lib: add `bufq` and `dynhds`

Adding `bufq`:
- at init() time configured to hold up to `n` chunks of `m` bytes each.
- various methods for reading from and writing to it.
- `peek` support to get access to buffered data without copy
- `pass` support to allow buffer flushing on write if it becomes full
- use case: IO buffers for dynamic reads and writes that do not blow up
- distinct from `dynbuf` in that:
  - it maintains a read position
  - writes on a full bufq return CURLE_AGAIN instead of nuking itself
- Init options:
  - SOFT_LIMIT: allow writes into a full bufq
  - NO_SPARES: free empty chunks right away
- a `bufc_pool` that can keep a number of spare chunks to
  be shared between different `bufq` instances

Adding `dynhds`:
- a straightforward list of name+value pairs as used for HTTP headers
- headers can be appended dynamically
- headers can be removed again
- headers can be replaced
- headers can be looked up
- http/1.1 formatting into a `dynbuf`
- configured at init() with limits on header counts and total string
  sizes
- use case: pass a HTTP request or response around without being version
  specific
- express a HTTP request without a curl easy handle (used in h2 proxy
  tunnels)
- future extension possibilities:
  - conversions of `dynhds` to nghttp2/nghttp3 name+value arrays

Closes #10720

1 files changed, 303 insertions, 0 deletions

diff --git a/lib/dynhds.c b/lib/dynhds.c
new file mode 100644
index 000000000..9cf6656b6
--- /dev/null
+++ b/lib/dynhds.c
@@ -0,0 +1,303 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * SPDX-License-Identifier: curl
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+#include "dynhds.h"
+#include "strcase.h"
+
+/* The last 3 #include files should be in this order */
+#include "curl_printf.h"
+#include "curl_memory.h"
+#include "memdebug.h"
+
+
+static struct dynhds_entry *
+entry_new(const char *name, size_t namelen,
+          const char *value, size_t valuelen)
+{
+  struct dynhds_entry *e;
+  char *p;
+
+  DEBUGASSERT(name);
+  DEBUGASSERT(value);
+  e = calloc(1, sizeof(*e) + namelen + valuelen + 2);
+  if(!e)
+    return NULL;
+  e->name = p = ((char *)e) + sizeof(*e);
+  memcpy(p, name, namelen);
+  e->namelen = namelen;
+  e->value = p += namelen + 1; /* leave a \0 at the end of name */
+  memcpy(p, value, valuelen);
+  e->valuelen = valuelen;
+  return e;
+}
+
+static void entry_free(struct dynhds_entry *e)
+{
+  free(e);
+}
+
+void Curl_dynhds_init(struct dynhds *dynhds, size_t max_entries,
+                      size_t max_strs_size)
+{
+  DEBUGASSERT(dynhds);
+  DEBUGASSERT(max_strs_size);
+  dynhds->hds = NULL;
+  dynhds->hds_len = dynhds->hds_allc = dynhds->strs_len = 0;
+  dynhds->max_entries = max_entries;
+  dynhds->max_strs_size = max_strs_size;
+}
+
+void Curl_dynhds_free(struct dynhds *dynhds)
+{
+  DEBUGASSERT(dynhds);
+  if(dynhds->hds && dynhds->hds_len) {
+    size_t i;
+    DEBUGASSERT(dynhds->hds);
+    for(i = 0; i < dynhds->hds_len; ++i) {
+      entry_free(dynhds->hds[i]);
+    }
+  }
+  Curl_safefree(dynhds->hds);
+  dynhds->hds_len = dynhds->hds_allc = dynhds->strs_len = 0;
+}
+
+void Curl_dynhds_reset(struct dynhds *dynhds)
+{
+  DEBUGASSERT(dynhds);
+  if(dynhds->hds_len) {
+    size_t i;
+    DEBUGASSERT(dynhds->hds);
+    for(i = 0; i < dynhds->hds_len; ++i) {
+      entry_free(dynhds->hds[i]);
+      dynhds->hds[i] = NULL;
+    }
+  }
+  dynhds->hds_len = dynhds->strs_len = 0;
+}
+
+size_t Curl_dynhds_count(struct dynhds *dynhds)
+{
+  return dynhds->hds_len;
+}
+
+struct dynhds_entry *Curl_dynhds_getn(struct dynhds *dynhds, size_t n)
+{
+  DEBUGASSERT(dynhds);
+  return (n < dynhds->hds_len)? dynhds->hds[n] : NULL;
+}
+
+struct dynhds_entry *Curl_dynhds_get(struct dynhds *dynhds, const char *name,
+                                     size_t namelen)
+{
+  size_t i;
+  for(i = 0; i < dynhds->hds_len; ++i) {
+    if(dynhds->hds[i]->namelen == namelen &&
+       strncasecompare(dynhds->hds[i]->name, name, namelen)) {
+      return dynhds->hds[i];
+    }
+  }
+  return NULL;
+}
+
+struct dynhds_entry *Curl_dynhds_cget(struct dynhds *dynhds, const char *name)
+{
+  return Curl_dynhds_get(dynhds, name, strlen(name));
+}
+
+bool Curl_dynhds_contains(struct dynhds *dynhds,
+                          const char *name, size_t namelen)
+{
+  return !!Curl_dynhds_get(dynhds, name, namelen);
+}
+
+bool Curl_dynhds_ccontains(struct dynhds *dynhds, const char *name)
+{
+  return Curl_dynhds_contains(dynhds, name, strlen(name));
+}
+
+CURLcode Curl_dynhds_add(struct dynhds *dynhds,
