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/* SPDX-License-Identifier: GPL-2.0 */
/** \file audioc_common.c Code shared between para_gui and para_audioc.
*
* There is only one public function here: \ref connect_audiod().
*/
#include "para.h"
#include <netinet/in.h>
#include <sys/socket.h>
#include <netdb.h>
#include "audioc.h"
#include "string.h"
#include "fd.h"
#include "error.h"
#include "net.h"
/*
* Prepend \0, and cocatenate all arguments using \0 as the separater.
*/
static size_t concat_args(unsigned num_inputs, char * const *argv,
char **result)
{
size_t len = 0;
char *p;
assert(num_inputs > 0);
for (unsigned n = 0; n < num_inputs; n++)
len += strlen(argv[n]) + 1;
p = *result = alloc(len + 1);
p[0] = '\0';
p++;
for (unsigned n = 0; n < num_inputs; n++)
p += sprintf(p, "%s", argv[n]) + 1;
assert(p == *result + len + 1);
return len + 1;
}
#ifdef HAVE_UCRED
/*
* Send a buffer and the credentials of the current process to a socket. On
* success, this call returns the number of bytes sent.
*/
static ssize_t send_cred_buffer(int sock, struct iovec *iov)
{
char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
struct msghdr msg;
struct cmsghdr *cmsg;
struct ucred c;
int ret;
/* Response data */
c.pid = getpid();
c.uid = getuid();
c.gid = getgid();
/* compose the message */
memset(&msg, 0, sizeof(msg));
msg.msg_iov = iov;
msg.msg_iovlen = 1;
msg.msg_control = control;
msg.msg_controllen = sizeof(control);
/* attach the ucred struct */
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_CREDENTIALS;
cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
*(struct ucred *)CMSG_DATA(cmsg) = c;
msg.msg_controllen = cmsg->cmsg_len;
ret = sendmsg(sock, &msg, 0);
if (ret < 0)
return -ERRNO_TO_PARA_ERROR(errno);
return ret;
}
#else /* no ucred */
static ssize_t send_cred_buffer(int fd, struct iovec *iov)
{
return xwrite(fd, iov->iov_base, iov->iov_len);
}
#endif /* HAVE_UCRED */
/**
* Establish a connection to the local socket and send a command.
*
* \param sname The path to the local socket. NULL for default.
* \param num_inputs Number of arguments, including subcommand and options.
* \param argv Argument vector, does not need to be NULL terminated.
*
* \return The file descriptor on success, negative error code otherwise.
*/
int connect_audiod(const char *sname, unsigned num_inputs, char **argv)
{
int fd = -1, ret;
char *args;
struct iovec iov;
iov.iov_len = concat_args(num_inputs, argv, &args);
assert(args);
iov.iov_base = args;
if (!sname) {
char *tmp = make_message("/var/paraslash/audiod_socket.%s",
para_hostname());
ret = connect_local_socket(tmp);
free(tmp);
} else
ret = connect_local_socket(sname);
if (ret < 0)
goto free_args;
fd = ret;
ret = send_cred_buffer(fd, &iov);
if (ret < 0)
close(fd);
else
ret = fd;
free_args:
free(args);
if (ret < 0)
PARA_NOTICE_LOG("failed to connect to para_audiod\n");
return ret;
}
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