*/
#define _GNU_SOURCE
-#ifdef WIN32
+
#include <winsock2.h>
-#else
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <arpa/inet.h>
-#include <sys/select.h>
-#include <netinet/ip.h>
-#include <netinet/ip_icmp.h>
-#include <netinet/in.h>
-#endif
+#include <ws2tcpip.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdint.h>
#include <time.h>
-
-#ifdef WIN32
-typedef unsigned int uid_t;
-typedef SOCKET Socket;
-typedef unsigned short ushort;
-#define ICMP_ECHO 8
-#define IPDEFTTL 64 /* default ttl, from RFC 1340 */
-#define ICMP_TIME_EXCEEDED 11 /* Time Exceeded */
-#define IP_HDRINCL 3 /* int; Header is included with data. */
-#else
-typedef int Socket;
-#endif
+/**
+ * Should we print some debug output?
+ */
+#define VERBOSE 0
/**
* Must match IP given in the client.
*/
#define DUMMY_IP "192.0.2.86"
-#define VERBOSE 0
+/**
+ * TTL to use for our outgoing messages.
+ */
+#define IPDEFTTL 64
+
+#define ICMP_ECHO 8
+
+#define ICMP_TIME_EXCEEDED 11 /* Time Exceeded */
/**
* How often do we send our ICMP messages to receive replies?
*/
#define ICMP_SEND_FREQUENCY_MS 500
+/**
+ * IPv4 header.
+ */
struct ip_packet
{
- uint8_t vers_ihl;
- uint8_t tos;
- uint16_t pkt_len;
- uint16_t id;
- uint16_t flags_frag_offset;
- uint8_t ttl;
- uint8_t proto;
- uint16_t checksum;
- uint32_t src_ip;
- uint32_t dst_ip;
+
+ /**
+ * Version (4 bits) + Internet header length (4 bits)
+ */
+ uint8_t vers_ihl;
+
+ /**
+ * Type of service
+ */
+ uint8_t tos;
+
+ /**
+ * Total length
+ */
+ uint16_t pkt_len;
+
+ /**
+ * Identification
+ */
+ uint16_t id;
+
+ /**
+ * Flags (3 bits) + Fragment offset (13 bits)
+ */
+ uint16_t flags_frag_offset;
+
+ /**
+ * Time to live
+ */
+ uint8_t ttl;
+
+ /**
+ * Protocol
+ */
+ uint8_t proto;
+
+ /**
+ * Header checksum
+ */
+ uint16_t checksum;
+
+ /**
+ * Source address
+ */
+ uint32_t src_ip;
+
+ /**
+ * Destination address
+ */
+ uint32_t dst_ip;
};
+/**
+ * Format of ICMP packet.
+ */
struct icmp_packet
{
uint8_t type;
+
uint8_t code;
+
uint16_t checksum;
+
uint32_t reserved;
};
+/**
+ * Beginning of UDP packet.
+ */
struct udp_packet
{
uint16_t src_port;
uint32_t length;
};
-static Socket icmpsock;
+/**
+ * Socket we use to receive "fake" ICMP replies.
+ */
+static SOCKET icmpsock;
-static Socket rawsock;
+/**
+ * Socket we use to send our ICMP requests.
+ */
+static SOCKET rawsock;
+/**
+ * Target "dummy" address.
+ */
static struct in_addr dummy;
+
+/**
+ * CRC-16 for IP/ICMP headers.
+ *
+ * @param data what to calculate the CRC over
+ * @param bytes number of bytes in data (must be multiple of 2)
+ * @return the CRC 16.
+ */
static uint16_t
calc_checksum(const uint16_t *data,
unsigned int bytes)
return sum;
}
-#if WIN32
+
/**
+ * Convert IPv4 address from text to binary form.
