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Ignore malformed Cache-Control directives per RFC 7234 #12670

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Ignore malformed Cache-Control directives per RFC 7234 #12670

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226cc5b
Ignore malformed Cache-Control directives per RFC 7234
bneradt Nov 17, 2025
11d2a6e
Handling other malformed CC
bneradt Dec 4, 2025
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79 changes: 64 additions & 15 deletions src/proxy/hdrs/MIME.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -3752,6 +3752,9 @@ MIMEHdrImpl::recompute_cooked_stuff(MIMEField *changing_field_or_null)

for (s = csv_iter.get_first(field, &len); s != nullptr; s = csv_iter.get_next(&len)) {
e = s + len;
// Store set mask bits from this CSV value so we can clear them if needed.
uint32_t csv_value_mask = 0;

for (c = s; (c < e) && (ParseRules::is_token(*c)); c++) {
;
}
Expand All @@ -3766,6 +3769,7 @@ MIMEHdrImpl::recompute_cooked_stuff(MIMEField *changing_field_or_null)
HdrTokenHeapPrefix *p = hdrtoken_wks_to_prefix(token_wks);
mask = p->wks_type_specific.u.cache_control.cc_mask;
m_cooked_stuff.m_cache_control.m_mask |= mask;
csv_value_mask |= mask;

#if TRACK_COOKING
Dbg(dbg_ctl_http, " set mask 0x%0X", mask);
Expand All @@ -3774,27 +3778,72 @@ MIMEHdrImpl::recompute_cooked_stuff(MIMEField *changing_field_or_null)
if (mask & (MIME_COOKED_MASK_CC_MAX_AGE | MIME_COOKED_MASK_CC_S_MAXAGE | MIME_COOKED_MASK_CC_MAX_STALE |
MIME_COOKED_MASK_CC_MIN_FRESH)) {
int value;
// Per RFC 7230 Section 3.2.3, there should be no whitespace around '='.
const char *value_start = c;

// Check if the next character is '=' (no space allowed before '=').
if (c < e && *c == '=') {
++c; // Move past the '='

// Again: no whitespace after the '=' either. Keep in mind that values can be negative.
bool valid_syntax = (c < e) && (is_digit(*c) || *c == '-');

if (mime_parse_integer(c, e, &value)) {
if (valid_syntax) {
// Reset to value_start to let mime_parse_integer do its work.
c = value_start;
if (mime_parse_integer(c, e, &value)) {
#if TRACK_COOKING
Dbg(dbg_ctl_http, " set integer value %d", value);
Dbg(dbg_ctl_http, " set integer value %d", value);
#endif
if (token_wks == MIME_VALUE_MAX_AGE.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_max_age = value;
} else if (token_wks == MIME_VALUE_MIN_FRESH.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_min_fresh = value;
} else if (token_wks == MIME_VALUE_MAX_STALE.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_max_stale = value;
} else if (token_wks == MIME_VALUE_S_MAXAGE.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_s_maxage = value;
}
} else {
if (token_wks == MIME_VALUE_MAX_AGE.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_max_age = value;
} else if (token_wks == MIME_VALUE_MIN_FRESH.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_min_fresh = value;
} else if (token_wks == MIME_VALUE_MAX_STALE.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_max_stale = value;
} else if (token_wks == MIME_VALUE_S_MAXAGE.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_s_maxage = value;
}
} else {
#if TRACK_COOKING
Dbg(dbg_ctl_http, " set integer value %d", INT_MAX);
Dbg(dbg_ctl_http, " set integer value %d", INT_MAX);
#endif
if (token_wks == MIME_VALUE_MAX_STALE.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_max_stale = INT_MAX;
if (token_wks == MIME_VALUE_MAX_STALE.c_str()) {
m_cooked_stuff.m_cache_control.m_secs_max_stale = INT_MAX;
}
}
} else {
// Syntax is malformed (e.g., whitespace after '=', quotes around value, or no value).
// Treat this as unrecognized and clear the mask.
csv_value_mask = 0;
m_cooked_stuff.m_cache_control.m_mask &= ~mask;
}
} else {
// No '=' found, or whitespace before '='. This is malformed.
// For directives that require values, this is an error.
// Clear the mask for this directive.
csv_value_mask = 0;
m_cooked_stuff.m_cache_control.m_mask &= ~mask;
}
}

// Detect whether there is any more non-whitespace content after the
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@zwoop zwoop Dec 10, 2025

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This feels little heavy on the comments, but oh well.

// directive. This indicates an unrecognized or malformed directive.
// This can happen, for instance, if the host uses semicolons
// instead of commas as separators which is against RFC 7234 (see
// issue #12029). Regardless of the cause, this means we need to
// ignore the directive and clear any mask bits we set from it.
while (c < e && ParseRules::is_ws(*c)) {
++c;
}
if (c < e) {
// There's non-whitespace content that wasn't parsed. This means
// that we cannot really understand what this directive is.
// Per RFC 7234 Section 5.2: "A cache MUST ignore unrecognized cache
// directives."
if (csv_value_mask != 0) {
// Reverse the mask that we set above.
m_cooked_stuff.m_cache_control.m_mask &= ~csv_value_mask;
}
}
}
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