of function udp_open.
/*------------------------------------------------------------------------------
This function opens a UDP port for listening.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Return value:
>= 0 fd of successfully opened UDP port.
eSOCKET_FAILED could not open UDP socket;
eBIND_FAILED could not bind the socket;
eNONBLOCKING_FAILED could not put port into non-blocking mode.
------------------------------------------------------------------------------*/
//----------------------//
// udp_open //
//----------------------//
int udp_open(sockaddr_in& bname) {
// Create a UDP socket.
int fd = socket(PF_INET, SOCK_DGRAM, 0);
if (fd < 0) {
cout << "udp_open(): Could not open UDP socket." << endl;
perror("socket");
return eSOCKET_FAILED;
}
// Try to bind the port.
int err = bind_in(fd, bname);
if (err < 0) {
cout << "udp_open(): Could not bind UDP port." << endl;
perror("bind");
::close(fd);
return eBIND_FAILED;
}
// Put socket into non-blocking mode:
#if defined(SOLARIS) || defined(linux)
int ret = fcntl(fd, F_SETFL, (fcntl(fd, F_GETFL, 0) | O_NONBLOCK));
if (ret < 0) {
cout << "udp_open(): Error while calling fcntl to set non-blocking."
<< endl;
perror("fcntl");
::close(fd);
return eNONBLOCKING_FAILED;
}
#elif defined(WIN32)
unsigned long x = true;
if (ioctlsocket(fd, FIONBIO, &x) < 0) {
cout << "udp_open(): Error calling ioctlsocket to set non-blocking."
<< endl;
perror("ioctlsocket");
::close(fd);
return eNONBLOCKING_FAILED;
}
#else
int x = true;
if (ioctl(fd, FIONBIO, &x) < 0) {
cout << "udp_open(): Error while calling ioctl to set non-blocking."
<< endl;
perror("ioctl");
::close(fd);
return eNONBLOCKING_FAILED;
}
#endif
return fd;
} // End of function udp_open.
/*------------------------------------------------------------------------------
This opens the TCP port in the passive mode.
Function return value:
>= 0 fd of successfully opened TCP port.
eSOCKET_FAILED could not open TCP socket.
eBIND_FAILED could not bind the TCP socket.
eLISTEN_FAILED failed to put the TCP socket into listen-mode.
eNONBLOCKING_FAILED could not put TCP port into non-blocking mode.
------------------------------------------------------------------------------*/
//----------------------//
// tcp_open //
//----------------------//
int tcp_open(uint16 loc_port, uint32 loc_ip, int backlog) {
// Open the new TCP control port for proxying:
int fd0 = socket(PF_INET, SOCK_STREAM, 0);
if (fd0 < 0) {
cout << "tcp_open: could not open TCP socket." << endl;
perror("socket");
return eSOCKET_FAILED;
}
// Bind the local port:
struct sockaddr_in bname;
set_in(bname, loc_ip, loc_port);
int err = bind_in(fd0, bname);
if (err < 0) {
cout << "tcp_open: could not bind TCP port " << loc_port << endl;
perror("bind");
::close(fd0);
return eBIND_FAILED;
}
// Put the socket into passive mode, using listen():
err = listen(fd0, backlog);
if (err < 0) {
cout << "tcp_open: error putting TCP port into passive mode."
<< endl;
perror("listen");
::close(fd0);
return eLISTEN_FAILED;
}
// Put the socket into non-blocking mode:
#if defined(SOLARIS) || defined(linux)
err = fcntl(fd0, F_SETFL, (fcntl(fd0, F_GETFL, 0) | O_NONBLOCK));
if (err < 0) {
cout << "tcp_open: error setting socket non-blocking mode." << endl;
perror("fcntl");
::close(fd0);
return eNONBLOCKING_FAILED;
}
#elif defined(WIN32)
unsigned long x = true;
if (ioctlsocket(fd0, FIONBIO, &x) < 0) {
cout << "tcp_open: error setting socket non-blocking mode." << endl;
perror("ioctlsocket");
::close(fd0);
return eNONBLOCKING_FAILED;
}
#else
int x = true;
if (ioctl(fd0, FIONBIO, &x) < 0) {
cout << "tcp_open: error setting socket non-blocking mode." << endl;
perror("ioctl");
::close(fd0);
return eNONBLOCKING_FAILED;
}
#endif
// Return the fd for the control port fd:
return fd0;
} // End of function tcp_open.
