diff --git a/src/common/compress.c b/src/common/compress.c
index 9a24025db0..8502dee25c 100644
--- a/src/common/compress.c
+++ b/src/common/compress.c
@@ -285,6 +285,26 @@ tor_compress_supports_method(compress_method_t method)
}
}
+/**
+ * Return a bitmask of the supported compression types, where 1<<m is
+ * set in the bitmask if and only if compression with method m is
+ * supported.
+ */
+unsigned
+tor_compress_get_supported_method_bitmask(void)
+{
+ static unsigned supported = 0;
+ if (supported == 0) {
+ compress_method_t m;
+ for (m = NO_METHOD; m <= UNKNOWN_METHOD; ++m) {
+ if (tor_compress_supports_method(m)) {
+ supported |= (1u << m);
+ }
+ }
+ }
+ return supported;
+}
+
/** Table of compression method names. These should have an "x-" prefix,
* if they are not listed in the IANA content coding registry. */
static const struct {
diff --git a/src/common/compress.h b/src/common/compress.h
index 95b70c02ec..5b47c5d458 100644
--- a/src/common/compress.h
+++ b/src/common/compress.h
@@ -16,12 +16,12 @@
* functions here. Call tor_compress_supports_method() to check if a given
* compression schema is supported by Tor. */
typedef enum {
- NO_METHOD=0,
+ NO_METHOD=0, // This method must be first.
GZIP_METHOD=1,
ZLIB_METHOD=2,
LZMA_METHOD=3,
ZSTD_METHOD=4,
- UNKNOWN_METHOD=5
+ UNKNOWN_METHOD=5, // This method must be last. Add new ones in the middle.
} compress_method_t;
/**
@@ -48,6 +48,7 @@ compress_method_t detect_compression_method(const char *in, size_t in_len);
int tor_compress_is_compression_bomb(size_t size_in, size_t size_out);
int tor_compress_supports_method(compress_method_t method);
+unsigned tor_compress_get_supported_method_bitmask(void);
const char * compression_method_get_name(compress_method_t method);
compress_method_t compression_method_get_by_name(const char *name);
diff --git a/src/or/directory.c b/src/or/directory.c
index 751d46910e..e53bc78a35 100644
--- a/src/or/directory.c
+++ b/src/or/directory.c
@@ -2928,6 +2928,31 @@ write_http_response_header(dir_connection_t *conn, ssize_t length,
cache_lifetime);
}
+/** Parse the compression methods listed in an Accept-Encoding header h,
+ * and convert them to a bitfield where compression method x is supported if
+ * and only if 1 << x is set in the bitfield. */
+STATIC unsigned
+parse_accept_encoding_header(const char *h)
+{
+ unsigned result = (1u << NO_METHOD);
+ smartlist_t *methods = smartlist_new();
+ smartlist_split_string(methods, h, ",",
+ SPLIT_SKIP_SPACE|SPLIT_STRIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+
+ SMARTLIST_FOREACH_BEGIN(methods, const char *, m) {
+ compress_method_t method = compression_method_get_by_name(m);
+ if (method != UNKNOWN_METHOD) {
+ tor_assert(method < 8*sizeof(unsigned));
+ result |= (1u << method);
+ }
+ } SMARTLIST_FOREACH_END(m);
+ SMARTLIST_FOREACH_BEGIN(methods, char *, m) {
+ tor_free(m);
+ } SMARTLIST_FOREACH_END(m);
+ smartlist_free(methods);
+ return result;
+}
+
/** Decide whether a client would accept the consensus we have.
*
* Clients can say they only want a consensus if it's signed by more
@@ -3002,8 +3027,9 @@ choose_compression_level(ssize_t n_bytes)
/** Information passed to handle a GET request. */
typedef struct get_handler_args_t {
- /** True if the client asked for compressed data. */
- int compressed;
+ /** Bitmask of compression methods that the client said (or implied) it
+ * supported. */
+ unsigned compression_supported;
/** If nonzero, the time included an if-modified-since header with this
* value. */
time_t if_modified_since;
@@ -3077,8 +3103,9 @@ directory_handle_command_get,(dir_connection_t *conn, const char *headers,
{
char *url, *url_mem, *header;
time_t if_modified_since = 0;
- int compressed;
+ int zlib_compressed_in_url;
size_t url_len;
+ unsigned compression_methods_supported;
/* We ignore the body of a GET request. */
(void)req_body;
@@ -3109,17 +3136,30 @@ directory_handle_command_get,(dir_connection_t *conn, const char *headers,
url_mem = url;
url_len = strlen(url);
- compressed = url_len > 2 && !strcmp(url+url_len-2, ".z");
- if (compressed) {
+
+ zlib_compressed_in_url = url_len > 2 && !strcmp(url+url_len-2, ".z");
+ if (zlib_compressed_in_url) {
url[url_len-2] = '\0';
url_len -= 2;
}
+ if ((header = http_get_header(headers, "Accept-Encoding"))) {
+ compression_methods_supported = parse_accept_encoding_header(header);
+ tor_free(header);
+ } else {
+ compression_methods_supported = (1u << NO_METHOD);
+ if (zlib_compressed_in_url)
+ compression_methods_supported |= (1u << ZLIB_METHOD);
+ }
+
+ /* Remove all methods that we don't both support. */
