Refactor XDR code, add support for fixed-length opaque data.

1 files changed, 90 insertions, 132 deletions

diff --git a/xdr.c b/xdr.c
index e7c81b2..9a958ac 100644
--- a/xdr.c
+++ b/xdr.c
@@ -2,8 +2,9 @@
  * xdr.c
  * -----
  * Serialization/deserialization routines, using XDR (RFC 4506) encoding.
+ * These functions are not part of the public libhal API.
  *
- * Copyright (c) 2016, NORDUnet A/S All rights reserved.
+ * Copyright (c) 2016-2018, NORDUnet A/S All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
@@ -38,7 +39,7 @@
 #include <string.h>             /* memcpy, memset */
 
 #include "hal.h"
-#include "hal_internal.h"
+#include "hal_internal.h"	/* htonl/ntohl */
 #include "xdr_internal.h"
 
 /* encode/decode_int. This covers int, unsigned int, enum, and bool types,
@@ -61,7 +62,8 @@ hal_error_t hal_xdr_encode_int(uint8_t ** const outbuf, const uint8_t * const li
     return HAL_OK;
 }
 
-hal_error_t hal_xdr_decode_int(const uint8_t ** const inbuf, const uint8_t * const limit, uint32_t *value)
+/* decode an integer value without advancing the input pointer */
+hal_error_t hal_xdr_decode_int_peek(const uint8_t ** const inbuf, const uint8_t * const limit, uint32_t *value)
 {
     /* arg checks */
     if (inbuf == NULL || *inbuf == NULL || limit == NULL || value == NULL)
@@ -72,44 +74,38 @@ hal_error_t hal_xdr_decode_int(const uint8_t ** const inbuf, const uint8_t * con
         return HAL_ERROR_XDR_BUFFER_OVERFLOW;
 
     *value = ntohl(**(uint32_t **)inbuf);
-    *inbuf += sizeof(*value);
     return HAL_OK;
 }
 
-/* Undo the last decode_int - roll back the input pointer.
- */
-hal_error_t hal_xdr_undecode_int(const uint8_t ** const inbuf)
+/* decode an integer value the regular way */
+hal_error_t hal_xdr_decode_int(const uint8_t ** const inbuf, const uint8_t * const limit, uint32_t *value)
 {
-    if (inbuf == NULL || *inbuf == NULL)
-        return HAL_ERROR_BAD_ARGUMENTS;
+    hal_error_t err;
 
-    *inbuf -= sizeof(uint32_t);
-    return HAL_OK;
+    if ((err = hal_xdr_decode_int_peek(inbuf, limit, value)) == HAL_OK)
+        *inbuf += sizeof(*value);
+
+    return err;
 }
 
-/* encode/decode_buffer. This covers variable-length string and opaque types.
- * The data is preceded by a 4-byte length word (encoded as above), and padded
- * to a multiple of 4 bytes as necessary.
+/* encode/decode_fixed_opaque. This covers fixed-length string and opaque types.
+ * The data is padded to a multiple of 4 bytes as necessary.
  */
 
-hal_error_t hal_xdr_encode_buffer(uint8_t **outbuf, const uint8_t * const limit, const uint8_t *value, const uint32_t len)
+hal_error_t hal_xdr_encode_fixed_opaque(uint8_t ** const outbuf, const uint8_t * const limit, const uint8_t * const value, const size_t len)
 {
-    hal_error_t ret;
+    if (len == 0)
+        return HAL_OK;
 
     /* arg checks */
-    if (outbuf == NULL || *outbuf == NULL || limit == NULL ||
-        (value == NULL && len != 0))
+    if (outbuf == NULL || *outbuf == NULL || limit == NULL || value == NULL)
         return HAL_ERROR_BAD_ARGUMENTS;
 
     /* buffer overflow check */
-    if (limit - *outbuf < (ptrdiff_t)(((len + 3) & ~3) + sizeof(len)))
+    if (limit - *outbuf < (ptrdiff_t)((len + 3) & ~3))
         return HAL_ERROR_XDR_BUFFER_OVERFLOW;
 
-    /* encode length */
-    if ((ret = hal_xdr_encode_int(outbuf, limit, len)) != HAL_OK)
-        return ret;
-
-    /* write the string or opaque data */
+    /* write the data */
     memcpy(*outbuf, value, len);
     *outbuf += len;
 
