]> andersk Git - openssh.git/blobdiff - channels.c
- stevesk@cvs.openbsd.org 2001/05/19 19:43:57
[openssh.git] / channels.c
index 6ca31b840b7ee978694afaf00a17a51ebe9abe79..55cef42c23482367d2502208b0d891f8601f2b89 100644 (file)
@@ -40,7 +40,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: channels.c,v 1.101 2001/04/05 10:42:48 markus Exp $");
+RCSID("$OpenBSD: channels.c,v 1.116 2001/05/16 22:09:20 markus Exp $");
 
 #include <openssl/rsa.h>
 #include <openssl/dsa.h>
@@ -51,6 +51,7 @@ RCSID("$OpenBSD: channels.c,v 1.101 2001/04/05 10:42:48 markus Exp $");
 #include "packet.h"
 #include "xmalloc.h"
 #include "buffer.h"
+#include "bufaux.h"
 #include "uidswap.h"
 #include "log.h"
 #include "misc.h"
@@ -71,18 +72,17 @@ RCSID("$OpenBSD: channels.c,v 1.101 2001/04/05 10:42:48 markus Exp $");
  * Pointer to an array containing all allocated channels.  The array is
  * dynamically extended as needed.
  */
-static Channel *channels = NULL;
+static Channel **channels = NULL;
 
 /*
  * Size of the channel array.  All slots of the array must always be
- * initialized (at least the type field); unused slots are marked with type
- * SSH_CHANNEL_FREE.
+ * initialized (at least the type field); unused slots set to NULL
  */
 static int channels_alloc = 0;
 
 /*
  * Maximum file descriptor value used in any of the channels.  This is
- * updated in channel_allocate.
+ * updated in channel_new.
  */
 static int channel_max_fd = 0;
 
@@ -133,6 +133,8 @@ static int have_hostname_in_open = 0;
 /* AF_UNSPEC or AF_INET or AF_INET6 */
 extern int IPv4or6;
 
+void    port_open_helper(Channel *c, char *rtype);
+
 /* Sets specific protocol options. */
 
 void
@@ -147,12 +149,13 @@ Channel *
 channel_lookup(int id)
 {
        Channel *c;
+
        if (id < 0 || id > channels_alloc) {
                log("channel_lookup: %d: bad id", id);
                return NULL;
        }
-       c = &channels[id];
-       if (c->type == SSH_CHANNEL_FREE) {
+       c = channels[id];
+       if (c == NULL) {
                log("channel_lookup: %d: bad id: channel free", id);
                return NULL;
        }
@@ -209,7 +212,7 @@ channel_register_fds(Channel *c, int rfd, int wfd, int efd,
  * remote_name to be freed.
  */
 
-int
+Channel *
 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
     int window, int maxpack, int extusage, char *remote_name, int nonblock)
 {
@@ -220,9 +223,9 @@ channel_new(char *ctype, int type, int rfd, int wfd, int efd,
        if (channels_alloc == 0) {
                chan_init();
                channels_alloc = 10;
-               channels = xmalloc(channels_alloc * sizeof(Channel));
+               channels = xmalloc(channels_alloc * sizeof(Channel *));
                for (i = 0; i < channels_alloc; i++)
-                       channels[i].type = SSH_CHANNEL_FREE;
+                       channels[i] = NULL;
                /*
                 * Kludge: arrange a call to channel_stop_listening if we
                 * terminate with fatal().
@@ -231,7 +234,7 @@ channel_new(char *ctype, int type, int rfd, int wfd, int efd,
        }
        /* Try to find a free slot where to put the new channel. */
        for (found = -1, i = 0; i < channels_alloc; i++)
-               if (channels[i].type == SSH_CHANNEL_FREE) {
+               if (channels[i] == NULL) {
                        /* Found a free slot. */
                        found = i;
                        break;
@@ -241,12 +244,12 @@ channel_new(char *ctype, int type, int rfd, int wfd, int efd,
                found = channels_alloc;
                channels_alloc += 10;
                debug2("channel: expanding %d", channels_alloc);
-               channels = xrealloc(channels, channels_alloc * sizeof(Channel));
+               channels = xrealloc(channels, channels_alloc * sizeof(Channel *));
                for (i = found; i < channels_alloc; i++)
-                       channels[i].type = SSH_CHANNEL_FREE;
+                       channels[i] = NULL;
        }
-       /* Initialize and return new channel number. */
-       c = &channels[found];
+       /* Initialize and return new channel. */
+       c = channels[found] = xmalloc(sizeof(Channel));
        buffer_init(&c->input);
        buffer_init(&c->output);
        buffer_init(&c->extended);
@@ -269,16 +272,9 @@ channel_new(char *ctype, int type, int rfd, int wfd, int efd,
        c->dettach_user = NULL;
        c->input_filter = NULL;
        debug("channel %d: new [%s]", found, remote_name);
-       return found;
-}
-/* old interface XXX */
-int
-channel_allocate(int type, int sock, char *remote_name)
-{
-       return channel_new("", type, sock, sock, -1, 0, 0, 0, remote_name, 1);
+       return c;
 }
 
