Initial revision
diff --git a/channels.c b/channels.c
new file mode 100644
index 0000000..38a65a0
--- /dev/null
+++ b/channels.c
@@ -0,0 +1,1500 @@
+/*
+
+channels.c
+
+Author: Tatu Ylonen <ylo@cs.hut.fi>
+
+Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ All rights reserved
+
+Created: Fri Mar 24 16:35:24 1995 ylo
+
+This file contains functions for generic socket connection forwarding.
+There is also code for initiating connection forwarding for X11 connections,
+arbitrary tcp/ip connections, and the authentication agent connection.
+
+*/
+
+#include "includes.h"
+RCSID("$Id: channels.c,v 1.1 1999/10/27 03:42:44 damien Exp $");
+
+#include "ssh.h"
+#include "packet.h"
+#include "xmalloc.h"
+#include "buffer.h"
+#include "authfd.h"
+#include "uidswap.h"
+#include "servconf.h"
+
+#include "channels.h"
+#include "nchan.h"
+#include "compat.h"
+
+/* Maximum number of fake X11 displays to try. */
+#define MAX_DISPLAYS 1000
+
+/* Max len of agent socket */
+#define MAX_SOCKET_NAME 100
+
+/* Pointer to an array containing all allocated channels. The array is
+ dynamically extended as needed. */
+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. */
+static int channels_alloc = 0;
+
+/* Maximum file descriptor value used in any of the channels. This is updated
+ in channel_allocate. */
+static int channel_max_fd_value = 0;
+
+/* Name and directory of socket for authentication agent forwarding. */
+static char *channel_forwarded_auth_socket_name = NULL;
+static char *channel_forwarded_auth_socket_dir = NULL;
+
+/* Saved X11 authentication protocol name. */
+char *x11_saved_proto = NULL;
+
+/* Saved X11 authentication data. This is the real data. */
+char *x11_saved_data = NULL;
+unsigned int x11_saved_data_len = 0;
+
+/* Fake X11 authentication data. This is what the server will be sending
+ us; we should replace any occurrences of this by the real data. */
+char *x11_fake_data = NULL;
+unsigned int x11_fake_data_len;
+
+/* Data structure for storing which hosts are permitted for forward requests.
+ The local sides of any remote forwards are stored in this array to prevent
+ a corrupt remote server from accessing arbitrary TCP/IP ports on our
+ local network (which might be behind a firewall). */
+typedef struct
+{
+ char *host; /* Host name. */
+ int port; /* Port number. */
+} ForwardPermission;
+
+/* List of all permitted host/port pairs to connect. */
+static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
+/* Number of permitted host/port pairs in the array. */
+static int num_permitted_opens = 0;
+/* If this is true, all opens are permitted. This is the case on the
+ server on which we have to trust the client anyway, and the user could
+ do anything after logging in anyway. */
+static int all_opens_permitted = 0;
+
+/* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */
+static int have_hostname_in_open = 0;
+
+/* Sets specific protocol options. */
+
+void channel_set_options(int hostname_in_open)
+{
+ have_hostname_in_open = hostname_in_open;
+}
+
+/* Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually
+ called by the server, because the user could connect to any port anyway,
+ and the server has no way to know but to trust the client anyway. */
+
+void channel_permit_all_opens()
+{
+ all_opens_permitted = 1;
+}
+
+/* Allocate a new channel object and set its type and socket.
+ This will cause remote_name to be freed. */
+
+int channel_allocate(int type, int sock, char *remote_name)
+{
+ int i, old_channels;
+
+ /* Update the maximum file descriptor value. */
+ if (sock > channel_max_fd_value)
+ channel_max_fd_value = sock;
+
+ /* Do initial allocation if this is the first call. */
+ if (channels_alloc == 0)
+ {
+ channels_alloc = 10;
+ channels = xmalloc(channels_alloc * sizeof(Channel));
+ for (i = 0; i < channels_alloc; i++)
+ channels[i].type = SSH_CHANNEL_FREE;
+
+ /* Kludge: arrange a call to channel_stop_listening if we terminate
+ with fatal(). */
+ fatal_add_cleanup((void (*)(void *))channel_stop_listening, NULL);
+ }
+
+ /* Try to find a free slot where to put the new channel. */
+ for (i = 0; i < channels_alloc; i++)
+ if (channels[i].type == SSH_CHANNEL_FREE)
+ {
+ /* Found a free slot. Initialize the fields and return its number. */
+ buffer_init(&channels[i].input);
+ buffer_init(&channels[i].output);
+ channels[i].self = i;
+ channels[i].type = type;
+ channels[i].x11 = 0;
+ channels[i].sock = sock;
+ channels[i].remote_id = -1;
+ channels[i].remote_name = remote_name;
+ chan_init_iostates(&channels[i]);
+ return i;
+ }
+
+ /* There are no free slots. Must expand the array. */
+ old_channels = channels_alloc;
+ channels_alloc += 10;