@@ -123,139 +119,101 @@ hal_error_t hal_xdr_encode_buffer(uint8_t **outbuf, const uint8_t * const limit,
     return HAL_OK;
 }
 
-/* This version returns a pointer to the data in the input buffer.
- * It is used in the rpc server.
- */
-hal_error_t hal_xdr_decode_buffer_in_place(const uint8_t **inbuf, const uint8_t * const limit, const uint8_t ** const value, uint32_t * const len)
+hal_error_t hal_xdr_decode_fixed_opaque_ptr(const uint8_t ** const inbuf, const uint8_t * const limit, const uint8_t ** const value, const size_t len)
 {
-    hal_error_t ret;
-    uint32_t xdr_len;
-    const uint8_t *orig_inbuf = *inbuf;
-
     /* arg checks */
-    if (inbuf == NULL || *inbuf == NULL || limit == NULL || value == NULL || len == NULL)
+    if (inbuf == NULL || *inbuf == NULL || limit == NULL || value == NULL)
         return HAL_ERROR_BAD_ARGUMENTS;
 
-    /* decode the length */
-    if ((ret = hal_xdr_decode_int(inbuf, limit, &xdr_len)) != HAL_OK)
-        return ret;
-
-    /* input and output buffer overflow checks vs decoded length */
-
-    /* decoded length is past the end of the input buffer;
-     * we're probably out of sync, but nothing we can do now
-     */
-    if (limit - *inbuf < (ptrdiff_t)xdr_len) {
-        /* undo read of length */
-        *inbuf = orig_inbuf;
+    /* buffer overflow check */
+    if (limit - *inbuf < (ptrdiff_t)len)
         return HAL_ERROR_XDR_BUFFER_OVERFLOW;
-    }
 
-    /* return a pointer to the string or opaque data */
+    /* return a pointer to the data */
     *value = *inbuf;
-    *len = xdr_len;
 
     /* update the buffer pointer, skipping any padding bytes */
-    *inbuf += (xdr_len + 3) & ~3;
+    *inbuf += ((len + 3) & ~3);
 
     return HAL_OK;
 }
 
-/* This version copies the data to the user-supplied buffer.
- * It is used in the rpc client.
- */
-hal_error_t hal_xdr_decode_buffer(const uint8_t **inbuf, const uint8_t * const limit, uint8_t * const value, uint32_t * const len)
+hal_error_t hal_xdr_decode_fixed_opaque(const uint8_t ** const inbuf, const uint8_t * const limit, uint8_t * const value, const size_t len)
 {
-    if (inbuf == NULL || value == NULL || len == NULL)
-        return HAL_ERROR_BAD_ARGUMENTS;
+    const uint8_t *p;
+    hal_error_t err;
 
-    hal_error_t ret;
-    const uint8_t *vptr;
-    const uint8_t *orig_inbuf = *inbuf;
-    uint32_t xdr_len;
+    /* get and advance the input data pointer */
+    if ((err = hal_xdr_decode_fixed_opaque_ptr(inbuf, limit, &p, len)) == HAL_OK)
+        /* read the data */
+        memcpy(value, p, len);
+
+    return err;
+}
 
-    if ((ret = hal_xdr_decode_buffer_in_place(inbuf, limit, &vptr, &xdr_len)) != HAL_OK)
-        return ret;
+/* encode/decode_variable_opaque. This covers variable-length string and opaque types.
+ * The data is preceded by a 4-byte length word (encoded as above), and padded
+ * to a multiple of 4 bytes as necessary.
+ */
 
-    if (*len < xdr_len) {
-        /* user buffer is too small, undo read of length */
-        *inbuf = orig_inbuf;
-	ret = HAL_ERROR_XDR_BUFFER_OVERFLOW;
-    }
-    else {
-        memcpy(value, vptr, xdr_len);
-    }
+hal_error_t hal_xdr_encode_variable_opaque(uint8_t ** const outbuf, const uint8_t * const limit, const uint8_t * const value, const size_t len)
+{
+    hal_error_t err;
 
-    *len = xdr_len;
+    /* encode length */
+    if ((err = hal_xdr_encode_int(outbuf, limit, (uint32_t)len)) == HAL_OK) {
+        /* encode data */
+        if ((err = hal_xdr_encode_fixed_opaque(outbuf, limit, value, len)) != HAL_OK)
+            /* undo write of length */
+            *outbuf -= 4;
+    }
 
