/* Bind to "::" to get a port number not used by any address. */
static grpc_error *get_unused_port(int *port) {
grpc_resolved_address wild;
grpc_sockaddr_make_wildcard6(0, &wild);
grpc_dualstack_mode dsmode;
int fd;
grpc_error *err =
grpc_create_dualstack_socket(&wild, SOCK_STREAM, 0, &dsmode, &fd);
if (err != GRPC_ERROR_NONE) {
return err;
}
if (dsmode == GRPC_DSMODE_IPV4) {
grpc_sockaddr_make_wildcard4(0, &wild);
}
if (bind(fd, (const struct sockaddr *)wild.addr, (socklen_t)wild.len) != 0) {
err = GRPC_OS_ERROR(errno, "bind");
close(fd);
return err;
}
if (getsockname(fd, (struct sockaddr *)wild.addr, (socklen_t *)&wild.len) !=
0) {
err = GRPC_OS_ERROR(errno, "getsockname");
close(fd);
return err;
}
close(fd);
*port = grpc_sockaddr_get_port(&wild);
return *port <= 0 ? GRPC_ERROR_CREATE_FROM_STATIC_STRING("Bad port")
: GRPC_ERROR_NONE;
}
void grpc_sockaddr_make_wildcards(int port, struct sockaddr_in *wild4_out,
struct sockaddr_in6 *wild6_out) {
grpc_sockaddr_make_wildcard4(port, wild4_out);
grpc_sockaddr_make_wildcard6(port, wild6_out);
}
static bool is_port_available(int *port, bool is_tcp) {
GPR_ASSERT(*port >= 0);
GPR_ASSERT(*port <= 65535);
/* For a port to be considered available, the kernel must support
at least one of (IPv6, IPv4), and the port must be available
on each supported family. */
bool got_socket = false;
for (int is_ipv6 = 1; is_ipv6 >= 0; is_ipv6--) {
const int fd =
socket(is_ipv6 ? AF_INET6 : AF_INET, is_tcp ? SOCK_STREAM : SOCK_DGRAM,
is_tcp ? IPPROTO_TCP : 0);
if (fd >= 0) {
got_socket = true;
} else {
continue;
}
/* Reuseaddr lets us start up a server immediately after it exits */
const int one = 1;
if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) < 0) {
gpr_log(GPR_ERROR, "setsockopt() failed: %s", strerror(errno));
close(fd);
return false;
}
/* Try binding to port */
grpc_resolved_address addr;
if (is_ipv6) {
grpc_sockaddr_make_wildcard6(*port, &addr); /* [::]:port */
} else {
grpc_sockaddr_make_wildcard4(*port, &addr); /* 0.0.0.0:port */
}
if (bind(fd, (struct sockaddr *)addr.addr, (socklen_t)addr.len) < 0) {
gpr_log(GPR_DEBUG, "bind(port=%d) failed: %s", *port, strerror(errno));
close(fd);
return false;
}
/* Get the bound port number */
if (getsockname(fd, (struct sockaddr *)addr.addr, (socklen_t *)&addr.len) <
0) {
gpr_log(GPR_ERROR, "getsockname() failed: %s", strerror(errno));
close(fd);
return false;
}
GPR_ASSERT(addr.len <= sizeof(addr.addr));
const int actual_port = grpc_sockaddr_get_port(&addr);
GPR_ASSERT(actual_port > 0);
if (*port == 0) {
*port = actual_port;
} else {
GPR_ASSERT(*port == actual_port);
}
close(fd);
}
if (!got_socket) {
gpr_log(GPR_ERROR, "socket() failed: %s", strerror(errno));
return false;
}
return true;
}