/*------------------------------------------------------------------------------
This opens the TCP port in the active mode.
Function return value:
>= 0 fd of successfully opened (and connected) TCP port.
eIN_PROGRESS must wait for connection to be completed.
eSOCKET_FAILED could not open TCP socket.
eBIND_FAILED could not bind the TCP socket.
eNONBLOCKING_FAILED could not put TCP port into non-blocking mode.
eCONNECT_FAILED failed to initiate TCP port connection.
------------------------------------------------------------------------------*/
//----------------------//
// tcp_open //
//----------------------//
int tcp_open(uint16 rem_port, uint32 rem_ip, uint16 loc_port, uint32 loc_ip,
int& fd0) {
// Open the new TCP control port for proxying:
fd0 = socket(PF_INET, SOCK_STREAM, 0);
if (fd0 < 0) {
cout << "tcp_open: could not open TCP socket." << endl;
perror("socket");
return eSOCKET_FAILED;
}
// Bind the local port:
struct sockaddr_in bname;
set_in(bname, loc_ip, loc_port);
int err = bind_in(fd0, bname);
if (err < 0) {
cout << "tcp_open: could not bind TCP port " << loc_port << endl;
perror("bind");
::close(fd0);
return eBIND_FAILED;
}
// Put the socket into non-blocking mode (before connecting!!!):
#if defined(SOLARIS) || defined(linux)
err = fcntl(fd0, F_SETFL, (fcntl(fd0, F_GETFL, 0) | O_NONBLOCK));
if (err < 0) {
cout << "tcp_open: error setting socket non-blocking mode." << endl;
perror("fcntl");
::close(fd0);
return eNONBLOCKING_FAILED;
}
#elif defined(WIN32)
unsigned long x = true;
if (ioctlsocket(fd0, FIONBIO, &x) < 0) {
cout << "tcp_open: error setting socket non-blocking mode." << endl;
perror("ioctlsocket");
::close(fd0);
return eNONBLOCKING_FAILED;
}
#else
int x = true;
if (ioctl(fd0, FIONBIO, &x) < 0) {
cout << "tcp_open: error setting socket non-blocking mode." << endl;
perror("ioctl");
::close(fd0);
return eNONBLOCKING_FAILED;
}
#endif
// Put the socket into passive mode, using listen():
struct sockaddr_in cname;
set_in(cname, rem_ip, rem_port);
err = connect_in(fd0, cname);
if (err < 0) {
#ifndef WIN32
if (errno == EINPROGRESS) {
#else
if (errno == WSAEINPROGRESS) {
#endif
// In this case, must register a handler to deal with this!!!
// cout << flush;
// perror("connect");
return eIN_PROGRESS;
}
cout << "tcp_open: error while connecting putting TCP port."
<< endl;
perror("connect");
::close(fd0);
return eCONNECT_FAILED;
}
// Return the fd for the control port fd:
return fd0;
} // End of function tcp_open.
/*------------------------------------------------------------------------------
This reattempts opening a TCP port in the active mode.
"rem_port" and "rem_ip" should be the original values.
Returns:
fd >= 0 file descriptor (success)
eIN_PROGRESS must wait for completion
eBAD_ARGUMENT bad argument
eCONNECT_FAILED serious error in connect() call.
------------------------------------------------------------------------------*/
//----------------------//
// tcp_reopen //
//----------------------//
int tcp_reopen(int fd0, uint16 rem_port, uint32 rem_ip) {
if (fd0 < 0) {
cout << "tcp_reopen: negative file descriptor.\n";
return eBAD_ARGUMENT;
}
// Put the socket into passive mode, using listen():
struct sockaddr_in cname;
set_in(cname, rem_ip, rem_port);
int err = connect_in(fd0, cname);
if (err < 0) {
#ifndef WIN32
if (errno == EINPROGRESS || errno == EALREADY) {
#else
if (errno == WSAEINPROGRESS || errno == WSAEALREADY) {
#endif
// In this case, must register a handler to deal with this!!!