-
 /* Close all channel fd/socket. */
 
 void
@@ -305,18 +301,16 @@ channel_close_fds(Channel *c)
 /* Free the channel and close its fd/socket. */
 
 void
-channel_free(int id)
+channel_free(Channel *c)
 {
-       Channel *c = channel_lookup(id);
-       char *s = channel_open_message();
+       char *s;
 
-       if (c == NULL)
-               packet_disconnect("channel free: bad local channel %d", id);
-       debug("channel_free: channel %d: status: %s", id, s);
+       s = channel_open_message();
+       debug("channel_free: channel %d: status: %s", c->self, s);
        xfree(s);
 
        if (c->dettach_user != NULL) {
-               debug("channel_free: channel %d: dettaching channel user", id);
+               debug("channel_free: channel %d: dettaching channel user", c->self);
                c->dettach_user(c->self, NULL);
        }
        if (c->sock != -1)
@@ -325,11 +319,12 @@ channel_free(int id)
        buffer_free(&c->input);
        buffer_free(&c->output);
        buffer_free(&c->extended);
-       c->type = SSH_CHANNEL_FREE;
        if (c->remote_name) {
                xfree(c->remote_name);
                c->remote_name = NULL;
        }
+       channels[c->self] = NULL;
+       xfree(c);
 }
 
 /*
@@ -417,7 +412,7 @@ channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
                packet_put_int(c->remote_id);
                packet_send();
                c->type = SSH_CHANNEL_CLOSED;
-               debug("Closing channel %d after input drain.", c->self);
+               debug("channel %d: closing after input drain.", c->self);
        }
 }
 
@@ -425,7 +420,7 @@ void
 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 {
        if (buffer_len(&c->output) == 0)
-               channel_free(c->self);
+               chan_mark_dead(c);
        else
                FD_SET(c->sock, writeset);
 }
@@ -539,12 +534,123 @@ channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
        }
 }
 
+/* try to decode a socks4 header */
+int
+channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
+{
+       u_char *p, *host;
+       int len, have, i, found;
+       char username[256];     
+       struct {
+               u_int8_t version;
+               u_int8_t command;
+               u_int16_t dest_port;
+               struct in_addr dest_addr;
+       } s4_req, s4_rsp;
+
+       debug2("channel %d: decode socks4", c->self);
+
+       have = buffer_len(&c->input);
+       len = sizeof(s4_req);
+       if (have < len)
+               return 0;
+       p = buffer_ptr(&c->input);
+       for (found = 0, i = len; i < have; i++) {
+               if (p[i] == '\0') {
+                       found = 1;
+                       break;
+               }
+               if (i > 1024) {
+                       /* the peer is probably sending garbage */
+                       debug("channel %d: decode socks4: too long",
+                           c->self);
+                       return -1;
+               }
+       }
+       if (!found)
+               return 0;
+       buffer_get(&c->input, (char *)&s4_req.version, 1);
+       buffer_get(&c->input, (char *)&s4_req.command, 1);
+       buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
+       buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
+       have = buffer_len(&c->input);
+       p = buffer_ptr(&c->input);
+       len = strlen(p);
+       debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
+       if (len > have)
+               fatal("channel %d: decode socks4: len %d > have %d",
+                   c->self, len, have);
+       strlcpy(username, p, sizeof(username));
+       buffer_consume(&c->input, len);
+       buffer_consume(&c->input, 1);           /* trailing '\0' */
+
+       host = inet_ntoa(s4_req.dest_addr);
+       strlcpy(c->path, host, sizeof(c->path));
+       c->host_port = ntohs(s4_req.dest_port);
+       
+       debug("channel %d: dynamic request: socks4 host %s port %u command %u",
+           c->self, host, c->host_port, s4_req.command);
+
+       if (s4_req.command != 1) {
+               debug("channel %d: cannot handle: socks4 cn %d",
+                   c->self, s4_req.command);
+               return -1;
+       }
+       s4_rsp.version = 0;                     /* vn: 0 for reply */
+       s4_rsp.command = 90;                    /* cd: req granted */
+       s4_rsp.dest_port = 0;                   /* ignored */
+       s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
+       buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
+       return 1;
+}
+
+/* dynamic port forwarding */
+void
+channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
+{
+       u_char *p;
+       int have, ret;
+
+       have = buffer_len(&c->input);
+
+       debug2("channel %d: pre_dynamic: have %d", c->self, have);
+       /* buffer_dump(&c->input); */
+       /* check if the fixed size part of the packet is in buffer. */
+       if (have < 4) {
+               /* need more */
+               FD_SET(c->sock, readset);
+               return;
+       }
+       /* try to guess the protocol */
+       p = buffer_ptr(&c->input);
+       switch (p[0]) {
+       case 0x04:
+               ret = channel_decode_socks4(c, readset, writeset);
+               break;
+       default:
+               ret = -1;
+               break;
+       }
+       if (ret < 0) {
+               chan_mark_dead(c);
+       } else if (ret == 0) {
+               debug2("channel %d: pre_dynamic: need more", c->self);
+               /* need more */
+               FD_SET(c->sock, readset);
+       } else {
+               /* switch to the next state */
+               c->type = SSH_CHANNEL_OPENING;
+               port_open_helper(c, "direct-tcpip");
+       }
+}
+
 /* This is our fake X11 server socket. */
 void
 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
 {
+       Channel *nc;
        struct sockaddr addr;
-       int newsock, newch;
+       int newsock;
        socklen_t addrlen;
        char buf[16384], *remote_ipaddr;
        int remote_port;
@@ -562,14 +668,19 @@ channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
                snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
                    remote_ipaddr, remote_port);
 
