implement SSH buffer in C

3 files changed, 198 insertions, 0 deletions

diff --git a/src/protocol/CMakeLists.txt b/src/protocol/CMakeLists.txt
index 84d53d1..7a3ad8e 100644
--- a/src/protocol/CMakeLists.txt
+++ b/src/protocol/CMakeLists.txt
@@ -13,6 +13,7 @@ set(export_SRCS
 )
 
 set(internal_SRCS
+  internal/buffer.c
   internal/ssh_crypto_common.h
   internal/ssh_crypto_common.c
   internal/ssh_cipher.h
diff --git a/src/protocol/internal/buffer.c b/src/protocol/internal/buffer.c
new file mode 100644
index 0000000..388cbe0
--- /dev/null
+++ b/src/protocol/internal/buffer.c
@@ -0,0 +1,132 @@
+/*
+ * buffer.c: SSH buffer
+ * Copyright (C) 2018  Iru Cai <mytbk920423@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "buffer.h"
+#include <endian.h>
+
+#define INITSIZE 2048
+
+int buffer_init(buffer *b)
+{
+	b->p = (uint8_t *)malloc(INITSIZE);
+	if (b->p) {
+		b->alloc = INITSIZE;
+		b->offs = 0;
+		b->sz = 0;
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+static int ensure(buffer *b, size_t len)
+{
+	if (b->offs + b->sz + len <= b->alloc)
+		return 1;
+
+	uint8_t *r = (uint8_t *)realloc(b->p, (b->alloc + len) * 2);
+	if (r == NULL)
+		return 0;
+	b->alloc = (b->alloc + len) * 2;
+	b->p = r;
+	return 1;
+}
+
+int buffer_append(buffer *b, const uint8_t *s, size_t len)
+{
+	if (ensure(b, len)) {
+		memcpy(b->p + b->offs + b->sz, s, len);
+		b->sz += len;
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+int buffer_append_string(buffer *b, const char *s, size_t len)
+{
+	uint32_t beint = htobe32(len);
+	if (ensure(b, len + 4)) {
+		*(uint32_t *)(b->p + b->offs + b->sz) = beint;
+		memcpy(b->p + b->offs + b->sz + 4, s, len);
+		b->sz += len + 4;
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+int buffer_append_byte(buffer *b, uint8_t x)
+{
+	if (ensure(b, 1)) {
+		b->p[b->offs + b->sz] = x;
+		b->sz += 1;
+	} else {
+		return 0;
+	}
+}
+
+int buffer_append_be16(buffer *b, uint16_t x)
+{
+	uint16_t beint = htobe16(x);
+	if (ensure(b, 2)) {
+		*(uint16_t *)(b->p + b->offs + b->sz) = beint;
+		b->sz += 2;
+	} else {
+		return 0;
+	}
+}
+
+int buffer_append_be32(buffer *b, uint32_t x)
+{
+	uint32_t beint = htobe32(x);
+	if (ensure(b, 4)) {
+		*(uint32_t *)(b->p + b->offs + b->sz) = beint;
+		b->sz += 4;
+	} else {
+		return 0;
+	}
+}
+
+void buffer_get(buffer *b, uint8_t *s, size_t len)
+{
+	memcpy(s, buffer_data(b), len);
+	buffer_consume(b, len);
+}
+
+uint8_t buffer_get_u8(buffer *b)
+{
+	uint8_t c = *buffer_data(b);
+	buffer_consume(b, 1);
+	return c;
+}
+
+uint16_t buffer_get_u16(buffer *b)
+{
+	uint16_t u = be16toh(*(uint16_t *)buffer_data(b));
+	buffer_consume(b, 2);
+	return u;
+}
+
+uint32_t buffer_get_u32(buffer *b)
+{
+	uint32_t u = be32toh(*(uint32_t *)buffer_data(b));
+	buffer_consume(b, 4);
+	return u;
+}
diff --git a/src/protocol/internal/buffer.h b/src/protocol/internal/buffer.h
new file mode 100644
index 0000000..971f21c
--- /dev/null
+++ b/src/protocol/internal/buffer.h
@@ -0,0 +1,65 @@
+/*
+ * buffer.h: SSH buffer
+ * Copyright (C) 2018  Iru Cai <mytbk920423@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef BUFFER_H
+#define BUFFER_H
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* } */
+
+typedef struct
+{
+	uint8_t *p;
+	size_t alloc;
+	size_t offs;
+	size_t sz;
+} buffer;
+
+/* if success, return 1, otherwise return 0 */
+int buffer_init(buffer *);
+static inline void buffer_clear(buffer *b) { b->offs = b->sz = 0; }
+static inline void buffer_deinit(buffer *b) { free(b->p); }
+static inline uint8_t *buffer_data(buffer *b) { return b->p + b->offs; }
+static inline size_t buffer_len(buffer *b) { return b->sz; }
+int buffer_append(buffer *b, const uint8_t *s, size_t len);
+int buffer_append_string(buffer *b, const char *s, size_t len);
+int buffer_append_byte(buffer *b, uint8_t);
+int buffer_append_be16(buffer *b, uint16_t);
+int buffer_append_be32(buffer *b, uint32_t);
+
+/* the following functions doesn't check on buffer size */
+static inline void buffer_consume(buffer *b, size_t L)
+{
+	b->offs += L;
+	b->sz -= L;
+}
+void buffer_get(buffer *b, uint8_t *s, size_t len);
+uint32_t buffer_get_u32(buffer *b);
+uint16_t buffer_get_u16(buffer *b);
+uint8_t buffer_get_u8(buffer *b);
+#ifdef __cplusplus
+}
+#endif
+
+#endif