+ *
* @param af address family
* @param cp the address to print
* @param buf where to write the address result
+ * @return 1 on success
*/
-static int inet_pton (int af, char *cp, struct in_addr *buf)
+static int
+inet_pton (int af,
+ const char *cp,
+ struct in_addr *buf)
{
- //ret = WSAStringToAddress (cp, af, NULL, (LPSOCKADDR)buf, &ssize);
buf->s_addr = inet_addr(cp);
- if (buf->s_addr != INADDR_NONE)
+ if (buf->s_addr == INADDR_NONE)
{
- fprintf(stderr, "Error %d handling address %s", WSAGetLastError(), cp);
+ fprintf(stderr,
+ "Error %d handling address %s",
+ WSAGetLastError(),
+ cp);
return 0;
}
- else
- return 1;
-}
-#endif
-
-static void
-make_echo (const struct in_addr *src_ip,
- struct icmp_packet *echo)
-{
- memset(echo, 0, sizeof(struct icmp_packet));
- echo->type = ICMP_ECHO;
- echo->code = 0;
- echo->reserved = 0;
- echo->checksum = 0;
- echo->checksum = htons(calc_checksum((uint16_t*)echo, sizeof (struct icmp_packet)));
+ return 1;
}
ip_pkt.vers_ihl = 0x45;
ip_pkt.tos = 0;
ip_pkt.pkt_len = sizeof (packet);
- ip_pkt.id = 1;
+ ip_pkt.id = htons (256);
ip_pkt.flags_frag_offset = 0;
ip_pkt.ttl = IPDEFTTL;
ip_pkt.proto = IPPROTO_ICMP;
- ip_pkt.checksum = 0;
+ ip_pkt.checksum = 0;
ip_pkt.src_ip = my_ip->s_addr;
ip_pkt.dst_ip = dummy.s_addr;
ip_pkt.checksum = htons(calc_checksum((uint16_t*)&ip_pkt, sizeof (ip_pkt)));
memcpy (packet, &ip_pkt, sizeof (ip_pkt));
off += sizeof (ip_pkt);
- make_echo (my_ip, &icmp_echo);
+
+ icmp_echo.type = ICMP_ECHO;
+ icmp_echo.code = 0;
+ icmp_echo.reserved = 0;
+ icmp_echo.checksum = 0;
+ icmp_echo.checksum = htons(calc_checksum((uint16_t*) &icmp_echo,
+ sizeof (struct icmp_packet)));
memcpy (&packet[off], &icmp_echo, sizeof (icmp_echo));
off += sizeof (icmp_echo);
dst.sin_family = AF_INET;
dst.sin_addr = dummy;
err = sendto(rawsock,
- packet, off, 0,
- (struct sockaddr*)&dst,
- sizeof(dst));
+ packet, off, 0,
+ (struct sockaddr*)&dst,
+ sizeof(dst));
if (err < 0)
{
#if VERBOSE
}
+/**
+ * We've received an ICMP response. Process it.
+ */
static void
process_icmp_response ()
{
struct udp_packet udp_pkt;
size_t off;
int have_port;
- int have_udp;
uint32_t port;
+
have = read (icmpsock, buf, sizeof (buf));
if (have == -1)
{
return;
}
have_port = 0;
-
+#if VERBOSE
+ fprintf (stderr,
+ "Received message of %u bytes\n",
+ (unsigned int) have);
+#endif
if (have == sizeof (struct ip_packet) *2 + sizeof (struct icmp_packet) * 2 + sizeof(uint32_t))
{
have_port = 1;
memcpy(&sip,
&ip_pkt.src_ip,
sizeof (sip));
-
memcpy (&ip_pkt, &buf[off], sizeof (ip_pkt));