-               newch = channel_new("x11",
+               nc = channel_new("accepted x11 socket",
                    SSH_CHANNEL_OPENING, newsock, newsock, -1,
                    c->local_window_max, c->local_maxpacket,
                    0, xstrdup(buf), 1);
+               if (nc == NULL) {
+                       close(newsock);
+                       xfree(remote_ipaddr);
+                       return;
+               }
                if (compat20) {
                        packet_start(SSH2_MSG_CHANNEL_OPEN);
                        packet_put_cstring("x11");
-                       packet_put_int(newch);
+                       packet_put_int(nc->self);
                        packet_put_int(c->local_window_max);
                        packet_put_int(c->local_maxpacket);
                        /* originator ipaddr and port */
@@ -582,7 +693,7 @@ channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
                        packet_send();
                } else {
                        packet_start(SSH_SMSG_X11_OPEN);
-                       packet_put_int(newch);
+                       packet_put_int(nc->self);
                        if (have_hostname_in_open)
                                packet_put_string(buf, strlen(buf));
                        packet_send();
@@ -591,73 +702,100 @@ channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
        }
 }
 
+void
+port_open_helper(Channel *c, char *rtype)
+{
+       int direct;
+       char buf[1024];
+       char *remote_ipaddr = get_peer_ipaddr(c->sock);
+       u_short remote_port = get_peer_port(c->sock);
+
+       direct = (strcmp(rtype, "direct-tcpip") == 0);
+
+       snprintf(buf, sizeof buf,
+           "%s: listening port %d for %.100s port %d, "
+           "connect from %.200s port %d",
+           rtype, c->listening_port, c->path, c->host_port,
+           remote_ipaddr, remote_port);
+
+       xfree(c->remote_name);
+       c->remote_name = xstrdup(buf);
+
+       if (compat20) {
+               packet_start(SSH2_MSG_CHANNEL_OPEN);
+               packet_put_cstring(rtype);
+               packet_put_int(c->self);
+               packet_put_int(c->local_window_max);
+               packet_put_int(c->local_maxpacket);
+               if (direct) {
+                       /* target host, port */
+                       packet_put_cstring(c->path);
+                       packet_put_int(c->host_port);
+               } else {
+                       /* listen address, port */
+                       packet_put_cstring(c->path);
+                       packet_put_int(c->listening_port);
+               }
+               /* originator host and port */
+               packet_put_cstring(remote_ipaddr);
+               packet_put_int(remote_port);
+               packet_send();
+       } else {
+               packet_start(SSH_MSG_PORT_OPEN);
+               packet_put_int(c->self);
+               packet_put_cstring(c->path);
+               packet_put_int(c->host_port);
+               if (have_hostname_in_open)
+                       packet_put_cstring(c->remote_name);
+               packet_send();
+       }
+       xfree(remote_ipaddr);
+}
+
 /*
  * This socket is listening for connections to a forwarded TCP/IP port.
  */
 void
 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
 {
+       Channel *nc;
        struct sockaddr addr;
-       int newsock, newch;
+       int newsock, nextstate;
        socklen_t addrlen;
-       char buf[1024], *remote_ipaddr, *rtype;
-       int remote_port;
-
-       rtype = (c->type == SSH_CHANNEL_RPORT_LISTENER) ?
-           "forwarded-tcpip" : "direct-tcpip";
+       char *rtype;
 
        if (FD_ISSET(c->sock, readset)) {
                debug("Connection to port %d forwarding "
                    "to %.100s port %d requested.",
                    c->listening_port, c->path, c->host_port);
+
+               rtype = (c->type == SSH_CHANNEL_RPORT_LISTENER) ?
+                   "forwarded-tcpip" : "direct-tcpip";
+               nextstate = (c->host_port == 0 &&
+                   c->type != SSH_CHANNEL_RPORT_LISTENER) ?
+                   SSH_CHANNEL_DYNAMIC : SSH_CHANNEL_OPENING;
+
                addrlen = sizeof(addr);
                newsock = accept(c->sock, &addr, &addrlen);
                if (newsock < 0) {
                        error("accept: %.100s", strerror(errno));
                        return;
                }
-               remote_ipaddr = get_peer_ipaddr(newsock);
-               remote_port = get_peer_port(newsock);
-               snprintf(buf, sizeof buf,
-                   "listen port %d for %.100s port %d, "
-                   "connect from %.200s port %d",
-                   c->listening_port, c->path, c->host_port,
-                   remote_ipaddr, remote_port);
-
-               newch = channel_new(rtype,
-                   SSH_CHANNEL_OPENING, newsock, newsock, -1,
+               nc = channel_new(rtype,
+                   nextstate, newsock, newsock, -1,
                    c->local_window_max, c->local_maxpacket,
-                   0, xstrdup(buf), 1);
-               if (compat20) {
-                       packet_start(SSH2_MSG_CHANNEL_OPEN);
-                       packet_put_cstring(rtype);
-                       packet_put_int(newch);
-                       packet_put_int(c->local_window_max);
-                       packet_put_int(c->local_maxpacket);
-                       if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
-                               /* listen address, port */
-                               packet_put_string(c->path, strlen(c->path));
-                               packet_put_int(c->listening_port);
-                       } else {
-                               /* target host, port */
-                               packet_put_string(c->path, strlen(c->path));
-                               packet_put_int(c->host_port);
-                       }
-                       /* originator host and port */
-                       packet_put_cstring(remote_ipaddr);
-                       packet_put_int(remote_port);
-                       packet_send();
-               } else {
-                       packet_start(SSH_MSG_PORT_OPEN);
-                       packet_put_int(newch);
-                       packet_put_string(c->path, strlen(c->path));
-                       packet_put_int(c->host_port);
-                       if (have_hostname_in_open) {
-                               packet_put_string(buf, strlen(buf));
-                       }
-                       packet_send();
+                   0, xstrdup(rtype), 1);
+               if (nc == NULL) {
+                       error("channel_post_port_listener: no new channel:");
+                       close(newsock);
+                       return;
                }
-               xfree(remote_ipaddr);
+               nc->listening_port = c->listening_port;
+               nc->host_port = c->host_port;
+               strlcpy(nc->path, c->path, sizeof(nc->path));
+
+               if (nextstate != SSH_CHANNEL_DYNAMIC)
+                       port_open_helper(nc, rtype);
        }
 }
 