-    return ret;
+    return err;
 }
 
-/* ---------------------------------------------------------------- */
-
-#ifdef TEST
-static void hexdump(uint8_t *buf, uint32_t len)
+/* This version returns a pointer to the data in the input buffer.
+ * It is used in the rpc server.
+ */
+hal_error_t hal_xdr_decode_variable_opaque_ptr(const uint8_t ** const inbuf, const uint8_t * const limit, const uint8_t ** const value, size_t * const len)
 {
-    for (uint32_t i = 0; i < len; ++i)
-        printf("%02x%c", buf[i], ((i & 0x07) == 0x07) ? '\n' : ' ');
-    if ((len & 0x07) != 0)
-        printf("\n");
+    hal_error_t err;
+    uint32_t xdr_len;
+
+    /* arg checks */
+    if (len == NULL)
+        return HAL_ERROR_BAD_ARGUMENTS;
+
+    /* read length */
+    if ((err = hal_xdr_decode_int(inbuf, limit, &xdr_len)) == HAL_OK) {
+        /* get the data pointer */
+        if ((err = hal_xdr_decode_fixed_opaque_ptr(inbuf, limit, value, xdr_len)) == HAL_OK)
+            *len = xdr_len;
+        else
+            /* undo read of length */
+            *inbuf -= 4;
+    }
+
+    return err;
 }
 
-int main(int argc, char *argv[])
+/* This version copies the data to the user-supplied buffer.
+ * It is used in the rpc client.
+ */
+hal_error_t hal_xdr_decode_variable_opaque(const uint8_t ** const inbuf, const uint8_t * const limit, uint8_t * const value, size_t * const len)
 {
-    uint32_t i;
-    uint8_t buf[64] = {0};
-    uint8_t *bufptr = buf, *readptr;
-    uint8_t *limit = buf + sizeof(buf);
-    hal_error_t ret;
-    uint8_t alphabet[] = "abcdefghijklmnopqrstuvwxyz";
-    uint8_t readbuf[64] = {0};
-
-    printf("hal_xdr_encode_int: work to failure\n");
-    for (i = 1; i < 100; ++i) {
-        if ((ret = hal_xdr_encode_int(&bufptr, limit, i)) != HAL_OK) {
-            printf("%d: %s\n", i, hal_error_string(ret));
-            break;
-        }
-    }
-    hexdump(buf, ((uint8_t *)bufptr - buf));
-
-    printf("\nhal_xdr_decode_int:\n");
-    readptr = buf;
-    while (readptr < bufptr) {
-        if ((ret = hal_xdr_decode_int(&readptr, limit, &i)) != HAL_OK) {
-            printf("%s\n", hal_error_string(ret));
-            break;
-        }
-        printf("%u ", i);
-    }
-    printf("\n");
-
-    printf("\nhal_xdr_encode_buffer: work to failure\n");
-    memset(buf, 0, sizeof(buf));
-    bufptr = buf;
-     for (i = 1; i < 10; ++i) {
-        if ((ret = hal_xdr_encode_buffer(&bufptr, limit, alphabet, i)) != HAL_OK) {
-            printf("%d: %s\n", i, hal_error_string(ret));
-            break;
-        }
-    }
-    hexdump(buf, ((uint8_t *)bufptr - buf));
-
-    printf("\nhal_xdr_decode_buffer:\n");
-    readptr = buf;
-    i = sizeof(readbuf);
-    while (readptr < bufptr) {
-        if ((ret = hal_xdr_decode_buffer(&readptr, limit, readbuf, &i)) != HAL_OK) {
-            printf("%s\n", hal_error_string(ret));
-            break;
-        }
-        printf("%u: ", i); for (int j = 0; j < i; ++j) putchar(readbuf[j]); putchar('\n');
-        i = sizeof(readbuf);
-        memset(readbuf, 0, sizeof(readbuf));
+    hal_error_t err;
+    size_t xdr_len;
+    const uint8_t *p;
+
+    /* read data pointer and length */
+    if ((err = hal_xdr_decode_variable_opaque_ptr(inbuf, limit, &p, &xdr_len)) == HAL_OK) {
+        /* user buffer overflow check */
+        if (*len < xdr_len)
+            return HAL_ERROR_XDR_BUFFER_OVERFLOW;
+        /* read the data */
+        memcpy(value, p, xdr_len);
+        *len = xdr_len;
     }
 
-    return 0;
+    return err;
 }
-#endif