tmate/tmate-session.c

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#include <event2/dns.h>
#include <event2/util.h>
#include <event2/event.h>
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#include <netinet/in.h>
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#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "tmate.h"
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#define TMATE_DNS_RETRY_TIMEOUT 2
#define TMATE_RECONNECT_RETRY_TIMEOUT 2
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struct tmate_session tmate_session;
static void lookup_and_connect(void);
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static void on_dns_retry(__unused evutil_socket_t fd, __unused short what,
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void *arg)
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{
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struct tmate_session *session = arg;
assert(session->ev_dns_retry);
event_free(session->ev_dns_retry);
session->ev_dns_retry = NULL;
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lookup_and_connect();
}
static void dns_cb(int errcode, struct evutil_addrinfo *addr, void *ptr)
{
struct evutil_addrinfo *ai;
const char *host = ptr;
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evdns_base_free(tmate_session.ev_dnsbase, 0);
tmate_session.ev_dnsbase = NULL;
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if (errcode) {
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struct tmate_session *session = &tmate_session;
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if (session->ev_dns_retry)
return;
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struct timeval tv = { .tv_sec = TMATE_DNS_RETRY_TIMEOUT, .tv_usec = 0 };
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session->ev_dns_retry = evtimer_new(session->ev_base, on_dns_retry, session);
if (!session->ev_dns_retry)
tmate_fatal("out of memory");
evtimer_add(session->ev_dns_retry, &tv);
tmate_status_message("%s lookup failure. Retrying in %d seconds (%s)",
host, TMATE_DNS_RETRY_TIMEOUT,
evutil_gai_strerror(errcode));
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return;
}
tmate_status_message("Connecting to %s...", host);
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int i, num_clients = 0;
for (ai = addr; ai; ai = ai->ai_next)
num_clients++;
struct tmate_ssh_client *ssh_clients[num_clients];
for (ai = addr, i = 0; ai; ai = ai->ai_next, i++) {
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char buf[128];
const char *ip = NULL;
if (ai->ai_family == AF_INET) {
struct sockaddr_in *sin = (struct sockaddr_in *)ai->ai_addr;
ip = evutil_inet_ntop(AF_INET, &sin->sin_addr, buf, 128);
} else if (ai->ai_family == AF_INET6) {
struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)ai->ai_addr;
ip = evutil_inet_ntop(AF_INET6, &sin6->sin6_addr, buf, 128);
}
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ssh_clients[i] = tmate_ssh_client_alloc(&tmate_session, ip);
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}
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for (i = 0; i < num_clients; i++)
connect_ssh_client(ssh_clients[i]);
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evutil_freeaddrinfo(addr);
}
static void lookup_and_connect(void)
{
struct evutil_addrinfo hints;
const char *tmate_server_host;
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assert(!tmate_session.ev_dnsbase);
tmate_session.ev_dnsbase = evdns_base_new(tmate_session.ev_base, 1);
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if (!tmate_session.ev_dnsbase)
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tmate_fatal("Cannot initialize the DNS lookup service");
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_flags = EVUTIL_AI_ADDRCONFIG;
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hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
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tmate_server_host = options_get_string(global_options,
"tmate-server-host");
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tmate_debug("Looking up %s...", tmate_server_host);
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(void)evdns_getaddrinfo(tmate_session.ev_dnsbase, tmate_server_host, NULL,
&hints, dns_cb, (void *)tmate_server_host);
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}
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static void __tmate_session_init(struct tmate_session *session,
struct event_base *base)
{
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memset(session, 0, sizeof(*session));
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session->ev_base = base;
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/*
* Early initialization of encoder because we need to parse
* config files to get the server configs, but while we are parsing
* config files, we need to buffer bind commands and all for the
* slave.
* Decoder is setup later.
*/
tmate_encoder_init(&session->encoder, NULL, &tmate_session);
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session->min_sx = -1;
session->min_sy = -1;
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TAILQ_INIT(&session->clients);
}
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void tmate_session_init(struct event_base *base)
{
__tmate_session_init(&tmate_session, base);
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tmate_write_header();
}
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static void send_authorized_keys(void)
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{
char *path;
path = options_get_string(global_options, "tmate-authorized-keys");
if (strlen(path) == 0)
return;
path = xstrdup(path);
tmate_info("Using %s for access control", path);
FILE *f;
char *line;
size_t len;
if (path[0] == '~' && path[1] == '/') {
const char *home = find_home();
if (home) {
char *new_path;
xasprintf(&new_path, "%s%s", home, &path[1]);
free(path);
path = new_path;
}
}
if ((f = fopen(path, "r")) == NULL) {
cfg_add_cause("%s: %s", path, strerror(errno));
free(path);
return;
}
while ((line = fparseln(f, &len, NULL, NULL, 0)) != NULL) {
if (len == 0)
continue;
tmate_set_val("authorized_keys", line);
free(line);
}
if (ferror(f))
cfg_add_cause("%s: %s", path, strerror(errno));
fclose(f);
free(path);
}
void tmate_session_start(void)
{
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/*
* We split init and start because:
* - We need to process the tmux config file during the connection as
* we are setting up the tmate identity.
* - While we are parsing the config file, we need to be able to
* serialize it, and so we need a worker encoder.
*/
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if (tmate_foreground) {
tmate_set_val("foreground", "true");
tmate_info("To connect to the session locally, run: tmate -S %s attach", socket_path);
} else {
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cfg_add_cause("%s", "To see these messages again, run: tmate show-messages");
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cfg_add_cause("%s", "Press <Enter> to dismiss");
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cfg_add_cause("%s", "-----------------------------------------------------");
}
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send_authorized_keys();
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tmate_write_uname();
tmate_write_ready();
lookup_and_connect();
}
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static void on_reconnect_retry(__unused evutil_socket_t fd, __unused short what, void *arg)
{
struct tmate_session *session = arg;
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assert(session->ev_connection_retry);
event_free(session->ev_connection_retry);
session->ev_connection_retry = NULL;
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if (session->last_server_ip) {
/*
* We have a previous server ip. Let's try that again first,
* but then connect to any server if it fails again.
*/
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struct tmate_ssh_client *c = tmate_ssh_client_alloc(session,
session->last_server_ip);
connect_ssh_client(c);
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free(session->last_server_ip);
session->last_server_ip = NULL;
} else {
lookup_and_connect();
}
}
void tmate_reconnect_session(struct tmate_session *session, const char *message)
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{
/*
* We no longer have an SSH connection. Time to reconnect.
* We'll reuse some of the session information if we can,
* and we'll try to reconnect to the same server if possible,
* to avoid an SSH connection string change.
*/
struct timeval tv = { .tv_sec = TMATE_RECONNECT_RETRY_TIMEOUT, .tv_usec = 0 };
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if (session->ev_connection_retry)
return;
session->ev_connection_retry = evtimer_new(session->ev_base, on_reconnect_retry, session);
if (!session->ev_connection_retry)
tmate_fatal("out of memory");
evtimer_add(session->ev_connection_retry, &tv);
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if (message && !tmate_foreground)
tmate_status_message("Reconnecting... (%s)", message);
else
tmate_status_message("Reconnecting...");
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/*
* This says that we'll need to send a snapshot of the current state.
*/
session->reconnected = true;
}