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Diffstat (limited to 'src/lib/buf/buffers.c')
| -rw-r--r-- | src/lib/buf/buffers.c | 938 |
1 files changed, 938 insertions, 0 deletions
diff --git a/src/lib/buf/buffers.c b/src/lib/buf/buffers.c new file mode 100644 index 0000000000..a5031a47a6 --- /dev/null +++ b/src/lib/buf/buffers.c @@ -0,0 +1,938 @@ +/* Copyright (c) 2001 Matej Pfajfar. + * Copyright (c) 2001-2004, Roger Dingledine. + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2020, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file buffers.c + * \brief Implements a generic buffer interface. + * + * A buf_t is a (fairly) opaque byte-oriented FIFO that can read to or flush + * from memory, sockets, file descriptors, TLS connections, or another buf_t. + * Buffers are implemented as linked lists of memory chunks. + * + * All socket-backed and TLS-based connection_t objects have a pair of + * buffers: one for incoming data, and one for outcoming data. These are fed + * and drained from functions in connection.c, trigged by events that are + * monitored in main.c. + * + * This module only handles the buffer implementation itself. To use a buffer + * with the network, a compressor, or a TLS connection, see the other buffer_* + * modules. + **/ + +#define BUFFERS_PRIVATE +#include "orconfig.h" +#include <stddef.h> +#include "lib/buf/buffers.h" +#include "lib/cc/torint.h" +#include "lib/log/log.h" +#include "lib/log/util_bug.h" +#include "lib/ctime/di_ops.h" +#include "lib/malloc/malloc.h" +#include "lib/string/printf.h" +#include "lib/time/compat_time.h" + +#ifdef HAVE_UNISTD_H +#include <unistd.h> +#endif + +#include <stdlib.h> +#include <string.h> + +//#define PARANOIA + +#ifdef PARANOIA +/** Helper: If PARANOIA is defined, assert that the buffer in local variable + * <b>buf</b> is well-formed. */ +#define check() STMT_BEGIN buf_assert_ok(buf); STMT_END +#else +#define check() STMT_NIL +#endif /* defined(PARANOIA) */ + +/* Implementation notes: + * + * After flirting with memmove, and dallying with ring-buffers, we're finally + * getting up to speed with the 1970s and implementing buffers as a linked + * list of small chunks. Each buffer has such a list; data is removed from + * the head of the list, and added at the tail. The list is singly linked, + * and the buffer keeps a pointer to the head and the tail. + * + * Every chunk, except the tail, contains at least one byte of data. Data in + * each chunk is contiguous. + * + * When you need to treat the first N characters on a buffer as a contiguous + * string, use the buf_pullup function to make them so. Don't do this more + * than necessary. + * + * The major free Unix kernels have handled buffers like this since, like, + * forever. + */ + +/* Chunk manipulation functions */ + +#define CHUNK_HEADER_LEN offsetof(chunk_t, mem[0]) + +/* We leave this many NUL bytes at the end of the buffer. */ +#ifdef DISABLE_MEMORY_SENTINELS +#define SENTINEL_LEN 0 +#else +#define SENTINEL_LEN 4 +#endif + +/* Header size plus NUL bytes at the end */ +#define CHUNK_OVERHEAD (CHUNK_HEADER_LEN + SENTINEL_LEN) + +/** Return the number of bytes needed to allocate a chunk to hold + * <b>memlen</b> bytes. */ +#define CHUNK_ALLOC_SIZE(memlen) (CHUNK_OVERHEAD + (memlen)) +/** Return the number of usable bytes in a chunk allocated with + * malloc(<b>memlen</b>). */ +#define CHUNK_SIZE_WITH_ALLOC(memlen) ((memlen) - CHUNK_OVERHEAD) + +#define DEBUG_SENTINEL + +#if defined(DEBUG_SENTINEL) && !defined(DISABLE_MEMORY_SENTINELS) +#define DBG_S(s) s +#else +#define DBG_S(s) (void)0 +#endif + +#ifndef COCCI +#ifdef DISABLE_MEMORY_SENTINELS +#define CHUNK_SET_SENTINEL(chunk, alloclen) STMT_NIL +#else +#define CHUNK_SET_SENTINEL(chunk, alloclen) do { \ + uint8_t *a = (uint8_t*) &(chunk)->mem[(chunk)->memlen]; \ + DBG_S(uint8_t *b = &((uint8_t*)(chunk))[(alloclen)-SENTINEL_LEN]); \ + DBG_S(tor_assert(a == b)); \ + memset(a,0,SENTINEL_LEN); \ + } while (0) +#endif /* defined(DISABLE_MEMORY_SENTINELS) */ +#endif /* !defined(COCCI) */ + +/** Move all bytes stored in <b>chunk</b> to the front of <b>chunk</b>->mem, + * to free up space at the end. */ +static inline void +chunk_repack(chunk_t *chunk) +{ + if (chunk->datalen && chunk->data != &chunk->mem[0]) { + memmove(chunk->mem, chunk->data, chunk->datalen); + } + chunk->data = &chunk->mem[0]; +} + +/** Keep track of total size of allocated chunks for consistency asserts */ +static size_t total_bytes_allocated_in_chunks = 0; +static void +buf_chunk_free_unchecked(chunk_t *chunk) +{ + if (!chunk) + return; +#ifdef DEBUG_CHUNK_ALLOC + tor_assert(CHUNK_ALLOC_SIZE(chunk->memlen) == chunk->DBG_alloc); +#endif + tor_assert(total_bytes_allocated_in_chunks >= + CHUNK_ALLOC_SIZE(chunk->memlen)); + total_bytes_allocated_in_chunks -= CHUNK_ALLOC_SIZE(chunk->memlen); + tor_free(chunk); +} +static inline chunk_t * +chunk_new_with_alloc_size(size_t alloc) +{ + chunk_t *ch; + ch = tor_malloc(alloc); + ch->next = NULL; + ch->datalen = 0; +#ifdef DEBUG_CHUNK_ALLOC + ch->DBG_alloc = alloc; +#endif + ch->memlen = CHUNK_SIZE_WITH_ALLOC(alloc); + total_bytes_allocated_in_chunks += alloc; + ch->data = &ch->mem[0]; + CHUNK_SET_SENTINEL(ch, alloc); + return ch; +} + +/** Expand <b>chunk</b> until it can hold <b>sz</b> bytes, and return a + * new pointer to <b>chunk</b>. Old pointers are no longer valid. */ +static inline chunk_t * +chunk_grow(chunk_t *chunk, size_t sz) +{ + ptrdiff_t offset; + const size_t memlen_orig = chunk->memlen; + const size_t orig_alloc = CHUNK_ALLOC_SIZE(memlen_orig); + const size_t new_alloc = CHUNK_ALLOC_SIZE(sz); + tor_assert(sz > chunk->memlen); + offset = chunk->data - chunk->mem; + chunk = tor_realloc(chunk, new_alloc); + chunk->memlen = sz; + chunk->data = chunk->mem + offset; +#ifdef DEBUG_CHUNK_ALLOC + tor_assert(chunk->DBG_alloc == orig_alloc); + chunk->DBG_alloc = new_alloc; +#endif + total_bytes_allocated_in_chunks += new_alloc - orig_alloc; + CHUNK_SET_SENTINEL(chunk, new_alloc); + return chunk; +} + +/** Every chunk should take up at least this many bytes. */ +#define MIN_CHUNK_ALLOC 256 +/** No chunk should take up more than this many bytes. */ +#define MAX_CHUNK_ALLOC 65536 + +/** Return the allocation size we'd like to use to hold <b>target</b> + * bytes. */ +size_t +buf_preferred_chunk_size(size_t target) +{ + tor_assert(target <= SIZE_T_CEILING - CHUNK_OVERHEAD); + if (CHUNK_ALLOC_SIZE(target) >= MAX_CHUNK_ALLOC) + return CHUNK_ALLOC_SIZE(target); + size_t sz = MIN_CHUNK_ALLOC; + while (CHUNK_SIZE_WITH_ALLOC(sz) < target) { + sz <<= 1; + } + return sz; +} + +/** Collapse data from the first N chunks from <b>buf</b> into buf->head, + * growing it as necessary, until buf->head has the first <b>bytes</b> bytes + * of data from the buffer, or until buf->head has all the data in <b>buf</b>. + * + * Set *<b>head_out</b> to point to the first byte of available data, and + * *<b>len_out</b> to the number of bytes of data available at + * *<b>head_out</b>. Note that *<b>len_out</b> may be more or less than + * <b>bytes</b>, depending on the number of bytes available. + */ +void +buf_pullup(buf_t *buf, size_t bytes, const char **head_out, size_t *len_out) +{ + chunk_t *dest, *src; + size_t capacity; + if (!buf->head) { + *head_out = NULL; + *len_out = 0; + return; + } + + check(); + if (buf->datalen < bytes) + bytes = buf->datalen; + + capacity = bytes; + if (buf->head->datalen >= bytes) { + *head_out = buf->head->data; + *len_out = buf->head->datalen; + return; + } + + if (buf->head->memlen >= capacity) { + /* We don't need to grow the first chunk, but we might need to repack it.*/ + size_t needed = capacity - buf->head->datalen; + if (CHUNK_REMAINING_CAPACITY(buf->head) < needed) + chunk_repack(buf->head); + tor_assert(CHUNK_REMAINING_CAPACITY(buf->head) >= needed); + } else { + chunk_t *newhead; + size_t newsize; + /* We need to grow the chunk. */ + chunk_repack(buf->head); + newsize = CHUNK_SIZE_WITH_ALLOC(buf_preferred_chunk_size(capacity)); + newhead = chunk_grow(buf->head, newsize); + tor_assert(newhead->memlen >= capacity); + if (newhead != buf->head) { + if (buf->tail == buf->head) + buf->tail = newhead; + buf->head = newhead; + } + } + + dest = buf->head; + while (dest->datalen < bytes) { + size_t n = bytes - dest->datalen; + src = dest->next; + tor_assert(src); + if (n >= src->datalen) { + memcpy(CHUNK_WRITE_PTR(dest), src->data, src->datalen); + dest->datalen += src->datalen; + dest->next = src->next; + if (buf->tail == src) + buf->tail = dest; + buf_chunk_free_unchecked(src); + } else { + memcpy(CHUNK_WRITE_PTR(dest), src->data, n); + dest->datalen += n; + src->data += n; + src->datalen -= n; + tor_assert(dest->datalen == bytes); + } + } + + check(); + *head_out = buf->head->data; + *len_out = buf->head->datalen; +} + +#ifdef TOR_UNIT_TESTS +/* Write sz bytes from cp into a newly allocated buffer buf. + * Returns NULL when passed a NULL cp or zero sz. + * Asserts on failure: only for use in unit tests. + * buf must be freed using buf_free(). */ +buf_t * +buf_new_with_data(const char *cp, size_t sz) +{ + /* Validate arguments */ + if (!cp || sz <= 0 || sz > BUF_MAX_LEN) { + return NULL; + } + + tor_assert(sz < SSIZE_T_CEILING); + + /* Allocate a buffer */ + buf_t *buf = buf_new_with_capacity(sz); + tor_assert(buf); + buf_assert_ok(buf); + tor_assert(!buf->head); + + /* Allocate a chunk that is sz bytes long */ + buf->head = chunk_new_with_alloc_size(CHUNK_ALLOC_SIZE(sz)); + buf->tail = buf->head; + tor_assert(buf->head); + buf_assert_ok(buf); + tor_assert(buf_allocation(buf) >= sz); + + /* Copy the data and size the buffers */ + tor_assert(sz <= buf_slack(buf)); + tor_assert(sz <= CHUNK_REMAINING_CAPACITY(buf->head)); + memcpy(&buf->head->mem[0], cp, sz); + buf->datalen = sz; + buf->head->datalen = sz; + buf->head->data = &buf->head->mem[0]; + buf_assert_ok(buf); + + /* Make sure everything is large enough */ + tor_assert(buf_allocation(buf) >= sz); + tor_assert(buf_allocation(buf) >= buf_datalen(buf) + buf_slack(buf)); + /* Does the buffer implementation allocate more than the requested size? + * (for example, by rounding up). If so, these checks will fail. */ + tor_assert(buf_datalen(buf) == sz); + tor_assert(buf_slack(buf) == 0); + + return buf; +} +#endif /* defined(TOR_UNIT_TESTS) */ + +/** Remove the first <b>n</b> bytes from buf. */ +void +buf_drain(buf_t *buf, size_t n) +{ + tor_assert(buf->datalen >= n); + while (n) { + tor_assert(buf->head); + if (buf->head->datalen > n) { + buf->head->datalen -= n; + buf->head->data += n; + buf->datalen -= n; + return; + } else { + chunk_t *victim = buf->head; + n -= victim->datalen; + buf->datalen -= victim->datalen; + buf->head = victim->next; + if (buf->tail == victim) + buf->tail = NULL; + buf_chunk_free_unchecked(victim); + } + } + check(); +} + +/** Create and return a new buf with default chunk capacity <b>size</b>. + */ +buf_t * +buf_new_with_capacity(size_t size) +{ + buf_t *b = buf_new(); + b->default_chunk_size = buf_preferred_chunk_size(size); + return b; +} + +/** Allocate and return a new buffer with default capacity. */ +buf_t * +buf_new(void) +{ + buf_t *buf = tor_malloc_zero(sizeof(buf_t)); + buf->magic = BUFFER_MAGIC; + buf->default_chunk_size = 4096; + return buf; +} + +size_t +buf_get_default_chunk_size(const buf_t *buf) +{ + return buf->default_chunk_size; +} + +/** Remove all data from <b>buf</b>. */ +void +buf_clear(buf_t *buf) +{ + chunk_t *chunk, *next; + buf->datalen = 0; + for (chunk = buf->head; chunk; chunk = next) { + next = chunk->next; + buf_chunk_free_unchecked(chunk); + } + buf->head = buf->tail = NULL; +} + +/** Return the number of bytes stored in <b>buf</b> */ +MOCK_IMPL(size_t, +buf_datalen, (const buf_t *buf)) +{ + return buf->datalen; +} + +/** Return the total length of all chunks used in <b>buf</b>. */ +size_t +buf_allocation(const buf_t *buf) +{ + size_t total = 0; + const chunk_t *chunk; + for (chunk = buf->head; chunk; chunk = chunk->next) { + total += CHUNK_ALLOC_SIZE(chunk->memlen); + } + return total; +} + +/** Return the number of bytes that can be added to <b>buf</b> without + * performing any additional allocation. */ +size_t +buf_slack(const buf_t *buf) +{ + if (!buf->tail) + return 0; + else + return CHUNK_REMAINING_CAPACITY(buf->tail); +} + +/** Release storage held by <b>buf</b>. */ +void +buf_free_(buf_t *buf) +{ + if (!buf) + return; + + buf_clear(buf); + buf->magic = 0xdeadbeef; + tor_free(buf); +} + +/** Return a new copy of <b>in_chunk</b> */ +static chunk_t * +chunk_copy(const chunk_t *in_chunk) +{ + chunk_t *newch = tor_memdup(in_chunk, CHUNK_ALLOC_SIZE(in_chunk->memlen)); + total_bytes_allocated_in_chunks += CHUNK_ALLOC_SIZE(in_chunk->memlen); +#ifdef DEBUG_CHUNK_ALLOC + newch->DBG_alloc = CHUNK_ALLOC_SIZE(in_chunk->memlen); +#endif + newch->next = NULL; + if (in_chunk->data) { + ptrdiff_t offset = in_chunk->data - in_chunk->mem; + newch->data = newch->mem + offset; + } + return newch; +} + +/** Return a new copy of <b>buf</b> */ +buf_t * +buf_copy(const buf_t *buf) +{ + chunk_t *ch; + buf_t *out = buf_new(); + out->default_chunk_size = buf->default_chunk_size; + for (ch = buf->head; ch; ch = ch->next) { + chunk_t *newch = chunk_copy(ch); + if (out->tail) { + out->tail->next = newch; + out->tail = newch; + } else { + out->head = out->tail = newch; + } + } + out->datalen = buf->datalen; + return out; +} + +/** Append a new chunk with enough capacity to hold <b>capacity</b> bytes to + * the tail of <b>buf</b>. If <b>capped</b>, don't allocate a chunk bigger + * than MAX_CHUNK_ALLOC. */ +chunk_t * +buf_add_chunk_with_capacity(buf_t *buf, size_t capacity, int capped) +{ + chunk_t *chunk; + + if (CHUNK_ALLOC_SIZE(capacity) < buf->default_chunk_size) { + chunk = chunk_new_with_alloc_size(buf->default_chunk_size); + } else if (capped && CHUNK_ALLOC_SIZE(capacity) > MAX_CHUNK_ALLOC) { + chunk = chunk_new_with_alloc_size(MAX_CHUNK_ALLOC); + } else { + chunk = chunk_new_with_alloc_size(buf_preferred_chunk_size(capacity)); + } + + chunk->inserted_time = monotime_coarse_get_stamp(); + + if (buf->tail) { + tor_assert(buf->head); + buf->tail->next = chunk; + buf->tail = chunk; + } else { + tor_assert(!buf->head); + buf->head = buf->tail = chunk; + } + check(); + return chunk; +} + +/** Return the age of the oldest chunk in the buffer <b>buf</b>, in + * timestamp units. Requires the current monotonic timestamp as its + * input <b>now</b>. + */ +uint32_t +buf_get_oldest_chunk_timestamp(const buf_t *buf, uint32_t now) +{ + if (buf->head) { + return now - buf->head->inserted_time; + } else { + return 0; + } +} + +size_t +buf_get_total_allocation(void) +{ + return total_bytes_allocated_in_chunks; +} + +/** Append <b>string_len</b> bytes from <b>string</b> to the end of + * <b>buf</b>. + * + * Return the new length of the buffer on success, -1 on failure. + */ +int +buf_add(buf_t *buf, const char *string, size_t string_len) +{ + if (!string_len) + return (int)buf->datalen; + check(); + + if (BUG(buf->datalen > BUF_MAX_LEN)) + return -1; + if (BUG(buf->datalen > BUF_MAX_LEN - string_len)) + return -1; + + while (string_len) { + size_t copy; + if (!buf->tail || !CHUNK_REMAINING_CAPACITY(buf->tail)) + buf_add_chunk_with_capacity(buf, string_len, 1); + + copy = CHUNK_REMAINING_CAPACITY(buf->tail); + if (copy > string_len) + copy = string_len; + memcpy(CHUNK_WRITE_PTR(buf->tail), string, copy); + string_len -= copy; + string += copy; + buf->datalen += copy; + buf->tail->datalen += copy; + } + + check(); + tor_assert(buf->datalen <= BUF_MAX_LEN); + return (int)buf->datalen; +} + +/** Add a nul-terminated <b>string</b> to <b>buf</b>, not including the + * terminating NUL. */ +void +buf_add_string(buf_t *buf, const char *string) +{ + buf_add(buf, string, strlen(string)); +} + +/** As tor_snprintf, but write the results into a buf_t */ +void +buf_add_printf(buf_t *buf, const char *format, ...) +{ + va_list ap; + va_start(ap,format); + buf_add_vprintf(buf, format, ap); + va_end(ap); +} + +/** As tor_vsnprintf, but write