+ channels = xrealloc(channels, channels_alloc * sizeof(Channel));
+ for (i = old_channels; i < channels_alloc; i++)
+ channels[i].type = SSH_CHANNEL_FREE;
+
+ /* We know that the next one after the old maximum channel number is now
+ available. Initialize and return its number. */
+ buffer_init(&channels[old_channels].input);
+ buffer_init(&channels[old_channels].output);
+ channels[old_channels].self = old_channels;
+ channels[old_channels].type = type;
+ channels[old_channels].x11 = 0;
+ channels[old_channels].sock = sock;
+ channels[old_channels].remote_id = -1;
+ channels[old_channels].remote_name = remote_name;
+ chan_init_iostates(&channels[old_channels]);
+ return old_channels;
+}
+
+/* Free the channel and close its socket. */
+
+void channel_free(int channel)
+{
+ assert(channel >= 0 && channel < channels_alloc &&
+ channels[channel].type != SSH_CHANNEL_FREE);
+ if(compat13)
+ shutdown(channels[channel].sock, SHUT_RDWR);
+ close(channels[channel].sock);
+ buffer_free(&channels[channel].input);
+ buffer_free(&channels[channel].output);
+ channels[channel].type = SSH_CHANNEL_FREE;
+ if (channels[channel].remote_name)
+ {
+ xfree(channels[channel].remote_name);
+ channels[channel].remote_name = NULL;
+ }
+}
+
+/* This is called just before select() to add any bits relevant to
+ channels in the select bitmasks. */
+
+void channel_prepare_select(fd_set *readset, fd_set *writeset)
+{
+ int i;
+ Channel *ch;
+ unsigned char *ucp;
+ unsigned int proto_len, data_len;
+
+ for (i = 0; i < channels_alloc; i++)
+ {
+ ch = &channels[i];
+ redo:
+ switch (ch->type)
+ {
+ case SSH_CHANNEL_X11_LISTENER:
+ case SSH_CHANNEL_PORT_LISTENER:
+ case SSH_CHANNEL_AUTH_SOCKET:
+ FD_SET(ch->sock, readset);
+ break;
+
+ case SSH_CHANNEL_OPEN:
+ if(compat13){
+ if (buffer_len(&ch->input) < 32768)
+ FD_SET(ch->sock, readset);
+ if (buffer_len(&ch->output) > 0)
+ FD_SET(ch->sock, writeset);
+ break;
+ }
+ /* test whether sockets are 'alive' for read/write */
+ if (ch->istate == CHAN_INPUT_OPEN)
+ if (buffer_len(&ch->input) < 32768)
+ FD_SET(ch->sock, readset);
+ if (ch->ostate == CHAN_OUTPUT_OPEN || ch->ostate == CHAN_OUTPUT_WAIT_DRAIN){
+ if (buffer_len(&ch->output) > 0){
+ FD_SET(ch->sock, writeset);
+ }else if(ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
+ chan_obuf_empty(ch);
+ }
+ }
+ break;
+
+ case SSH_CHANNEL_INPUT_DRAINING:
+ if (!compat13)
+ fatal("cannot happen: IN_DRAIN");
+ if (buffer_len(&ch->input) == 0)
+ {
+ packet_start(SSH_MSG_CHANNEL_CLOSE);
+ packet_put_int(ch->remote_id);
+ packet_send();
+ ch->type = SSH_CHANNEL_CLOSED;
+ debug("Closing channel %d after input drain.", i);
+ break;
+ }
+ break;
+
+ case SSH_CHANNEL_OUTPUT_DRAINING:
+ if (!compat13)
+ fatal("cannot happen: OUT_DRAIN");
+ if (buffer_len(&ch->output) == 0)
+ {
+ /* debug("Freeing channel %d after output drain.", i); */
+ channel_free(i);
+ break;
+ }
+ FD_SET(ch->sock, writeset);
+ break;
+
+ case SSH_CHANNEL_X11_OPEN:
+ /* This is a special state for X11 authentication spoofing. An
+ opened X11 connection (when authentication spoofing is being
+ done) remains in this state until the first packet has been
+ completely read. The authentication data in that packet is
+ then substituted by the real data if it matches the fake data,
+ and the channel is put into normal mode. */
+
+ /* Check if the fixed size part of the packet is in buffer. */
+ if (buffer_len(&ch->output) < 12)
+ break;
+
+ /* Parse the lengths of variable-length fields. */
+ ucp = (unsigned char *)buffer_ptr(&ch->output);
+ if (ucp[0] == 0x42)
+ { /* Byte order MSB first. */
+ proto_len = 256 * ucp[6] + ucp[7];
+ data_len = 256 * ucp[8] + ucp[9];
+ }
+ else
+ if (ucp[0] == 0x6c)
+ { /* Byte order LSB first. */
+ proto_len = ucp[6] + 256 * ucp[7];
+ data_len = ucp[8] + 256 * ucp[9];
+ }
+ else
+ {
+ debug("Initial X11 packet contains bad byte order byte: 0x%x",
+ ucp[0]);
+ ch->type = SSH_CHANNEL_OPEN;
+ goto reject;
+ }
+
+ /* Check if the whole packet is in buffer. */
+ if (buffer_len(&ch->output) <
+ 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
+ break;
+
+ /* Check if authentication protocol matches. */
+ if (proto_len != strlen(x11_saved_proto) ||
+ memcmp(ucp + 12, x11_saved_proto, proto_len) != 0)
+ {
+ debug("X11 connection uses different authentication protocol.");
+ ch->type = SSH_CHANNEL_OPEN;
+ goto reject;
+ }
+
+ /* Check if authentication data matches our fake data. */
+ if (data_len != x11_fake_data_len ||
+ memcmp(ucp + 12 + ((proto_len + 3) & ~3),
+ x11_fake_data, x11_fake_data_len) != 0)
+ {
+ debug("X11 auth data does not match fake data.");
+ ch->type = SSH_CHANNEL_OPEN;
+ goto reject;
+ }
+
+ /* Received authentication protocol and data match our fake data.
