1 files changed, 95 insertions, 0 deletions
diff --git a/http_utils.c b/http_utils.c
new file mode 100644
index 0000000..149760e
--- /dev/null
+++ b/http_utils.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2023 Mikhail Burakov. This file is part of MQhTTp.
+ *
+ * MQhTTp is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * MQhTTp is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with MQhTTp.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "http_utils.h"
+
+#include <errno.h>
+#include <string.h>
+
+#include "toolbox/utils.h"
+
+static const char part1[] = {'H', 'T', 'T', 'P', '/', '1', '.', '1', ' '};
+static const char part2[] = {'\r', '\n', 'C', 'o', 'n', 't', 'e', 'n', 't',
+                             '-',  'L',  'e', 'n', 'g', 't', 'h', ':', ' '};
+static const char part3[] = {'\r', '\n', 'C', 'o', 'n', 't', 'e', 'n',
+                             't',  '-',  'T', 'y', 'p', 'e', ':', ' '};
+static const char part4[] = {'\r', '\n', '\r', '\n'};
+
+static size_t FormatSize(char* buffer, size_t size) {
+  if (!size) {
+    buffer[0] = '0';
+    return 1;
+  }
+  size_t power = 1, index = 0;
+  while (power <= size) power *= 10;
+  while (power /= 10) buffer[index++] = '0' + (size / power) % 10;
+  return index;
+}
+
+static void AppendIov(struct iovec** ptr, const char* base, size_t len) {
+  struct iovec* iov = *ptr;
+  iov->iov_base = *(void**)(void*)&base;
+  iov->iov_len = len;
+  *ptr = iov + 1;
+}
+
+static bool SendAll(int fd, struct iovec* iov, int iov_count) {
+  size_t total_size = 0;
+  for (int i = 0; i < iov_count; i++) {
+    total_size += iov[i].iov_len;
+  }
+  while (total_size) {
+    ssize_t result = writev(fd, iov, iov_count);
+    if (result == -1) {
+      LOGW("Failed to send body chunk (%s)", strerror(errno));
+      return false;
+    }
+    for (int i = 0; i < iov_count; i++) {
+      size_t delta = MIN(iov[i].iov_len, (size_t)result);
+      iov[i].iov_len -= delta;
+      total_size -= delta;
+      result -= delta;
+    }
+  }
+  return true;
+}
+
+bool SendHttpReply(int fd, const char* status, const char* content_type,
+                   const struct iovec* chunks, size_t chunks_count) {
+  size_t content_length = 0;
+  for (size_t i = 0; i < chunks_count; i++) {
+    content_length += chunks[i].iov_len;
+  }
+
+  char buffer[24];
+  struct iovec iov[7 + chunks_count];
+  struct iovec* ptr = iov;
+  AppendIov(&ptr, part1, sizeof(part1));
+  AppendIov(&ptr, status, strlen(status));
+  AppendIov(&ptr, part2, sizeof(part2));
+  AppendIov(&ptr, buffer, FormatSize(buffer, content_length));
+  if (content_length && content_type) {
+    AppendIov(&ptr, part3, sizeof(part3));
+    AppendIov(&ptr, content_type, strlen(content_type));
+  }
+  AppendIov(&ptr, part4, sizeof(part4));
+  for (size_t i = 0; i < chunks_count; i++) {
+    *ptr++ = *chunks++;
+  }
+
+  return SendAll(fd, iov, (int)(ptr - iov));
+}