ssh-keyscan.c

OpenSSL Source code for SFTP, SSH, and many others

/*
 * Copyright 1995, 1996 by David Mazieres <[e-mail]>.
 *
 * Modification and redistribution in source and binary forms is
 * permitted provided that due credit is given to the author and the
 * OpenBSD project by leaving this copyright notice intact.
 */

#include "includes.h"
RCSID("$OpenBSD: ssh-keyscan.c,v 1.36 2002/06/16 21:30:58 itojun Exp $");

#include "openbsd-compat/fake-queue.h"

#include <openssl/bn.h>

#include <setjmp.h>
#include "xmalloc.h"
#include "ssh.h"
#include "ssh1.h"
#include "key.h"
#include "kex.h"
#include "compat.h"
#include "myproposal.h"
#include "packet.h"
#include "dispatch.h"
#include "buffer.h"
#include "bufaux.h"
#include "log.h"
#include "atomicio.h"
#include "misc.h"

/* Flag indicating whether IPv4 or IPv6.  This can be set on the command line.
   Default value is AF_UNSPEC means both IPv4 and IPv6. */
#ifdef IPV4_DEFAULT
int IPv4or6 = AF_INET;
#else
int IPv4or6 = AF_UNSPEC;
#endif

int ssh_port = SSH_DEFAULT_PORT;

#define KT_RSA1	1
#define KT_DSA	2
#define KT_RSA	4

int get_keytypes = KT_RSA1;	/* Get only RSA1 keys by default */

#define MAXMAXFD 256

/* The number of seconds after which to give up on a TCP connection */
int timeout = 5;

int maxfd;
#define MAXCON (maxfd - 10)

#ifdef HAVE___PROGNAME
extern char *__progname;
#else
char *__progname;
#endif
fd_set *read_wait;
size_t read_wait_size;
int ncon;
int nonfatal_fatal = 0;
jmp_buf kexjmp;
Key *kexjmp_key;

/*
 * Keep a connection structure for each file descriptor.  The state
 * associated with file descriptor n is held in fdcon[n].
 */
typedef struct Connection {
	u_char c_status;	/* State of connection on this file desc. */
#define CS_UNUSED 0		/* File descriptor unused */
#define CS_CON 1		/* Waiting to connect/read greeting */
#define CS_SIZE 2		/* Waiting to read initial packet size */
#define CS_KEYS 3		/* Waiting to read public key packet */
	int c_fd;		/* Quick lookup: c->c_fd == c - fdcon */
	int c_plen;		/* Packet length field for ssh packet */
	int c_len;		/* Total bytes which must be read. */
	int c_off;		/* Length of data read so far. */
	int c_keytype;		/* Only one of KT_RSA1, KT_DSA, or KT_RSA */
	char *c_namebase;	/* Address to free for c_name and c_namelist */
	char *c_name;		/* Hostname of connection for errors */
	char *c_namelist;	/* Pointer to other possible addresses */
	char *c_output_name;	/* Hostname of connection for output */
	char *c_data;		/* Data read from this fd */
	Kex *c_kex;		/* The key-exchange struct for ssh2 */
	struct timeval c_tv;	/* Time at which connection gets aborted */
	TAILQ_ENTRY(Connection) c_link;	/* List of connections in timeout order. */
} con;

TAILQ_HEAD(conlist, Connection) tq;	/* Timeout Queue */
con *fdcon;

/*
 *  This is just a wrapper around fgets() to make it usable.
 */

/* Stress-test.  Increase this later. */
#define LINEBUF_SIZE 16

typedef struct {
	char *buf;
	u_int size;
	int lineno;
	const char *filename;
	FILE *stream;
	void (*errfun) (const char *,...);
} Linebuf;

static Linebuf *
Linebuf_alloc(const char *filename, void (*errfun) (const char *,...))
{
	Linebuf *lb;

	if (!(lb = malloc(sizeof(*lb)))) {
		if (errfun)
			(*errfun) ("linebuf (%s): malloc failed\n", lb->filename);
		return (NULL);
	}
	if (filename) {
		lb->filename = filename;
		if (!(lb->stream = fopen(filename, "r"))) {
			xfree(lb);
			if (errfun)
				(*errfun) ("%s: %s\n", filename, strerror(errno));
			return (NULL);
		}
	} else {
		lb->filename = "(stdin)";
		lb->stream = stdin;
	}

	if (!(lb->buf = malloc(lb->size = LINEBUF_SIZE))) {
		if (errfun)
			(*errfun) ("linebuf (%s): malloc failed\n", lb->filename);
		xfree(lb);
		return (NULL);
	}
	lb->errfun = errfun;
	lb->lineno = 0;
	return (lb);
}

static void
Linebuf_free(Linebuf * lb)
{
	fclose(lb->stream);
	xfree(lb->buf);
	xfree(lb);
}

#if 0
static void
Linebuf_restart(Linebuf * lb)
{
	clearerr(lb->stream);
	rewind(lb->stream);
	lb->lineno = 0;
}

static int
Linebuf_lineno(Linebuf * lb)
{
	return (lb->lineno);
}
#endif

static char *
Linebuf_getline(Linebuf * lb)
{
	int n = 0;

	lb->lineno++;
	for (;;) {
		/* Read a line */
		if (!fgets(&lb->buf[n], lb->size - n, lb->stream)) {
			if (ferror(lb->stream) && lb->errfun)
				(*lb->errfun) ("%s: %s\n", lb->filename,
				    strerror(errno));
			return (NULL);
		}
		n = strlen(lb->buf);