off += sizeof (ip_pkt);
- have_udp = 0;
- if (ip_pkt.proto == IPPROTO_UDP)
- {
- have_udp = 1;
- }
-
if (have_port)
{
- memcpy(&port, &buf[sizeof (struct ip_packet) *2 + sizeof (struct icmp_packet) * 2], sizeof(uint32_t));
+ memcpy(&port,
+ &buf[sizeof (struct ip_packet) *2 + sizeof (struct icmp_packet) * 2],
+ sizeof(uint32_t));
port = ntohs(port);
-#ifdef WIN32
DWORD ssize = sizeof(buf);
- WSAAddressToString((LPSOCKADDR)&sip, sizeof(sip), NULL, buf, &ssize);
- fprintf (stdout, "%s:%d\n", buf, port);
-#else
- fprintf (stdout,
- "%s:%d\n",
- inet_ntop (AF_INET,
- &sip,
- buf,
- sizeof (buf)), port);
-#endif
+ WSAAddressToString((LPSOCKADDR)&sip,
+ sizeof(sip),
+ NULL,
+ buf,
+ &ssize);
+ fprintf (stdout,
+ "%s:%d\n",
+ buf,
+ port);
}
- else if (have_udp)
+ else if (ip_pkt.proto == IPPROTO_UDP)
{
- memcpy(&udp_pkt, &buf[off], sizeof(udp_pkt));
-#ifdef WIN32
+ memcpy(&udp_pkt,
+ &buf[off],
+ sizeof(udp_pkt));
DWORD ssize = sizeof(buf);
- WSAAddressToString((LPSOCKADDR)&sip, sizeof(sip), NULL, buf, &ssize);
- fprintf (stdout, "%s:%d\n", buf, ntohs((int)udp_pkt.length));
-#else
- fprintf (stdout,
- "%s:%d\n",
- inet_ntop (AF_INET,
- &sip,
- buf,
- sizeof (buf)), ntohl(udp_pkt.length));
-#endif
+ WSAAddressToString((LPSOCKADDR)&sip,
+ sizeof(sip),
+ NULL,
+ buf,
+ &ssize);
+ fprintf (stdout,
+ "%s:%d\n",
+ buf,
+ ntohs((uint16_t)udp_pkt.length));
}
else
{
-#ifdef WIN32
DWORD ssize = sizeof(buf);
- WSAAddressToString((LPSOCKADDR)&sip, sizeof(sip), NULL, buf, &ssize);
- fprintf (stdout, "%s\n", buf);
-#else
- fprintf (stdout,
- "%s\n",
- inet_ntop (AF_INET,
- &sip,
- buf,
- sizeof (buf)));
-#endif
+ WSAAddressToString((LPSOCKADDR)&sip,
+ sizeof(sip),
+ NULL,
+ buf,
+ &ssize);
+ fprintf (stdout,
+ "%s\n",
+ buf);
}
fflush (stdout);
}
-static Socket
+/**
+ * Create an ICMP raw socket for reading.
+ *
+ * @return INVALID_SOCKET on error
+ */
+static SOCKET
make_icmp_socket ()
{
- Socket ret;
+ SOCKET ret;
ret = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP);
- if (-1 == ret)
+ if (INVALID_SOCKET == ret)
{
fprintf (stderr,
"Error opening RAW socket: %s\n",
strerror (errno));
- return -1;
+ return INVALID_SOCKET;
}
-#if WIN32
- if (ret == INVALID_SOCKET)
- {
- fprintf (stderr, "Invalid socket %d!\n", ret);
- closesocket (ret);
- }
-#else
- if (ret >= FD_SETSIZE)
- {
- fprintf (stderr,
- "Socket number too large (%d > %u)\n",
- ret,
- (unsigned int) FD_SETSIZE);
- close (ret);
- return -1;
- }
-#endif
return ret;
}
-static Socket
+/**
+ * Create an ICMP raw socket for writing.
