1 files changed, 135 insertions, 0 deletions
diff --git a/libnetdata/datetime/rfc3339.c b/libnetdata/datetime/rfc3339.c
new file mode 100644
index 000000000..157e340d3
--- /dev/null
+++ b/libnetdata/datetime/rfc3339.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+#include "rfc3339.h"
+
+size_t rfc3339_datetime_ut(char *buffer, size_t len, usec_t now_ut, size_t fractional_digits, bool utc) {
+    if (!buffer || len == 0)
+        return 0;
+
+    time_t t = (time_t)(now_ut / USEC_PER_SEC);
+    struct tm *tmp, tmbuf;
+
+    if (utc)
+        tmp = gmtime_r(&t, &tmbuf);
+    else
+        tmp = localtime_r(&t, &tmbuf);
+
+    if (!tmp) {
+        buffer[0] = '\0';
+        return 0;
+    }
+
+    size_t used_length = strftime(buffer, len, "%Y-%m-%dT%H:%M:%S", tmp);
+    if (used_length == 0) {
+        buffer[0] = '\0';
+        return 0;
+    }
+
+    if (fractional_digits >= 0 && fractional_digits <= 9) {
+        int fractional_part = (int)(now_ut % USEC_PER_SEC);
+        if (fractional_part && len - used_length > fractional_digits + 1) {
+            char format[] = ".%01d";
+            format[3] = (char)('0' + fractional_digits);
+
+            // Adjust fractional part
+            fractional_part /= (int)pow(10, 6 - fractional_digits);
+
+            used_length += snprintf(buffer + used_length, len - used_length,
+                                    format, fractional_part);
+        }
+    }
+
+    if (utc) {
+        if (used_length + 1 < len) {
+            buffer[used_length++] = 'Z';
+            buffer[used_length] = '\0';
+        }
+    }
+    else {
+        long offset = tmbuf.tm_gmtoff;
+        int hours = (int)(offset / 3600);
+        int minutes = abs((int)((offset % 3600) / 60));
+
+        if (used_length + 7 < len) { // Space for "+HH:MM\0"
+            used_length += snprintf(buffer + used_length, len - used_length, "%+03d:%02d", hours, minutes);
+        }
+    }
+
+    return used_length;
+}
+
+usec_t rfc3339_parse_ut(const char *rfc3339, char **endptr) {
+    struct tm tm = { 0 };
+    int tz_hours = 0, tz_mins = 0;
+    char *s;
+    usec_t timestamp, usec = 0;
+
+    // Use strptime to parse up to seconds
+    s = strptime(rfc3339, "%Y-%m-%dT%H:%M:%S", &tm);
+    if (!s)
+        return 0; // Parsing error
+
+    // Parse fractional seconds if present
+    if (*s == '.') {
+        char *next;
+        usec = strtoul(s + 1, &next, 10);
+        int digits_parsed = (int)(next - (s + 1));
+
+        if (digits_parsed < 1 || digits_parsed > 9)
+            return 0; // parsing error
+
+        static const usec_t fix_usec[] = {
+                1000000,  // 0 digits (not used)
+                100000,   // 1 digit
+                10000,    // 2 digits
+                1000,     // 3 digits
+                100,      // 4 digits
+                10,       // 5 digits
+                1,        // 6 digits
+                10,       // 7 digits
+                100,      // 8 digits
+                1000,     // 9 digits
+        };
+        usec = digits_parsed <= 6 ? usec * fix_usec[digits_parsed] : usec / fix_usec[digits_parsed];
+
+        s = next;
+    }
+
+    // Check and parse timezone if present
+    int tz_offset = 0;
+    if (*s == '+' || *s == '-') {
+        // Parse the hours:mins part of the timezone
+
+        if (!isdigit(s[1]) || !isdigit(s[2]) || s[3] != ':' ||
+            !isdigit(s[4]) || !isdigit(s[5]))
+            return 0; // Parsing error
+
+        char tz_sign = *s;
+        tz_hours = (s[1] - '0') * 10 + (s[2] - '0');
+        tz_mins = (s[4] - '0') * 10 + (s[5] - '0');
+
+        tz_offset = tz_hours * 3600 + tz_mins * 60;
+        tz_offset *= (tz_sign == '+' ? 1 : -1);
+
+        s += 6; // Move past the timezone part
+    }
+    else if (*s == 'Z')
+        s++;
+    else
+        return 0; // Invalid RFC 3339 format
+
+    // Convert to time_t (assuming local time, then adjusting for timezone later)
+    time_t epoch_s = mktime(&tm);
+    if (epoch_s == -1)
+        return 0; // Error in time conversion
+
+    timestamp = (usec_t)epoch_s * USEC_PER_SEC + usec;
+    timestamp -= tz_offset * USEC_PER_SEC;
+
+    if(endptr)
+        *endptr = s;
+
+    return timestamp;
+}