Magisk/native/jni/core/socket.cpp

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#include <fcntl.h>
#include <endian.h>
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#include <socket.hpp>
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#include <utils.hpp>
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using namespace std;
static size_t socket_len(sockaddr_un *sun) {
if (sun->sun_path[0])
return sizeof(sa_family_t) + strlen(sun->sun_path) + 1;
else
return sizeof(sa_family_t) + strlen(sun->sun_path + 1) + 1;
}
socklen_t setup_sockaddr(sockaddr_un *sun, const char *name) {
memset(sun, 0, sizeof(*sun));
sun->sun_family = AF_UNIX;
strcpy(sun->sun_path + 1, name);
return socket_len(sun);
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}
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int socket_accept(int sockfd, int timeout) {
struct pollfd pfd = {
.fd = sockfd,
.events = POLL_IN
};
return xpoll(&pfd, 1, timeout * 1000) <= 0 ? -1 : xaccept4(sockfd, nullptr, nullptr, SOCK_CLOEXEC);
}
void get_client_cred(int fd, struct ucred *cred) {
socklen_t ucred_length = sizeof(*cred);
getsockopt(fd, SOL_SOCKET, SO_PEERCRED, cred, &ucred_length);
}
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/*
* Receive a file descriptor from a Unix socket.
* Contributed by @mkasick
*
* Returns the file descriptor on success, or -1 if a file
* descriptor was not actually included in the message
*
* On error the function terminates by calling exit(-1)
*/
int recv_fd(int sockfd) {
// Need to receive data from the message, otherwise don't care about it.
char iovbuf;
struct cmsghdr *cmsg;
struct iovec iov = {
.iov_base = &iovbuf,
.iov_len = 1,
};
char cmsgbuf[CMSG_SPACE(sizeof(int))];
struct msghdr msg = {
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = cmsgbuf,
.msg_controllen = sizeof(cmsgbuf),
};
xrecvmsg(sockfd, &msg, MSG_WAITALL);
// Was a control message actually sent?
switch (msg.msg_controllen) {
case 0:
// No, so the file descriptor was closed and won't be used.
return -1;
case sizeof(cmsgbuf):
// Yes, grab the file descriptor from it.
break;
default:
goto error;
}
cmsg = CMSG_FIRSTHDR(&msg);
if (cmsg == nullptr ||
cmsg->cmsg_len != CMSG_LEN(sizeof(int)) ||
cmsg->cmsg_level != SOL_SOCKET ||
cmsg->cmsg_type != SCM_RIGHTS) {
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error:
LOGE("unable to read fd\n");
exit(-1);
}
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return *(int *)CMSG_DATA(cmsg);
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}
/*
* Send a file descriptor through a Unix socket.
* Contributed by @mkasick
*
* On error the function terminates by calling exit(-1)
*
* fd may be -1, in which case the dummy data is sent,
* but no control message with the FD is sent.
*/
void send_fd(int sockfd, int fd) {
// Need to send some data in the message, this will do.
char junk[] = { '\0' };
struct iovec iov = {
.iov_base = junk,
.iov_len = 1,
};
struct msghdr msg = {
.msg_iov = &iov,
.msg_iovlen = 1,
};
char cmsgbuf[CMSG_SPACE(sizeof(int))];
if (fd != -1) {
// Is the file descriptor actually open?
if (fcntl(fd, F_GETFD) == -1) {
if (errno != EBADF) {
PLOGE("unable to send fd");
}
// It's closed, don't send a control message or sendmsg will EBADF.
} else {
// It's open, send the file descriptor in a control message.
msg.msg_control = cmsgbuf;
msg.msg_controllen = sizeof(cmsgbuf);
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
*(int *)CMSG_DATA(cmsg) = fd;
}
}
xsendmsg(sockfd, &msg, 0);
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}
int read_int(int fd) {
int val;
if (xxread(fd, &val, sizeof(val)) != sizeof(val))
return -1;
return val;
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}
int read_int_be(int fd) {
uint32_t val;
if (xxread(fd, &val, sizeof(val)) != sizeof(val))
return -1;
return ntohl(val);
}
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void write_int(int fd, int val) {
if (fd < 0) return;
xwrite(fd, &val, sizeof(val));
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}
void write_int_be(int fd, int val) {
uint32_t nl = htonl(val);
xwrite(fd, &nl, sizeof(nl));
}
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void read_string(int fd, std::string &str) {
int len = read_int(fd);
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str.clear();
str.resize(len);
xxread(fd, str.data(), len);
}
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string read_string(int fd) {
string str;
read_string(fd, str);
return str;
}
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void write_string(int fd, string_view str) {
if (fd < 0) return;
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write_int(fd, str.size());
xwrite(fd, str.data(), str.size());
}