MEDIUM: cache: configuration parsing and initialization

Parse a configuration section "cache" and a http-{response,request}
actions.

Example:

    listen frt
        mode http
        http-response cache-store foobar
        http-request cache-use foobar

    cache foobar
        total-max-size 4   # size in megabytes
diff --git a/Makefile b/Makefile
index 6b9e634..8f1bcd2 100644
--- a/Makefile
+++ b/Makefile
@@ -857,7 +857,7 @@
        src/raw_sock.o src/lb_chash.o src/lb_fwlc.o src/lb_fwrr.o \
        src/lb_fas.o src/applet.o src/hdr_idx.o src/ev_select.o src/hash.o \
        src/lb_map.o src/base64.o src/sha1.o src/protocol.o src/h1.o \
-       src/action.o src/hathreads.o src/mux_pt.o
+       src/action.o src/hathreads.o src/mux_pt.o src/cache.o
 
 EBTREE_OBJS = $(EBTREE_DIR)/ebtree.o \
               $(EBTREE_DIR)/eb32tree.o $(EBTREE_DIR)/eb64tree.o \
diff --git a/include/types/cache.h b/include/types/cache.h
new file mode 100644
index 0000000..b7e6e58
--- /dev/null
+++ b/include/types/cache.h
@@ -0,0 +1,13 @@
+#ifndef _TYPES_CACHE_H
+#define _TYPES_CACHE_H
+
+struct cache_obj {
+	int exp;   /* expire time */
+	int etag;  /* e-tag entry */
+	int last;  /* last entry */
+	void *buf;  /* ptr to buffer */
+}
+
+#endif /*_TYPES_CACHE_H */
+
+
diff --git a/src/cache.c b/src/cache.c
new file mode 100644
index 0000000..7159a52
--- /dev/null
+++ b/src/cache.c
@@ -0,0 +1,393 @@
+/*
+ * Cache management
+ *
+ * Copyright 2017 HAProxy Technologies
+ * William Lallemand <wlallemand@haproxy.com>
+ *
+ * This program 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
+ * 2 of the License, or (at your option) any later version.
+ */
+
+
+#include <eb32tree.h>
+
+#include <proto/channel.h>
+#include <proto/proxy.h>
+#include <proto/hdr_idx.h>
+#include <proto/filters.h>
+#include <proto/proto_http.h>
+#include <proto/log.h>
+#include <proto/stream.h>
+#include <proto/stream_interface.h>
+#include <proto/shctx.h>
+
+#include <types/action.h>
+#include <types/filters.h>
+#include <types/proxy.h>
+#include <types/shctx.h>
+
+#include <common/cfgparse.h>
+#include <common/hash.h>
+
+/* flt_cache_store */
+
+static const char *cache_store_flt_id = "cache store filter";
+
+struct applet http_cache_applet;
+
+struct flt_ops cache_ops;
+
+struct cache {
+	char id[33];             /* cache name */
+	unsigned int maxage;  /* max-age */
+	unsigned int maxblocks;
+	struct list list;     /* cache linked list */
+	struct eb_root entries;  /* head of cache entries based on keys */
+};
+
+/*
+ * cache ctx for filters
+ */
+struct cache_st {
+	int hdrs_len;
+	struct shared_block *first_block;
+};
+
+struct cache_entry {
+	unsigned int latest_validation;     /* latest validation date */
+	unsigned int expire;      /* expiration date */
+	struct eb32_node eb;     /* ebtree node used to hold the cache object */
+	unsigned char data[0];
+};
+
+#define CACHE_BLOCKSIZE 1024
+
+static struct list caches = LIST_HEAD_INIT(caches);
+static struct cache *tmp_cache_config = NULL;
+
+static int
+cache_store_init(struct proxy *px, struct flt_conf *f1conf)
+{
+	return 0;
+}
+
+/*
+ * This fonction will store the headers of the response in a buffer and then
+ * register a filter to store the data
+ */
+enum act_return http_action_store_cache(struct act_rule *rule, struct proxy *px,
+                                              struct session *sess, struct stream *s, int flags)
+{
+	return ACT_RET_CONT;
+}
+
+enum act_parse_ret parse_cache_store(const char **args, int *orig_arg, struct proxy *proxy,
+                                          struct act_rule *rule, char **err)
+{
+	struct flt_conf *fconf;
+	int cur_arg = *orig_arg;
+	rule->action       = ACT_CUSTOM;
+	rule->action_ptr   = http_action_store_cache;
+
+	if (!*args[cur_arg] || strcmp(args[cur_arg], "if") == 0 || strcmp(args[cur_arg], "unless") == 0) {
+		memprintf(err, "expects a cache name");
+		return ACT_RET_PRS_ERR;
