Add uri and www-form-uri encode/decode functions

str.c

@@ -81,6 +81,112 @@ size_t strn_fromhex(unsigned char *dstBinary, ssize_t dstsiz, const char *srcHex
   return dstBinary - dstorig;
 }
 
+static size_t _uri_encodev(int www_form, char *const dstUrienc, ssize_t dstsiz, struct iovec ** iovp, int *iovcntp)
+{
+  char * dst = dstUrienc;
+  char * const dstend = dstUrienc + dstsiz;
+  while (*iovcntp && (dstsiz == -1 || dst < dstend)) {
+    if ((*iovp)->iov_len == 0) {
+      --*iovcntp;
+      ++*iovp;
+    } else {
+      unsigned char c = *(unsigned char *)(*iovp)->iov_base;
+      if (www_form && c == ' ') {
+	if (dstUrienc)
+	  *dst = '+';
+	++dst;
+      } else if (is_uri_char_unreserved(c)) {
+	if (dstUrienc)
+	  *dst = c;
+	++dst;
+      } else if (dst + 3 <= dstend) {
+	if (dstUrienc) {
+	  dst[0] = '%';
+	  dst[1] = hexdigit_upper[c & 0xf];
+	  dst[2] = hexdigit_upper[c >> 4];
+	}
+	dst += 3;
+      } else {
+	break;
+      }
+      ++(*iovp)->iov_base;
+      --(*iovp)->iov_len;
+    }
+  }
+  return dst - dstUrienc;
+}
+
+static size_t _uri_encode(int www_form, char *const dstUrienc, ssize_t dstsiz, const char *src, size_t srclen, const char **afterp)
+{
+  struct iovec _iov;
+  _iov.iov_base = (void *) src;
+  _iov.iov_len = srclen;
+  struct iovec *iov = &_iov;
+  int ioc = 1;
+  size_t encoded = _uri_encodev(www_form, dstUrienc, dstsiz, &iov, &ioc);
+  if (afterp)
+    *afterp = _iov.iov_base;
+  return encoded;
+}
+
+size_t uri_encode(char *const dstUrienc, ssize_t dstsiz, const char *src, size_t srclen, const char **afterp)
+{
+  return _uri_encode(0, dstUrienc, dstsiz, src, srclen, afterp);
+}
+
+size_t www_form_uri_encode(char *const dstUrienc, ssize_t dstsiz, const char *src, size_t srclen, const char **afterp)
+{
+  return _uri_encode(1, dstUrienc, dstsiz, src, srclen, afterp);
+}
+
+size_t uri_encodev(char *const dstUrienc, ssize_t dstsiz, struct iovec ** iovp, int *iovcntp)
+{
+  return _uri_encodev(0, dstUrienc, dstsiz, iovp, iovcntp);
+}
+
+size_t www_form_uri_encodev(char *const dstUrienc, ssize_t dstsiz, struct iovec ** iovp, int *iovcntp)
+{
+  return _uri_encodev(1, dstUrienc, dstsiz, iovp, iovcntp);
+}
+
+static size_t _uri_decode(int www_form, char *const dstOrig, ssize_t dstsiz, const char *srcUrienc, size_t srclen, const char **afterp)
+{
+  char *dst = dstOrig;
+  char *const dstend = dst + dstsiz;
+  while (srclen && (dstsiz == -1 || dst < dstend)) {
+    if (www_form && *srcUrienc == '+') {
+      if (dstOrig)
+	*dst = ' ';
+      ++srcUrienc;
+      --srclen;
+    } else if (srclen >= 3 && srcUrienc[0] == '%' && isxdigit(srcUrienc[1]) && isxdigit(srcUrienc[2])) {
+      if (dstOrig)
+	*dst = (hexvalue(srcUrienc[1]) << 4) + hexvalue(srcUrienc[2]);
+      srcUrienc += 3;
+      srclen -= 3;
+    } else {
+      if (dstOrig)
+	*dst = *srcUrienc;
+      ++srcUrienc;
+      --srclen;
+    }
+    ++dst;
+  }
+  if (afterp)
+    *afterp = srcUrienc;
+  return dst - dstOrig;
+}
+
+size_t uri_decode(char *const dst, ssize_t dstsiz, const char *srcUrienc, size_t srclen, const char **afterp)
+{
+  return _uri_decode(0, dst, dstsiz, srcUrienc, srclen, afterp);
+}
+
+size_t www_form_uri_decode(char *const dst, ssize_t dstsiz, const char *srcUrienc, size_t srclen, const char **afterp)
+{
+  return _uri_decode(1, dst, dstsiz, srcUrienc, srclen, afterp);
+}
+
 const char base64_symbols[65] = {
   'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
   'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f',