the results into a buf_t. */ +void +buf_add_vprintf(buf_t *buf, const char *format, va_list args) +{ + /* XXXX Faster implementations are easy enough, but let's optimize later */ + char *tmp; + tor_vasprintf(&tmp, format, args); + tor_assert(tmp != NULL); + buf_add(buf, tmp, strlen(tmp)); + tor_free(tmp); +} + +/** Return a heap-allocated string containing the contents of <b>buf</b>, plus + * a NUL byte. If <b>sz_out</b> is provided, set *<b>sz_out</b> to the length + * of the returned string, not including the terminating NUL. */ +char * +buf_extract(buf_t *buf, size_t *sz_out) +{ + tor_assert(buf); + + size_t sz = buf_datalen(buf); + char *result; + result = tor_malloc(sz+1); + buf_peek(buf, result, sz); + result[sz] = 0; + if (sz_out) + *sz_out = sz; + return result; +} + +/** Helper: copy the first <b>string_len</b> bytes from <b>buf</b> + * onto <b>string</b>. + */ +void +buf_peek(const buf_t *buf, char *string, size_t string_len) +{ + chunk_t *chunk; + + tor_assert(string); + /* make sure we don't ask for too much */ + tor_assert(string_len <= buf->datalen); + /* buf_assert_ok(buf); */ + + chunk = buf->head; + while (string_len) { + size_t copy = string_len; + tor_assert(chunk); + if (chunk->datalen < copy) + copy = chunk->datalen; + memcpy(string, chunk->data, copy); + string_len -= copy; + string += copy; + chunk = chunk->next; + } +} + +/** Remove <b>string_len</b> bytes from the front of <b>buf</b>, and store + * them into <b>string</b>. Return the new buffer size. <b>string_len</b> + * must be \<= the number of bytes on the buffer. + */ +int +buf_get_bytes(buf_t *buf, char *string, size_t string_len) +{ + /* There must be string_len bytes in buf; write them onto string, + * then memmove buf back (that is, remove them from buf). + * + * Return the number of bytes still on the buffer. */ + + check(); + buf_peek(buf, string, string_len); + buf_drain(buf, string_len); + check(); + tor_assert(buf->datalen <= BUF_MAX_LEN); + return (int)buf->datalen; +} + +/** Move up to *<b>buf_flushlen</b> bytes from <b>buf_in</b> to + * <b>buf_out</b>, and modify *<b>buf_flushlen</b> appropriately. + * Return the number of bytes actually copied. + */ +int +buf_move_to_buf(buf_t *buf_out, buf_t *buf_in, size_t *buf_flushlen) +{ + /* We can do way better here, but this doesn't turn up in any profiles. */ + char b[4096]; + size_t cp, len; + + if (BUG(buf_out->datalen > BUF_MAX_LEN || *buf_flushlen > BUF_MAX_LEN)) + return -1; + if (BUG(buf_out->datalen > BUF_MAX_LEN - *buf_flushlen)) + return -1; + + len = *buf_flushlen; + if (len > buf_in->datalen) + len = buf_in->datalen; + + cp = len; /* Remember the number of bytes we intend to copy. */ + tor_assert(cp <= BUF_MAX_LEN); + while (len) { + /* This isn't the most efficient implementation one could imagine, since + * it does two copies instead of 1, but I kinda doubt that this will be + * critical path. */ + size_t n = len > sizeof(b) ? sizeof(b) : len; + buf_get_bytes(buf_in, b, n); + buf_add(buf_out, b, n); + len -= n; + } + *buf_flushlen -= cp; + return (int)cp; +} + +/** Moves all data from <b>buf_in</b> to <b>buf_out</b>, without copying. + */ +void +buf_move_all(buf_t *buf_out, buf_t *buf_in) +{ + tor_assert(buf_out); + if (!buf_in) + return; + if (buf_datalen(buf_in) == 0) + return; + if (BUG(buf_out->datalen > BUF_MAX_LEN || buf_in->datalen > BUF_MAX_LEN)) + return; + if (BUG(buf_out->datalen > BUF_MAX_LEN - buf_in->datalen)) + return; + + if (buf_out->head == NULL) { + buf_out->head = buf_in->head; + buf_out->tail = buf_in->tail; + } else { + buf_out->tail->next = buf_in->head; + buf_out->tail = buf_in->tail; + } + + buf_out->datalen += buf_in->datalen; + buf_in->head = buf_in->tail = NULL; + buf_in->datalen = 0; +} + +/** Internal structure: represents a position in a buffer. */ +typedef struct buf_pos_t { + const chunk_t *chunk; /**< Which chunk are we pointing to? */ + ptrdiff_t pos;/**< Which character inside the chunk's data are we pointing + * to? */ + size_t chunk_pos; /**< Total length of all previous chunks. */ +} buf_pos_t; + +/** Initialize <b>out</b> to point to the first character of <b>buf</b>.*/ +static void +buf_pos_init(const buf_t *buf, buf_pos_t *out) +{ + out->chunk = buf->head; + out->pos = 0; + out->chunk_pos = 0; +} + +/** Advance <b>out</b> to the first appearance of <b>ch</b> at the current + * position of <b>out</b>, or later. Return -1 if no instances are found; + * otherwise returns the absolute position of the character. */ +static ptrdiff_t +buf_find_pos_of_char(char ch, buf_pos_t *out) +{ + const chunk_t *chunk; + ptrdiff_t pos; + tor_assert(out); + if (out->chunk) { + if (out->chunk->datalen) { + tor_assert(out->pos < (ptrdiff_t)out->chunk->datalen); + } else { + tor_assert(out->pos == 0); + } + } + pos = out->pos; + for (chunk = out->chunk; chunk; chunk = chunk->next) { + char *cp = memchr(chunk->data+pos, ch, chunk->datalen - pos); + if (cp) { + out->chunk = chunk; + tor_assert(cp - chunk->data <= BUF_MAX_LEN); + out->pos = (int)(cp - chunk->data); + return out->chunk_pos + out->pos; + } else { + out->chunk_pos += chunk->datalen; + pos = 0; + } + } + return -1; +} + +/** Advance <b>pos</b> by a single character, if there are any more characters + * in the buffer. Returns 0 on success, -1 on failure. */ +static inline int +buf_pos_inc(buf_pos_t *pos) +{ + tor_assert(pos->pos < BUF_MAX_LEN); + ++pos->pos; + if (pos->pos == (ptrdiff_t)pos->chunk->datalen) { + if (!pos->chunk->next) + return -1; + pos->chunk_pos += pos->chunk->datalen; + pos->chunk = pos->chunk->next; + pos->pos = 0; + } + return 0; +} + +/** Return true iff the <b>n</b>-character string in <b>s</b> appears + * (verbatim) at <b>pos</b>. */ +static int +buf_matches_at_pos(const buf_pos_t *pos, const char *s, size_t n) +{ + buf_pos_t p; + if (!n) + return 1; + + memcpy(&p, pos, sizeof(p)); + + while (1) { + char ch = p.chunk->data[p.pos]; + if (ch != *s) + return 0; + ++s; + /* If we're out of characters that don't match, we match. Check this + * _before_ we test incrementing pos, in case we're at the end of the + * string. */ + if (--n == 0) + return 1; + if (buf_pos_inc(&p)<0) + return 0; + } +} + +/** Return the first position in <b>buf</b> at which the <b>n</b>-character + * string <b>s</b> occurs, or -1 if it does not occur. */ +int +buf_find_string_offset(const buf_t *buf, const char *s, size_t n) +{ + buf_pos_t pos; + buf_pos_init(buf, &pos); + while (buf_find_pos_of_char(*s, &pos) >= 0) { + if (buf_matches_at_pos(&pos, s, n)) { + tor_assert(pos.chunk_pos + pos.pos <= BUF_MAX_LEN); + return (int)(pos.chunk_pos + pos.pos); + } else { + if (buf_pos_inc(&pos)<0) + return -1; + } + } + return -1; +} + +/** Return 1 iff <b>buf</b> starts with <b>cmd</b>. <b>cmd</b> must be a null + * terminated string, of no more than PEEK_BUF_STARTSWITH_MAX bytes. */ +int +buf_peek_startswith(const buf_t *buf, const char *cmd) +{ + char tmp[PEEK_BUF_STARTSWITH_MAX]; + size_t clen = strlen(cmd); + if (clen == 0) + return 1; + if (BUG(clen > sizeof(tmp))) + return 0; + if (buf->datalen < clen) + return 0; + buf_peek(buf, tmp, clen); + return fast_memeq(tmp, cmd, clen); +} + +/** Return the index within <b>buf</b> at which <b>ch</b> first appears, + * or -1 if <b>ch</b> does not appear on buf. */ +static ptrdiff_t +buf_find_offset_of_char(buf_t *buf, char ch) +{ + chunk_t *chunk; + ptrdiff_t offset = 0; + tor_assert(buf->datalen <= BUF_MAX_LEN); + for (chunk = buf->head; chunk; chunk = chunk->next) { + char *cp = memchr(chunk->data, ch, chunk->datalen); + if (cp) + return offset + (cp - chunk->data); + else + offset += chunk->datalen; + } + return -1; +} + +/** Try to read a single LF-terminated line from <b>buf</b>, and write it + * (including the LF), NUL-terminated, into the *<b>data_len</b> byte buffer + * at <b>data_out</b>. Set *<b>data_len</b> to the number of bytes in the + * line, not counting the terminating NUL. Return 1 if we read a whole line, + * return 0 if we don't have a whole line yet, and return -1 if the line + * length exceeds *<b>data_len</b>. + */ +int +buf_get_line(buf_t *buf, char *data_out, size_t *data_len) +{ + size_t sz; + ptrdiff_t offset; + + if (!buf->head) + return 0; + + offset = buf_find_offset_of_char(buf, '\n'); + if (offset < 0) + return 0; + sz = (size_t) offset; + if (sz+2 > *data_len) { + *data_len = sz + 2; + return -1; + } + buf_get_bytes(buf, data_out, sz+1); + data_out[sz+1] = '\0'; + *data_len = sz+1; + return 1; +} + +/** Set *<b>output</b> to contain a copy of the data in *<b>input</b> */ +int +buf_set_to_copy(buf_t **output, + const buf_t *input) +{ + if (*output) + buf_free(*output); + *output = buf_copy(input); + return 0; +} + +/** Log an error and exit if <b>buf</b> is corrupted. + */ +void +buf_assert_ok(buf_t *buf) +{ + tor_assert(buf); + tor_assert(buf->magic == BUFFER_MAGIC); + + if (! buf->head) { + tor_assert(!buf->tail); + tor_assert(buf->datalen == 0); + } else { + chunk_t *ch; + size_t total = 0; + tor_assert(buf->tail); + for (ch = buf->head; ch; ch = ch->next) { + total += ch->datalen; + tor_assert(ch->datalen <= ch->memlen); + tor_assert(ch->datalen <= BUF_MAX_LEN); + tor_assert(ch->data >= &ch->mem[0]); + tor_assert(ch->data <= &ch->mem[0]+ch->memlen); + if (ch->data == &ch->mem[0]+ch->memlen) { + /* LCOV_EXCL_START */ + static int warned = 0; + if (! warned) { + log_warn(LD_BUG, "Invariant violation in buf.c related to #15083"); + warned = 1; + } + /* LCOV_EXCL_STOP */ + } + tor_assert(ch->data+ch->datalen <= &ch->mem[0] + ch->memlen); + if (!ch->next) + tor_assert(ch == buf->tail); + } + tor_assert(buf->datalen == total); + } +} |