+	}
+
+	/* check if a cache filter was already registered with this cache
+	 * name, if that's the case, must use it. */
+	list_for_each_entry(fconf, &proxy->filter_configs, list) {
+		if (fconf->id == cache_store_flt_id && !strcmp((char *)fconf->conf, args[cur_arg])) {
+			rule->arg.act.p[0] = fconf->conf;
+			(*orig_arg)++;
+			/* filter already registered */
+			return ACT_RET_PRS_OK;
+		}
+	}
+
+	rule->arg.act.p[0] = strdup(args[cur_arg]);
+	if (!rule->arg.act.p[0]) {
+		Alert("config: %s '%s': out of memory\n", proxy_type_str(proxy), proxy->id);
+		err++;
+		goto err;
+	}
+	/* register a filter to fill the cache buffer */
+	fconf = calloc(1, sizeof(*fconf));
+	if (!fconf) {
+		Alert("config: %s '%s': out of memory\n",
+		      proxy_type_str(proxy), proxy->id);
+		err++;
+		goto err;
+	}
+	fconf->id   = cache_store_flt_id;
+	fconf->conf = rule->arg.act.p[0]; /* store the proxy name */
+	fconf->ops  = &cache_ops;
+	LIST_ADDQ(&proxy->filter_configs, &fconf->list);
+
+	(*orig_arg)++;
+
+	return ACT_RET_PRS_OK;
+
+err:
+	return ACT_RET_ERR;
+}
+
+
+enum act_return http_action_req_cache_use(struct act_rule *rule, struct proxy *px,
+                                         struct session *sess, struct stream *s, int flags)
+{
+	return ACT_RET_PRS_OK;
+}
+
+
+enum act_parse_ret parse_cache_use(const char **args, int *orig_arg, struct proxy *proxy,
+                                          struct act_rule *rule, char **err)
+{
+	int cur_arg = *orig_arg;
+
+	rule->action       = ACT_CUSTOM;
+	rule->action_ptr   = http_action_req_cache_use;
+
+	if (!*args[cur_arg] || strcmp(args[cur_arg], "if") == 0 || strcmp(args[cur_arg], "unless") == 0) {
+		memprintf(err, "expects a cache name");
+		return ACT_RET_PRS_ERR;
+	}
+
+	rule->arg.act.p[0] = strdup(args[cur_arg]);
+	if (!rule->arg.act.p[0]) {
+		Alert("config: %s '%s': out of memory\n", proxy_type_str(proxy), proxy->id);
+		err++;
+		goto err;
+	}
+
+	(*orig_arg)++;
+	return ACT_RET_PRS_OK;
+
+err:
+	return ACT_RET_ERR;
+
+}
+
+int cfg_parse_cache(const char *file, int linenum, char **args, int kwm)
+{
+	int err_code = 0;
+
+	if (strcmp(args[0], "cache") == 0) { /* new cache section */
+
+		if (!*args[1]) {
+			Alert("parsing [%s:%d] : '%s' expects an <id> argument\n",
+			      file, linenum, args[0]);
+			err_code |= ERR_ALERT | ERR_ABORT;
+			goto out;
+		}
+
+		if (alertif_too_many_args(1, file, linenum, args, &err_code)) {
+			err_code |= ERR_ABORT;
+			goto out;
+		}
+
+		if (tmp_cache_config == NULL) {
+			tmp_cache_config = calloc(1, sizeof(*tmp_cache_config));
+			if (!tmp_cache_config) {
+				Alert("parsing [%s:%d]: out of memory.\n", file, linenum);
+				err_code |= ERR_ALERT | ERR_ABORT;
+				goto out;
+			}
+
+			strlcpy2(tmp_cache_config->id, args[1], 33);
+			if (strlen(args[1]) > 32) {
+				Warning("parsing [%s:%d]: cache id is limited to 32 characters, truncate to '%s'.\n",
+				        file, linenum, tmp_cache_config->id);
+				err_code |= ERR_WARN;
+			}
+
+			tmp_cache_config->maxblocks = 0;
+		}
+	} else if (strcmp(args[0], "total-max-size") == 0) {
+		int maxsize;
+
+		if (alertif_too_many_args(1, file, linenum, args, &err_code)) {
+			err_code |= ERR_ABORT;
+			goto out;
+		}
+
+		/* size in megabytes */
+		maxsize = atoi(args[1]) * 1024 * 1024 / CACHE_BLOCKSIZE;
+		tmp_cache_config->maxblocks = maxsize;
+
+	} else if (*args[0] != 0) {
+		Alert("parsing [%s:%d] : unknown keyword '%s' in 'cache' section\n", file, linenum, args[0]);
+		err_code |= ERR_ALERT | ERR_FATAL;
+		goto out;
+	}
+out:
+	return err_code;
+}
+
+/* once the cache section is parsed */
+
+int cfg_post_parse_section_cache()
+{
+	struct shared_context *shctx;
+	int err_code = 0;
+	int ret_shctx;
+
+	if (tmp_cache_config) {
+		struct cache *cache;
+
+		if (tmp_cache_config->maxblocks <= 0) {
+			Alert("Size not specified for cache '%s'\n", tmp_cache_config->id);
+			err_code |= ERR_FATAL | ERR_ALERT;
