Publish mongoose src and tests

CL: Mongoose Web Server: Publish sources and tests

Resolves https://github.com/cesanta/mongoose/issues/745

PUBLISHED_FROM=7ecd7a3c518cfa614a6ba0838678dcb91b75a8c0

src/dns.h

@@ -0,0 +1,164 @@
+/*
+ * Copyright (c) 2014 Cesanta Software Limited
+ * All rights reserved
+ */
+
+/*
+ * === DNS API reference
+ */
+
+#ifndef CS_MONGOOSE_SRC_DNS_H_
+#define CS_MONGOOSE_SRC_DNS_H_
+
+#include "mongoose/src/net.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+#define MG_DNS_A_RECORD 0x01     /* Lookup IP address */
+#define MG_DNS_CNAME_RECORD 0x05 /* Lookup CNAME */
+#define MG_DNS_PTR_RECORD 0x0c   /* Lookup PTR */
+#define MG_DNS_TXT_RECORD 0x10   /* Lookup TXT */
+#define MG_DNS_AAAA_RECORD 0x1c  /* Lookup IPv6 address */
+#define MG_DNS_SRV_RECORD 0x21   /* Lookup SRV */
+#define MG_DNS_MX_RECORD 0x0f    /* Lookup mail server for domain */
+#define MG_DNS_ANY_RECORD 0xff
+#define MG_DNS_NSEC_RECORD 0x2f
+
+#define MG_MAX_DNS_QUESTIONS 32
+#define MG_MAX_DNS_ANSWERS 32
+
+#define MG_DNS_MESSAGE 100 /* High-level DNS message event */
+
+enum mg_dns_resource_record_kind {
+  MG_DNS_INVALID_RECORD = 0,
+  MG_DNS_QUESTION,
+  MG_DNS_ANSWER
+};
+
+/* DNS resource record. */
+struct mg_dns_resource_record {
+  struct mg_str name; /* buffer with compressed name */
+  int rtype;
+  int rclass;
+  int ttl;
+  enum mg_dns_resource_record_kind kind;
+  struct mg_str rdata; /* protocol data (can be a compressed name) */
+};
+
+/* DNS message (request and response). */
+struct mg_dns_message {
+  struct mg_str pkt; /* packet body */
+  uint16_t flags;
+  uint16_t transaction_id;
+  int num_questions;
+  int num_answers;
+  struct mg_dns_resource_record questions[MG_MAX_DNS_QUESTIONS];
+  struct mg_dns_resource_record answers[MG_MAX_DNS_ANSWERS];
+};
+
+struct mg_dns_resource_record *mg_dns_next_record(
+    struct mg_dns_message *msg, int query, struct mg_dns_resource_record *prev);
+
+/*
+ * Parses the record data from a DNS resource record.
+ *
+ *  - A:     struct in_addr *ina
+ *  - AAAA:  struct in6_addr *ina
+ *  - CNAME: char buffer
+ *
+ * Returns -1 on error.
+ *
+ * TODO(mkm): MX
+ */
+int mg_dns_parse_record_data(struct mg_dns_message *msg,
+                             struct mg_dns_resource_record *rr, void *data,
+                             size_t data_len);
+
+/*
+ * Sends a DNS query to the remote end.
+ */
+void mg_send_dns_query(struct mg_connection *nc, const char *name,
+                       int query_type);
+
+/*
+ * Inserts a DNS header to an IO buffer.
+ *
+ * Returns the number of bytes inserted.
+ */
+int mg_dns_insert_header(struct mbuf *io, size_t pos,
+                         struct mg_dns_message *msg);
+
+/*
+ * Appends already encoded questions from an existing message.
+ *
+ * This is useful when generating a DNS reply message which includes
+ * all question records.
+ *
+ * Returns the number of appended bytes.
+ */
+int mg_dns_copy_questions(struct mbuf *io, struct mg_dns_message *msg);
+
+/*
+ * Encodes and appends a DNS resource record to an IO buffer.
+ *
+ * The record metadata is taken from the `rr` parameter, while the name and data
+ * are taken from the parameters, encoded in the appropriate format depending on
+ * record type and stored in the IO buffer. The encoded values might contain
+ * offsets within the IO buffer. It's thus important that the IO buffer doesn't
+ * get trimmed while a sequence of records are encoded while preparing a DNS
+ * reply.
+ *
+ * This function doesn't update the `name` and `rdata` pointers in the `rr`
+ * struct because they might be invalidated as soon as the IO buffer grows
+ * again.
+ *
+ * Returns the number of bytes appended or -1 in case of error.
+ */
+int mg_dns_encode_record(struct mbuf *io, struct mg_dns_resource_record *rr,
+                         const char *name, size_t nlen, const void *rdata,
+                         size_t rlen);
+
+/*
+ * Encodes a DNS name.
+ */
+int mg_dns_encode_name(struct mbuf *io, const char *name, size_t len);
+
+/* Low-level: parses a DNS response. */
+int mg_parse_dns(const char *buf, int len, struct mg_dns_message *msg);
+
+/*
+ * Uncompresses a DNS compressed name.
+ *
+ * The containing DNS message is required because of the compressed encoding
+ * and reference suffixes present elsewhere in the packet.
+ *
+ * If the name is less than `dst_len` characters long, the remainder
+ * of `dst` is terminated with `\0` characters. Otherwise, `dst` is not
+ * terminated.
+ *
+ * If `dst_len` is 0 `dst` can be NULL.
+ * Returns the uncompressed name length.
+ */
+size_t mg_dns_uncompress_name(struct mg_dns_message *msg, struct mg_str *name,
+                              char *dst, int dst_len);
+
+/*
+ * Attaches a built-in DNS event handler to the given listening connection.
+ *
+ * The DNS event handler parses the incoming UDP packets, treating them as DNS
+ * requests. If an incoming packet gets successfully parsed by the DNS event
+ * handler, a user event handler will receive an `MG_DNS_REQUEST` event, with
+ * `ev_data` pointing to the parsed `struct mg_dns_message`.
+ *
+ * See
+ * [captive_dns_server](https://github.com/cesanta/mongoose/tree/master/examples/captive_dns_server)
+ * example on how to handle DNS request and send DNS reply.
+ */
+void mg_set_protocol_dns(struct mg_connection *nc);
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+#endif /* CS_MONGOOSE_SRC_DNS_H_ */