Added support for ranged requests

main.c

@@ -31,6 +31,11 @@ struct ConnectionState {
   struct stat targetStat;
 };
 
+struct RequestRange {
+  off_t start;
+  off_t length;
+};
+
 char *shareRoot;
 struct MHD_Response *error403Response;
 struct MHD_Response *error404Response;
@@ -54,12 +59,97 @@ void request_completed(void *cls,
   free(connstate);
 }
 
+int parse_range(const char *range, off_t total_len, struct RequestRange *result) {
+  char *numstr;
+  char *dashptr;
+  int dashpos;
+  off_t num;
+
+  LOG(LVL_DEBUG, "Requested Range is %s", range);
+
+  if(range == NULL) {
+    result->start = 0;
+    result->length = total_len;
+    return 0;
+  }
+
+  numstr = strchr(range, '=');
+  if(numstr == NULL) {
+    return -1;
+  }
+
+  numstr += 1;
+
+  LOG(LVL_DUMP, "Numeric part of range: %s", numstr);
+
+  dashptr = strchr(numstr, '-');
+  if(dashptr == NULL) {
+    // no '-' found
+    return -1;
+  }
+
+  dashpos = dashptr - numstr;
+  LOG(LVL_DUMP, "Dash found at position: %i", dashpos);
+
+  if(dashpos == 0) {
+    // example: bytes=-500
+    // -> letzte 500 bytes ausgeben
+    if(sscanf(dashptr+1, "%li", &num) != 1) {
+      return -1;
+    }
+
+    // total = 1000, num = 100 -> start=500, length=500
+    result->start = total_len - num - 1;
+    result->length = num;
+  } else {
+    // examples: bytes=100-200; bytes=300-
+
+    // parse the first number
+    if(sscanf(numstr, "%li", &num) != 1) {
+      return -1;
+    }
+
+    result->start = num;
+
+    if(numstr[dashpos + 1] == '\0') {
+      // everything from num to the end
+      result->length = total_len - num;
+      return 0;
+    }
+
+    // a complete range was given -> parse the second number
+    if(sscanf(numstr+dashpos+1, "%li", &num) != 1) {
+      return -1;
+    }
+
+    if(num < result->start) {
+      return -1;
+    }
+
+    result->length = num - result->start + 1;
+  }
+
+  return 0;
+}
+
 int serv_regular_file(struct MHD_Connection *connection, struct ConnectionState *connstate) {
   struct MHD_Response *response;
+  struct RequestRange range;
+  const char *rangestr;
+  char buf[256];
   int ret;
 
   LOG(LVL_DEBUG, "Serving %s as a regular file.", connstate->localFileName);
 
+  rangestr = MHD_lookup_connection_value(connection, MHD_HEADER_KIND, "Range");
+
+  if(0 != parse_range(rangestr, connstate->targetStat.st_size, &range)) {
+    LOG(LVL_ERR, "Cannot parse range header.");
+    return MHD_queue_response(connection, MHD_HTTP_INTERNAL_SERVER_ERROR, error500Response);
+  }
+
+  LOG(LVL_DUMP, "Requested range: start=%lu, length=%lu", range.start, range.length);
+
   // open a file descriptor to the file
   int fd = open(connstate->localFileName, O_RDONLY);
 
@@ -71,9 +161,16 @@ int serv_regular_file(struct MHD_Connection *connection, struct ConnectionState
   }
 
   // no error so far -> serve the file
-  response = MHD_create_response_from_fd(
-      connstate->targetStat.st_size,
-      fd);
+  response = MHD_create_response_from_fd_at_offset(
+      range.length,
+      fd,
+      range.start);
+
+  // build content range header
+  sprintf(buf, "bytes %li-%li/%li", range.start, range.start+range.length-1, connstate->targetStat.st_size);
+  MHD_add_response_header(response, MHD_HTTP_HEADER_CONTENT_RANGE, buf);
+
+  LOG(LVL_DUMP, "Content-Range: %s", buf);
 
 #ifdef HAVE_MAGIC
   // if libmagic is available, determine the correct MIME type for the file