+ *
+ * @return INVALID_SOCKET on error
+ */
+static SOCKET
make_raw_socket ()
{
- const int one = 1;
- Socket ret;
+ DWORD bOptVal = TRUE;
+ int bOptLen = sizeof(bOptVal);
- ret = socket (AF_INET, SOCK_RAW, IPPROTO_RAW);
- if (-1 == ret)
+ rawsock = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP);
+ if (INVALID_SOCKET == rawsock)
{
fprintf (stderr,
"Error opening RAW socket: %s\n",
strerror (errno));
- return -1;
- }
- if (setsockopt(ret, SOL_SOCKET, SO_BROADCAST,
- (char *)&one, sizeof(one)) == -1)
- fprintf(stderr,
- "setsockopt failed: %s\n",
- strerror (errno));
- if (setsockopt(ret, IPPROTO_IP, IP_HDRINCL,
- (char *)&one, sizeof(one)) == -1)
- fprintf(stderr,
- "setsockopt failed: %s\n",
- strerror (errno));
- return ret;
+ return INVALID_SOCKET;
+ }
+
+ if (setsockopt(rawsock,
+ SOL_SOCKET,
+ SO_BROADCAST,
+ (char*)&bOptVal, bOptLen) != 0)
+ {
+ fprintf(stderr,
+ "Error setting SO_BROADCAST to ON: %s\n",
+ strerror (errno));
+ closesocket(rawsock);
+ return INVALID_SOCKET;
+ }
+ if (setsockopt(rawsock,
+ IPPROTO_IP,
+ IP_HDRINCL,
+ (char*)&bOptVal, bOptLen) != 0)
+ {
+ fprintf(stderr,
+ "Error setting IP_HDRINCL to ON: %s\n",
+ strerror (errno));
+ closesocket(rawsock);
+ return INVALID_SOCKET;
+ }
+ return rawsock;
}
int
-main (int argc, char *const *argv)
+main (int argc,
+ char *const *argv)
{
struct in_addr external;
fd_set rs;
struct timeval tv;
-#ifndef WIN32
- uid_t uid;
-#else
- struct sockaddr_storage saddr;
-#endif
-
-#ifdef WIN32
- // WSA startup
WSADATA wsaData;
- if (WSAStartup (MAKEWORD (2, 1), &wsaData) != 0)
- {
- fprintf (stderr, "Failed to find Winsock 2.1 or better.\n");
- return 4; // ERROR
- }
-#endif
- if (-1 == (icmpsock = make_icmp_socket()))
- return 1;
- if (-1 == (rawsock = make_raw_socket()))
- {
- close (icmpsock);
- return 1;
- }
-#ifndef WIN32
- uid = getuid ();
- if (0 != setresuid (uid, uid, uid))
- fprintf (stderr,
- "Failed to setresuid: %s\n",
- strerror (errno));
-#endif
if (argc != 2)
{
fprintf (stderr,
"This program must be started with our (internal NAT) IP as the only argument.\n");
return 1;
}
-
if (1 != inet_pton (AF_INET, argv[1], &external))
{
fprintf (stderr,
argv[1], strerror (errno));
return 1;
}
-
- if (1 != inet_pton (AF_INET, DUMMY_IP, &dummy)) abort ();
+ if (1 != inet_pton (AF_INET, DUMMY_IP, &dummy))
+ {
+ fprintf (stderr,
+ "Internal error converting dummy IP to binary.\n");
+ return 2;
+ }
+ if (WSAStartup (MAKEWORD (2, 1), &wsaData) != 0)
+ {
+ fprintf (stderr, "Failed to find Winsock 2.1 or better.\n");
+ return 2;
+ }
+ if (INVALID_SOCKET == (icmpsock = make_icmp_socket()))
+ {
+ return 3;
+ }
+ if (INVALID_SOCKET == (make_raw_socket()))
+ {
+ closesocket (icmpsock);
+ return 3;
+ }
while (1)
{
FD_ZERO (&rs);
FD_SET (icmpsock, &rs);
tv.tv_sec = 0;
tv.tv_usec = ICMP_SEND_FREQUENCY_MS * 1000;
- select (icmpsock + 1, &rs, NULL, NULL, &tv);
+ if (-1 == select (icmpsock + 1, &rs, NULL, NULL, &tv))
+ {
+ if (errno == EINTR)
+ continue;
+ fprintf (stderr,
+ "select failed: %s\n",
+ strerror (errno));
+ break;
+ }
if (FD_ISSET (icmpsock, &rs))
- process_icmp_response ();
+ process_icmp_response ();
send_icmp_echo (&external);
- }
-
-#ifdef WIN32
+ }
+ /* select failed (internal error or OS out of resources) */
closesocket(icmpsock);
closesocket(rawsock);
WSACleanup ();
-#endif
- return 0;
+ return 4;
}
projects / oweals / gnunet.git / blobdiff