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HTTP: multipart parser well-instrumented and made more tolerant (#65)

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Dell C2665dnf returns multipart message with malformed
    Content-Type: header (missed quotes around parameter that
    contains special characters, per RFC 2045). This change makes
    parser more tolerant to such errors and adds a lot of
    instrumentation to easy fix similar problems in a future
This commit is contained in:
Alexander Pevzner
2020-08-19 01:14:41 +03:00
parent 5ba97c0b44
commit 40c89d465f
6 changed files with 206 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files
.gitignore
+1
View File
@@ -4,6 +4,7 @@ libsane-airscan.so.1
airscan-discover
test
test-decode
test-multipart
test-uri
tags
Makefile
+6 -3
View File
@@ -74,9 +74,9 @@ $(OBJDIR)%.o: %.c Makefile airscan.h
.PHONY: all clean install man
all: tags $(BACKEND) $(DISCOVER) test test-decode test-uri
all: tags $(BACKEND) $(DISCOVER) test test-decode test-multipart test-uri
tags: $(SRC) airscan.h test.c test-decode.c test-uri.c
tags: $(SRC) airscan.h test.c test-decode.c test-multipart.c test-uri.c
-ctags -R .
$(BACKEND): $(OBJDIR)airscan.o $(LIBAIRSCAN) airscan.sym
@@ -103,7 +103,7 @@ install: all
[ "$(COMPRESS)" = "" ] || $(COMPRESS) -f $(DESTDIR)$(PREFIX)$(MANDIR)/man5/$(MAN_BACKEND)
clean:
rm -f test test-decode test-uri $(BACKEND) tags
rm -f test test-decode test-multipart test-uri $(BACKEND) tags
rm -rf $(OBJDIR)
uninstall:
@@ -127,5 +127,8 @@ test: $(BACKEND) test.c
test-decode: test-decode.c $(LIBAIRSCAN)
$(CC) -o test-decode test-decode.c $(CPPFLAGS) $(common_CFLAGS) $(LIBAIRSCAN) $(tests_LDFLAGS)
test-multipart: test-multipart.c $(LIBAIRSCAN)
$(CC) -o test-multipart test-multipart.c $(CPPFLAGS) $(common_CFLAGS) $(LIBAIRSCAN) $(tests_LDFLAGS)
test-uri: test-uri.c $(LIBAIRSCAN)
$(CC) -o test-uri test-uri.c $(CPPFLAGS) $(common_CFLAGS) $(LIBAIRSCAN) $(tests_LDFLAGS)
airscan-eloop.c
+5 -9
View File
@@ -25,7 +25,7 @@ static bool eloop_thread_running;
static ll_head eloop_call_pending_list;
static bool eloop_poll_restart;
static char *eloop_estring = NULL;
static __thread char eloop_estring[256];
static void (*eloop_start_stop_callbacks[ELOOP_START_STOP_CALLBACKS_MAX]) (bool);
static int eloop_start_stop_callbacks_count;
@@ -544,19 +544,15 @@ eloop_fdpoll_set_mask (eloop_fdpoll *fdpoll, ELOOP_FDPOLL_MASK mask)
error
eloop_eprintf(const char *fmt, ...)
{
char *estring;
va_list ap;
log_assert(NULL, pthread_equal(pthread_self(), eloop_thread));
char buf[sizeof(eloop_estring)];
va_start(ap, fmt);
estring = str_vprintf(fmt, ap);
vsnprintf(buf, sizeof(buf), fmt, ap);
strcpy(eloop_estring, buf);
va_end(ap);
mem_free(eloop_estring);
eloop_estring = estring;
return ERROR(estring);
return ERROR(eloop_estring);
}
/* vim:ts=8:sw=4:et
airscan-http.c
+78 -30
View File
@@ -1214,7 +1214,7 @@ http_hdr_params_chr_isspec (char c)
return true;
default:
return false;
return safe_isspace(c);
}
}
@@ -1239,7 +1239,7 @@ http_hdr_params_chr_isspace (char c)
* Result is saved into `params' as collection of name/value fields
*/
static error
http_hdr_params_parse (http_hdr *params, const char *in)
http_hdr_params_parse (http_hdr *params, const char *name, const char *in)
{
enum {
/* params ::= param [';' params]
@@ -1292,7 +1292,8 @@ http_hdr_params_parse (http_hdr *params, const char *in)
state = SP1;
field = NULL;
} else {
return ERROR("http: invalid parameter");
return eloop_eprintf(
"http %s: expected '=' or ';', got: %s", name, in);
}
break;
@@ -1321,7 +1322,7 @@ http_hdr_params_parse (http_hdr *params, const char *in)
break;
case TOKEN:
if (!http_hdr_params_chr_isspec(c)) {
if (c != ';' && c != '"' && !safe_isspace(c)) {
field->value = str_append_c(field->value, c);
} else {
state = SP4;
@@ -1331,7 +1332,8 @@ http_hdr_params_parse (http_hdr *params, const char *in)
case END:
if (c != ';') {
return ERROR("http: invalid parameter");
return eloop_eprintf(
"http %s: expected ';', got: %s", name, in);
}
state = SP1;
