source: trunk/third/openssh/ssh-keyscan.c @ 18759

/*
 * Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>.
 *
 * 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 1.40 2002/07/06 17:47:58 stevesk Exp $");

#include "openbsd-compat/sys-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",
                            filename ? filename : "(stdin)");
                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;
        void *p;

        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 */
                lb->size *= 2;
                if ((p = realloc(lb->buf, lb->size)) == NULL) {
                        lb->size /= 2;
                        if (lb->errfun)
                                (*lb->errfun)("linebuf (%s): realloc failed\n",
                                    lb->filename);
                        return (NULL);
                }
                lb->buf = p;
        }
}

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;
}

static int
conalloc(char *iname, char *oname, int keytype)
{
        char *namebase, *name, *namelist;
        int s;

        namebase = namelist = xstrdup(iname);

        do {
                name = xstrsep(&namelist, ",");
                if (!name) {
                        xfree(namebase);
                        return (-1);
                }
        } while ((s = tcpconnect(name)) < 0);

        if (s >= maxfd)
                fatal("conalloc: fdno %d too high", s);
        if (fdcon[s].c_status)
                fatal("conalloc: attempt to reuse fdno %d", s);

        fdcon[s].c_fd = s;
        fdcon[s].c_status = CS_CON;
        fdcon[s].c_namebase = namebase;
        fdcon[s].c_name = name;
        fdcon[s].c_namelist = namelist;
        fdcon[s].c_output_name = xstrdup(oname);
        fdcon[s].c_data = (char *) &fdcon[s].c_plen;
        fdcon[s].c_len = 4;
        fdcon[s].c_off = 0;
        fdcon[s].c_keytype = keytype;
        gettimeofday(&fdcon[s].c_tv, NULL);
        fdcon[s].c_tv.tv_sec += timeout;
        TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
        FD_SET(s, read_wait);
        ncon++;
        return (s);
}

static void
confree(int s)
{
        if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
                fatal("confree: attempt to free bad fdno %d", s);
        close(s);
        xfree(fdcon[s].c_namebase);
        xfree(fdcon[s].c_output_name);
        if (fdcon[s].c_status == CS_KEYS)
                xfree(fdcon[s].c_data);
        fdcon[s].c_status = CS_UNUSED;
        fdcon[s].c_keytype = 0;
        TAILQ_REMOVE(&tq, &fdcon[s], c_link);
        FD_CLR(s, read_wait);
        ncon--;
}

static void
contouch(int s)
{
        TAILQ_REMOVE(&tq, &fdcon[s], c_link);
        gettimeofday(&fdcon[s].c_tv, NULL);
        fdcon[s].c_tv.tv_sec += timeout;
        TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
}

static int
conrecycle(int s)
{
        con *c = &fdcon[s];
        int ret;

        ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
        confree(s);
        return (ret);
}

static void
congreet(int s)
{
        int remote_major, remote_minor, n = 0;
        char buf[256], *cp;
        char remote_version[sizeof buf];
        size_t bufsiz;
        con *c = &fdcon[s];