+ compression_methods_supported &= tor_compress_get_supported_method_bitmask();
+
get_handler_args_t args;
args.url = url;
args.headers = headers;
args.if_modified_since = if_modified_since;
- args.compressed = compressed;
+ args.compression_supported = compression_methods_supported;
int i, result = -1;
for (i = 0; url_table[i].string; ++i) {
@@ -3198,7 +3238,7 @@ handle_get_current_consensus(dir_connection_t *conn,
const get_handler_args_t *args)
{
const char *url = args->url;
- const int compressed = args->compressed;
+ const int compressed = args->compression_supported & (1u << ZLIB_METHOD);
const time_t if_modified_since = args->if_modified_since;
int clear_spool = 0;
@@ -3339,7 +3379,7 @@ static int
handle_get_status_vote(dir_connection_t *conn, const get_handler_args_t *args)
{
const char *url = args->url;
- const int compressed = args->compressed;
+ const int compressed = args->compression_supported & (1u << ZLIB_METHOD);
{
int current;
ssize_t body_len = 0;
@@ -3446,7 +3486,7 @@ static int
handle_get_microdesc(dir_connection_t *conn, const get_handler_args_t *args)
{
const char *url = args->url;
- const int compressed = args->compressed;
+ const int compressed = args->compression_supported & (1u << ZLIB_METHOD);
int clear_spool = 1;
{
conn->spool = smartlist_new();
@@ -3496,7 +3536,7 @@ static int
handle_get_descriptor(dir_connection_t *conn, const get_handler_args_t *args)
{
const char *url = args->url;
- const int compressed = args->compressed;
+ const int compressed = args->compression_supported & (1u << ZLIB_METHOD);
const or_options_t *options = get_options();
int clear_spool = 1;
if (!strcmpstart(url,"/tor/server/") ||
@@ -3589,7 +3629,7 @@ static int
handle_get_keys(dir_connection_t *conn, const get_handler_args_t *args)
{
const char *url = args->url;
- const int compressed = args->compressed;
+ const int compressed = args->compression_supported & (1u << ZLIB_METHOD);
const time_t if_modified_since = args->if_modified_since;
{
smartlist_t *certs = smartlist_new();
diff --git a/src/or/directory.h b/src/or/directory.h
index e4fbbe6891..8473d39e85 100644
--- a/src/or/directory.h
+++ b/src/or/directory.h
@@ -196,6 +196,7 @@ STATIC int next_random_exponential_delay(int delay, int max_delay);
STATIC int parse_hs_version_from_post(const char *url, const char *prefix,
const char **end_pos);
+STATIC unsigned parse_accept_encoding_header(const char *h);
#endif
#endif
diff --git a/src/test/test_dir_handle_get.c b/src/test/test_dir_handle_get.c
index 392fa4dde0..7794bd7d65 100644
--- a/src/test/test_dir_handle_get.c
+++ b/src/test/test_dir_handle_get.c
@@ -2497,6 +2497,52 @@ test_dir_handle_get_status_vote_current_authority(void* data)
dirvote_free_all();
}
+static void
+test_dir_handle_get_parse_accept_encoding(void *arg)
+{
+ (void)arg;
+ const unsigned B_NONE = 1u << NO_METHOD;
+ const unsigned B_ZLIB = 1u << ZLIB_METHOD;
+ const unsigned B_GZIP = 1u << GZIP_METHOD;
+ const unsigned B_LZMA = 1u << LZMA_METHOD;
+ const unsigned B_ZSTD = 1u << ZSTD_METHOD;
+
+ unsigned encodings;
+
+ encodings = parse_accept_encoding_header("");
+ tt_uint_op(B_NONE, OP_EQ, encodings);
+
+ encodings = parse_accept_encoding_header(" ");
+ tt_uint_op(B_NONE, OP_EQ, encodings);
+
+ encodings = parse_accept_encoding_header("dewey, cheatham, and howe ");
+ tt_uint_op(B_NONE, OP_EQ, encodings);
+
+ encodings = parse_accept_encoding_header("dewey, cheatham, and gzip");
+ tt_uint_op(B_NONE, OP_EQ, encodings);
+
+ encodings = parse_accept_encoding_header("dewey, cheatham, and, gzip");
+ tt_uint_op(B_NONE|B_GZIP, OP_EQ, encodings);
+
+ encodings = parse_accept_encoding_header(" gzip");
+ tt_uint_op(B_NONE|B_GZIP, OP_EQ, encodings);
+
+ encodings = parse_accept_encoding_header("gzip");
+ tt_uint_op(B_NONE|B_GZIP, OP_EQ, encodings);
+
+ encodings = parse_accept_encoding_header("x-zstd, deflate, x-lzma");
+ tt_uint_op(B_NONE|B_ZLIB|B_ZSTD|B_LZMA, OP_EQ, encodings);
+
+ encodings = parse_accept_encoding_header("x-zstd, deflate, x-lzma, gzip");
+ tt_uint_op(B_NONE|B_ZLIB|B_ZSTD|B_LZMA|B_GZIP, OP_EQ, encodings);
+
+ encodings = parse_accept_encoding_header("x-zstd,deflate,x-lzma,gzip");
+ tt_uint_op(B_NONE|B_ZLIB|B_ZSTD|B_LZMA|B_GZIP, OP_EQ, encodings);
+
+ done:
+ ;
+}
+
#define DIR_HANDLE_CMD(name,flags) \
{ #name, test_dir_handle_get_##name, (flags), NULL, NULL }
@@ -2555,6 +2601,7 @@ struct testcase_t dir_handle_get_tests[] = {
DIR_HANDLE_CMD(status_vote_next_consensus_signatures_not_found, 0),
DIR_HANDLE_CMD(status_vote_next_consensus_signatures_busy, 0),
DIR_HANDLE_CMD(status_vote_next_consensus_signatures, 0),
+ DIR_HANDLE_CMD(parse_accept_encoding, 0),
END_OF_TESTCASES
};