@@ -1343,7 +1345,7 @@ http_hdr_params_parse (http_hdr *params, const char *in)
}
if (state == STRING || state == STRING_BSLASH) {
return ERROR("http: invalid parameter");
return eloop_eprintf( "http %s: unterminated quoted string");
}
return NULL;
@@ -1408,7 +1410,7 @@ http_multipart_find_boundary (const char *boundary, size_t boundary_len,
* 1) skip header
* 2) fetch content type
*/
static bool
static error
http_multipart_adjust_part (http_data *part)
{
const char *split;
@@ -1419,7 +1421,7 @@ http_multipart_adjust_part (http_data *part)
/* Locate end of headers */
split = memmem(part->bytes, part->size, "\r\n\r\n", 4);
if (split == NULL) {
return false;
return ERROR("http multipart: can't locate end of part headers");
}
/* Parse headers and obtain content-type */
@@ -1434,7 +1436,7 @@ http_multipart_adjust_part (http_data *part)
http_hdr_cleanup(&hdr);
if (err != NULL) {
return false;
return eloop_eprintf("http multipart: %s", ESTRING(err));
}
/* Cut of header */
@@ -1444,7 +1446,7 @@ http_multipart_adjust_part (http_data *part)
part->size -= 2; /* CR/LF preceding next boundary */
return true;
return NULL;
}
/* Free http_multipart
@@ -1462,26 +1464,38 @@ http_multipart_free (http_multipart *mp)
}
/* Parse MIME multipart message body
* Saves result into `out'. Result may be NULL, if no multipart
*/
static http_multipart*
http_multipart_parse (http_data *data, const char *content_type)
static error
http_multipart_parse (http_multipart **out, log_ctx *log,
http_data *data, const char *content_type)
{
http_multipart *mp;
http_hdr params;
const char *boundary;
size_t boundary_len = 0;
const char *data_beg, *data_end, *data_prev;
error err;
ll_node *node;
/* Check MIME type */
*out = NULL;
if (strncmp(data->content_type, "multipart/", 10)) {
return NULL;
}
/* Obtain boundary */
http_hdr_init(&params);
if (http_hdr_params_parse(&params, content_type) != NULL) {
err = http_hdr_params_parse(&params, "Content-Type", content_type);
if (err != NULL) {
http_hdr_cleanup(&params);
return NULL;
return err;
}
log_debug(log, "http multipart parameters:");
for (LL_FOR_EACH(node, &params.fields)) {
http_hdr_field *field = OUTER_STRUCT(node, http_hdr_field, chain);
log_debug(log, " %s=\"%s\"", field->name, field->value);
}
boundary = http_hdr_get (&params, "boundary");
@@ -1499,7 +1513,7 @@ http_multipart_parse (http_data *data, const char *content_type)
http_hdr_cleanup(&params);
if (!boundary) {
return NULL;
return ERROR("http multipart: missed boundary parameter");
}
/* Create http_multipart structure */
@@ -1522,9 +1536,10 @@ http_multipart_parse (http_data *data, const char *content_type)
data_prev, part - data_prev);
http_multipart_add_body(mp, body);
if (!http_multipart_adjust_part(body)) {
err = http_multipart_adjust_part(body);
if (err != NULL) {
http_multipart_free(mp);
return NULL;
return err;
}
}
@@ -1539,7 +1554,19 @@ http_multipart_parse (http_data *data, const char *content_type)
data_beg = next;
}
return mp;
if (mp->count == 0) {
http_multipart_free(mp);
return ERROR("http multipart: no parts found");
}
if (data_beg != data_end) {
log_debug(log,
"http multipart: found %d bytes of garbage at the end of message",
(int)(data_end - data_beg));
}
*out = mp;
return NULL;
}
/******************** HTTP data ********************/
@@ -1865,7 +1892,6 @@ struct http_query {
bool submitted; /* http_query_submit() called */
uint64_t eloop_callid; /* For eloop_call_cancel */
error err; /* Transport error */
bool oom; /* Out of memory error */
struct addrinfo *addrs; /* Addresses to connect to */
struct addrinfo *addr_next; /* Next address to try */
int sock; /* HTTP socket */
@@ -2326,10 +2352,10 @@ http_query_on_body_callback (http_parser *parser,
}
if (!http_data_append(q->response_data, data, size)) {
q->oom = true;
q->err = ERROR_ENOMEM;
}
return 0;
return q->err ? 1 : 0;
}
/* HTTP parser on_headers_complete callback
@@ -2367,14 +2393,15 @@ http_query_on_message_complete (http_parser *parser)
content_type = http_query_get_response_header(q, "Content-Type");