// cout << flush;
// perror("connect");
return eIN_PROGRESS;
}
#ifndef WIN32
if (errno == EISCONN) {
#else
if (errno == WSAEISCONN) {
#endif
// In this case, must register a handler to deal with this!!!
// cout << flush;
// perror("connect");
return fd0;
}
cout << "tcp_reopen: error putting TCP port into active mode."
<< endl;
perror("connect");
::close(fd0);
return eCONNECT_FAILED;
}
// Return the fd for the control port fd:
return err;
} // End of function tcp_reopen.
/*------------------------------------------------------------------------------
If a full IP header is not present, then nothing is altered.
If a reset is performed, then the header checksum is recalculated.
------------------------------------------------------------------------------*/
//----------------------//
// reset_ip_src_dst //
//----------------------//
int reset_ip_src_dst(nbytes& buf, uint32 src_ip, uint32 dst_ip) {
if (buf.n_bytes() < 20)
return -1;
// Look up the IP header length:
uint8 x8 = uint8(buf[0]);
int IHL_bytes = (x8 & 0x0f) * 4;
if (buf.n_bytes() < IHL_bytes)
return -2;
// Modify the addresses:
buf.set32(12, src_ip);
buf.set32(16, dst_ip);
// Clear the old header checksum:
buf.set16(10, 0);
// Calculate the header checksum:
uint16 hcs_calc = ~u16checksum_addx(buf.bytes(), IHL_bytes);
// Insert the new header checksum:
buf.set16(10, hcs_calc);
return 0;
} // End of function reset_ip_src_dst.
/*------------------------------------------------------------------------------
If a full IP and TCP header are not present, then nothing is altered.
If a reset is performed, then the TCP header checksum is recalculated.
------------------------------------------------------------------------------*/
//----------------------//
// reset_tcp_src_dst //
//----------------------//
int reset_tcp_src_dst(nbytes& buf, uint16 src_port, uint16 dst_port) {
// Return if buffer is shorter than minimal IP + TCP headers:
if (buf.n_bytes() < 40)
return -1;
const char* pc = buf.bytes();
// Look up the IP header length:
uint8 x8 = uint8(pc[0]);
// cout << "buf[0] = 0x" << hex2(buf[0]) << "\n";
int IHL_bytes = (x8 & 0x0f) * 4;
// Return if buffer is shorter than IP header + minimal TCP header:
if (buf.n_bytes() < IHL_bytes + 20 || IHL_bytes < 20)
return -2;
// Modify the TCP ports:
buf.set16(IHL_bytes, src_port);
buf.set16(IHL_bytes + 2, dst_port);
// Clear the old header checksum:
buf.set16(IHL_bytes + 16, 0);
// Calculate the TCP header checksum:
uint16 tcp_hcs_calc = u16checksum_addx(pc + 12, 8);
// The protocol:
uint8 protocol = pc[9];
tcp_hcs_calc = u16checksum_fold(tcp_hcs_calc, uint16(protocol));
// TCP packet length:
uint16 tcp_length = buf.n_bytes() - IHL_bytes;
tcp_hcs_calc = u16checksum_fold(tcp_hcs_calc, tcp_length);
// The first 16 bytes of TCP header:
tcp_hcs_calc = ~u16checksum_fold(tcp_hcs_calc,
u16checksum_addx(pc + IHL_bytes, tcp_length));
// Insert the new header checksum:
buf.set16(IHL_bytes + 16, tcp_hcs_calc);
return 0;
} // End of function reset_tcp_src_dst.
/*------------------------------------------------------------------------------
Calls the Unix accept() function for passive TCP socket fd1.
If the call succeeds, the calling TCP port is written to "from", and
the function return value is the non-negative fd for the new data socket.
Otherwise "from" is unaltered, and the function return value is negative.
------------------------------------------------------------------------------*/
//----------------------//
// accept_in //
//----------------------//
int accept_in(int fd1, sockaddr_in& from) {
if (fd1 < 0)
return eBAD_ARGUMENT;
// Accept the data socket from the control socket:
sockaddr cname;
#ifdef linux
socklen_t cnamelen = sizeof(cname);
#else
int cnamelen = sizeof(cname);
#endif
int fd0 = ::accept(fd1, &cname, &cnamelen);
if (fd0 < 0) {
cout << "tcp_handler::handler: could not accept TCP socket."