        bufsiz = sizeof(buf);
        cp = buf;
        while (bufsiz-- && (n = read(s, cp, 1)) == 1 && *cp != '\n') {
                if (*cp == '\r')
                        *cp = '\n';
                cp++;
        }
        if (n < 0) {
                if (errno != ECONNREFUSED)
                        error("read (%s): %s", c->c_name, strerror(errno));
                conrecycle(s);
                return;
        }
        if (n == 0) {
                error("%s: Connection closed by remote host", c->c_name);
                conrecycle(s);
                return;
        }
        if (*cp != '\n' && *cp != '\r') {
                error("%s: bad greeting", c->c_name);
                confree(s);
                return;
        }
        *cp = '\0';
        if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
            &remote_major, &remote_minor, remote_version) == 3)
                compat_datafellows(remote_version);
        else
                datafellows = 0;
        if (c->c_keytype != KT_RSA1) {
                if (!ssh2_capable(remote_major, remote_minor)) {
                        debug("%s doesn't support ssh2", c->c_name);
                        confree(s);
                        return;
                }
        } else if (remote_major != 1) {
                debug("%s doesn't support ssh1", c->c_name);
                confree(s);
                return;
        }
        fprintf(stderr, "# %s %s\n", c->c_name, chop(buf));
        n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
            c->c_keytype == KT_RSA1? PROTOCOL_MAJOR_1 : PROTOCOL_MAJOR_2,
            c->c_keytype == KT_RSA1? PROTOCOL_MINOR_1 : PROTOCOL_MINOR_2);
        if (atomicio(write, s, buf, n) != n) {
                error("write (%s): %s", c->c_name, strerror(errno));
                confree(s);
                return;
        }
        if (c->c_keytype != KT_RSA1) {
                keyprint(c, keygrab_ssh2(c));
                confree(s);
                return;
        }
        c->c_status = CS_SIZE;
        contouch(s);
}

static void
conread(int s)
{
        con *c = &fdcon[s];
        int n;

        if (c->c_status == CS_CON) {
                congreet(s);
                return;
        }
        n = read(s, c->c_data + c->c_off, c->c_len - c->c_off);
        if (n < 0) {
                error("read (%s): %s", c->c_name, strerror(errno));
                confree(s);
                return;
        }
        c->c_off += n;

        if (c->c_off == c->c_len)
                switch (c->c_status) {
                case CS_SIZE:
                        c->c_plen = htonl(c->c_plen);
                        c->c_len = c->c_plen + 8 - (c->c_plen & 7);
                        c->c_off = 0;
                        c->c_data = xmalloc(c->c_len);
                        c->c_status = CS_KEYS;
                        break;
                case CS_KEYS:
                        keyprint(c, keygrab_ssh1(c));
                        confree(s);
                        return;
                        break;
                default:
                        fatal("conread: invalid status %d", c->c_status);
                        break;
                }

        contouch(s);
}

static void
conloop(void)
{
        struct timeval seltime, now;
        fd_set *r, *e;
        con *c;
        int i;

        gettimeofday(&now, NULL);
        c = TAILQ_FIRST(&tq);

        if (c && (c->c_tv.tv_sec > now.tv_sec ||
            (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec > now.tv_usec))) {
                seltime = c->c_tv;
                seltime.tv_sec -= now.tv_sec;
                seltime.tv_usec -= now.tv_usec;
                if (seltime.tv_usec < 0) {
                        seltime.tv_usec += 1000000;
                        seltime.tv_sec--;
                }
        } else
                seltime.tv_sec = seltime.tv_usec = 0;

        r = xmalloc(read_wait_size);
        memcpy(r, read_wait, read_wait_size);
        e = xmalloc(read_wait_size);
        memcpy(e, read_wait, read_wait_size);

        while (select(maxfd, r, NULL, e, &seltime) == -1 &&
            (errno == EAGAIN || errno == EINTR))
                ;

        for (i = 0; i < maxfd; i++) {
                if (FD_ISSET(i, e)) {
                        error("%s: exception!", fdcon[i].c_name);
                        confree(i);
                } else if (FD_ISSET(i, r))
                        conread(i);
        }
        xfree(r);
        xfree(e);

        c = TAILQ_FIRST(&tq);
        while (c && (c->c_tv.tv_sec < now.tv_sec ||
            (c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec < now.tv_usec))) {
                int s = c->c_fd;

                c = TAILQ_NEXT(c, c_link);
                conrecycle(s);
        }
}

static void
do_host(char *host)
{
        char *name = strnnsep(&host, " \t\n");
        int j;

        if (name == NULL)
                return;
        for (j = KT_RSA1; j <= KT_RSA; j *= 2) {
                if (get_keytypes & j) {
                        while (ncon >= MAXCON)
                                conloop();
                        conalloc(name, *host ? host : name, j);
                }
        }
}