+ Substitute the fake data with real data. */
+ assert(x11_fake_data_len == x11_saved_data_len);
+ memcpy(ucp + 12 + ((proto_len + 3) & ~3),
+ x11_saved_data, x11_saved_data_len);
+
+ /* Start normal processing for the channel. */
+ ch->type = SSH_CHANNEL_OPEN;
+ /* Enable X11 Problem FIX */
+ ch->x11 = 1;
+ goto redo;
+
+ reject:
+ /* We have received an X11 connection that has bad authentication
+ information. */
+ log("X11 connection rejected because of wrong authentication.\r\n");
+ buffer_clear(&ch->input);
+ buffer_clear(&ch->output);
+ if (compat13) {
+ close(ch->sock);
+ ch->sock = -1;
+ ch->type = SSH_CHANNEL_CLOSED;
+ packet_start(SSH_MSG_CHANNEL_CLOSE);
+ packet_put_int(ch->remote_id);
+ packet_send();
+ }else{
+ debug("X11 rejected %d 0x%x 0x%x", ch->self, ch->istate, ch->ostate);
+ chan_read_failed(ch);
+ chan_write_failed(ch);
+ debug("X11 rejected %d 0x%x 0x%x", ch->self, ch->istate, ch->ostate);
+ }
+ break;
+
+ case SSH_CHANNEL_FREE:
+ default:
+ continue;
+ }
+ }
+}
+
+/* After select, perform any appropriate operations for channels which
+ have events pending. */
+
+void channel_after_select(fd_set *readset, fd_set *writeset)
+{
+ struct sockaddr addr;
+ int addrlen, newsock, i, newch, len;
+ Channel *ch;
+ char buf[16384], *remote_hostname;
+
+ /* Loop over all channels... */
+ for (i = 0; i < channels_alloc; i++)
+ {
+ ch = &channels[i];
+ switch (ch->type)
+ {
+ case SSH_CHANNEL_X11_LISTENER:
+ /* This is our fake X11 server socket. */
+ if (FD_ISSET(ch->sock, readset))
+ {
+ debug("X11 connection requested.");
+ addrlen = sizeof(addr);
+ newsock = accept(ch->sock, &addr, &addrlen);
+ if (newsock < 0)
+ {
+ error("accept: %.100s", strerror(errno));
+ break;
+ }
+ remote_hostname = get_remote_hostname(newsock);
+ snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
+ remote_hostname, get_peer_port(newsock));
+ xfree(remote_hostname);
+ newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
+ xstrdup(buf));
+ packet_start(SSH_SMSG_X11_OPEN);
+ packet_put_int(newch);
+ if (have_hostname_in_open)
+ packet_put_string(buf, strlen(buf));
+ packet_send();
+ }
+ break;
+
+ case SSH_CHANNEL_PORT_LISTENER:
+ /* This socket is listening for connections to a forwarded TCP/IP
+ port. */
+ if (FD_ISSET(ch->sock, readset))
+ {
+ debug("Connection to port %d forwarding to %.100s:%d requested.",
+ ch->listening_port, ch->path, ch->host_port);
+ addrlen = sizeof(addr);
+ newsock = accept(ch->sock, &addr, &addrlen);
+ if (newsock < 0)
+ {
+ error("accept: %.100s", strerror(errno));
+ break;
+ }
+ remote_hostname = get_remote_hostname(newsock);
+ snprintf(buf, sizeof buf, "port %d, connection from %.200s port %d",
+ ch->listening_port, remote_hostname,
+ get_peer_port(newsock));
+ xfree(remote_hostname);
+ newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
+ xstrdup(buf));
+ packet_start(SSH_MSG_PORT_OPEN);
+ packet_put_int(newch);
+ packet_put_string(ch->path, strlen(ch->path));
+ packet_put_int(ch->host_port);
+ if (have_hostname_in_open)
+ packet_put_string(buf, strlen(buf));
+ packet_send();
+ }
+ break;
+
+ case SSH_CHANNEL_AUTH_SOCKET:
+ /* This is the authentication agent socket listening for connections
+ from clients. */
+ if (FD_ISSET(ch->sock, readset))
+ {
+ int nchan;
+ len = sizeof(addr);
+ newsock = accept(ch->sock, &addr, &len);
+ if (newsock < 0)
+ {
+ error("accept from auth socket: %.100s", strerror(errno));
+ break;
+ }
+
+ nchan = channel_allocate(SSH_CHANNEL_OPENING, newsock,
+ xstrdup("accepted auth socket"));
+ packet_start(SSH_SMSG_AGENT_OPEN);
+ packet_put_int(nchan);
+ packet_send();
+ }
+ break;
+
+ case SSH_CHANNEL_OPEN:
+ /* This is an open two-way communication channel. It is not of
+ interest to us at this point what kind of data is being
+ transmitted. */
+
+ /* Read available incoming data and append it to buffer;
+ shutdown socket, if read or write failes */
+ if (FD_ISSET(ch->sock, readset))
+ {
+ len = read(ch->sock, buf, sizeof(buf));
+ if (len <= 0)
+ {
+ if (compat13) {
+ buffer_consume(&ch->output, buffer_len(&ch->output));
+ ch->type = SSH_CHANNEL_INPUT_DRAINING;
+ debug("Channel %d status set to input draining.", i);
+ }else{
+ chan_read_failed(ch);
+ }
+ break;
+ }
+ buffer_append(&ch->input, buf, len);
+ }
+ /* Send buffered output data to the socket. */
+ if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0)
+ {
+ len = write(ch->sock, buffer_ptr(&ch->output),
+ buffer_len(&ch->output));
+ if (len <= 0)
+ {
+ if (compat13) {
+ buffer_consume(&ch->output, buffer_len(&ch->output));
+ debug("Channel %d status set to input draining.", i);
+ ch->type = SSH_CHANNEL_INPUT_DRAINING;
+ }else{
+ chan_write_failed(ch);
+ }
+ break;
+ }
+ buffer_consume(&ch->output, len);
+ }
+ break;
+
+ case SSH_CHANNEL_OUTPUT_DRAINING:
+ if (!compat13)
+ fatal("cannot happen: OUT_DRAIN");
+ /* Send buffered output data to the socket. */
+ if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0)
+ {
+ len = write(ch->sock, buffer_ptr(&ch->output),
+ buffer_len(&ch->output));
+ if (len <= 0)
+ buffer_consume(&ch->output, buffer_len(&ch->output));
+ else
+ buffer_consume(&ch->output, len);
+ }
+ break;
+
+ case SSH_CHANNEL_X11_OPEN:
+ case SSH_CHANNEL_FREE:
+ default:
+ continue;
+ }
+ }
+}
+
+/* If there is data to send to the connection, send some of it now. */
+
+void channel_output_poll()
+{
+ int len, i;
+ Channel *ch;
+
+ for (i = 0; i < channels_alloc; i++)
+ {
+ ch = &channels[i];
+ /* We are only interested in channels that can have buffered incoming
+ data. */
+ if (ch->type != SSH_CHANNEL_OPEN &&
+ ch->type != SSH_CHANNEL_INPUT_DRAINING)
+ continue;
+
+ /* Get the amount of buffered data for this channel. */
+ len = buffer_len(&ch->input);
+ if (len > 0)
+ {
+ /* Send some data for the other side over the secure connection. */
+ if (packet_is_interactive())
+ {
+ if (len > 1024)
+ len = 512;
+ }
+ else
+ {
+ if (len > 16384)
+ len = 16384; /* Keep the packets at reasonable size. */
+ }
+ packet_start(SSH_MSG_CHANNEL_DATA);
+ packet_put_int(ch->remote_id);
+ packet_put_string(buffer_ptr(&ch->input), len);
+ packet_send();
+ buffer_consume(&ch->input, len);
+ }
+ else if(ch->istate == CHAN_INPUT_WAIT_DRAIN)
+ {
+ if (compat13)
+ fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
+ /* input-buffer is empty and read-socket shutdown:
+ tell peer, that we will not send more data: send IEOF */
+ chan_ibuf_empty(ch);
+ }
+ }
+}
+
+/* This is called when a packet of type CHANNEL_DATA has just been received.
