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/*
* SSH agent client code.
*/
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <fcntl.h>
#include "putty.h"
#include "misc.h"
#include "tree234.h"
#include "puttymem.h"
bool agent_exists(void)
{
const char *p = getenv("SSH_AUTH_SOCK");
if (p && *p)
return true;
return false;
}
static tree234 *agent_pending_queries;
struct agent_pending_query {
int fd;
char *retbuf;
char sizebuf[4];
int retsize, retlen;
void (*callback)(void *, void *, int);
void *callback_ctx;
};
static int agent_conncmp(void *av, void *bv)
{
agent_pending_query *a = (agent_pending_query *) av;
agent_pending_query *b = (agent_pending_query *) bv;
if (a->fd < b->fd)
return -1;
if (a->fd > b->fd)
return +1;
return 0;
}
static int agent_connfind(void *av, void *bv)
{
int afd = *(int *) av;
agent_pending_query *b = (agent_pending_query *) bv;
if (afd < b->fd)
return -1;
if (afd > b->fd)
return +1;
return 0;
}
/*
* Attempt to read from an agent socket fd. Returns false if the
* expected response is as yet incomplete; returns true if it's either
* complete (conn->retbuf non-NULL and filled with something useful)
* or has failed totally (conn->retbuf is NULL).
*/
static bool agent_try_read(agent_pending_query *conn)
{
int ret;
ret = read(conn->fd, conn->retbuf+conn->retlen,
conn->retsize-conn->retlen);
if (ret <= 0) {
if (conn->retbuf != conn->sizebuf) sfree(conn->retbuf);
conn->retbuf = NULL;
conn->retlen = 0;
return true;
}
conn->retlen += ret;
if (conn->retsize == 4 && conn->retlen == 4) {
conn->retsize = toint(GET_32BIT_MSB_FIRST(conn->retbuf) + 4);
if (conn->retsize <= 0) {
conn->retbuf = NULL;
conn->retlen = 0;
return true; /* way too large */
}
assert(conn->retbuf == conn->sizebuf);
conn->retbuf = snewn(conn->retsize, char);
memcpy(conn->retbuf, conn->sizebuf, 4);
}
if (conn->retlen < conn->retsize)
return false; /* more data to come */
return true;
}
void agent_cancel_query(agent_pending_query *conn)
{
uxsel_del(conn->fd);
close(conn->fd);
del234(agent_pending_queries, conn);
if (conn->retbuf && conn->retbuf != conn->sizebuf)
sfree(conn->retbuf);
sfree(conn);
}
static void agent_select_result(int fd, int event)
{
agent_pending_query *conn;
assert(event == SELECT_R); /* not selecting for anything but R */
conn = find234(agent_pending_queries, &fd, agent_connfind);
if (!conn) {
uxsel_del(fd);
return;
}
if (!agent_try_read(conn))
return; /* more data to come */
/*
* We have now completed the agent query. Do the callback.
*/
conn->callback(conn->callback_ctx, conn->retbuf, conn->retlen);
/* Null out conn->retbuf, since ownership of that buffer has
* passed to the callback. */
conn->retbuf = NULL;
agent_cancel_query(conn);
}
static const char *agent_socket_path(void)
{
return getenv("SSH_AUTH_SOCK");
}
Socket *agent_connect(Plug *plug)
{
const char *path = agent_socket_path();
if (!path)
return new_error_socket_fmt(plug, "SSH_AUTH_SOCK not set");
return sk_new(unix_sock_addr(path), 0, false, false, false, false, plug);
}
agent_pending_query *agent_query(
strbuf *query, void **out, int *outlen,
void (*callback)(void *, void *, int), void *callback_ctx)
{
const char *name;
int sock;
struct sockaddr_un addr;
int done;
agent_pending_query *conn;
name = agent_socket_path();
if (!name || strlen(name) >= sizeof(addr.sun_path))
goto failure;
sock = socket(PF_UNIX, SOCK_STREAM, 0);
if (sock < 0) {
perror("socket(PF_UNIX)");
exit(1);
}
cloexec(sock);
addr.sun_family = AF_UNIX;
strcpy(addr.sun_path, name);
if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
close(sock);
goto failure;
}
strbuf_finalise_agent_query(query);
for (done = 0; done < query->len ;) {
int ret = write(sock, query->s + done,
query->len - done);
if (ret <= 0) {
close(sock);
goto failure;
}
done += ret;
}
conn = snew(agent_pending_query);
conn->fd = sock;
conn->retbuf = conn->sizebuf;
conn->retsize = 4;
conn->retlen = 0;
conn->callback = callback;
conn->callback_ctx = callback_ctx;
if (!callback) {
/*
* Bodge to permit making deliberately synchronous agent
* requests. Used by Unix Pageant in command-line client mode,
* which is legit because it really is true that no other part
* of the program is trying to get anything useful done
* simultaneously. But this special case shouldn't be used in
* any more general program.
*/
no_nonblock(conn->fd);
while (!agent_try_read(conn))
/* empty loop body */;
*out = conn->retbuf;
*outlen = conn->retlen;
sfree(conn);
return NULL;
}
/*
* Otherwise do it properly: add conn to the tree of agent
* connections currently in flight, return 0 to indicate that the
* response hasn't been received yet, and call the callback when
* select_result comes back to us.
*/
if (!agent_pending_queries)
agent_pending_queries = newtree234(agent_conncmp);
add234(agent_pending_queries, conn);
uxsel_set(sock, SELECT_R, agent_select_result);
return conn;
failure:
*out = NULL;
*outlen = 0;
return NULL;
}
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