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#include "util.h"
 31
 32static int control_fd = -1;
 33
 34/* Open the control socket, either in server or client mode */
 35void control_init(const char *control_host,
 36		  const char *control_port,
 37		  bool server)
 38{
 39	struct addrinfo hints = {
 40		.ai_socktype = SOCK_STREAM,
 41	};
 42	struct addrinfo *result = NULL;
 43	struct addrinfo *ai;
 44	int ret;
 45
 46	ret = getaddrinfo(control_host, control_port, &hints, &result);
 47	if (ret != 0) {
 48		fprintf(stderr, "%s\n", gai_strerror(ret));
 49		exit(EXIT_FAILURE);
 50	}
 51
 52	for (ai = result; ai; ai = ai->ai_next) {
 53		int fd;
 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		setsockopt_int_check(fd, SOL_SOCKET, SO_REUSEADDR, 1,
 69				     "setsockopt SO_REUSEADDR");
 70
 71		if (bind(fd, ai->ai_addr, ai->ai_addrlen) < 0)
 72			goto next;
 73		if (listen(fd, 1) < 0)
 74			goto next;
 75
 76		printf("Control socket listening on %s:%s\n",
 77		       control_host, control_port);
 78		fflush(stdout);
 79
 80		control_fd = accept(fd, NULL, 0);
 81		close(fd);
 82
 83		if (control_fd < 0) {
 84			perror("accept");
 85			exit(EXIT_FAILURE);
 86		}
 87		printf("Control socket connection accepted...\n");
 88		break;
 89
 90next:
 91		close(fd);
 92	}
 93
 94	if (control_fd < 0) {
 95		fprintf(stderr, "Control socket initialization failed.  Invalid address %s:%s?\n",
 96			control_host, control_port);
 97		exit(EXIT_FAILURE);
 98	}
 99
100	freeaddrinfo(result);
101}
102
103/* Free resources */
104void control_cleanup(void)
105{
106	close(control_fd);
107	control_fd = -1;
108}
109
110/* Write a line to the control socket */
111void control_writeln(const char *str)
112{
113	ssize_t len = strlen(str);
114	ssize_t ret;
115
116	timeout_begin(TIMEOUT);
117
118	do {
119		ret = send(control_fd, str, len, MSG_MORE);
120		timeout_check("send");
121	} while (ret < 0 && errno == EINTR);
122
123	if (ret != len) {
124		perror("send");
125		exit(EXIT_FAILURE);
126	}
127
128	do {
129		ret = send(control_fd, "\n", 1, 0);
130		timeout_check("send");
131	} while (ret < 0 && errno == EINTR);
132
133	if (ret != 1) {
134		perror("send");
135		exit(EXIT_FAILURE);
136	}
137
138	timeout_end();
139}
140
141void control_writeulong(unsigned long value)
142{
143	char str[32];
144
145	if (snprintf(str, sizeof(str), "%lu", value) >= sizeof(str)) {
146		perror("snprintf");
147		exit(EXIT_FAILURE);
148	}
149
150	control_writeln(str);
151}
152
153unsigned long control_readulong(void)
154{
155	unsigned long value;
156	char *str;
157
158	str = control_readln();
159
160	if (!str)
161		exit(EXIT_FAILURE);
162
163	value = strtoul(str, NULL, 10);
164	free(str);
165
166	return value;
167}
168
169/* Return the next line from the control socket (without the trailing newline).
170 *
171 * The program terminates if a timeout occurs.
172 *
173 * The caller must free() the returned string.
174 */
175char *control_readln(void)
176{
177	char *buf = NULL;
178	size_t idx = 0;
179	size_t buflen = 0;
180
181	timeout_begin(TIMEOUT);
182
183	for (;;) {
184		ssize_t ret;
185
186		if (idx >= buflen) {
187			char *new_buf;
188
189			new_buf = realloc(buf, buflen + 80);
190			if (!new_buf) {
191				perror("realloc");
192				exit(EXIT_FAILURE);
193			}
194
195			buf = new_buf;
196			buflen += 80;
197		}
198
199		do {
200			ret = recv(control_fd, &buf[idx], 1, 0);
201			timeout_check("recv");
202		} while (ret < 0 && errno == EINTR);
203
204		if (ret == 0) {
205			fprintf(stderr, "unexpected EOF on control socket\n");
206			exit(EXIT_FAILURE);
207		}
208
209		if (ret != 1) {
210			perror("recv");
211			exit(EXIT_FAILURE);
212		}
213
214		if (buf[idx] == '\n') {
215			buf[idx] = '\0';
216			break;
217		}
218
219		idx++;
220	}
221
222	timeout_end();
223
224	return buf;
225}
226
227/* Wait until a given line is received or a timeout occurs */
228void control_expectln(const char *str)
229{
230	char *line;
231
232	line = control_readln();
233
234	control_cmpln(line, str, true);
235
236	free(line);
237}
238
239bool control_cmpln(char *line, const char *str, bool fail)
240{
241	if (strcmp(str, line) == 0)
242		return true;
243
244	if (fail) {
245		fprintf(stderr, "expected \"%s\" on control socket, got \"%s\"\n",
246			str, line);
247		exit(EXIT_FAILURE);
248	}
249
250	return false;
251}