fe835ae95c
On at least some Linux distributions, dumpcap is either installed with elevated privileges sufficient to support traffic capture by default or can optionally be given those privileges. If it has those privileges, it's typically made group-executable but not world-executable and owned by a special group, e.g. "wireshark", so that only users in that group can use dumpcap to capture traffic. The user installing the Wireshark package is *not* necessarily put into that group by default; this means that any attempt by Wireshark or TShark to run dumpcap will fail with EACCES. If the exec call in the child process sends text error mesages, intended for end users, up the message pipe, as we had been doing, then figuring out *why* the exec failed would require some heuristic parsing to figure out whether it's a permissions problem or not. Instead of doing that, just send a message giving the errno for exec failing. For now, we just format an error message for that in the parent process, but this leaves room to do a better job. While we're at it, fix some cases where an empty error message could be printed.
98 lines
3.3 KiB
C
98 lines
3.3 KiB
C
/* sync_pipe.h
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* Low-level synchronization pipe routines for use by Wireshark/TShark
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* and dumpcap
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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/** @file
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*
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* Low-level sync pipe interfaces.
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*/
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#ifndef __SYNC_PIPE_H__
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#define __SYNC_PIPE_H__
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#include <ws_posix_compat.h>
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/*
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* Maximum length of sync pipe message data. Must be < 2^24, as the
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* message length is 3 bytes.
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* XXX - this must be large enough to handle a Really Big Filter
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* Expression, as the error message for an incorrect filter expression
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* is a bit larger than the filter expression.
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*/
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#define SP_MAX_MSG_LEN 4096
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/*
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* Indications sent out on the sync pipe (from child to parent).
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* We might want to switch to something like Thrift
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* (http://thrift.apache.org/) or Protocol Buffers
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* (http://code.google.com/p/protobuf-c/) if we ever need to use more
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* complex messages.
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*/
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#define SP_EXEC_FAILED 'X' /* errno value for the exec failing */
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#define SP_FILE 'F' /* the name of the recently opened file */
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#define SP_ERROR_MSG 'E' /* error message */
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#define SP_BAD_FILTER 'B' /* error message for bad capture filter */
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#define SP_PACKET_COUNT 'P' /* count of packets captured since last message */
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#define SP_DROPS 'D' /* count of packets dropped in capture */
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#define SP_SUCCESS 'S' /* success indication, no extra data */
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#define SP_TOOLBAR_CTRL 'T' /* interface toolbar control packet */
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/*
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* Win32 only: Indications sent out on the signal pipe (from parent to child)
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* (UNIX-like sends signals for this)
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*/
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#define SP_QUIT 'Q' /* "gracefully" capture quit message (SIGUSR1) */
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/* Write a message, with a string body, to the recipient pipe in the
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standard format (1-byte message indicator, 3-byte message length
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(excluding length and indicator field), and the string.
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If msg is NULL, the message has only a length and indicator. */
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extern void
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sync_pipe_write_string_msg(int pipe_fd, char indicator, const char *msg);
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/* Write a message, with an unsigned integer body, to the recipient
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pipe in the standard format (1-byte message indicator, 3-byte
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message length (excluding length and indicator field), and the
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unsigned integer, as a string. */
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extern void
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sync_pipe_write_uint_msg(int pipe_fd, char indicator, unsigned int num);
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/* Write a message, with an integer body, to the recipient pipe in the
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standard format (1-byte message indicator, 3-byte message length
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(excluding length and indicator field), and the integer, as a string. */
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extern void
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sync_pipe_write_int_msg(int pipe_fd, char indicator, int num);
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/** the child encountered an error, notify the parent */
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extern void
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sync_pipe_write_errmsgs_to_parent(int pipe_fd, const char *error_msg,
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const char *secondary_error_msg);
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/** Has the parent signalled the child to stop? */
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#define SIGNAL_PIPE_CTRL_ID_NONE "none"
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#ifdef _WIN32
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#define SIGNAL_PIPE_FORMAT "\\\\.\\pipe\\wireshark.%s.signal"
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#endif
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#endif /* sync_pipe.h */
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/*
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* Editor modelines - https://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 4
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* vi: set shiftwidth=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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