if (content_type != NULL) {
http_data_set_content_type(q->response_data, content_type);
q->response_multipart = http_multipart_parse(q->response_data,
content_type);
q->err = http_multipart_parse(
&q->response_multipart, q->client->log,
q->response_data, content_type);
}
}
q->http_parser_done = true;
return 0;
return q->err ? 1 : 0;
}
/* HTTP parser callbacks
@@ -2476,14 +2503,13 @@ http_query_fdpoll_callback (int fd, void *data, ELOOP_FDPOLL_MASK mask)
io_buf, rc);
if (q->http_parser.http_errno != HPE_OK) {
error err = ERROR(http_errno_description(q->http_parser.http_errno));
http_query_complete(q, err);
} else if (q->http_parser_done) {
error err = NULL;
if (q->oom) {
err = ERROR_ENOMEM;
error err = q->err;
if (err == NULL) {
err = ERROR(http_errno_description(q->http_parser.http_errno));
}
http_query_complete(q, err);
} else if (q->http_parser_done) {
http_query_complete(q, NULL);
} else if (rc == 0) {
error err = ERROR("connection closed by device");
http_query_complete(q, err);
@@ -3016,6 +3042,28 @@ http_query_foreach_response_header (const http_query *q,
hdr_for_each(&q->response_header, callback, ptr);
}
/* Decode response part of the query.
* This function is intended for testing purposes, not for regular use
*/
error
http_query_test_decode_response (http_query *q, const void *data, size_t size)
{
http_parser_execute(&q->http_parser, &http_query_callbacks, data, size);
if (q->http_parser.http_errno != HPE_OK) {
if (q->err != NULL) {
return q->err;
}
return ERROR(http_errno_description(q->http_parser.http_errno));
}
if (!q->http_parser_done) {
return ERROR("truncated response");
}
return NULL;
}
/******************** HTTP initialization & cleanup ********************/
/* Initialize HTTP client
*/
airscan.h
+6
View File
@@ -1742,6 +1742,12 @@ http_query_foreach_response_header (const http_query *q,
void (*callback)(const char *name, const char *value, void *ptr),
void *ptr);
/* Decode response part of the query.
* This function is intended for testing purposes, not for regular use
*/
error
http_query_test_decode_response (http_query *q, const void *data, size_t size);
/* HTTP schemes
*/
typedef enum {
test-multipart.c
+110
View File
@@ -0,0 +1,110 @@
/* sane-airscan HTTP multipart decoder test
*
* Copyright (C) 2019 and up by Alexander Pevzner (pzz@apevzner.com)
* See LICENSE for license terms and conditions
*/
#include "airscan.h"
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Print error message and exit
*/
void __attribute__((noreturn))
die (const char *format, ...)
{
va_list ap;
va_start(ap, format);
vprintf(format, ap);
printf("\n");
va_end(ap);
exit(1);
}
/* The main function
*/
int
main (int argc, char **argv)
{
const char *file;
FILE *fp;
long size;
int rc;
void *data;
error err;
http_client *client;
http_uri *uri;
http_query *q;
int i, cnt;
/* Parse command-line arguments */
if (argc != 2) {
die("usage: %s file", argv[0]);
}
file = argv[1];
/* Load the file */
fp = fopen(file, "rb");
if (fp == NULL) {
die("%s: %s", file, strerror(errno));
}
rc = fseek(fp, 0, SEEK_END);
if (rc < 0) {
die("%s: %s", file, strerror(errno));
}
size = ftell(fp);
if (size < 0) {
die("%s: %s", file, strerror(errno));
}
rc = fseek(fp, 0, SEEK_SET);
if (rc < 0) {
die("%s: %s", file, strerror(errno));
}
data = mem_new(char, size);
if ((size_t) size != fread(data, 1, size, fp)) {
die("%s: read error", file);
}
fclose(fp);
/* Initialize logging */
log_init();
conf.dbg_enabled = true;
log_configure();
/* Decode the image */
client = http_client_new(NULL, NULL);
uri = http_uri_new("http://localhost", false);
q = http_query_new(client, uri, "GET", NULL, NULL);
err = http_query_test_decode_response(q, data, size);
if (err != NULL) {
die("%s", ESTRING(err));
}
cnt = http_query_get_mp_response_count(q);
if (cnt > 0) {
printf("Part Size Content-Type\n");
printf("==== ==== ============\n");
for (i = 0; i < cnt; i ++) {
http_data *data = http_query_get_mp_response_data(q, i);
printf("%3d %8d %s\n", i, (int) data->size, data->content_type);
}
}
return 0;
}
/* vim:ts=8:sw=4:et
*/