1// SPDX-License-Identifier: GPL-2.0-only
  2/* Control socket for client/server test execution
  3 *
  4 * Copyright (C) 2017 Red Hat, Inc.
  5 *
  6 * Author: Stefan Hajnoczi <stefanha@redhat.com>
  7 */
  8
  9/* The client and server may need to coordinate to avoid race conditions like
 10 * the client attempting to connect to a socket that the server is not
 11 * listening on yet.  The control socket offers a communications channel for
 12 * such coordination tasks.
 13 *
 14 * If the client calls control_expectln("LISTENING"), then it will block until
 15 * the server calls control_writeln("LISTENING").  This provides a simple
 16 * mechanism for coordinating between the client and the server.
 17 */
 18
 19#include <errno.h>
 20#include <netdb.h>
 21#include <stdio.h>
 22#include <stdlib.h>
 23#include <string.h>
 24#include <unistd.h>
 25#include <sys/types.h>
 26#include <sys/socket.h>
 27
 28#include "timeout.h"
 29#include "control.h"
 30
 31static int control_fd = -1;
 32
 33/* Open the control socket, either in server or client mode */
 34void control_init(const char *control_host,
 35		  const char *control_port,
 36		  bool server)
 37{
 38	struct addrinfo hints = {
 39		.ai_socktype = SOCK_STREAM,
 40	};
 41	struct addrinfo *result = NULL;
 42	struct addrinfo *ai;
 43	int ret;
 44
 45	ret = getaddrinfo(control_host, control_port, &hints, &result);
 46	if (ret != 0) {
 47		fprintf(stderr, "%s\n", gai_strerror(ret));
 48		exit(EXIT_FAILURE);
 49	}
 50
 51	for (ai = result; ai; ai = ai->ai_next) {
 52		int fd;
 53		int val = 1;
 54
 55		fd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 56		if (fd < 0)
 57			continue;
 58
 59		if (!server) {
 60			if (connect(fd, ai->ai_addr, ai->ai_addrlen) < 0)
 61				goto next;
 62			control_fd = fd;
 63			printf("Control socket connected to %s:%s.\n",
 64			       control_host, control_port);
 65			break;
 66		}
 67
 68		if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
 69			       &val, sizeof(val)) < 0) {
 70			perror("setsockopt");
 71			exit(EXIT_FAILURE);
 72		}
 73
 74		if (bind(fd, ai->ai_addr, ai->ai_addrlen) < 0)
 75			goto next;
 76		if (listen(fd, 1) < 0)
 77			goto next;
 78
 79		printf("Control socket listening on %s:%s\n",
 80		       control_host, control_port);
 81		fflush(stdout);
 82
 83		control_fd = accept(fd, NULL, 0);
 84		close(fd);
 85
 86		if (control_fd < 0) {
 87			perror("accept");
 88			exit(EXIT_FAILURE);
 89		}
 90		printf("Control socket connection accepted...\n");
 91		break;
 92
 93next:
 94		close(fd);
 95	}
 96
 97	if (control_fd < 0) {
 98		fprintf(stderr, "Control socket initialization failed.  Invalid address %s:%s?\n",
 99			control_host, control_port);
100		exit(EXIT_FAILURE);
101	}
102
103	freeaddrinfo(result);
104}
105
106/* Free resources */
107void control_cleanup(void)
108{
109	close(control_fd);
110	control_fd = -1;
111}
112
113/* Write a line to the control socket */
114void control_writeln(const char *str)
115{
116	ssize_t len = strlen(str);
117	ssize_t ret;
118
119	timeout_begin(TIMEOUT);
120
121	do {
122		ret = send(control_fd, str, len, MSG_MORE);
123		timeout_check("send");
124	} while (ret < 0 && errno == EINTR);
125
126	if (ret != len) {
127		perror("send");
128		exit(EXIT_FAILURE);
129	}
130
131	do {
132		ret = send(control_fd, "\n", 1, 0);
133		timeout_check("send");
134	} while (ret < 0 && errno == EINTR);
135
136	if (ret != 1) {
137		perror("send");
138		exit(EXIT_FAILURE);
139	}
140
141	timeout_end();
142}
143
144/* Return the next line from the control socket (without the trailing newline).
145 *
146 * The program terminates if a timeout occurs.
147 *
148 * The caller must free() the returned string.
149 */
150char *control_readln(void)
151{
152	char *buf = NULL;
153	size_t idx = 0;
154	size_t buflen = 0;
155
156	timeout_begin(TIMEOUT);
157
158	for (;;) {
159		ssize_t ret;
160
161		if (idx >= buflen) {
162			char *new_buf;
163
164			new_buf = realloc(buf, buflen + 80);
165			if (!new_buf) {
166				perror("realloc");
167				exit(EXIT_FAILURE);
168			}
169
170			buf = new_buf;
171			buflen += 80;
172		}
173
174		do {
175			ret = recv(control_fd, &buf[idx], 1, 0);
176			timeout_check("recv");
177		} while (ret < 0 && errno == EINTR);
178
179		if (ret == 0) {
180			fprintf(stderr, "unexpected EOF on control socket\n");
181			exit(EXIT_FAILURE);
182		}
183
184		if (ret != 1) {
185			perror("recv");
186			exit(EXIT_FAILURE);
187		}
188
189		if (buf[idx] == '\n') {
190			buf[idx] = '\0';
191			break;
192		}
193
194		idx++;
195	}
196
197	timeout_end();
198
199	return buf;
200}
201
202/* Wait until a given line is received or a timeout occurs */
203void control_expectln(const char *str)
204{
205	char *line;
206
207	line = control_readln();
208
209	control_cmpln(line, str, true);
210
211	free(line);
212}
213
214bool control_cmpln(char *line, const char *str, bool fail)
215{
216	if (strcmp(str, line) == 0)
217		return true;
218
219	if (fail) {
220		fprintf(stderr, "expected \"%s\" on control socket, got \"%s\"\n",
221			str, line);
222		exit(EXIT_FAILURE);
223	}
224
225	return false;
226}