Added support for HTTP Date format

ngx_http_hmac_secure_link_module.c

@@ -6,9 +6,20 @@
 #include <openssl/evp.h>
 #include <openssl/hmac.h>
 #include <openssl/crypto.h>
+#include <stdbool.h>
+
 
 #define NGX_DEFAULT_HASH_FUNCTION "sha256"
 
+static const char * wdays[7] = {
+ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+};
+
+static const char * months[12] = {
+ "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+ "Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
+};
+
 typedef struct {
  ngx_http_complex_value_t *hmac_variable;
  ngx_http_complex_value_t *hmac_message;
@@ -170,44 +181,67 @@ ngx_http_secure_link_variable(ngx_http_request_t *r,
  (ngx_tm_mday_t *) &mday, (ngx_tm_hour_t *) &hour,
  (ngx_tm_min_t *) &min, (ngx_tm_sec_t *) &sec,
  &gmtoff_sign, &gmtoff_hour, &gmtoff_min) < 9) {
- goto not_found;
- }
-
- /* Put February last because it has leap day */
- month -= 2;
- if (month <= 0) {
- month += 12;
- year -= 1;
- }
-
- /* Gauss' formula for Gregorian days since March 1, 1 BC */
- /* Taken from ngx_http_parse_time.c */
- timestamp = (time_t) (
- /* days in years including leap years since March 1, 1 BC */
- 365 * year + year / 4 - year / 100 + year / 400
- /* days before the month */
- + 367 * month / 12 - 30
- /* days before the day */
- + mday - 1
- /*
- * 719527 days were between March 1, 1 BC and March 1, 1970,
- * 31 and 28 days were in January and February 1970
- */
- - 719527 + 31 + 28) * 86400 + hour * 3600 + min * 60 + sec;
-
- /* Determine the time offset with respect to GMT */
- gmtoff = 3600 * gmtoff_hour + 60 * gmtoff_min;
-
- if (gmtoff_sign == '+') {
- timestamp -= gmtoff;
+ /* Parse timestamp in HTTP Date format RFC7231 - 7.1.1.1
+ https://tools.ietf.org/html/rfc7231#section-7.1.1.1 */
+ if (sscanf((char *)p, "%*[a-zA-Z,] %d %3s %d %d:%d:%d",
+ (ngx_tm_mday_t *) &mday, (char M[4] *) &M,
+ (ngx_tm_year_t *) &year,(ngx_tm_hour_t *) &hour,
+ (ngx_tm_min_t *) &min, (ngx_tm_sec_t *) &sec) < 5) {
+ goto not_found;
+ }
+ /* Parse month from string of months */
+ ngx_tm_mon_t month;
+ bool valid_month = false;
+ for (int i = 0; i < 12; i++) {
+ if (strncmp (M, months[i], 3) == 0) {
+ month = i;
+ valid_month = true;
+ break;
+ }
+ }
+ if(!valid_month) {
+ goto not_found;
+ }
+ year -= 1900;
+ timestamp = timegm (& g);
  }
-
- if (gmtoff_sign == '-') {
- timestamp += gmtoff;
+ else {
+ /* Put February last because it has leap day */
+ month -= 2;
+ if (month <= 0) {
+ month += 12;
+ year -= 1;
+ }
+
+ /* Gauss' formula for Gregorian days since March 1, 1 BC */
+ /* Taken from ngx_http_parse_time.c */
+ timestamp = (time_t) (
+ /* days in years including leap years since March 1, 1 BC */
+ 365 * year + year / 4 - year / 100 + year / 400
+ /* days before the month */
+ + 367 * month / 12 - 30
+ /* days before the day */
+ + mday - 1
+ /*
+ * 719527 days were between March 1, 1 BC and March 1, 1970,
+ * 31 and 28 days were in January and February 1970
+ */
+ - 719527 + 31 + 28) * 86400 + hour * 3600 + min * 60 + sec;
+
+ /* Determine the time offset with respect to GMT */
+ gmtoff = 3600 * gmtoff_hour + 60 * gmtoff_min;
+
+ if (gmtoff_sign == '+') {
+ timestamp -= gmtoff;
+ }
+
+ if (gmtoff_sign == '-') {
+ timestamp += gmtoff;
+ }
+
+ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+ "secure link timestamp: \"%T\"", timestamp);
  }
-
- ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
- "secure link timestamp: \"%T\"", timestamp);
  }
 
  if (timestamp <= 0) {