@@ -668,8 +806,9 @@ channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
 void
 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
 {
+       Channel *nc;
+       int newsock;
        struct sockaddr addr;
-       int newsock, newch;
        socklen_t addrlen;
 
        if (FD_ISSET(c->sock, readset)) {
@@ -679,19 +818,23 @@ channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
                        error("accept from auth socket: %.100s", strerror(errno));
                        return;
                }
-               newch = channel_new("accepted auth socket",
+               nc = channel_new("accepted auth socket",
                    SSH_CHANNEL_OPENING, newsock, newsock, -1,
                    c->local_window_max, c->local_maxpacket,
                    0, xstrdup("accepted auth socket"), 1);
+               if (nc == NULL) {
+                       error("channel_post_auth_listener: channel_new failed");
+                       close(newsock);
+               }
                if (compat20) {
                        packet_start(SSH2_MSG_CHANNEL_OPEN);
                        packet_put_cstring("auth-agent@openssh.com");
-                       packet_put_int(newch);
+                       packet_put_int(nc->self);
                        packet_put_int(c->local_window_max);
                        packet_put_int(c->local_maxpacket);
                } else {
                        packet_start(SSH_SMSG_AGENT_OPEN);
-                       packet_put_int(newch);
+                       packet_put_int(nc->self);
                }
                packet_send();
        }
@@ -700,22 +843,47 @@ channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
 void
 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 {
+       int err = 0;
+       int sz = sizeof(err);
+
        if (FD_ISSET(c->sock, writeset)) {
-               int err = 0;
-               int sz = sizeof(err);
-               c->type = SSH_CHANNEL_OPEN;
-               if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, (char *)&err, &sz) < 0) {
-                       debug("getsockopt SO_ERROR failed");
+               if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, (char *)&err,
+                   &sz) < 0) {
+                       err = errno;
+                       error("getsockopt SO_ERROR failed");
+               }
+               if (err == 0) {
+                       debug("channel %d: connected", c->self);
+                       c->type = SSH_CHANNEL_OPEN;
+                       if (compat20) {
+                               packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
+                               packet_put_int(c->remote_id);
+                               packet_put_int(c->self);
+                               packet_put_int(c->local_window);
+                               packet_put_int(c->local_maxpacket);
+                       } else {
+                               packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
+                               packet_put_int(c->remote_id);
+                               packet_put_int(c->self);
+                       }
                } else {
-                       if (err == 0) {
-                               debug("channel %d: connected)", c->self);
+                       debug("channel %d: not connected: %s",
+                           c->self, strerror(err));
+                       if (compat20) {
+                               packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
+                               packet_put_int(c->remote_id);
+                               packet_put_int(SSH2_OPEN_CONNECT_FAILED);
+                               if (!(datafellows & SSH_BUG_OPENFAILURE)) {
+                                       packet_put_cstring(strerror(err));
+                                       packet_put_cstring("");
+                               }
                        } else {
-                               debug("channel %d: not connected: %s",
-                                   c->self, strerror(err));
-                               chan_read_failed(c);
-                               chan_write_failed(c);
+                               packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
+                               packet_put_int(c->remote_id);
                        }
+                       chan_mark_dead(c);
                }
+               packet_send();
        }
 }
 
@@ -725,7 +893,7 @@ channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
        char buf[16*1024];
        int len;
 
