forked from osmocom/wireshark
204 lines
5.7 KiB
C
204 lines
5.7 KiB
C
/* pem.c
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*
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* Implements loading of files in the format specified by RFC 7468.
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "config.h"
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#include "pem.h"
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#include "file_wrappers.h"
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#include "wtap-int.h"
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#include <wsutil/buffer.h>
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#include <glib.h>
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#include <string.h>
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/* 128 bytes should be enough to contain any line. Strictly speaking, 64 is
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enough, but we provide some leeway to accomodate nonconformant producers and
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trailing whitespace. The 2 extra bytes are for the trailing newline and NUL
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terminator. */
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#define MAX_LINE_LENGTH (128 + 2)
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/* based on the `label` production in RFC 7468 */
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#define RE_LABEL "([!-,.-~]([-\\s]?[!-,.-~])*)?"
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struct pem_priv {
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GRegex *re_blank_line;
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GRegex *re_pre_eb;
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GRegex *re_post_eb;
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};
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static char *read_complete_text_line(char line[MAX_LINE_LENGTH], FILE_T fh, int *err, gchar **err_info)
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{
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char *line_end;
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if (!(line_end = file_getsp(line, MAX_LINE_LENGTH, fh))) {
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*err = file_error(fh, err_info);
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return NULL;
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}
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if (strlen(line) != (size_t)(line_end - line)) {
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*err = WTAP_ERR_BAD_FILE;
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*err_info = g_strdup("unexpected NUL inside a line");
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return NULL;
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}
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if (line_end[-1] != '\n' && !file_eof(fh)) {
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*err = WTAP_ERR_BAD_FILE;
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*err_info = g_strdup("overlong line");
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return NULL;
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}
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return line_end;
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}
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static gboolean pem_read_value(wtap *wth, FILE_T fh, wtap_rec *rec,
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Buffer *buf, int *err, gchar **err_info)
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{
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struct pem_priv *priv = (struct pem_priv *)wth->priv;
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char line[MAX_LINE_LENGTH];
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// skip blank lines
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do {
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if (!read_complete_text_line(line, fh, err, err_info)) return FALSE;
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} while (g_regex_match(priv->re_blank_line, line, (GRegexMatchFlags)0, NULL));
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if (!g_regex_match(priv->re_pre_eb, line, (GRegexMatchFlags)0, NULL)) {
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*err = WTAP_ERR_BAD_FILE;
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*err_info = g_strdup("invalid pre-encapsulation boundary");
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return FALSE;
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}
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gint base64_state = 0;
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guint base64_save = 0;
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ws_buffer_clean(buf);
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for (; ; ) {
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char *line_end = read_complete_text_line(line, fh, err, err_info);
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if (!line_end) {
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if (*err == 0) {
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*err = WTAP_ERR_BAD_FILE;
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*err_info = g_strdup("missing post-encapsulation boundary");
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}
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return FALSE;
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}
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if (g_regex_match(priv->re_post_eb, line, (GRegexMatchFlags)0, NULL))
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break;
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guchar decoded[(sizeof(line) / 4) * 3 + 3];
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guint32 decoded_size = (guint32) g_base64_decode_step(
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line, line_end - line, decoded, &base64_state, &base64_save);
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if ((guint32)ws_buffer_length(buf) > G_MAXUINT32 - decoded_size) {
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// we can't set the packet length if this happens
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*err = WTAP_ERR_BAD_FILE;
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*err_info = g_strdup("encoded value too large");
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return FALSE;
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}
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ws_buffer_append(buf, decoded, decoded_size);
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}
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rec->rec_type = REC_TYPE_PACKET;
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rec->presence_flags = 0;
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rec->rec_header.packet_header.len =
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rec->rec_header.packet_header.caplen =
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(guint32)ws_buffer_length(buf);
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return TRUE;
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}
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static gboolean pem_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
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{
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*data_offset = file_tell(wth->fh);
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return pem_read_value(wth, wth->fh, &wth->rec, wth->rec_data, err, err_info);
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}
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static gboolean pem_seek_read(wtap *wth, gint64 seek_off, wtap_rec *rec,
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Buffer *buf, int *err, gchar **err_info)
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{
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if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
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return FALSE;
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return pem_read_value(wth, wth->random_fh, rec, buf, err, err_info);
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}
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static void pem_close(wtap *wth)
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{
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struct pem_priv *priv = (struct pem_priv *)wth->priv;
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g_regex_unref(priv->re_pre_eb);
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g_regex_unref(priv->re_post_eb);
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}
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wtap_open_return_val pem_open(wtap *wth, int *err, gchar **err_info)
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{
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static const char expected_magic[] = "-----BEGIN ";
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char actual_magic[sizeof(expected_magic) - 1];
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if (!wtap_read_bytes(wth->fh, &actual_magic, sizeof(actual_magic), err, err_info)) {
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if (*err == WTAP_ERR_SHORT_READ)
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return WTAP_OPEN_NOT_MINE;
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return WTAP_OPEN_ERROR;
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}
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if (memcmp(expected_magic, actual_magic, sizeof(actual_magic)) != 0)
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return WTAP_OPEN_NOT_MINE;
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if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
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return WTAP_OPEN_ERROR;
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wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_PEM;
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wth->file_encap = WTAP_ENCAP_BER;
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wth->snapshot_length = 0;
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wth->file_tsprec = WTAP_TSPREC_SEC;
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struct pem_priv *priv = g_new0(struct pem_priv, 1);
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priv->re_blank_line = g_regex_new("^\\s*$", G_REGEX_RAW, (GRegexMatchFlags)0, NULL);
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priv->re_pre_eb = g_regex_new("^-----BEGIN " RE_LABEL "-----\\s*$",
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(GRegexCompileFlags)(G_REGEX_RAW | G_REGEX_NO_AUTO_CAPTURE),
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(GRegexMatchFlags)0, NULL);
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priv->re_post_eb = g_regex_new("^-----END " RE_LABEL "-----\\s*$",
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(GRegexCompileFlags)(G_REGEX_RAW | G_REGEX_NO_AUTO_CAPTURE),
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(GRegexMatchFlags)0, NULL);
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wth->priv = priv;
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wth->subtype_read = pem_read;
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wth->subtype_seek_read = pem_seek_read;
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wth->subtype_close = pem_close;
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if (!priv->re_blank_line || !priv->re_pre_eb || !priv->re_post_eb) {
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*err = WTAP_ERR_INTERNAL;
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*err_info = g_strdup("failed to initialize reader");
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return WTAP_OPEN_ERROR;
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}
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return WTAP_OPEN_MINE;
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}
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/*
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* Editor modelines - http://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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