+ The message type has already been consumed, but channel number and data
+ is still there. */
+
+void channel_input_data(int payload_len)
+{
+ int channel;
+ char *data;
+ unsigned int data_len;
+
+ /* Get the channel number and verify it. */
+ channel = packet_get_int();
+ if (channel < 0 || channel >= channels_alloc ||
+ channels[channel].type == SSH_CHANNEL_FREE)
+ packet_disconnect("Received data for nonexistent channel %d.", channel);
+
+ /* Ignore any data for non-open channels (might happen on close) */
+ if (channels[channel].type != SSH_CHANNEL_OPEN &&
+ channels[channel].type != SSH_CHANNEL_X11_OPEN)
+ return;
+
+ /* Get the data. */
+ data = packet_get_string(&data_len);
+ packet_integrity_check(payload_len, 4 + 4+data_len, SSH_MSG_CHANNEL_DATA);
+ buffer_append(&channels[channel].output, data, data_len);
+ xfree(data);
+}
+
+/* Returns true if no channel has too much buffered data, and false if
+ one or more channel is overfull. */
+
+int channel_not_very_much_buffered_data()
+{
+ unsigned int i;
+ Channel *ch;
+
+ for (i = 0; i < channels_alloc; i++)
+ {
+ ch = &channels[i];
+ switch (ch->type)
+ {
+ case SSH_CHANNEL_X11_LISTENER:
+ case SSH_CHANNEL_PORT_LISTENER:
+ case SSH_CHANNEL_AUTH_SOCKET:
+ continue;
+ case SSH_CHANNEL_OPEN:
+ if (buffer_len(&ch->input) > 32768)
+ return 0;
+ if (buffer_len(&ch->output) > 32768)
+ return 0;
+ continue;
+ case SSH_CHANNEL_INPUT_DRAINING:
+ case SSH_CHANNEL_OUTPUT_DRAINING:
+ case SSH_CHANNEL_X11_OPEN:
+ case SSH_CHANNEL_FREE:
+ default:
+ continue;
+ }
+ }
+ return 1;
+}
+
+/* This is called after receiving CHANNEL_CLOSE/IEOF. */
+
+void channel_input_close()
+{
+ int channel;
+
+ /* Get the channel number and verify it. */
+ channel = packet_get_int();
+ if (channel < 0 || channel >= channels_alloc ||
+ channels[channel].type == SSH_CHANNEL_FREE)
+ packet_disconnect("Received data for nonexistent channel %d.", channel);
+
+ if(!compat13){
+ /* proto version 1.5 overloads CLOSE with IEOF */
+ chan_rcvd_ieof(&channels[channel]);
+ return;
+ }
+
+ /* Send a confirmation that we have closed the channel and no more data is
+ coming for it. */
+ packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
+ packet_put_int(channels[channel].remote_id);
+ packet_send();
+
+ /* If the channel is in closed state, we have sent a close request, and
+ the other side will eventually respond with a confirmation. Thus,
+ we cannot free the channel here, because then there would be no-one to
+ receive the confirmation. The channel gets freed when the confirmation
+ arrives. */
+ if (channels[channel].type != SSH_CHANNEL_CLOSED)
+ {
+ /* Not a closed channel - mark it as draining, which will cause it to
+ be freed later. */
+ buffer_consume(&channels[channel].input,
+ buffer_len(&channels[channel].input));
+ channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING;
+ /* debug("Setting status to output draining; output len = %d",
+ buffer_len(&channels[channel].output)); */
+ }
+}
+
+/* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */
+
+void channel_input_close_confirmation()
+{
+ int channel;
+
+ /* Get the channel number and verify it. */
+ channel = packet_get_int();
+ if (channel < 0 || channel >= channels_alloc)
+ packet_disconnect("Received close confirmation for out-of-range channel %d.",
+ channel);
+
+ if(!compat13){
+ /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
+ chan_rcvd_oclose(&channels[channel]);
+ return;
+ }
+
+ if (channels[channel].type != SSH_CHANNEL_CLOSED)
+ packet_disconnect("Received close confirmation for non-closed channel %d (type %d).",
+ channel, channels[channel].type);
+
+ /* Free the channel. */
+ channel_free(channel);
+}
+
+/* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */
+
+void channel_input_open_confirmation()
+{
+ int channel, remote_channel;
+
+ /* Get the channel number and verify it. */
+ channel = packet_get_int();
+ if (channel < 0 || channel >= channels_alloc ||
+ channels[channel].type != SSH_CHANNEL_OPENING)
+ packet_disconnect("Received open confirmation for non-opening channel %d.",
+ channel);
+
+ /* Get remote side's id for this channel. */
+ remote_channel = packet_get_int();
+
+ /* Record the remote channel number and mark that the channel is now open. */
+ channels[channel].remote_id = remote_channel;
+ channels[channel].type = SSH_CHANNEL_OPEN;
+}
+
+/* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */
+
+void channel_input_open_failure()
+{
+ int channel;
+
+ /* Get the channel number and verify it. */
+ channel = packet_get_int();
+ if (channel < 0 || channel >= channels_alloc ||
+ channels[channel].type != SSH_CHANNEL_OPENING)
