From dc6f59b5185ade4e36d95a46380ca40a67161a55 Mon Sep 17 00:00:00 2001
From: Patrick McDermott <patrick.mcdermott@libiquity.com>
Date: Mon, 29 Jul 2019 16:11:35 -0400
Subject: s_client: Poll, read, and write FDs

---
diff --git a/src/s_client.c b/src/s_client.c
index 99fba35..863dd12 100644
--- a/src/s_client.c
+++ b/src/s_client.c
@@ -19,12 +19,15 @@
  * along with wolfssl-util.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <errno.h>
 #include <netdb.h>
+#include <poll.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <sys/socket.h>
+#include <unistd.h>
 
 #include <wolfssl/ssl.h>
 #include <wolfssl/wolfcrypt/settings.h>
@@ -33,6 +36,10 @@
 
 #define CA_CERTS "/etc/ssl/certs"
 
+#define ARRAY_SIZE(a)  (sizeof(a) / sizeof((a)[0]))
+#define MAX(a, b)      (((a) > (b)) ? (a) : (b))
+#define MIN(a, b)      (((a) < (b)) ? (a) : (b))
+
 static _Bool
 parse_host_port(char *hostport, char **host, char **port)
 {
@@ -92,6 +99,83 @@ connect_socket(const char *host, const char *port)
 	return sfd;
 }
 
+static _Bool
+write_all(int fd, const void *buf, size_t count)
+{
+	ssize_t ret;
+
+	while (count > 0) {
+		while ((ret = write(fd, buf, count)) < 0 && errno == EINTR) {
+			continue;
+		}
+		if (ret < 0) {
+			return false;
+		}
+		buf = ((const char *) buf) + ret;
+		count -= ret;
+	}
+
+	return true;
+}
+
+static _Bool
+poll_fds(int sfd, WOLFSSL *ssl)
+{
+	struct pollfd fds[2] = {
+		{ .fd = -1, .events = POLLIN|POLLERR, .revents = 0 },
+		{ .fd = -1, .events = POLLIN|POLLERR, .revents = 0 },
+	};
+	char          buf[MAX(8192, WOLFSSL_MAX_ERROR_SZ)];
+	ssize_t       len;
+	int           ret;
+
+	fds[0].fd = STDIN_FILENO;
+	fds[1].fd = sfd;
+
+	for (;;) {
+		while (poll(fds, ARRAY_SIZE(fds), -1) < 0 && (errno == EINTR ||
+					errno == EAGAIN)) {
+			continue;
+		}
+		if (fds[0].revents > 0) {  /* stdin */
+			len = read(STDIN_FILENO, buf, sizeof(buf));
+			if (len < 0) {
+				fputs("Input read error\n", stderr);
+				return false;
+			} else if (len == 0) {
+				fds[0].fd = -1;  /* Stop polling. */
+			} else if ((ret = wolfSSL_write(ssl, buf, len)) <= 0) {
+				wolfSSL_ERR_error_string(wolfSSL_get_error(ssl,
+							ret), buf);
+				fprintf(stderr, "Socket write error: %s\n",
+						buf);
+				return false;
+			}
+		}
+		if (fds[1].revents > 0) {  /* socket */
+			ret = wolfSSL_read(ssl, buf, MIN(sizeof(buf), 1024));
+			if (ret < 0) {
+				wolfSSL_ERR_error_string(wolfSSL_get_error(ssl,
+							ret), buf);
+				fprintf(stderr, "Socket read error: %s\n",
+						buf);
+				return false;
+			} else if (ret == 0) {
+				fds[1].fd = -1;  /* Stop polling. */
+				close(STDOUT_FILENO);  /* Signal socket EOF. */
+			} else if (write_all(STDOUT_FILENO, buf, (size_t) ret)
+					== false) {
+				return false;
+			}
+		}
+		if (fds[0].fd == fds[1].fd) {  /* Both -1 (no longer polled) */
+			return true;
+		}
+	}
+
+	/* Unreached */
+}
+
 int
 s_client(int argc, char **argv)
 {
@@ -177,6 +261,10 @@ s_client(int argc, char **argv)
 		goto ssl_free;
 	}
 
+	if (poll_fds(sfd, ssl) == false) {
+		ret = EXIT_FAILURE;
+	}
+
 	close(sfd);
 
 ssl_free:
--
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