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@@ -2,16 +2,18 @@
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/* See LICENSE for licensing information */
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/* $Id$ */
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-/* buffers.c */
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+/*****
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+ * buffers.c: Abstractions for buffered IO.
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+ *****/
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#include "or.h"
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#define BUFFER_MAGIC 0xB0FFF312u
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struct buf_t {
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- uint32_t magic; /* for debugging */
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- char *mem;
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- size_t len;
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- size_t datalen;
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+ uint32_t magic; /* Magic cookie for debugging: Must be set to BUFFER_MAGIC */
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+ char *mem; /* Storage for data in the buffer */
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+ size_t len; /* Maximum amount of data that 'mem' can hold. */
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+ size_t datalen; /* Number of bytes currently in 'mem'. */
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};
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/* Size, in bytes, for newly allocated buffers. Should be a power of 2. */
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@@ -23,7 +25,7 @@ struct buf_t {
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* than this size. */
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#define MIN_BUF_SHRINK_SIZE (16*1024)
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-/* Change a buffer's capacity. Must only be called when */
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+/* Change a buffer's capacity. new_capacity must be <= buf->datalen. */
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static INLINE void buf_resize(buf_t *buf, size_t new_capacity)
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{
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tor_assert(buf->datalen <= new_capacity);
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@@ -88,33 +90,42 @@ static INLINE void buf_remove_from_front(buf_t *buf, size_t n) {
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buf_shrink_if_underfull(buf);
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}
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-/* Find the first instance of str on buf. If none exists, return -1.
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- * Otherwise, return index of the first character in buf _after_ the
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- * first instance of str.
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+/* Find the first instance of the str_len byte string 'sr' on the
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+ * buf_len byte string 'bufstr'. Strings are not necessary
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+ * NUL-terminated. If none exists, return -1. Otherwise, return index
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+ * of the first character in bufstr _after_ the first instance of str.
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*/
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-static int find_str_in_str(const char *str, int str_len,
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- const char *buf, int buf_len)
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+/* XXXX The way this function is used, we could always get away with
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+ * XXXX assuming that str is NUL terminated, and use strstr instead. */
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+static int find_mem_in_mem(const char *str, int str_len,
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+ const char *bufstr, int buf_len)
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{
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const char *location;
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- const char *last_possible = buf + buf_len - str_len;
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+ const char *last_possible = bufstr + buf_len - str_len;
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- tor_assert(str && str_len > 0 && buf);
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+ tor_assert(str && str_len > 0 && bufstr);
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if(buf_len < str_len)
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return -1;
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- for(location = buf; location <= last_possible; location++)
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+ for(location = bufstr; location <= last_possible; location++)
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if((*location == *str) && !memcmp(location+1, str+1, str_len-1))
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- return location-buf+str_len;
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+ return location-bufstr+str_len;
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return -1;
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}
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-int find_on_inbuf(char *string, int string_len, buf_t *buf) {
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- return find_str_in_str(string, string_len, buf->mem, buf->datalen);
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+#if 0
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+/* Find the first occurence of the string_len byte string 'str' on the
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+ * buffer 'buf'. If none exists, return -1. Otherwise, return index
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+ * of the first character on the buffer _after_ the first instance of str.
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+ */
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+int find_on_inbuf(char *str, int string_len, buf_t *buf) {
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+ return find_mem_in_mem(str, string_len, buf->mem, buf->datalen);
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}
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+#endif
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-/* Create and return a new buf of size 'size'
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+/* Create and return a new buf with capacity 'capacity'.
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*/
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buf_t *buf_new_with_capacity(size_t size) {
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buf_t *buf;
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@@ -129,31 +140,40 @@ buf_t *buf_new_with_capacity(size_t size) {
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return buf;
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}
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+/* Allocate and return a new buffer with default capacity. */
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buf_t *buf_new()
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{
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return buf_new_with_capacity(INITIAL_BUF_SIZE);
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}
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+/* Remove all data from 'buf' */
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void buf_clear(buf_t *buf)
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{
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buf->datalen = 0;
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}
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+/* Return the number of bytes stored in 'buf' */
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size_t buf_datalen(const buf_t *buf)
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{
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return buf->datalen;
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}
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+/* Return the maximum bytes that can be stored in 'buf' before buf
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+ * needs to resize. */
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size_t buf_capacity(const buf_t *buf)
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{
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return buf->len;
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}
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+/* For testing only: Return a pointer to the raw memory stored in 'buf'.
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+ */
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const char *_buf_peek_raw_buffer(const buf_t *buf)
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{
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return buf->mem;
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}
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+/* Release storage held by 'buf'.
