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Diffstat (limited to 'src/lib/net/buffers_net.c')
| -rw-r--r-- | src/lib/net/buffers_net.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/src/lib/net/buffers_net.c b/src/lib/net/buffers_net.c new file mode 100644 index 0000000000..01be30f5af --- /dev/null +++ b/src/lib/net/buffers_net.c @@ -0,0 +1,192 @@ +/* Copyright (c) 2001 Matej Pfajfar. + * Copyright (c) 2001-2004, Roger Dingledine. + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2018, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +#define BUFFERS_PRIVATE +#include "lib/net/buffers_net.h" +#include "lib/container/buffers.h" +#include "lib/log/torlog.h" +#include "lib/log/util_bug.h" + +#include <stdlib.h> + +#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) */ + +/** Read up to <b>at_most</b> bytes from the socket <b>fd</b> into + * <b>chunk</b> (which must be on <b>buf</b>). If we get an EOF, set + * *<b>reached_eof</b> to 1. Return -1 on error, 0 on eof or blocking, + * and the number of bytes read otherwise. */ +static inline int +read_to_chunk(buf_t *buf, chunk_t *chunk, tor_socket_t fd, size_t at_most, + int *reached_eof, int *socket_error) +{ + ssize_t read_result; + if (at_most > CHUNK_REMAINING_CAPACITY(chunk)) + at_most = CHUNK_REMAINING_CAPACITY(chunk); + read_result = tor_socket_recv(fd, CHUNK_WRITE_PTR(chunk), at_most, 0); + + if (read_result < 0) { + int e = tor_socket_errno(fd); + if (!ERRNO_IS_EAGAIN(e)) { /* it's a real error */ +#ifdef _WIN32 + if (e == WSAENOBUFS) + log_warn(LD_NET,"recv() failed: WSAENOBUFS. Not enough ram?"); +#endif + *socket_error = e; + return -1; + } + return 0; /* would block. */ + } else if (read_result == 0) { + log_debug(LD_NET,"Encountered eof on fd %d", (int)fd); + *reached_eof = 1; + return 0; + } else { /* actually got bytes. */ + buf->datalen += read_result; + chunk->datalen += read_result; + log_debug(LD_NET,"Read %ld bytes. %d on inbuf.", (long)read_result, + (int)buf->datalen); + tor_assert(read_result < INT_MAX); + return (int)read_result; + } +} + +/** Read from socket <b>s</b>, writing onto end of <b>buf</b>. Read at most + * <b>at_most</b> bytes, growing the buffer as necessary. If recv() returns 0 + * (because of EOF), set *<b>reached_eof</b> to 1 and return 0. Return -1 on + * error; else return the number of bytes read. + */ +/* XXXX indicate "read blocked" somehow? */ +int +buf_read_from_socket(buf_t *buf, tor_socket_t s, size_t at_most, + int *reached_eof, + int *socket_error) +{ + /* XXXX It's stupid to overload the return values for these functions: + * "error status" and "number of bytes read" are not mutually exclusive. + */ + int r = 0; + size_t total_read = 0; + + check(); + tor_assert(reached_eof); + tor_assert(SOCKET_OK(s)); + + if (BUG(buf->datalen >= INT_MAX)) + return -1; + if (BUG(buf->datalen >= INT_MAX - at_most)) + return -1; + + while (at_most > total_read) { + size_t readlen = at_most - total_read; + chunk_t *chunk; + if (!buf->tail || CHUNK_REMAINING_CAPACITY(buf->tail) < MIN_READ_LEN) { + chunk = buf_add_chunk_with_capacity(buf, at_most, 1); + if (readlen > chunk->memlen) + readlen = chunk->memlen; + } else { + size_t cap = CHUNK_REMAINING_CAPACITY(buf->tail); + chunk = buf->tail; + if (cap < readlen) + readlen = cap; + } + + r = read_to_chunk(buf, chunk, s, readlen, reached_eof, socket_error); + check(); + if (r < 0) + return r; /* Error */ + tor_assert(total_read+r < INT_MAX); + total_read += r; + if ((size_t)r < readlen) { /* eof, block, or no more to read. */ + break; + } + } + return (int)total_read; +} + +/** Helper for buf_flush_to_socket(): try to write <b>sz</b> bytes from chunk + * <b>chunk</b> of buffer <b>buf</b> onto socket <b>s</b>. On success, deduct + * the bytes written from *<b>buf_flushlen</b>. Return the number of bytes + * written on success, 0 on blocking, -1 on failure. + */ +static inline int +flush_chunk(tor_socket_t s, buf_t *buf, chunk_t *chunk, size_t sz, + size_t *buf_flushlen) +{ + ssize_t write_result; + + if (sz > chunk->datalen) + sz = chunk->datalen; + write_result = tor_socket_send(s, chunk->data, sz, 0); + + if (write_result < 0) { + int e = tor_socket_errno(s); + if (!ERRNO_IS_EAGAIN(e)) { /* it's a real error */ +#ifdef _WIN32 + if (e == WSAENOBUFS) + log_warn(LD_NET,"write() failed: WSAENOBUFS. Not enough ram?"); +#endif + return -1; + } + log_debug(LD_NET,"write() would block, returning."); + return 0; + } else { + *buf_flushlen -= write_result; + buf_drain(buf, write_result); + tor_assert(write_result < INT_MAX); + return (int)write_result; + } +} + +/** Write data from <b>buf</b> to the socket <b>s</b>. Write at most + * <b>sz</b> bytes, decrement *<b>buf_flushlen</b> by + * the number of bytes actually written, and remove the written bytes + * from the buffer. Return the number of bytes written on success, + * -1 on failure. Return 0 if write() would block. + */ +int +buf_flush_to_socket(buf_t *buf, tor_socket_t s, size_t sz, + size_t *buf_flushlen) +{ + /* XXXX It's stupid to overload the return values for these functions: + * "error status" and "number of bytes flushed" are not mutually exclusive. + */ + int r; + size_t flushed = 0; + tor_assert(buf_flushlen); + tor_assert(SOCKET_OK(s)); + if (BUG(*buf_flushlen > buf->datalen)) { + *buf_flushlen = buf->datalen; + } + if (BUG(sz > *buf_flushlen)) { + sz = *buf_flushlen; + } + + check(); + while (sz) { + size_t flushlen0; + tor_assert(buf->head); + if (buf->head->datalen >= sz) + flushlen0 = sz; + else + flushlen0 = buf->head->datalen; + + r = flush_chunk(s, buf, buf->head, flushlen0, buf_flushlen); + check(); + if (r < 0) + return r; + flushed += r; + sz -= r; + if (r == 0 || (size_t)r < flushlen0) /* can't flush any more now. */ + break; + } + tor_assert(flushed < INT_MAX); + return (int)flushed; +} |