void
fatal(const char *fmt,...)
{
        va_list args;

        va_start(args, fmt);
        do_log(SYSLOG_LEVEL_FATAL, fmt, args);
        va_end(args);
        if (nonfatal_fatal)
                longjmp(kexjmp, -1);
        else
                fatal_cleanup();
}

static void
usage(void)
{
        fprintf(stderr, "usage: %s [-v46] [-p port] [-T timeout] [-f file]\n"
            "\t\t   [host | addrlist namelist] [...]\n",
            __progname);
        exit(1);
}

int
main(int argc, char **argv)
{
        int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
        int opt, fopt_count = 0;
        char *tname;

        extern int optind;
        extern char *optarg;

        __progname = get_progname(argv[0]);
        init_rng();
        seed_rng();
        TAILQ_INIT(&tq);

        if (argc <= 1)
                usage();

        while ((opt = getopt(argc, argv, "v46p:T:t:f:")) != -1) {
                switch (opt) {
                case 'p':
                        ssh_port = a2port(optarg);
                        if (ssh_port == 0) {
                                fprintf(stderr, "Bad port '%s'\n", optarg);
                                exit(1);
                        }
                        break;
                case 'T':
                        timeout = convtime(optarg);
                        if (timeout == -1 || timeout == 0) {
                                fprintf(stderr, "Bad timeout '%s'\n", optarg);
                                usage();
                        }
                        break;
                case 'v':
                        if (!debug_flag) {
                                debug_flag = 1;
                                log_level = SYSLOG_LEVEL_DEBUG1;
                        }
                        else if (log_level < SYSLOG_LEVEL_DEBUG3)
                                log_level++;
                        else
                                fatal("Too high debugging level.");
                        break;
                case 'f':
                        if (strcmp(optarg, "-") == 0)
                                optarg = NULL;
                        argv[fopt_count++] = optarg;
                        break;
                case 't':
                        get_keytypes = 0;
                        tname = strtok(optarg, ",");
                        while (tname) {
                                int type = key_type_from_name(tname);
                                switch (type) {
                                case KEY_RSA1:
                                        get_keytypes |= KT_RSA1;
                                        break;
                                case KEY_DSA:
                                        get_keytypes |= KT_DSA;
                                        break;
                                case KEY_RSA:
                                        get_keytypes |= KT_RSA;
                                        break;
                                case KEY_UNSPEC:
                                        fatal("unknown key type %s", tname);
                                }
                                tname = strtok(NULL, ",");
                        }
                        break;
                case '4':
                        IPv4or6 = AF_INET;
                        break;
                case '6':
                        IPv4or6 = AF_INET6;
                        break;
                case '?':
                default:
                        usage();
                }
        }
        if (optind == argc && !fopt_count)
                usage();

        log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);

        maxfd = fdlim_get(1);
        if (maxfd < 0)
                fatal("%s: fdlim_get: bad value", __progname);
        if (maxfd > MAXMAXFD)
                maxfd = MAXMAXFD;
        if (MAXCON <= 0)
                fatal("%s: not enough file descriptors", __progname);
        if (maxfd > fdlim_get(0))
                fdlim_set(maxfd);
        fdcon = xmalloc(maxfd * sizeof(con));
        memset(fdcon, 0, maxfd * sizeof(con));

        read_wait_size = howmany(maxfd, NFDBITS) * sizeof(fd_mask);
        read_wait = xmalloc(read_wait_size);
        memset(read_wait, 0, read_wait_size);

        if (fopt_count) {
                Linebuf *lb;
                char *line;
                int j;

                for (j = 0; j < fopt_count; j++) {
                        lb = Linebuf_alloc(argv[j], error);
                        if (!lb)
                                continue;
                        while ((line = Linebuf_getline(lb)) != NULL)
                                do_host(line);
                        Linebuf_free(lb);
                }
        }

        while (optind < argc)
                do_host(argv[optind++]);

        while (ncon > 0)
                conloop();

        return (0);
}