-       if (c->rfd != -1 &&
+       if (c->istate == CHAN_INPUT_OPEN &&
            FD_ISSET(c->rfd, readset)) {
                len = read(c->rfd, buf, sizeof(buf));
                if (len < 0 && (errno == EINTR || errno == EAGAIN))
@@ -733,10 +901,14 @@ channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
                if (len <= 0) {
                        debug("channel %d: read<=0 rfd %d len %d",
                            c->self, c->rfd, len);
-                       if (compat13) {
+                       if (c->type != SSH_CHANNEL_OPEN) {
+                               debug("channel %d: not open", c->self);
+                               chan_mark_dead(c);
+                               return -1;
+                       } else if (compat13) {
                                buffer_consume(&c->output, buffer_len(&c->output));
                                c->type = SSH_CHANNEL_INPUT_DRAINING;
-                               debug("Channel %d status set to input draining.", c->self);
+                               debug("channel %d: status set to input draining.", c->self);
                        } else {
                                chan_read_failed(c);
                        }
@@ -744,7 +916,7 @@ channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
                }
                if(c->input_filter != NULL) {
                        if (c->input_filter(c, buf, len) == -1) {
-                               debug("filter stops channel %d", c->self);
+                               debug("channel %d: filter stops", c->self);
                                chan_read_failed(c);
                        }
                } else {
@@ -760,7 +932,8 @@ channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
        int len;
 
        /* Send buffered output data to the socket. */
-       if (c->wfd != -1 &&
+       if ((c->ostate == CHAN_OUTPUT_OPEN ||
+           c->ostate == CHAN_OUTPUT_WAIT_DRAIN) &&
            FD_ISSET(c->wfd, writeset) &&
            buffer_len(&c->output) > 0) {
                len = write(c->wfd, buffer_ptr(&c->output),
@@ -768,9 +941,13 @@ channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
                if (len < 0 && (errno == EINTR || errno == EAGAIN))
                        return 1;
                if (len <= 0) {
-                       if (compat13) {
+                       if (c->type != SSH_CHANNEL_OPEN) {
+                               debug("channel %d: not open", c->self);
+                               chan_mark_dead(c);
+                               return -1;
+                       } else if (compat13) {
                                buffer_consume(&c->output, buffer_len(&c->output));
-                               debug("Channel %d status set to input draining.", c->self);
+                               debug("channel %d: status set to input draining.", c->self);
                                c->type = SSH_CHANNEL_INPUT_DRAINING;
                        } else {
                                chan_write_failed(c);
@@ -845,7 +1022,8 @@ channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
 int
 channel_check_window(Channel *c)
 {
-       if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
+       if (c->type == SSH_CHANNEL_OPEN &&
+           !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
            c->local_window < c->local_window_max/2 &&
            c->local_consumed > 0) {
                packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
@@ -903,6 +1081,7 @@ channel_handler_init_20(void)
        channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
        channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
        channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
+       channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
 
        channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_2;
        channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
@@ -910,6 +1089,7 @@ channel_handler_init_20(void)
        channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
        channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
        channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
+       channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open_2;
 }
 
 void
@@ -923,6 +1103,7 @@ channel_handler_init_13(void)
        channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
        channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
        channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
+       channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
 
        channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_1;
        channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
@@ -930,6 +1111,7 @@ channel_handler_init_13(void)
        channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
        channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
        channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
+       channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open_1;
 }
 
 void
@@ -941,12 +1123,14 @@ channel_handler_init_15(void)
        channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
        channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
        channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
+       channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
 
        channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
        channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
        channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
        channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_1;
        channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
+       channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open_1;
 }
 
 void
@@ -977,8 +1161,8 @@ channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
                did_init = 1;
        }
        for (i = 0; i < channels_alloc; i++) {
-               c = &channels[i];
-               if (c->type == SSH_CHANNEL_FREE)
+               c = channels[i];
+               if (c == NULL)
                        continue;
                if (ftab[c->type] == NULL)
                        continue;
@@ -999,7 +1183,7 @@ channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
                                if (c->extended_usage == CHAN_EXTENDED_WRITE)
                                        FD_CLR(c->efd, writeset);
                        }
-                       channel_free(c->self);
+                       channel_free(c);
                }
        }
 }
@@ -1045,7 +1229,10 @@ channel_output_poll()
        Channel *c;
 
        for (i = 0; i < channels_alloc; i++) {
-               c = &channels[i];
+
+               c = channels[i];
+               if (c == NULL)
+                       continue;
 
                /* We are only interested in channels that can have buffered incoming data. */
                if (compat13) {
@@ -1229,8 +1416,8 @@ channel_not_very_much_buffered_data()
        Channel *c;
 
        for (i = 0; i < channels_alloc; i++) {
-               c = &channels[i];
-               if (c->type == SSH_CHANNEL_OPEN) {
+               c = channels[i];
+               if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
                        if (!compat20 && buffer_len(&c->input) > packet_get_maxsize()) {
                                debug("channel %d: big input buffer %d",
                                    c->self, buffer_len(&c->input));
@@ -1324,7 +1511,7 @@ channel_input_close_confirmation(int type, int plen, void *ctxt)
        if (c->type != SSH_CHANNEL_CLOSED)
                packet_disconnect("Received close confirmation for "
                    "non-closed channel %d (type %d).", id, c->type);
-       channel_free(c->self);
+       channel_free(c);
 }
 
 void
@@ -1361,6 +1548,22 @@ channel_input_open_confirmation(int type, int plen, void *ctxt)
        }
 }
 