<< endl;
perror("accept");
return eACCEPT_FAILED;
}
// Check that the peer is an IP socket:
if (cnamelen != sizeof(from) || cname.sa_family != AF_INET) {
cout << "accept_in(): received non-IP TCP connection.\n";
::close(fd0);
return eACCEPT_FAILED;
}
// Make a copy of the peer address and fd:
memcpy(&from, &cname, cnamelen);
return fd0;
} // End of function accept_in.
//----------------------//
// tcp_packet::print //
//----------------------//
void tcp_packet::print(ostream& os) {
os << "TCP packet contents.\n";
os << "n_bytes = " << n_bytes << NL;
os << "status = " << status << NL;
os << "src_port = " << int(src_port) << NL;
os << "dst_port = " << int(dst_port) << NL;
os << "seq_no = " << seq_no << NL;
os << "ack_no = " << ack_no << NL;
os << "data_offset = " << int(data_offset) << NL;
os << "res0 = 0x" << hex2(res0) << NL;
os << "flags = 0x" << hex2(flags) << NL;
os << "window = " << int(window) << NL;
os << "checksum = 0x" << hex4(checksum) << NL;
os << "urgent_pointer = " << int(urgent_pointer) << NL;
if (payload.empty())
os << "no data payload\n";
else {
os << "payload (" << payload.n_bytes() << " bytes):\n";
hex_print(payload, os);
}
os << "urg = " << bool_string(urg) << NL;
os << "ack = " << bool_string(ack) << NL;
os << "psh = " << bool_string(psh) << NL;
os << "rst = " << bool_string(rst) << NL;
os << "syn = " << bool_string(syn) << NL;
os << "fin = " << bool_string(fin) << NL;
// os << "dcs_calc = 0x" << hex4(dcs_calc) << NL;
// os << "dcs_syndrome = 0x" << hex4(dcs_syndrome) << NL;
os << flush;
} // End of function tcp_packet::print.
//----------------------//
// ip_packet::ip_packet //
//----------------------//
ip_packet::ip_packet() {
// Basic status variables:
n_bytes = 0;
status = 0;
// Directly parsed fields:
version = 0;
IHL = 0;
type_of_service = 0;
total_length = 0;
id = 0;
flags = 0;
fragment_offset = 0;
time_to_live = 0;
protocol = 0;
header_checksum = 0;
source = 0;
destination = 0;
// Indirectly parsed fields.
precedence = 0;
low_delay = false;
high_throughput = false;
high_reliability = false;
dont_fragment = false;
more_fragments = false;
// Header checksum things:
hcs_calc = 0;
hcs_syndrome = 0;
tcp = 0;
} // End of function ip_packet::ip_packet.
//------------------------------//
// ip_packet::decode_options //
//------------------------------//
int ip_packet::decode_options(const char* pc, int n) {
if (!pc || n <= 0)
return -1;
bool_enum found_error = false;
while (!found_error && n > 0) {
ip_option* po1 = new ip_option;
po1->type = uint8(*pc++);
n -= 1;
po1->optclass = (po1->type >> 5) & 0x03;
po1->number = po1->type & 0x1f;
switch(po1->optclass) {
case 0: // Class: Control.
switch(po1->number) {
case 0: // 1 byte. End of option list.
n = 0; // Terminate parsing of options.
break;
case 1: // 1 byte. No operation.
