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[settings] Re-add "uristring" setting type
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Commit 09b057c ("[settings] Remove "uristring" setting type") removed
support for URI-encoded settings via the "uristring" setting type, on
the basis that such encoding was no longer necessary to avoid problems
with the command line parser.

Other valid use cases for the "uristring" setting type do exist: for
example, a password containing a '/' character expanded via

  chain http://username:${password:uristring}@server.name/boot.php

Restore the existence of the "uristring" setting, avoiding the
potentially large stack allocations that were used in the old code
prior to commit 09b057c ("[settings] Remove "uristring" setting
type").

Requested-by: Robin Smidsrød <robin@smidsrod.no>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
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@mcb30
mcb30 committed Aug 25, 2015
1 parent 4e03af8 commit ba36953
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Showing 5 changed files with 126 additions and 30 deletions.
38 changes: 33 additions & 5 deletions src/core/settings.c
View file
Expand Up @@ -1666,15 +1666,43 @@ const struct setting_type setting_type_string __setting_type = {
.format = format_string_setting,
};

/** A URI-encoded string setting type
/**
* Parse URI-encoded string setting value
*
* This setting type is obsolete; the name ":uristring" is retained to
* avoid breaking existing scripts.
* @v type Setting type
* @v value Formatted setting value
* @v buf Buffer to contain raw value
* @v len Length of buffer
* @ret len Length of raw value, or negative error
*/
static int parse_uristring_setting ( const struct setting_type *type __unused,
const char *value, void *buf, size_t len ){

return uri_decode ( value, buf, len );
}

/**
* Format URI-encoded string setting value
*
* @v type Setting type
* @v raw Raw setting value
* @v raw_len Length of raw setting value
* @v buf Buffer to contain formatted value
* @v len Length of buffer
* @ret len Length of formatted value, or negative error
*/
static int format_uristring_setting ( const struct setting_type *type __unused,
const void *raw, size_t raw_len,
char *buf, size_t len ) {

return uri_encode ( 0, raw, raw_len, buf, len );
}

/** A URI-encoded string setting type */
const struct setting_type setting_type_uristring __setting_type = {
.name = "uristring",
.parse = parse_string_setting,
.format = format_string_setting,
.parse = parse_uristring_setting,
.format = format_uristring_setting,
};

/**
Expand Down
93 changes: 71 additions & 22 deletions src/core/uri.c
View file
Expand Up @@ -39,34 +39,62 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <ipxe/uri.h>

/**
* Decode URI field (in place)
* Decode URI field
*
* @v string String
* @v encoded Encoded field
* @v buf Data buffer
* @v len Length
* @ret len Length of data
*
* URI decoding can never increase the length of a string; we can
* therefore safely decode in place.
*/
static void uri_decode ( char *string ) {
char *dest = string;
size_t uri_decode ( const char *encoded, void *buf, size_t len ) {
uint8_t *out = buf;
unsigned int count = 0;
char hexbuf[3];
char *hexbuf_end;
char c;
char decoded;
unsigned int skip;

/* Copy string, decoding escaped characters as necessary */
do {
c = *(string++);
while ( ( c = *(encoded++) ) ) {
if ( c == '%' ) {
snprintf ( hexbuf, sizeof ( hexbuf ), "%s", string );
snprintf ( hexbuf, sizeof ( hexbuf ), "%s", encoded );
decoded = strtoul ( hexbuf, &hexbuf_end, 16 );
skip = ( hexbuf_end - hexbuf );
string += skip;
encoded += skip;
if ( skip )
c = decoded;
}
*(dest++) = c;
} while ( c );
if ( count < len )
out[count] = c;
count++;
}
return count;
}

/**
* Decode URI field in-place
*
* @v uri URI
* @v field URI field index
*/
static void uri_decode_inplace ( struct uri *uri, unsigned int field ) {
const char *encoded = uri_field ( uri, field );
char *decoded = ( ( char * ) encoded );
size_t len;

/* Do nothing if field is not present */
if ( ! encoded )
return;

/* Decode field in place */
len = uri_decode ( encoded, decoded, strlen ( encoded ) );

/* Terminate decoded string */
decoded[len] = '\0';
}

/**
Expand Down Expand Up @@ -115,10 +143,15 @@ static int uri_character_escaped ( char c, unsigned int field ) {
* '%', the full set of characters with significance to the
* URL parser is "/#:@?". We choose for each URI field which
* of these require escaping in our use cases.
*
* For the scheme field (equivalently, if field is zero), we
* escape anything that has significance not just for our URI
* parser but for any other URI parsers (e.g. HTTP query
* string parsers, which care about '=' and '&').
*/
static const char *escaped[URI_FIELDS] = {
/* Scheme: escape everything */
[URI_SCHEME] = "/#:@?",
/* Scheme or default: escape everything */
[URI_SCHEME] = "/#:@?=&",
/* Opaque part: escape characters which would affect
* the reparsing of the URI, allowing everything else
* (e.g. ':', which will appear in iSCSI URIs).
Expand Down Expand Up @@ -157,14 +190,16 @@ static int uri_character_escaped ( char c, unsigned int field ) {
/**
* Encode URI field
*
* @v uri URI
* @v field URI field index
* @v buf Buffer to contain encoded string
* @v raw Raw data
* @v raw_len Length of raw data
* @v buf Buffer
* @v len Length of buffer
* @ret len Length of encoded string (excluding NUL)
*/
size_t uri_encode ( const char *string, unsigned int field,
size_t uri_encode ( unsigned int field, const void *raw, size_t raw_len,
char *buf, ssize_t len ) {
const uint8_t *raw_bytes = ( ( const uint8_t * ) raw );
ssize_t remaining = len;
size_t used;
char c;
Expand All @@ -174,7 +209,8 @@ size_t uri_encode ( const char *string, unsigned int field,
buf[0] = '\0';