+ packet_disconnect("Received open failure for non-opening channel %d.",
+ channel);
+
+ /* Free the channel. This will also close the socket. */
+ channel_free(channel);
+}
+
+/* Stops listening for channels, and removes any unix domain sockets that
+ we might have. */
+
+void channel_stop_listening()
+{
+ int i;
+ for (i = 0; i < channels_alloc; i++)
+ {
+ switch (channels[i].type)
+ {
+ case SSH_CHANNEL_AUTH_SOCKET:
+ close(channels[i].sock);
+ remove(channels[i].path);
+ channel_free(i);
+ break;
+ case SSH_CHANNEL_PORT_LISTENER:
+ case SSH_CHANNEL_X11_LISTENER:
+ close(channels[i].sock);
+ channel_free(i);
+ break;
+ default:
+ break;
+ }
+ }
+}
+
+/* Closes the sockets of all channels. This is used to close extra file
+ descriptors after a fork. */
+
+void channel_close_all()
+{
+ int i;
+ for (i = 0; i < channels_alloc; i++)
+ {
+ if (channels[i].type != SSH_CHANNEL_FREE)
+ close(channels[i].sock);
+ }
+}
+
+/* Returns the maximum file descriptor number used by the channels. */
+
+int channel_max_fd()
+{
+ return channel_max_fd_value;
+}
+
+/* Returns true if any channel is still open. */
+
+int channel_still_open()
+{
+ unsigned int i;
+ for (i = 0; i < channels_alloc; i++)
+ switch (channels[i].type)
+ {
+ case SSH_CHANNEL_FREE:
+ case SSH_CHANNEL_X11_LISTENER:
+ case SSH_CHANNEL_PORT_LISTENER:
+ case SSH_CHANNEL_CLOSED:
+ case SSH_CHANNEL_AUTH_SOCKET:
+ continue;
+ case SSH_CHANNEL_OPENING:
+ case SSH_CHANNEL_OPEN:
+ case SSH_CHANNEL_X11_OPEN:
+ return 1;
+ case SSH_CHANNEL_INPUT_DRAINING:
+ case SSH_CHANNEL_OUTPUT_DRAINING:
+ if (!compat13)
+ fatal("cannot happen: OUT_DRAIN");
+ return 1;
+ default:
+ fatal("channel_still_open: bad channel type %d", channels[i].type);
+ /*NOTREACHED*/
+ }
+ return 0;
+}
+
+/* Returns a message describing the currently open forwarded
+ connections, suitable for sending to the client. The message
+ contains crlf pairs for newlines. */
+
+char *channel_open_message()
+{
+ Buffer buffer;
+ 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];
+ switch (c->type)
+ {
+ case SSH_CHANNEL_FREE:
+ case SSH_CHANNEL_X11_LISTENER:
+ case SSH_CHANNEL_PORT_LISTENER:
+ case SSH_CHANNEL_CLOSED:
+ case SSH_CHANNEL_AUTH_SOCKET:
+ continue;
+ case SSH_CHANNEL_OPENING:
+ case SSH_CHANNEL_OPEN:
+ case SSH_CHANNEL_X11_OPEN:
+ case SSH_CHANNEL_INPUT_DRAINING:
+ case SSH_CHANNEL_OUTPUT_DRAINING:
+ snprintf(buf, sizeof buf, " #%d/%d %.300s\r\n",
+ c->self,c->type,c->remote_name);
+ buffer_append(&buffer, buf, strlen(buf));
+ continue;
+ default:
+ fatal("channel_still_open: bad channel type %d", c->type);
+ /*NOTREACHED*/
+ }
+ }
+ buffer_append(&buffer, "\0", 1);
+ cp = xstrdup(buffer_ptr(&buffer));
+ buffer_free(&buffer);
+ return cp;
+}
+
+/* Initiate forwarding of connections to local port "port" through the secure
+ channel to host:port from remote side. */
+
+void channel_request_local_forwarding(int port, const char *host,
+ int host_port)
+{
+ int ch, sock;
+ struct sockaddr_in sin;
+ extern Options options;
+
+ if (strlen(host) > sizeof(channels[0].path) - 1)
+ packet_disconnect("Forward host name too long.");
+
+ /* Create a port to listen for the host. */
+ sock = socket(AF_INET, SOCK_STREAM, 0);
+ if (sock < 0)
+ packet_disconnect("socket: %.100s", strerror(errno));
+
+ /* Initialize socket address. */
+ memset(&sin, 0, sizeof(sin));
+ sin.sin_family = AF_INET;
+ if (options.gateway_ports == 1)
+ sin.sin_addr.s_addr = htonl(INADDR_ANY);
+ else
+ sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+ sin.sin_port = htons(port);
+
+ /* Bind the socket to the address. */
+ if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0)
+ packet_disconnect("bind: %.100s", strerror(errno));
+
+ /* Start listening for connections on the socket. */
+ if (listen(sock, 5) < 0)
+ packet_disconnect("listen: %.100s", strerror(errno));
+
+ /* Allocate a channel number for the socket. */
+ ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock,
+ xstrdup("port listener"));
+ strcpy(channels[ch].path, host); /* note: host name stored here */
+ channels[ch].host_port = host_port; /* port on host to connect to */
+ channels[ch].listening_port = port; /* port being listened */
+}
+
+/* Initiate forwarding of connections to port "port" on remote host through
+ the secure channel to host:port from local side. */
+
+void channel_request_remote_forwarding(int port, const char *host,
+ int remote_port)
+{
+ int payload_len;
+ /* Record locally that connection to this host/port is permitted. */
+ if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
+ fatal("channel_request_remote_forwarding: too many forwards");