str.h

@@ -495,7 +495,55 @@ int uint64_scaled_to_str(char *str, size_t len, uint64_t value);
  */
 int str_to_uint64_interval_ms(const char *str, int64_t *result, const char **afterp);
 
-/* -------------------- URI strings -------------------- */
+/* -------------------- URI encoding and decoding -------------------- */
+
+/* Encode up to 'srclen' bytes of byte data (or up to first nul if 'srclen' == -1) at 'src' into at
+ * most 'dstsiz' bytes of URI-encoded (or www-form-urlencoded) representation at 'dstUrienc'.  If
+ * 'dstsiz' is -1 or 'dstUrienc' is NULL, does not write any encoded bytes, but still counts them.
+ * If 'afterp' is not NULL, then sets *afterp to point to the source byte immediately following the
+ * last character encoded.  A "%xx" sequence will never be partially encoded; if all the "%xx" does
+ * not fit within the destination buffer, then none of it is produced.
+ *
+ *
+ * Returns the total number of encoded bytes written at 'dstUrienc'.
+ *
+ * Can be used to count encoded bytes without actually encoding, eg:
+ *
+ *    uri_encode(NULL, -1, buf, buflen, NULL);
+ *
+ * The uri_encodev() and www_form_uri_encodev() functions are a multi-buffer gather variants,
+ * analagous to readv(2) and writev(2).  Modifies the supplied *iovp, *iovcntp parameters and the
+ * iovec structures at (*iovp)[...] to represent the remaining source bytes not encoded.
+ *
+ * @author Andrew Bettison <andrew@servalproject.com>
+ */
+size_t uri_encode(char *const dstUrienc, ssize_t dstsiz, const char *src, size_t srclen, const char **afterp);
+size_t www_form_uri_encode(char *const dstUrienc, ssize_t dstsiz, const char *src, size_t srclen, const char **afterp);
+
+size_t uri_encodev(char *const dstUrienc, ssize_t dstsiz, struct iovec **iovp, int *iovcntp); // modifies *iovp, (*iovp)[...] and *iovcntp
+size_t www_form_uri_encodev(char *const dstUrienc, ssize_t dstsiz, struct iovec **iovp, int *iovcntp); // modifies *iovp, (*iovp)[...] and *iovcntp
+
+/* Decode up to 'srclen' bytes of URI-encoded (or www-form-urlencoded) data at 'srcUrienc' into at
+ * most 'dstsiz' bytes at 'dst'.  If 'dstsiz' is -1 or 'dst' is NULL, then does not write any
+ * decoded bytes, but still counts them.  If 'afterp' is not NULL, then sets *afterp to point to the
+ * source byte immediately following the last byte decoded.
+ *
+ * Returns the total number of decoded bytes written at 'dst'.
+ *
+ * Can be used to decode in-place, eg:
+ *
+ *    uri_decode((char *)buf, n, (const unsigned char *)buf, n, NULL);
+ *
+ * Can be used to count decoded bytes without actually decoding, eg:
+ *
+ *    uri_decode(NULL, -1, buf, buflen, NULL);
+ *
+ * @author Andrew Bettison <andrew@servalproject.com>
+ */
+size_t uri_decode(char *const dst, ssize_t dstsiz, const char *srcUrienc, size_t srclen, const char **afterp);
+size_t www_form_uri_decode(char *const dst, ssize_t dstsiz, const char *srcUrienc, size_t srclen, const char **afterp);
+
+/* -------------------- URI parsing -------------------- */
 
 /* Return true if the string resembles a nul-terminated URI.
  * Based on RFC-3986 generic syntax, assuming nothing about the hierarchical part.