+char *
+reason2txt(int reason)
+{
+       switch(reason) {
+       case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
+               return "administratively prohibited";
+       case SSH2_OPEN_CONNECT_FAILED:
+               return "connect failed";
+       case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
+               return "unknown channel type";
+       case SSH2_OPEN_RESOURCE_SHORTAGE:
+               return "resource shortage";
+       }
+       return "unkown reason";
+}
+
 void
 channel_input_open_failure(int type, int plen, void *ctxt)
 {
@@ -1379,20 +1582,20 @@ channel_input_open_failure(int type, int plen, void *ctxt)
                    "non-opening channel %d.", id);
        if (compat20) {
                reason = packet_get_int();
-               if (packet_remaining() > 0) {
+               if (!(datafellows & SSH_BUG_OPENFAILURE)) {
                        msg  = packet_get_string(NULL);
                        lang = packet_get_string(NULL);
                }
                packet_done();
-               log("channel_open_failure: %d: reason %d %s", id,
-                   reason, msg ? msg : "<no additional info>");
+               log("channel %d: open failed: %s%s%s", id,
+                   reason2txt(reason), msg ? ": ": "", msg ? msg : "");
                if (msg != NULL)
                        xfree(msg);
                if (lang != NULL)
                        xfree(lang);
        }
        /* Free the channel.  This will also close the socket. */
-       channel_free(id);
+       channel_free(c);
 }
 
 void
@@ -1453,21 +1656,26 @@ void
 channel_stop_listening()
 {
        int i;
+       Channel *c;
+
        for (i = 0; i < channels_alloc; i++) {
-               switch (channels[i].type) {
-               case SSH_CHANNEL_AUTH_SOCKET:
-                       close(channels[i].sock);
-                       unlink(channels[i].path);
-                       channel_free(i);
-                       break;
-               case SSH_CHANNEL_PORT_LISTENER:
-               case SSH_CHANNEL_RPORT_LISTENER:
-               case SSH_CHANNEL_X11_LISTENER:
-                       close(channels[i].sock);
-                       channel_free(i);
-                       break;
-               default:
-                       break;
+               c = channels[i];
+               if (c != NULL) {
+                       switch (c->type) {
+                       case SSH_CHANNEL_AUTH_SOCKET:
+                               close(c->sock);
+                               unlink(c->path);
+                               channel_free(c);
+                               break;
+                       case SSH_CHANNEL_PORT_LISTENER:
+                       case SSH_CHANNEL_RPORT_LISTENER:
+                       case SSH_CHANNEL_X11_LISTENER:
+                               close(c->sock);
+                               channel_free(c);
+                               break;
+                       default:
+                               break;
+                       }
                }
        }
 }
@@ -1481,9 +1689,10 @@ void
 channel_close_all()
 {
        int i;
+
        for (i = 0; i < channels_alloc; i++)
-               if (channels[i].type != SSH_CHANNEL_FREE)
-                       channel_close_fds(&channels[i]);
+               if (channels[i] != NULL)
+                       channel_close_fds(channels[i]);
 }
 
 /* Returns true if any channel is still open. */
@@ -1491,16 +1700,21 @@ channel_close_all()
 int
 channel_still_open()
 {
-       u_int i;
-       for (i = 0; i < channels_alloc; i++)
-               switch (channels[i].type) {
-               case SSH_CHANNEL_FREE:
+       int i;
+       Channel *c;
+
+       for (i = 0; i < channels_alloc; i++) {
+               c = channels[i];
+               if (c == NULL)
+                       continue;
+               switch (c->type) {
                case SSH_CHANNEL_X11_LISTENER:
                case SSH_CHANNEL_PORT_LISTENER:
                case SSH_CHANNEL_RPORT_LISTENER:
                case SSH_CHANNEL_CLOSED:
                case SSH_CHANNEL_AUTH_SOCKET:
-               case SSH_CHANNEL_CONNECTING:    /* XXX ??? */
+               case SSH_CHANNEL_DYNAMIC:
+               case SSH_CHANNEL_CONNECTING:
                        continue;
                case SSH_CHANNEL_LARVAL:
                        if (!compat20)
@@ -1516,12 +1730,53 @@ channel_still_open()
                                fatal("cannot happen: OUT_DRAIN");
                        return 1;
                default:
-                       fatal("channel_still_open: bad channel type %d", channels[i].type);
+                       fatal("channel_still_open: bad channel type %d", c->type);
                        /* NOTREACHED */
                }
+       }
        return 0;
 }
 