+ permitted_opens[num_permitted_opens].host = xstrdup(host);
+ permitted_opens[num_permitted_opens].port = remote_port;
+ num_permitted_opens++;
+
+ /* Send the forward request to the remote side. */
+ packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
+ packet_put_int(port);
+ packet_put_string(host, strlen(host));
+ packet_put_int(remote_port);
+ packet_send();
+ packet_write_wait();
+
+ /* Wait for response from the remote side. It will send a disconnect
+ message on failure, and we will never see it here. */
+ packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
+}
+
+/* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
+ listening for the port, and sends back a success reply (or disconnect
+ message if there was an error). This never returns if there was an
+ error. */
+
+void channel_input_port_forward_request(int is_root)
+{
+ int port, host_port;
+ char *hostname;
+
+ /* Get arguments from the packet. */
+ port = packet_get_int();
+ hostname = packet_get_string(NULL);
+ host_port = packet_get_int();
+
+ /* Port numbers are 16 bit quantities. */
+ if ((port & 0xffff) != port)
+ packet_disconnect("Requested forwarding of nonexistent port %d.", port);
+
+ /* Check that an unprivileged user is not trying to forward a privileged
+ port. */
+ if (port < IPPORT_RESERVED && !is_root)
+ packet_disconnect("Requested forwarding of port %d but user is not root.",
+ port);
+
+ /* Initiate forwarding. */
+ channel_request_local_forwarding(port, hostname, host_port);
+
+ /* Free the argument string. */
+ xfree(hostname);
+}
+
+/* This is called after receiving PORT_OPEN message. This attempts to connect
+ to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION or
+ CHANNEL_OPEN_FAILURE. */
+
+void channel_input_port_open(int payload_len)
+{
+ int remote_channel, sock, newch, host_port, i;
+ struct sockaddr_in sin;
+ char *host, *originator_string;
+ struct hostent *hp;
+ int host_len, originator_len;
+
+ /* Get remote channel number. */
+ remote_channel = packet_get_int();
+
+ /* Get host name to connect to. */
+ host = packet_get_string(&host_len);
+
+ /* Get port to connect to. */
+ host_port = packet_get_int();
+
+ /* Get remote originator name. */
+ if (have_hostname_in_open)
+ originator_string = packet_get_string(&originator_len);
+ else
+ originator_string = xstrdup("unknown (remote did not supply name)");
+
+ packet_integrity_check(payload_len,
+ 4 + 4 + host_len + 4 + 4 + originator_len,
+ SSH_MSG_PORT_OPEN);
+
+ /* Check if opening that port is permitted. */
+ if (!all_opens_permitted)
+ {
+ /* Go trough all permitted ports. */
+ for (i = 0; i < num_permitted_opens; i++)
+ if (permitted_opens[i].port == host_port &&
+ strcmp(permitted_opens[i].host, host) == 0)
+ break;
+
+ /* Check if we found the requested port among those permitted. */
+ if (i >= num_permitted_opens)
+ {
+ /* The port is not permitted. */
+ log("Received request to connect to %.100s:%d, but the request was denied.",
+ host, host_port);
+ packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
+ packet_put_int(remote_channel);
+ packet_send();
+ }
+ }
+
+ memset(&sin, 0, sizeof(sin));
+ sin.sin_addr.s_addr = inet_addr(host);
+ if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff)
+ {
+ /* It was a valid numeric host address. */
+ sin.sin_family = AF_INET;
+ }
+ else
+ {
+ /* Look up the host address from the name servers. */
+ hp = gethostbyname(host);
+ if (!hp)
+ {
+ error("%.100s: unknown host.", host);
+ goto fail;
+ }
+ if (!hp->h_addr_list[0])
+ {
+ error("%.100s: host has no IP address.", host);
+ goto fail;
+ }
+ sin.sin_family = hp->h_addrtype;
+ memcpy(&sin.sin_addr, hp->h_addr_list[0],
+ sizeof(sin.sin_addr));
+ }
+ sin.sin_port = htons(host_port);
+
+ /* Create the socket. */
+ sock = socket(sin.sin_family, SOCK_STREAM, 0);
+ if (sock < 0)
+ {
+ error("socket: %.100s", strerror(errno));
+ goto fail;
+ }
+
+ /* Connect to the host/port. */
+ if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0)
+ {
+ error("connect %.100s:%d: %.100s", host, host_port,
+ strerror(errno));
+ close(sock);
+ goto fail;
+ }
+
+ /* Successful connection. */
+
+ /* Allocate a channel for this connection. */
+ newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string);
+ 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();
+
+ /* Free the argument string. */
+ xfree(host);
+
+ return;
+
+ fail:
+ /* Free the argument string. */
+ xfree(host);
+
+ /* Send refusal to the remote host. */
+ packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
+ packet_put_int(remote_channel);
+ packet_send();
+}
+
+/* Creates an internet domain socket for listening for X11 connections.