		/* Return it or an error if it fits */
		if (n > 0 && lb->buf[n - 1] == '\n') {
			lb->buf[n - 1] = '\0';
			return (lb->buf);
		}
		if (n != lb->size - 1) {
			if (lb->errfun)
				(*lb->errfun) ("%s: skipping incomplete last line\n",
				    lb->filename);
			return (NULL);
		}
		/* Double the buffer if we need more space */
		if (!(lb->buf = realloc(lb->buf, (lb->size *= 2)))) {
			if (lb->errfun)
				(*lb->errfun) ("linebuf (%s): realloc failed\n",
				    lb->filename);
			return (NULL);
		}
	}
}

static int
fdlim_get(int hard)
{
#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
	struct rlimit rlfd;

	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
		return (-1);
	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
		return 10000;
	else
		return hard ? rlfd.rlim_max : rlfd.rlim_cur;
#elif defined (HAVE_SYSCONF)
	return sysconf (_SC_OPEN_MAX);
#else
	return 10000;
#endif
}

static int
fdlim_set(int lim)
{
#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
	struct rlimit rlfd;
#endif
	if (lim <= 0)
		return (-1);
#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
		return (-1);
	rlfd.rlim_cur = lim;
	if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0)
		return (-1);
#elif defined (HAVE_SETDTABLESIZE)
	setdtablesize(lim);
#endif
	return (0);
}

/*
 * This is an strsep function that returns a null field for adjacent
 * separators.  This is the same as the 4.4BSD strsep, but different from the
 * one in the GNU libc.
 */
static char *
xstrsep(char **str, const char *delim)
{
	char *s, *e;

	if (!**str)
		return (NULL);

	s = *str;
	e = s + strcspn(s, delim);

	if (*e != '\0')
		*e++ = '\0';
	*str = e;

	return (s);
}

/*
 * Get the next non-null token (like GNU strsep).  Strsep() will return a
 * null token for two adjacent separators, so we may have to loop.
 */
static char *
strnnsep(char **stringp, char *delim)
{
	char *tok;

	do {
		tok = xstrsep(stringp, delim);
	} while (tok && *tok == '\0');
	return (tok);
}

static Key *
keygrab_ssh1(con *c)
{
	static Key *rsa;
	static Buffer msg;

	if (rsa == NULL) {
		buffer_init(&msg);
		rsa = key_new(KEY_RSA1);
	}
	buffer_append(&msg, c->c_data, c->c_plen);
	buffer_consume(&msg, 8 - (c->c_plen & 7));	/* padding */
	if (buffer_get_char(&msg) != (int) SSH_SMSG_PUBLIC_KEY) {
		error("%s: invalid packet type", c->c_name);
		buffer_clear(&msg);
		return NULL;
	}
	buffer_consume(&msg, 8);		/* cookie */

	/* server key */
	(void) buffer_get_int(&msg);
	buffer_get_bignum(&msg, rsa->rsa->e);
	buffer_get_bignum(&msg, rsa->rsa->n);

	/* host key */
	(void) buffer_get_int(&msg);
	buffer_get_bignum(&msg, rsa->rsa->e);
	buffer_get_bignum(&msg, rsa->rsa->n);

	buffer_clear(&msg);

	return (rsa);
}

static int
hostjump(Key *hostkey)
{
	kexjmp_key = hostkey;
	longjmp(kexjmp, 1);
}

static int
ssh2_capable(int remote_major, int remote_minor)
{
	switch (remote_major) {
	case 1:
		if (remote_minor == 99)
			return 1;
		break;
	case 2:
		return 1;
	default:
		break;
	}
	return 0;
}

static Key *
keygrab_ssh2(con *c)
{
	int j;

	packet_set_connection(c->c_fd, c->c_fd);
	enable_compat20();
	myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = c->c_keytype == KT_DSA?
	    "ssh-dss": "ssh-rsa";
	c->c_kex = kex_setup(myproposal);
	c->c_kex->verify_host_key = hostjump;

	if (!(j = setjmp(kexjmp))) {
		nonfatal_fatal = 1;
		dispatch_run(DISPATCH_BLOCK, &c->c_kex->done, c->c_kex);
		fprintf(stderr, "Impossible! dispatch_run() returned!\n");
		exit(1);
	}
	nonfatal_fatal = 0;
	xfree(c->c_kex);
	c->c_kex = NULL;
	packet_close();

	return j < 0? NULL : kexjmp_key;
}

static void
keyprint(con *c, Key *key)
{
	if (!key)
		return;

	fprintf(stdout, "%s ", c->c_output_name ? c->c_output_name : c->c_name);
	key_write(key, stdout);
	fputs("\n", stdout);
}

static int
tcpconnect(char *host)
{
	struct addrinfo hints, *ai, *aitop;
	char strport[NI_MAXSERV];
	int gaierr, s = -1;

	snprintf(strport, sizeof strport, "%d", ssh_port);
	memset(&hints, 0, sizeof(hints));
	hints.ai_family = IPv4or6;
	hints.ai_socktype = SOCK_STREAM;
	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
		fatal("getaddrinfo %s: %s", host, gai_strerror(gaierr));
	for (ai = aitop; ai; ai = ai->ai_next) {
		s = socket(ai->ai_family, SOCK_STREAM, 0);
		if (s < 0) {
			error("socket: %s", strerror(errno));
			continue;
		}
		if (fcntl(s, F_SETFL, O_NONBLOCK) < 0)
			fatal("F_SETFL: %s", strerror(errno));
		if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0 &&
		    errno != EINPROGRESS)
			error("connect (`%s'): %s", host, strerror(errno));
		else
			break;
		close(s);
		s = -1;
	}
	freeaddrinfo(aitop);
	return s;