+/* Returns the id of an open channel suitable for keepaliving */
+
+int
+channel_find_open()
+{
+       int i;
+       Channel *c;
+
+       for (i = 0; i < channels_alloc; i++) {
+               c = channels[i];
+               if (c == NULL)
+                       continue;
+               switch (c->type) {
+               case SSH_CHANNEL_CLOSED:
+               case SSH_CHANNEL_DYNAMIC:
+               case SSH_CHANNEL_X11_LISTENER:
+               case SSH_CHANNEL_PORT_LISTENER:
+               case SSH_CHANNEL_RPORT_LISTENER:
+               case SSH_CHANNEL_OPENING:
+               case SSH_CHANNEL_CONNECTING:
+                       continue;
+               case SSH_CHANNEL_LARVAL:
+               case SSH_CHANNEL_AUTH_SOCKET:
+               case SSH_CHANNEL_OPEN:
+               case SSH_CHANNEL_X11_OPEN:
+                       return i;
+               case SSH_CHANNEL_INPUT_DRAINING:
+               case SSH_CHANNEL_OUTPUT_DRAINING:
+                       if (!compat13)
+                               fatal("cannot happen: OUT_DRAIN");
+                       return i;
+               default:
+                       fatal("channel_find_open: bad channel type %d", c->type);
+                       /* NOTREACHED */
+               }
+       }
+       return -1;
+}
+
+
 /*
  * Returns a message describing the currently open forwarded connections,
  * suitable for sending to the client.  The message contains crlf pairs for
@@ -1532,16 +1787,18 @@ char *
 channel_open_message()
 {
        Buffer buffer;
+       Channel *c;
+       char buf[1024], *cp;
        int i;
-       char buf[512], *cp;
 
        buffer_init(&buffer);
        snprintf(buf, sizeof buf, "The following connections are open:\r\n");
        buffer_append(&buffer, buf, strlen(buf));
        for (i = 0; i < channels_alloc; i++) {
-               Channel *c = &channels[i];
+               c = channels[i];
+               if (c == NULL)
+                       continue;
                switch (c->type) {
-               case SSH_CHANNEL_FREE:
                case SSH_CHANNEL_X11_LISTENER:
                case SSH_CHANNEL_PORT_LISTENER:
                case SSH_CHANNEL_RPORT_LISTENER:
@@ -1551,6 +1808,7 @@ channel_open_message()
                case SSH_CHANNEL_LARVAL:
                case SSH_CHANNEL_OPENING:
                case SSH_CHANNEL_CONNECTING:
+               case SSH_CHANNEL_DYNAMIC:
                case SSH_CHANNEL_OPEN:
                case SSH_CHANNEL_X11_OPEN:
                case SSH_CHANNEL_INPUT_DRAINING:
@@ -1598,7 +1856,8 @@ channel_request_forwarding(
     const char *host_to_connect, u_short port_to_connect,
     int gateway_ports, int remote_fwd)
 {
-       int success, ch, sock, on = 1, ctype;
+       Channel *c;
+       int success, sock, on = 1, ctype;
        struct addrinfo hints, *ai, *aitop;
        char ntop[NI_MAXHOST], strport[NI_MAXSERV];
        const char *host;
@@ -1614,7 +1873,7 @@ channel_request_forwarding(
                ctype  =SSH_CHANNEL_PORT_LISTENER;
        }
 
-       if (strlen(host) > sizeof(channels[0].path) - 1) {
+       if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
                error("Forward host name too long.");
                return success;
        }
@@ -1675,12 +1934,17 @@ channel_request_forwarding(
                        continue;
                }
                /* Allocate a channel number for the socket. */
-               ch = channel_new("port listener", ctype, sock, sock, -1,
+               c = channel_new("port listener", ctype, sock, sock, -1,
                    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
                    0, xstrdup("port listener"), 1);
-               strlcpy(channels[ch].path, host, sizeof(channels[ch].path));
-               channels[ch].host_port = port_to_connect;
-               channels[ch].listening_port = listen_port;
+               if (c == NULL) {
+                       error("channel_request_forwarding: channel_new failed");
+                       close(sock);
+                       continue;
+               }
+               strlcpy(c->path, host, sizeof(c->path));
+               c->host_port = port_to_connect;
+               c->listening_port = listen_port;
                success = 1;
        }
        if (success == 0)
@@ -1917,11 +2181,12 @@ channel_connect_to(const char *host, u_short port)
 void
 channel_input_port_open(int type, int plen, void *ctxt)
 {
+       Channel *c = NULL;
        u_short host_port;
        char *host, *originator_string;
-       int remote_channel, sock = -1, newch;
+       int remote_id, sock = -1;
 
-       remote_channel = packet_get_int();
+       remote_id = packet_get_int();
        host = packet_get_string(NULL);
        host_port = packet_get_int();
 
@@ -1933,18 +2198,19 @@ channel_input_port_open(int type, int plen, void *ctxt)
        packet_done();
        sock = channel_connect_to(host, host_port);
        if (sock != -1) {
-               newch = channel_allocate(SSH_CHANNEL_CONNECTING,
-                   sock, originator_string);
-               channels[newch].remote_id = remote_channel;
-
-               /*XXX delay answer? */
-               packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
-               packet_put_int(remote_channel);
-               packet_put_int(newch);
-               packet_send();
-       } else {
+               c = channel_new("connected socket",
+                   SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
+                   originator_string, 1);
+               if (c == NULL) {
+                       error("channel_input_port_open: channel_new failed");
+                       close(sock);
+               } else {
+                       c->remote_id = remote_id;
+               }
+       }
+       if (c == NULL) {
                packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
-               packet_put_int(remote_channel);
+               packet_put_int(remote_id);
                packet_send();
        }
        xfree(host);
@@ -2231,46 +2497,45 @@ x11_connect_display(void)
 void
 x11_input_open(int type, int plen, void *ctxt)
 {
-       int remote_channel, sock = 0, newch;
+       Channel *c = NULL;
+       int remote_id, sock = 0;
        char *remote_host;
-       u_int remote_len;
 