+ Returns a suitable value for the DISPLAY variable, or NULL if an error
+ occurs. */
+
+char *x11_create_display_inet(int screen_number)
+{
+ extern ServerOptions options;
+ int display_number, port, sock;
+ struct sockaddr_in sin;
+ char buf[512];
+ char hostname[MAXHOSTNAMELEN];
+
+ for (display_number = options.x11_display_offset; display_number < MAX_DISPLAYS; display_number++)
+ {
+ port = 6000 + display_number;
+ memset(&sin, 0, sizeof(sin));
+ sin.sin_family = AF_INET;
+ sin.sin_addr.s_addr = htonl(INADDR_ANY);
+ sin.sin_port = htons(port);
+
+ sock = socket(AF_INET, SOCK_STREAM, 0);
+ if (sock < 0)
+ {
+ error("socket: %.100s", strerror(errno));
+ return NULL;
+ }
+
+ if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0)
+ {
+ debug("bind port %d: %.100s", port, strerror(errno));
+ shutdown(sock, SHUT_RDWR);
+ close(sock);
+ continue;
+ }
+ break;
+ }
+ if (display_number >= MAX_DISPLAYS)
+ {
+ error("Failed to allocate internet-domain X11 display socket.");
+ return NULL;
+ }
+
+ /* Start listening for connections on the socket. */
+ if (listen(sock, 5) < 0)
+ {
+ error("listen: %.100s", strerror(errno));
+ shutdown(sock, SHUT_RDWR);
+ close(sock);
+ return NULL;
+ }
+
+ /* Set up a suitable value for the DISPLAY variable. */
+ if (gethostname(hostname, sizeof(hostname)) < 0)
+ fatal("gethostname: %.100s", strerror(errno));
+ snprintf(buf, sizeof buf, "%.400s:%d.%d", hostname,
+ display_number, screen_number);
+
+ /* Allocate a channel for the socket. */
+ (void)channel_allocate(SSH_CHANNEL_X11_LISTENER, sock,
+ xstrdup("X11 inet listener"));
+
+ /* Return a suitable value for the DISPLAY environment variable. */
+ return xstrdup(buf);
+}
+
+#ifndef X_UNIX_PATH
+#define X_UNIX_PATH "/tmp/.X11-unix/X"
+#endif
+
+static
+int
+connect_local_xsocket(unsigned dnr)
+{
+ static const char *const x_sockets[] = {
+ X_UNIX_PATH "%u",
+ "/var/X/.X11-unix/X" "%u",
+ "/usr/spool/sockets/X11/" "%u",
+ NULL
+ };
+ int sock;
+ struct sockaddr_un addr;
+ const char *const *path;
+
+ for (path = x_sockets; *path; ++path)
+ {
+ sock = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (sock < 0)
+ error("socket: %.100s", strerror(errno));
+ memset(&addr, 0, sizeof(addr));
+ addr.sun_family = AF_UNIX;
+ snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr);
+ if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
+ return sock;
+ close(sock);
+ }
+ error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
+ return -1;
+}
+
+
+/* This is called when SSH_SMSG_X11_OPEN is received. The packet contains
+ the remote channel number. We should do whatever we want, and respond
+ with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */
+
+void x11_input_open(int payload_len)
+{
+ int remote_channel, display_number, sock, newch;
+ const char *display;
+ struct sockaddr_in sin;
+ char buf[1024], *cp, *remote_host;
+ struct hostent *hp;
+ int remote_len;
+
+ /* Get remote channel number. */
+ remote_channel = packet_get_int();
+
+ /* Get remote originator name. */
+ if (have_hostname_in_open)
+ remote_host = packet_get_string(&remote_len);
+ else
+ remote_host = xstrdup("unknown (remote did not supply name)");
+
+ debug("Received X11 open request.");
+ packet_integrity_check(payload_len, 4 + 4+remote_len, SSH_SMSG_X11_OPEN);
+
+ /* Try to open a socket for the local X server. */
+ display = getenv("DISPLAY");
+ if (!display)
+ {
+ error("DISPLAY not set.");
+ goto fail;
+ }
+
+ /* Now we decode the value of the DISPLAY variable and make a connection
+ to the real X server. */
+
+ /* Check if it is a unix domain socket. Unix domain displays are in one
+ of the following formats: unix:d[.s], :d[.s], ::d[.s] */
+ if (strncmp(display, "unix:", 5) == 0 ||
+ display[0] == ':')
+ {
+ /* Connect to the unix domain socket. */
+ if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1)
+ {
+ error("Could not parse display number from DISPLAY: %.100s",
+ display);
+ goto fail;
+ }
+ /* Create a socket. */
+ sock = connect_local_xsocket(display_number);
+ if (sock < 0)
+ goto fail;
+
+ /* OK, we now have a connection to the display. */
+ goto success;
+ }
+
+ /* Connect to an inet socket. The DISPLAY value is supposedly
+ hostname:d[.s], where hostname may also be numeric IP address. */
+ strncpy(buf, display, sizeof(buf));
+ buf[sizeof(buf) - 1] = 0;
+ cp = strchr(buf, ':');
+ if (!cp)
+ {
+ error("Could not find ':' in DISPLAY: %.100s", display);
+ goto fail;
+ }
+ *cp = 0;
+ /* buf now contains the host name. But first we parse the display number. */
+ if (sscanf(cp + 1, "%d", &display_number) != 1)
+ {
+ error("Could not parse display number from DISPLAY: %.100s",
+ display);
+ goto fail;
+ }
+
+ /* Try to parse the host name as a numeric IP address. */
+ memset(&sin, 0, sizeof(sin));
+ sin.sin_addr.s_addr = inet_addr(buf);
+ if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff)
+ {
+ /* It was a valid numeric host address. */
+ sin.sin_family = AF_INET;
+ }
+ else
+ {
+ /* Not a numeric IP address. */
+ /* Look up the host address from the name servers. */
+ hp = gethostbyname(buf);
+ if (!hp)
+ {
+ error("%.100s: unknown host.", buf);
+ goto fail;
+ }
+ if (!hp->h_addr_list[0])
+ {
+ error("%.100s: host has no IP address.", buf);
+ goto fail;
+ }
+ sin.sin_family = hp->h_addrtype;
+ memcpy(&sin.sin_addr, hp->h_addr_list[0],
+ sizeof(sin.sin_addr));
+ }
+ /* Set port number. */
+ sin.sin_port = htons(6000 + display_number);
+
+ /* Create a socket. */
+ sock = socket(sin.sin_family, SOCK_STREAM, 0);
+ if (sock < 0)
+ {
+ error("socket: %.100s", strerror(errno));
