From fa901c543599dab1c3105fb41ade2b7da98ff261 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Tue, 10 Jan 2017 04:50:42 +0100
Subject: tools: ipc: read from socket incrementally

---
 src/tools/ipc.c | 90 ++++++++++++++++++++++++++++++---------------------------
 1 file changed, 48 insertions(+), 42 deletions(-)

(limited to 'src/tools/ipc.c')

diff --git a/src/tools/ipc.c b/src/tools/ipc.c
index 6237961..05609b4 100644
--- a/src/tools/ipc.c
+++ b/src/tools/ipc.c
@@ -18,7 +18,6 @@
 #include <unistd.h>
 #include <time.h>
 #include <dirent.h>
-#include <poll.h>
 #include <signal.h>
 #include <sys/socket.h>
 #include <sys/types.h>
@@ -41,7 +40,7 @@ struct inflatable_buffer {
 	size_t pos;
 };
 
-#define max(a, b) (a > b ? a : b)
+#define max(a, b) ((a) > (b) ? (a) : (b))
 
 static int add_next_to_inflatable_buffer(struct inflatable_buffer *buffer)
 {
@@ -190,68 +189,75 @@ out:
 	return (int)ret;
 }
 
+#define READ_BYTES(bytes) ({ \
+	void *__p; \
+	size_t __bytes = (bytes); \
+	if (bytes_left < __bytes) { \
+		offset = p - buffer; \
+		bytes_left += buffer_size; \
+		buffer_size *= 2; \
+		ret = -ENOMEM; \
+		p = realloc(buffer, buffer_size); \
+		if (!p) \
+			goto out; \
+		buffer = p; \
+		p += offset; \
+	} \
+	bytes_left -= __bytes; \
+	ret = read(fd, p, __bytes); \
+	if (ret < 0) \
+		goto out; \
+	if ((size_t)ret != __bytes) { \
+		ret = -EBADMSG; \
+		goto out; \
+	} \
+	__p = p; \
+	p += __bytes; \
+	__p; \
+})
 static int userspace_get_device(struct wgdevice **dev, const char *interface)
 {
-	struct pollfd pollfd = { .events = POLLIN };
-	int len;
-	char byte = 0;
-	size_t i;
-	struct wgpeer *peer;
+	unsigned int len = 0, i;
+	size_t buffer_size, bytes_left;
 	ssize_t ret;
+	ptrdiff_t offset;
+	uint8_t *buffer = NULL, *p, byte = 0;
+
 	int fd = userspace_interface_fd(interface);
 	if (fd < 0)
 		return fd;
-	*dev = NULL;
+
 	ret = write(fd, &byte, sizeof(byte));
 	if (ret < 0)
 		goto out;
-
-	pollfd.fd = fd;
-	if (poll(&pollfd, 1, -1) < 0)
-		goto out;
-	ret = -ECONNABORTED;
-	if (!(pollfd.revents & POLLIN))
-		goto out;
-
-	ret = ioctl(fd, FIONREAD, &len);
-	if (ret < 0) {
-		ret = -errno;
+	if (ret != sizeof(byte)) {
+		ret = -EBADMSG;
 		goto out;
 	}
-	ret = -EBADMSG;
-	if ((size_t)len < sizeof(struct wgdevice))
-		goto out;
 
+	ioctl(fd, FIONREAD, &len);
+	bytes_left = buffer_size = max(len, sizeof(struct wgdevice) + sizeof(struct wgpeer) + sizeof(struct wgipmask));
+	p = buffer = malloc(buffer_size);
 	ret = -ENOMEM;
-	*dev = malloc(len);
-	if (!*dev)
+	if (!buffer)
 		goto out;
 
-	ret = read(fd, *dev, len);
-	if (ret < 0)
-		goto out;
-	if (ret != len) {
-		ret = -EBADMSG;
-		goto out;
-	}
-
-	ret = -EBADMSG;
-	for_each_wgpeer(*dev, peer, i) {
-		if ((uint8_t *)peer + sizeof(struct wgpeer) > (uint8_t *)*dev + len)
-			goto out;
-		if ((uint8_t *)peer + sizeof(struct wgpeer) + sizeof(struct wgipmask) * peer->num_ipmasks > (uint8_t *)*dev + len)
-		goto out;
-	}
+	len = ((struct wgdevice *)READ_BYTES(sizeof(struct wgdevice)))->num_peers;
+	for (i = 0; i < len; ++i)
+		READ_BYTES(sizeof(struct wgipmask) * ((struct wgpeer *)READ_BYTES(sizeof(struct wgpeer)))->num_ipmasks);
 	ret = 0;
 out:
-	if (*dev && ret) {
-		free(*dev);
-		*dev = NULL;
+	if (buffer && ret) {
+		free(buffer);
+		buffer = NULL;
 	}
+	*dev = (struct wgdevice *)buffer;
 	close(fd);
 	errno = -ret;
 	return ret;
+
 }
+#undef READ_BYTES
 
 #ifdef __linux__
 static int parse_linkinfo(const struct nlattr *attr, void *data)
-- 
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