-       /* Get remote channel number. */
-       remote_channel = packet_get_int();
+       debug("Received X11 open request.");
 
-       /* Get remote originator name. */
+       remote_id = packet_get_int();
        if (have_hostname_in_open) {
-               remote_host = packet_get_string(&remote_len);
-               remote_len += 4;
+               remote_host = packet_get_string(NULL);
        } else {
                remote_host = xstrdup("unknown (remote did not supply name)");
-               remote_len = 0;
        }
-
-       debug("Received X11 open request.");
-       packet_integrity_check(plen, 4 + remote_len, SSH_SMSG_X11_OPEN);
+       packet_done();
 
        /* Obtain a connection to the real X display. */
        sock = x11_connect_display();
-       if (sock == -1) {
+       if (sock != -1) {
+               /* Allocate a channel for this connection. */
+               c = channel_new("connected x11 socket",
+                   SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
+                   remote_host, 1);
+               if (c == NULL) {
+                       error("x11_input_open: channel_new failed");
+                       close(sock);
+               } else {
+                       c->remote_id = remote_id;
+               }
+       }
+       if (c == NULL) {
                /* Send refusal to the remote host. */
                packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
-               packet_put_int(remote_channel);
-               packet_send();
+               packet_put_int(remote_id);
        } else {
-               /* Allocate a channel for this connection. */
-               newch = channel_allocate(
-                    (x11_saved_proto == NULL) ?
-                    SSH_CHANNEL_OPEN : SSH_CHANNEL_X11_OPEN,
-                    sock, remote_host);
-               channels[newch].remote_id = remote_channel;
-
                /* Send a confirmation to the remote host. */
                packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
-               packet_put_int(remote_channel);
-               packet_put_int(newch);
-               packet_send();
+               packet_put_int(remote_id);
+               packet_put_int(c->self);
        }
+       packet_send();
 }
 
 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
@@ -2403,14 +2668,15 @@ cleanup_socket(void)
 int
 auth_input_request_forwarding(struct passwd * pw)
 {
-       int sock, newch;
+       Channel *nc;
+       int sock;
        struct sockaddr_un sunaddr;
 
        if (auth_get_socket_name() != NULL)
                fatal("Protocol error: authentication forwarding requested twice.");
 
        /* Temporarily drop privileged uid for mkdir/bind. */
-       temporarily_use_uid(pw->pw_uid);
+       temporarily_use_uid(pw);
 
        /* Allocate a buffer for the socket name, and format the name. */
        channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME);
@@ -2458,13 +2724,16 @@ auth_input_request_forwarding(struct passwd * pw)
                packet_disconnect("listen: %.100s", strerror(errno));
 
        /* Allocate a channel for the authentication agent socket. */
-       newch = channel_new("auth socket",
+       nc = channel_new("auth socket",
            SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
            CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
            0, xstrdup("auth socket"), 1);
-
-       strlcpy(channels[newch].path, channel_forwarded_auth_socket_name,
-           sizeof(channels[newch].path));
+       if (nc == NULL) {
+               error("auth_input_request_forwarding: channel_new failed");
+               close(sock);
+               return 0;
+       }
+       strlcpy(nc->path, channel_forwarded_auth_socket_name, sizeof(nc->path));
        return 1;
 }
 
@@ -2473,13 +2742,14 @@ auth_input_request_forwarding(struct passwd * pw)
 void
 auth_input_open_request(int type, int plen, void *ctxt)
 {
-       int remch, sock, newch;
+       Channel *c = NULL;
+       int remote_id, sock;
        char *dummyname;
 
        packet_integrity_check(plen, 4, type);
 
        /* Read the remote channel number from the message. */
-       remch = packet_get_int();
+       remote_id = packet_get_int();
 
        /*
         * Get a connection to the local authentication agent (this may again
@@ -2493,28 +2763,26 @@ auth_input_open_request(int type, int plen, void *ctxt)
         * because authentication forwarding is only enabled if we have an
         * agent.
         */
-       if (sock < 0) {
+       if (sock >= 0) {
+               dummyname = xstrdup("authentication agent connection");
+               c = channel_new("", SSH_CHANNEL_OPEN, sock, sock, -1, 0, 0, 0, dummyname, 1);
+               if (c == NULL) {
+                       error("auth_input_open_request: channel_new failed");
+                       close(sock);
+               } else {
+                       c->remote_id = remote_id;
+               }
+       }
+       if (c == NULL) {
                packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
-               packet_put_int(remch);
-               packet_send();
-               return;
+               packet_put_int(remote_id);
+       } else {
+               /* Send a confirmation to the remote host. */
+               debug("Forwarding authentication connection.");
+               packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
+               packet_put_int(remote_id);
+               packet_put_int(c->self);
        }
-       debug("Forwarding authentication connection.");
-
-       /*
-        * Dummy host name.  This will be freed when the channel is freed; it
-        * will still be valid in the packet_put_string below since the
-        * channel cannot yet be freed at that point.
-        */
-       dummyname = xstrdup("authentication agent connection");
-
-       newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname);
-       channels[newch].remote_id = remch;
-
-       /* Send a confirmation to the remote host. */
-       packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
-       packet_put_int(remch);
-       packet_put_int(newch);
        packet_send();
 }
 
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