+ goto fail;
+ }
+ /* Connect it to the display. */
+ if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0)
+ {
+ error("connect %.100s:%d: %.100s", buf, 6000 + display_number,
+ strerror(errno));
+ close(sock);
+ goto fail;
+ }
+
+ success:
+ /* We have successfully obtained a connection to the real X display. */
+
+ /* Allocate a channel for this connection. */
+ if (x11_saved_proto == NULL)
+ newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host);
+ else
+ newch = channel_allocate(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();
+
+ return;
+
+ fail:
+ /* Send refusal to the remote host. */
+ packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
+ packet_put_int(remote_channel);
+ packet_send();
+}
+
+/* Requests forwarding of X11 connections, generates fake authentication
+ data, and enables authentication spoofing. */
+
+void x11_request_forwarding_with_spoofing(const char *proto, const char *data)
+{
+ unsigned int data_len = (unsigned int)strlen(data) / 2;
+ unsigned int i, value;
+ char *new_data;
+ int screen_number;
+ const char *cp;
+ u_int32_t rand = 0;
+
+ cp = getenv("DISPLAY");
+ if (cp)
+ cp = strchr(cp, ':');
+ if (cp)
+ cp = strchr(cp, '.');
+ if (cp)
+ screen_number = atoi(cp + 1);
+ else
+ screen_number = 0;
+
+ /* Save protocol name. */
+ x11_saved_proto = xstrdup(proto);
+
+ /* Extract real authentication data and generate fake data of the same
+ length. */
+ x11_saved_data = xmalloc(data_len);
+ x11_fake_data = xmalloc(data_len);
+ for (i = 0; i < data_len; i++)
+ {
+ if (sscanf(data + 2 * i, "%2x", &value) != 1)
+ fatal("x11_request_forwarding: bad authentication data: %.100s", data);
+ if (i % 4 == 0)
+ rand = arc4random();
+ x11_saved_data[i] = value;
+ x11_fake_data[i] = rand & 0xff;
+ rand >>= 8;
+ }
+ x11_saved_data_len = data_len;
+ x11_fake_data_len = data_len;
+
+ /* Convert the fake data into hex. */
+ new_data = xmalloc(2 * data_len + 1);
+ for (i = 0; i < data_len; i++)
+ sprintf(new_data + 2 * i, "%02x", (unsigned char)x11_fake_data[i]);
+
+ /* Send the request packet. */
+ packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
+ packet_put_string(proto, strlen(proto));
+ packet_put_string(new_data, strlen(new_data));
+ packet_put_int(screen_number);
+ packet_send();
+ packet_write_wait();
+ xfree(new_data);
+}
+
+/* Sends a message to the server to request authentication fd forwarding. */
+
+void auth_request_forwarding()
+{
+ packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
+ packet_send();
+ packet_write_wait();
+}
+
+/* Returns the name of the forwarded authentication socket. Returns NULL
+ if there is no forwarded authentication socket. The returned value
+ points to a static buffer. */
+
+char *auth_get_socket_name()
+{
+ return channel_forwarded_auth_socket_name;
+}
+
+/* removes the agent forwarding socket */
+
+void cleanup_socket(void) {
+ remove(channel_forwarded_auth_socket_name);
+ rmdir(channel_forwarded_auth_socket_dir);
+}
+
+/* This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
+ This starts forwarding authentication requests. */
+
+void auth_input_request_forwarding(struct passwd *pw)
+{
+ int sock, newch;
+ 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);
+
+ /* Allocate a buffer for the socket name, and format the name. */
+ channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME);
+ channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME);
+ strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME);
+
+ /* Create private directory for socket */
+ if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL)
+ packet_disconnect("mkdtemp: %.100s", strerror(errno));
+ snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME,
+ "%s/agent.%d", channel_forwarded_auth_socket_dir, (int)getpid());
+
+ if (atexit(cleanup_socket) < 0) {
+ int saved=errno;
+ cleanup_socket();
+ packet_disconnect("socket: %.100s", strerror(saved));
+ }
+
+ /* Create the socket. */
+ sock = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (sock < 0)
+ packet_disconnect("socket: %.100s", strerror(errno));
+
+ /* Bind it to the name. */
+ memset(&sunaddr, 0, sizeof(sunaddr));
+ sunaddr.sun_family = AF_UNIX;
+ strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name,
+ sizeof(sunaddr.sun_path));
+
+ if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0)
+ packet_disconnect("bind: %.100s", strerror(errno));
+
+ /* Restore the privileged uid. */
+ restore_uid();
+
+ /* Start listening on the socket. */
+ if (listen(sock, 5) < 0)
+ packet_disconnect("listen: %.100s", strerror(errno));
+
+ /* Allocate a channel for the authentication agent socket. */
+ newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock,
+ xstrdup("auth socket"));
+ strcpy(channels[newch].path, channel_forwarded_auth_socket_name);
+}
+
+/* This is called to process an SSH_SMSG_AGENT_OPEN message. */
+
+void auth_input_open_request()
+{
+ int remch, sock, newch;
+ char *dummyname;
+
+ /* Read the remote channel number from the message. */
+ remch = packet_get_int();
+
+ /* Get a connection to the local authentication agent (this may again get
+ forwarded). */
+ sock = ssh_get_authentication_socket();
+
+ /* If we could not connect the agent, send an error message back to
+ the server. This should never happen unless the agent
+ dies, because authentication forwarding is only enabled if we have an
+ agent. */
+ if (sock < 0){
+ packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
+ packet_put_int(remch);
+ packet_send();
+ return;
+ }
+
+ 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();
+}