/* Copy string, escaping as necessary */
while ( ( c = *(string++) ) ) {
while ( raw_len-- ) {
c = *(raw_bytes++);
if ( uri_character_escaped ( c, field ) ) {
used = ssnprintf ( buf, remaining, "%%%02X", c );
} else {
Expand All @@ -187,6 +223,21 @@ size_t uri_encode ( const char *string, unsigned int field,
return ( len - remaining );
}

/**
* Encode URI field string
*
* @v field URI field index
* @v string String
* @v buf Buffer
* @v len Length of buffer
* @ret len Length of encoded string (excluding NUL)
*/
size_t uri_encode_string ( unsigned int field, const char *string,
char *buf, ssize_t len ) {

return uri_encode ( field, string, strlen ( string ), buf, len );
}

/**
* Dump URI for debugging
*
Expand Down Expand Up @@ -368,10 +419,8 @@ struct uri * parse_uri ( const char *uri_string ) {
}

/* Decode fields in-place */
for ( field = 0 ; field < URI_FIELDS ; field++ ) {
if ( uri_field ( uri, field ) )
uri_decode ( ( char * ) uri_field ( uri, field ) );
}
for ( field = 0 ; field < URI_FIELDS ; field++ )
uri_decode_inplace ( uri, field );

done:
DBGC ( uri, "URI parsed \"%s\" to", uri_string );
Expand Down Expand Up @@ -444,8 +493,8 @@ size_t format_uri ( const struct uri *uri, char *buf, size_t len ) {
}

/* Encode this field */
used += uri_encode ( uri_field ( uri, field ), field,
( buf + used ), ( len - used ) );
used += uri_encode_string ( field, uri_field ( uri, field ),
( buf + used ), ( len - used ) );

/* Suffix this field, if applicable */
if ( ( field == URI_SCHEME ) && ( ! uri->opaque ) ) {
Expand Down
5 changes: 4 additions & 1 deletion src/include/ipxe/uri.h
View file
Expand Up @@ -191,8 +191,11 @@ uri_put ( struct uri *uri ) {

extern struct uri *cwuri;

extern size_t uri_encode ( const char *string, unsigned int field,
extern size_t uri_decode ( const char *encoded, void *buf, size_t len );
extern size_t uri_encode ( unsigned int field, const void *raw, size_t raw_len,
char *buf, ssize_t len );
extern size_t uri_encode_string ( unsigned int field, const char *string,
char *buf, ssize_t len );
extern struct uri * parse_uri ( const char *uri_string );
extern size_t format_uri ( const struct uri *uri, char *buf, size_t len );
extern char * format_uri_alloc ( const struct uri *uri );
Expand Down
4 changes: 2 additions & 2 deletions src/net/tcp/httpcore.c
View file
Expand Up @@ -1826,7 +1826,7 @@ static size_t http_params ( struct parameters *params, char *buf, size_t len ) {
}

/* URI-encode the key */
frag_len = uri_encode ( param->key, 0, buf, remaining );
frag_len = uri_encode_string ( 0, param->key, buf, remaining );
buf += frag_len;
len += frag_len;
remaining -= frag_len;
Expand All @@ -1839,7 +1839,7 @@ static size_t http_params ( struct parameters *params, char *buf, size_t len ) {
remaining--;

/* URI-encode the value */
frag_len = uri_encode ( param->value, 0, buf, remaining );
frag_len = uri_encode_string ( 0, param->value, buf, remaining);
buf += frag_len;
len += frag_len;
remaining -= frag_len;
Expand Down
16 changes: 16 additions & 0 deletions src/tests/settings_test.c
View file
Expand Up @@ -166,6 +166,12 @@ static struct setting test_string_setting = {
.type = &setting_type_string,
};

/** Test URI-encoded string setting */
static struct setting test_uristring_setting = {
.name = "test_uristring",
.type = &setting_type_uristring,
};

/** Test IPv4 address setting type */
static struct setting test_ipv4_setting = {
.name = "test_ipv4",
Expand Down Expand Up @@ -265,6 +271,16 @@ static void settings_test_exec ( void ) {
fetchf_ok ( &test_settings, &test_string_setting,
RAW ( 'w', 'o', 'r', 'l', 'd' ), "world" );

/* "uristring" setting type */
storef_ok ( &test_settings, &test_uristring_setting, "hello%20world",
RAW ( 'h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l',
'd' ) );
fetchf_ok ( &test_settings, &test_uristring_setting,
RAW ( 1, 2, 3, 4, 5 ), "%01%02%03%04%05" );
fetchf_ok ( &test_settings, &test_uristring_setting,
RAW ( 0, ' ', '%', '/', '#', ':', '@', '?', '=', '&' ),
"%00%20%25%2F%23%3A%40%3F%3D%26" );

/* "ipv4" setting type */
storef_ok ( &test_settings, &test_ipv4_setting, "192.168.0.1",
RAW ( 192, 168, 0, 1 ) );
Expand Down

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