+			goto out;
+		}
+
+		ret_shctx = shctx_init(&shctx, tmp_cache_config->maxblocks, CACHE_BLOCKSIZE, sizeof(struct cache), 1);
+		if (ret_shctx < 0) {
+			if (ret_shctx == SHCTX_E_INIT_LOCK)
+				Alert("Unable to initialize the lock for the cache.\n");
+			else
+				Alert("Unable to allocate cache.\n");
+
+			err_code |= ERR_FATAL | ERR_ALERT;
+			goto out;
+		}
+		memcpy(shctx->data, tmp_cache_config, sizeof(struct cache));
+		cache = (struct cache *)shctx->data;
+		cache->entries = EB_ROOT_UNIQUE;
+
+		LIST_ADDQ(&caches, &cache->list);
+	}
+out:
+	free(tmp_cache_config);
+	tmp_cache_config = NULL;
+	return err_code;
+
+}
+
+/*
+ * Resolve the cache name to a pointer once the file is completely read.
+ */
+int cfg_cache_postparser()
+{
+	struct act_rule *hresrule, *hrqrule;
+	void *cache_ptr;
+	struct cache *cache;
+	struct proxy *curproxy = NULL;
+	int err = 0;
+	struct flt_conf *fconf;
+
+	for (curproxy = proxy; curproxy; curproxy = curproxy->next) {
+
+		/* resolve the http response cache name to a ptr in the action rule */
+		list_for_each_entry(hresrule, &curproxy->http_res_rules, list) {
+			if (hresrule->action  != ACT_CUSTOM ||
+			    hresrule->action_ptr != http_action_store_cache)
+				continue;
+
+			cache_ptr = hresrule->arg.act.p[0];
+
+			list_for_each_entry(cache, &caches, list) {
+				if (!strcmp(cache->id, cache_ptr)) {
+					/* don't free there, it's still used in the filter conf */
+					cache_ptr = cache;
+					break;
+				}
+			}
+
+			if (cache_ptr == hresrule->arg.act.p[0]) {
+				Alert("Proxy '%s': unable to find the cache '%s' referenced by http-response cache-store rule.\n",
+				      curproxy->id, (char *)hresrule->arg.act.p[0]);
+				err++;
+			}
+
+			hresrule->arg.act.p[0] = cache_ptr;
+		}
+
+		/* resolve the http request cache name to a ptr in the action rule */
+		list_for_each_entry(hrqrule, &curproxy->http_req_rules, list) {
+			if (hrqrule->action  != ACT_CUSTOM ||
+			    hrqrule->action_ptr != http_action_req_cache_use)
+				continue;
+
+			cache_ptr = hrqrule->arg.act.p[0];
+
+			list_for_each_entry(cache, &caches, list) {
+				if (!strcmp(cache->id, cache_ptr)) {
+					free(cache_ptr);
+					cache_ptr = cache;
+					break;
+				}
+			}
+
+			if (cache_ptr == hrqrule->arg.act.p[0]) {
+				Alert("Proxy '%s': unable to find the cache '%s' referenced by http-request cache-use rule.\n",
+				      curproxy->id, (char *)hrqrule->arg.act.p[0]);
+				err++;
+			}
+
+			hrqrule->arg.act.p[0] = cache_ptr;
+		}
+
+		/* resolve the cache name to a ptr in the filter config */
+		list_for_each_entry(fconf, &curproxy->filter_configs, list) {
+
+			cache_ptr = fconf->conf;
+
+			list_for_each_entry(cache, &caches, list) {
+				if (!strcmp(cache->id, cache_ptr)) {
+					/* there can be only one filter per cache, so we free it there */
+					free(cache_ptr);
+					cache_ptr = cache;
+					break;
+				}
+			}
+
+			if (cache_ptr == fconf->conf) {
+				Alert("Proxy '%s': unable to find the cache '%s' referenced by the filter 'cache'.\n",
+				      curproxy->id, (char *)fconf->conf);
+				err++;
+			}
+			fconf->conf = cache_ptr;
+		}
+	}
+	return err;
+}
+
+
+struct flt_ops cache_ops = {
+	.init   = cache_store_init,
+
+};
+
+static struct action_kw_list http_res_actions = {
+	.kw = {
+		{ "cache-store", parse_cache_store },
+		{ NULL, NULL }
+	}
+};
+
+static struct action_kw_list http_req_actions = {
+	.kw = {
+		{ "cache-use", parse_cache_use },
+		{ NULL, NULL }
+	}
+};
+
+struct applet http_cache_applet = {
+	.obj_type = OBJ_TYPE_APPLET,
+	.name = "<CACHE>", /* used for logging */
+	.fct = NULL,
+	.release = NULL,
+};
+
+__attribute__((constructor))
+static void __cache_init(void)
+{
+	cfg_register_section("cache", cfg_parse_cache, cfg_post_parse_section_cache);
+	cfg_register_postparser("cache", cfg_cache_postparser);
+	http_res_keywords_register(&http_res_actions);
+	http_req_keywords_register(&http_req_actions);
+}
+