// Just ignore it.
break;
case 2: // 11 bytes. Security.
if (n < 10) {
cout << "Security option too short in IP packet.\n";
found_error = true;
// Copy as much of the option as possible:
if (n >= 1)
po1->length = uint8(*pc++);
n -= 1;
if (n > 0) {
po1->data.copy_from(pc, n);
pc += n;
n = 0;
}
break;
}
// Copy all fields:
po1->length = uint8(*pc++);
if (po1->length != 11) {
cout << "IP security option length field error.\n";
found_error = true;
}
po1->data.copy_from(pc, 9);
pc += 9;
n -= 10;
break;
case 3: // Variable bytes. Loose source routing.
if (n < 1) {
cout << "Loose source routing option short in IP packet.\n";
found_error = true;
break;
}
po1->length = uint8(*pc++);
n -= 1;
if (n < po1->length - 2) {
cout << "Loose source routing option short in IP packet.\n";
found_error = true;
// Copy as much of the option as possible:
if (n > 0) {
po1->data.copy_from(pc, n);
pc += n;
n = 0;
}
break;
}
// Copy the data.
po1->data.copy_from(pc, po1->length - 2);
pc += po1->length - 2;
n -= po1->length - 2;
break;
case 7: // Variable bytes. Record route.
if (n < 1) {
cout << "Record route option short in IP packet.\n";
found_error = true;
break;
}
po1->length = uint8(*pc++);
n -= 1;
if (n < po1->length - 2) {
cout << "Record route option short in IP packet.\n";
found_error = true;
// Copy as much of the option as possible:
if (n > 0) {
po1->data.copy_from(pc, n);
pc += n;
n = 0;
}
break;
}
// Copy the data.
po1->data.copy_from(pc, po1->length - 2);
pc += po1->length - 2;
n -= po1->length - 2;
break;
case 8: // 4 bytes. Stream identifier.
if (n < 3) {
cout <<"Stream identifier option too short in IP packet.\n";
found_error = true;
// Copy as much of the option as possible:
if (n >= 1)
po1->length = uint8(*pc++);
n -= 1;
if (n > 0) {
po1->data.copy_from(pc, n);
pc += n;
n = 0;
}
break;
}
// Copy all fields:
po1->length = uint8(*pc++);
if (po1->length != 4) {
cout << "Stream identifier option length field error.\n";
found_error = true;
}
po1->data.copy_from(pc, 2);
pc += 2;
n -= 3;
break;
case 9: // Variable bytes. Strict source routing.
if (n < 1) {
cout <<"Strict source routing option short in IP packet.\n";
found_error = true;
break;
}
po1->length = uint8(*pc++);
n -= 1;
if (n < po1->length - 2) {
cout <<"Strict source routing option short in IP packet.\n";
found_error = true;
// Copy as much of the option as possible:
if (n > 0) {
po1->data.copy_from(pc, n);
pc += n;
n = 0;
}
break;
}
// Copy the data.
po1->data.copy_from(pc, po1->length - 2);
pc += po1->length - 2;
n -= po1->length - 2;
break;
default:
cout << "Unrecognised control option in IP packet.\n";
found_error = true;
break;
} // End of switch(number).
break;
case 2: // Class: Debugging and measurement.
switch(po1->number) {
case 4: // Variable bytes. Internet timestamp.
if (n < 1) {
cout << "Internet timestamp option short in IP packet.\n";
found_error = true;
break;
}
po1->length = uint8(*pc++);
n -= 1;
if (n < po1->length - 2) {
cout << "Internet timestamp option short in IP packet.\n";
found_error = true;
// Copy as much of the option as possible:
if (n > 0) {
po1->data.copy_from(pc, n);
pc += n;
n = 0;
}
break;
}
// Copy the data.
po1->data.copy_from(pc, po1->length - 2);
pc += po1->length - 2;
n -= po1->length - 2;
break;
default:
cout << "Unrecognised debug/measmt option in IP packet.\n";
found_error = true;
break;
} // End of switch(number).
break;
case 1: // Class: Reserved classes.
case 3:
cout << "Found reserved option class in IP packet.\n";
found_error = true;
break;
} // End of switch(optclass).
options.append(po1);
} // End of while (!found_error && n > 0).
return 0;
} // End of function ip_packet::decode_options.
/*------------------------------------------------------------------------------
This function decodes n bytes as an IP packet.
If the interpretation is successful, 0 is returned.
Otherwise -1 is returned. The "status" field indicates the type of error that
occurred, if any. If parsing is successful, "status" is set to 1.
Therefore "status" is never equal to 0 after this function has been called.
Status codes:
1 Successfully parsed. All parsed fields are valid.
0 Nothing has been parsed.