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+ */
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void buf_free(buf_t *buf) {
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assert_buf_ok(buf);
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buf->magic = 0xDEADBEEF;
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@@ -161,12 +181,11 @@ void buf_free(buf_t *buf) {
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tor_free(buf);
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}
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-/* read from socket s, writing onto end of buf.
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- * read at most 'at_most' bytes, and in any case don't read more than
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- * will fit based on buflen.
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- * If read() returns 0, set *reached_eof to 1 and return 0. If you want
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- * to tear down the connection return -1, else return the number of
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- * bytes read.
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+/* Read from socket s, writing onto end of buf. Read at most
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+ * 'at_most' bytes, resizing the buffer as necessary. If read()
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+ * returns 0, set *reached_eof to 1 and return 0. Return -1 on error;
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+ * else return the number of bytes read. Return 0 if read() would
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+ * block.
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*/
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int read_to_buf(int s, size_t at_most, buf_t *buf, int *reached_eof) {
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@@ -190,7 +209,7 @@ int read_to_buf(int s, size_t at_most, buf_t *buf, int *reached_eof) {
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if(!ERRNO_IS_EAGAIN(tor_socket_errno(s))) { /* it's a real error */
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return -1;
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}
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- return 0;
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+ return 0; /* would block. */
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} else if (read_result == 0) {
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log_fn(LOG_DEBUG,"Encountered eof");
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*reached_eof = 1;
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@@ -203,6 +222,8 @@ int read_to_buf(int s, size_t at_most, buf_t *buf, int *reached_eof) {
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}
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}
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+/* As read_to_buf, but reads from a TLS connection.
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+ */
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int read_to_buf_tls(tor_tls *tls, size_t at_most, buf_t *buf) {
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int r;
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tor_assert(tls);
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@@ -233,9 +254,13 @@ int read_to_buf_tls(tor_tls *tls, size_t at_most, buf_t *buf) {
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return r;
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}
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+/* Write data from 'buf' to the socket 's'. Write at most
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+ * *buf_flushlen bytes, and decrement *buf_flushlen by the number of
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+ * bytes actually written. Return the number of bytes written on
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+ * success, -1 on failure. Returns 0 if write() would block.
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+ */
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int flush_buf(int s, buf_t *buf, int *buf_flushlen)
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{
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-
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/* push from buf onto s
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* then memmove to front of buf
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* return -1 or how many bytes you just flushed */
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@@ -267,6 +292,8 @@ int flush_buf(int s, buf_t *buf, int *buf_flushlen)
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}
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}
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+/* As flush_buf, but writes data to a TLS connection.
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+ */
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int flush_buf_tls(tor_tls *tls, buf_t *buf, int *buf_flushlen)
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{
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int r;
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@@ -286,6 +313,9 @@ int flush_buf_tls(tor_tls *tls, buf_t *buf, int *buf_flushlen)
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return r;
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}
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+/* Append string_len bytes from 'string' to the end of 'buf'.
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+ * Return the new length of the buffer on success, -1 on failure.
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+ */
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int write_to_buf(const char *string, int string_len, buf_t *buf) {
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/* append string to buf (growing as needed, return -1 if "too big")
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@@ -306,6 +336,11 @@ int write_to_buf(const char *string, int string_len, buf_t *buf) {
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return buf->datalen;
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}
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+
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+/* Remove string_len bytes from the front of 'buf', and store them
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+ * into 'string'. Returns the new buffer size. string_len must be <=
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+ * the number of bytes on the buffer.
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+ */
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int fetch_from_buf(char *string, size_t string_len, buf_t *buf) {
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/* There must be string_len bytes in buf; write them onto string,
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@@ -346,7 +381,7 @@ int fetch_from_buf_http(buf_t *buf,
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assert_buf_ok(buf);
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headers = buf->mem;
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- i = find_on_inbuf("\r\n\r\n", 4, buf);
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+ i = find_mem_in_mem("\r\n\r\n", 4, buf->mem, buf->datalen);
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if(i < 0) {
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log_fn(LOG_DEBUG,"headers not all here yet.");
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return 0;
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@@ -366,7 +401,7 @@ int fetch_from_buf_http(buf_t *buf,
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}
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#define CONTENT_LENGTH "\r\nContent-Length: "
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- i = find_str_in_str(CONTENT_LENGTH, strlen(CONTENT_LENGTH),
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+ i = find_mem_in_mem(CONTENT_LENGTH, strlen(CONTENT_LENGTH),
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headers, headerlen);
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if(i > 0) {
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contentlen = atoi(headers+i);
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@@ -585,7 +620,8 @@ int fetch_from_buf_socks(buf_t *buf, socks_request_t *req) {
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}
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}
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-
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+/* Log an error and exit if 'buf' is corrupted.
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+ */
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void assert_buf_ok(buf_t *buf)
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{
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tor_assert(buf);
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