+                         const char *name, size_t namelen,
+                         const char *value, size_t valuelen)
+{
+  struct dynhds_entry *entry = NULL;
+  CURLcode result = CURLE_OUT_OF_MEMORY;
+
+  DEBUGASSERT(dynhds);
+  if(dynhds->max_entries && dynhds->hds_len >= dynhds->max_entries)
+    return CURLE_OUT_OF_MEMORY;
+  if(dynhds->strs_len + namelen + valuelen > dynhds->max_strs_size)
+    return CURLE_OUT_OF_MEMORY;
+
+  entry = entry_new(name, namelen, value, valuelen);
+  if(!entry)
+    goto out;
+
+  if(dynhds->hds_len + 1 >= dynhds->hds_allc) {
+    size_t nallc = dynhds->hds_len + 16;
+    struct dynhds_entry **nhds;
+
+    if(dynhds->max_entries && nallc > dynhds->max_entries)
+      nallc = dynhds->max_entries;
+
+    nhds = calloc(nallc, sizeof(struct dynhds_entry *));
+    if(!nhds)
+      goto out;
+    if(dynhds->hds) {
+      memcpy(nhds, dynhds->hds,
+             dynhds->hds_len * sizeof(struct dynhds_entry *));
+      Curl_safefree(dynhds->hds);
+    }
+    dynhds->hds = nhds;
+    dynhds->hds_allc = nallc;
+  }
+  dynhds->hds[dynhds->hds_len++] = entry;
+  entry = NULL;
+  dynhds->strs_len += namelen + valuelen;
+  result = CURLE_OK;
+
+out:
+  if(entry)
+    entry_free(entry);
+  return result;
+}
+
+CURLcode Curl_dynhds_cadd(struct dynhds *dynhds,
+                          const char *name, const char *value)
+{
+  return Curl_dynhds_add(dynhds, name, strlen(name), value, strlen(value));
+}
+
+CURLcode Curl_dynhds_set(struct dynhds *dynhds,
+                         const char *name, size_t namelen,
+                         const char *value, size_t valuelen)
+{
+  Curl_dynhds_remove(dynhds, name, namelen);
+  return Curl_dynhds_add(dynhds, name, namelen, value, valuelen);
+}
+
+CURLcode Curl_dynhds_cset(struct dynhds *dynhds,
+                          const char *name, const char *value)
+{
+  return Curl_dynhds_set(dynhds, name, strlen(name), value, strlen(value));
+}
+
+CURLcode Curl_dynhds_h1_cadd_line(struct dynhds *dynhds, const char *line)
+{
+  const char *p;
+  const char *name;
+  size_t namelen;
+  const char *value;
+  size_t valuelen;
+
+  if(!line)
+    return CURLE_OK;
+  p = strchr(line, ':');
+  if(!p) {
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+  }
+
+  name = line;
+  namelen = p - line;
+  p++; /* move past the colon */
+  while(ISBLANK(*p))
+    p++;
+  value = p;
+  p = strchr(value, '\r');
+  if(!p)
+    p = strchr(value, '\n');
+  valuelen = p? ((size_t)(p - value)) : strlen(value);
+
+  return Curl_dynhds_add(dynhds, name, namelen, value, valuelen);
+}
+
+size_t Curl_dynhds_count_name(struct dynhds *dynhds,
+                              const char *name, size_t namelen)
+{
+  size_t n = 0;
+  if(dynhds->hds_len) {
+    size_t i;
+    for(i = 0; i < dynhds->hds_len; ++i) {
+      if((namelen == dynhds->hds[i]->namelen) &&
+         strncasecompare(name, dynhds->hds[i]->name, namelen))
+         ++n;
+    }
+  }
+  return n;
+}
+
+size_t Curl_dynhds_ccount_name(struct dynhds *dynhds, const char *name)
+{
+  return Curl_dynhds_count_name(dynhds, name, strlen(name));
+}
+
+size_t Curl_dynhds_remove(struct dynhds *dynhds,
+                          const char *name, size_t namelen)
+{
+  size_t n = 0;
+  if(dynhds->hds_len) {
+    size_t i, len;
+    for(i = 0; i < dynhds->hds_len; ++i) {
+      if((namelen == dynhds->hds[i]->namelen) &&
+         strncasecompare(name, dynhds->hds[i]->name, namelen)) {
+        ++n;
+        --dynhds->hds_len;
+        dynhds->strs_len -= (dynhds->hds[i]->namelen +
+                             dynhds->hds[i]->valuelen);
+        entry_free(dynhds->hds[i]);
+        len = dynhds->hds_len - i; /* remaining entries */
+        if(len) {
+          memmove(&dynhds->hds[i], &dynhds->hds[i + 1],
+                  len * sizeof(dynhds->hds[i]));
+        }
+        --i; /* do this index again */
+      }
+    }
+  }
+  return n;
+}
+
+size_t Curl_dynhds_cremove(struct dynhds *dynhds, const char *name)
+{
+  return Curl_dynhds_remove(dynhds, name, strlen(name));
+}
+
+CURLcode Curl_dynhds_h1_dprint(struct dynhds *dynhds, struct dynbuf *dbuf)
+{
+  CURLcode result = CURLE_OK;
+  size_t i;
+
+  if(!dynhds->hds_len)
+    return result;
+
+  for(i = 0; i < dynhds->hds_len; ++i) {
+    result = Curl_dyn_addf(dbuf, "%.*s: %.*s\r\n",
+               (int)dynhds->hds[i]->namelen, dynhds->hds[i]->name,
+               (int)dynhds->hds[i]->valuelen, dynhds->hds[i]->value);
+    if(result)
+      break;
+  }
+
+  return result;
+}