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/* Control socket for client/server test execution
*
* Copyright (C) 2017 Red Hat, Inc.
*
* Author: Stefan Hajnoczi <stefanha@redhat.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2
* of the License.
*/
/* The client and server may need to coordinate to avoid race conditions like
* the client attempting to connect to a socket that the server is not
* listening on yet. The control socket offers a communications channel for
* such coordination tasks.
*
* If the client calls control_expectln("LISTENING"), then it will block until
* the server calls control_writeln("LISTENING"). This provides a simple
* mechanism for coordinating between the client and the server.
*/
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include "timeout.h"
#include "control.h"
static int control_fd = -1;
/* Open the control socket, either in server or client mode */
void control_init(const char *control_host,
const char *control_port,
bool server)
{
struct addrinfo hints = {
.ai_socktype = SOCK_STREAM,
};
struct addrinfo *result = NULL;
struct addrinfo *ai;
int ret;
ret = getaddrinfo(control_host, control_port, &hints, &result);
if (ret != 0) {
fprintf(stderr, "%s\n", gai_strerror(ret));
exit(EXIT_FAILURE);
}
for (ai = result; ai; ai = ai->ai_next) {
int fd;
int val = 1;
fd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (fd < 0)
continue;
if (!server) {
if (connect(fd, ai->ai_addr, ai->ai_addrlen) < 0)
goto next;
control_fd = fd;
printf("Control socket connected to %s:%s.\n",
control_host, control_port);
break;
}
if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
&val, sizeof(val)) < 0) {
perror("setsockopt");
exit(EXIT_FAILURE);
}
if (bind(fd, ai->ai_addr, ai->ai_addrlen) < 0)
goto next;
if (listen(fd, 1) < 0)
goto next;
printf("Control socket listening on %s:%s\n",
control_host, control_port);
fflush(stdout);
control_fd = accept(fd, NULL, 0);
close(fd);
if (control_fd < 0) {
perror("accept");
exit(EXIT_FAILURE);
}
printf("Control socket connection accepted...\n");
break;
next:
close(fd);
}
if (control_fd < 0) {
fprintf(stderr, "Control socket initialization failed. Invalid address %s:%s?\n",
control_host, control_port);
exit(EXIT_FAILURE);
}
freeaddrinfo(result);
}
/* Free resources */
void control_cleanup(void)
{
close(control_fd);
control_fd = -1;
}
/* Write a line to the control socket */
void control_writeln(const char *str)
{
ssize_t len = strlen(str);
ssize_t ret;
timeout_begin(TIMEOUT);
do {
ret = send(control_fd, str, len, MSG_MORE);
timeout_check("send");
} while (ret < 0 && errno == EINTR);
if (ret != len) {
perror("send");
exit(EXIT_FAILURE);
}
do {
ret = send(control_fd, "\n", 1, 0);
timeout_check("send");
} while (ret < 0 && errno == EINTR);
if (ret != 1) {
perror("send");
exit(EXIT_FAILURE);
}
timeout_end();
}
/* Return the next line from the control socket (without the trailing newline).
*
* The program terminates if a timeout occurs.
*
* The caller must free() the returned string.
*/
char *control_readln(void)
{
char *buf = NULL;
size_t idx = 0;
size_t buflen = 0;
timeout_begin(TIMEOUT);
for (;;) {
ssize_t ret;
if (idx >= buflen) {
char *new_buf;
new_buf = realloc(buf, buflen + 80);
if (!new_buf) {
perror("realloc");
exit(EXIT_FAILURE);
}
buf = new_buf;
buflen += 80;
}
do {
ret = recv(control_fd, &buf[idx], 1, 0);
timeout_check("recv");
} while (ret < 0 && errno == EINTR);
if (ret == 0) {
fprintf(stderr, "unexpected EOF on control socket\n");
exit(EXIT_FAILURE);
}
if (ret != 1) {
perror("recv");
exit(EXIT_FAILURE);
}
if (buf[idx] == '\n') {
buf[idx] = '\0';
break;
}
idx++;
}
timeout_end();
return buf;
}
/* Wait until a given line is received or a timeout occurs */
void control_expectln(const char *str)
{
char *line;
line = control_readln();
if (strcmp(str, line) != 0) {
fprintf(stderr, "expected \"%s\" on control socket, got \"%s\"\n",
str, line);
exit(EXIT_FAILURE);
}
free(line);
}
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