move soures to src subdir

1 files changed, 247 insertions, 0 deletions

diff --git a/src/mtu.c b/src/mtu.c
new file mode 100644
index 0000000..77766eb
--- /dev/null
+++ b/src/mtu.c
@@ -0,0 +1,247 @@
+#include <errno.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <linux/if.h>
+#include <linux/sockios.h>
+#include <netinet/ip_icmp.h>
+
+#include "icmp.h"
+
+static int fd, mtu_size;
+static struct sockaddr_in to;
+
+static void usage(void)
+{
+	fprintf(stderr,
+		"usage: mtu -i <mtu-size> <host>\n"
+		"       mtu -I <host>\n"
+		"       mtu -d <host>\n"
+		"       mtu -D <host>\n"
+		"\n"
+		" -i <mtu-size>   Inject <mtu-size> as PMTU to <host>\n"
+		" -I              Inject local PMTU as PMTU to <host>\n"
+		" -d              Discover PMTU to <host>\n"
+		" -D              Discover PMTU to <host> and assign it to interface MTU\n"
+		"\n");
+	exit(3);
+}
+
+static int do_ping(int seq, int size)
+{
+	__u8 buf[1500];
+	struct iphdr *ip = (struct iphdr *) buf;
+	struct icmphdr *icp;
+	struct sockaddr_in from;
+	int len, retry;
+
+	for (retry = 0; retry < 3; retry++) {
+		icmp_send_ping(fd, (struct sockaddr *) &to, sizeof(to),
+			       seq, size);
+
+not_mine:
+		if ((len = icmp_read_reply(fd, (struct sockaddr *) &from,
+					   sizeof(from), buf, sizeof(buf))) <= 0)
+			continue;
+
+		if (icmp_parse_reply(buf, len, seq,
+				     (struct sockaddr *) &from,
+				     (struct sockaddr *) &to))
+			goto not_mine;
+
+		icp = (struct icmphdr *) &buf[ip->ihl * 4];
+		switch (icp->type) {
+		case ICMP_ECHOREPLY:
+			return 0;
+		case ICMP_DEST_UNREACH:
+			if (icp->code != ICMP_FRAG_NEEDED)
+				return 0;
+			return ntohs(icp->un.frag.mtu);
+		default:
+			return -1;
+		}
+	}
+
+	return -1;
+}
+
+static int discover_mtu(void)
+{
+	int seq = 1, low_mtu, high_mtu, try_mtu, r;
+
+	/* Check if the host is up */
+	if (do_ping(seq++, 0) < 0)
+		return -1;
+
+	/* Discover PMTU */
+	low_mtu = 68/2;
+	high_mtu = 1500/2;
+	try_mtu = 1500/2;
+	while (1) {
+		r = do_ping(seq++, try_mtu * 2);
+		if (r > 0 && r < try_mtu * 2) {
+			/* pmtu */
+			high_mtu = r/2;
+			try_mtu = high_mtu;
+			continue;
+		}
+		if (r == 0)
+			low_mtu = try_mtu;
+		else
+			high_mtu = try_mtu - 1;
+		if (low_mtu >= high_mtu)
+			return 2 * low_mtu;
+
+		try_mtu = low_mtu + (high_mtu - low_mtu + 1) / 2;
+	}
+}
+
+static void do_discover(void)
+{
+	int mtu;
+
+	mtu = discover_mtu();
+	if (mtu > 0)
+		fprintf(stdout, "%d\n", mtu);
+	else
+		fprintf(stderr, "Host is not up\n");
+}
+
+static int set_mtu(const char *dev, int mtu)
+{
+	struct ifreq ifr;
+	int fd;
+
+	fd = socket(PF_INET, SOCK_DGRAM, 0);
+	if (fd < 0)
+		return -1;
+
+	memset(&ifr, 0, sizeof(ifr));
+	strncpy(ifr.ifr_name, dev, IFNAMSIZ);
+	ifr.ifr_mtu = mtu;
+	if (ioctl(fd, SIOCSIFMTU, &ifr) < 0) {
+		perror("SIOCSIFMTU");
+		close(fd);
+		return -1;
+	}
+	close(fd);
+	return 0; 
+}
+
+static void do_discover_and_write(void)
+{
+	int mtu;
+	char iface[IFNAMSIZ];
+
+	mtu = discover_mtu();
+	if (mtu < 0) {
+		fprintf(stderr, "Failed to determine MTU\n");
+		return;
+	}
+
+	if (!netlink_route_get(&to, NULL, iface)) {
+		fprintf(stderr, "Failed to determine route interface\n");
+		return;
+	}
+
+	printf("Writing %d to %s\n", mtu, iface);
+	set_mtu(iface, mtu);
+}
+
+static void do_inject(void)
+{
+	__u8 buf[1500];
+	struct sockaddr_in from;
+	int len, i, seq = 0;
+
+	icmp_send_ping(fd, (struct sockaddr *) &to, sizeof(to),
+		       ++seq, mtu_size);
+	for (i = 0; i < 5; i++) {
+		if ((len = icmp_read_reply(fd, (struct sockaddr *) &from,
+					   sizeof(from),
+					   buf, sizeof(buf))) <= 0)
+			continue;
+
+		if (icmp_parse_reply(buf, len, seq,
+				     (struct sockaddr *) &from,
+				     (struct sockaddr *) &to))
+			continue;
+
+		if (seq != 1)
+			sleep(1);
+
+		icmp_send_ping(fd, (struct sockaddr *) &to, sizeof(to),
+			       ++seq, mtu_size);
+		icmp_send_frag_needed(fd, (struct sockaddr *) &to, sizeof(to),
+				      (struct iphdr *) buf, mtu_size - 2);
+	}
+}
+
+static void do_inject_pmtu(void)
+{
+	u_int16_t mtu;
+
+	if (!netlink_route_get(&to, &mtu, NULL)) {
+		fprintf(stderr, "Failed to determine Path MTU\n");
+		return;
+	}
+	if (mtu == 1500)
+		return;
+
+	mtu_size = mtu;
+	do_inject();
+}
+
+int main(int argc, char **argv)
+{
+	struct hostent *hp;
+	void (*action)(void) = NULL;
+	char *target;
+	int opt;
+
+	while ((opt = getopt(argc, argv, "DdIi:")) != -1) {
+		switch (opt) {
+		case 'D':
+			action = do_discover_and_write;
+			break;
+		case 'd':
+			action = do_discover;
+			break;
+		case 'i':
+			action = do_inject;
+			mtu_size = atoi(optarg);
+			break;
+		case 'I':
+			action = do_inject_pmtu;
+			break;
+		default:
+			usage();
+		}
+	}
+
+	if (action == NULL || optind >= argc)
+		usage();
+
+	target = argv[optind];
+
+	fd = icmp_open(1.0);
+	if (fd < 0)
+		exit(1);
+
+	memset((char *) &to, 0, sizeof(to));
+	to.sin_family = AF_INET;
+	if (inet_aton(target, &to.sin_addr) != 1) {
+		hp = gethostbyname(target);
+		if (!hp) {
+			fprintf(stderr, "mtu: unknown host %s\n", target);
+			exit(2);
+		}
+		memcpy(&to.sin_addr, hp->h_addr, 4);
+	}
+
+	action();
+}
+