From f0448448b01cf04cc7b04a81c4480734c5bfe84b Mon Sep 17 00:00:00 2001
From: zfl9 <zfl9.com@gmail.com>
Date: Sat, 31 Aug 2019 13:55:12 +0800
Subject: add netutils

---
 Makefile   |  2 +-
 netutils.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 netutils.h | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 netutils.c
 create mode 100644 netutils.h

diff --git a/Makefile b/Makefile
index ff112d4..99eaa57 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CC = gcc
 CFLAGS = -std=c99 -Wall -Wextra -O3
-SRCS = dns2tcp.c
+SRCS = netutils.c dns2tcp.c
 OBJS = $(SRCS:.c=.o)
 MAIN = dns2tcp
 DESTDIR = /usr/local/bin
diff --git a/netutils.c b/netutils.c
new file mode 100644
index 0000000..03fbb44
--- /dev/null
+++ b/netutils.c
@@ -0,0 +1,43 @@
+#define _GNU_SOURCE
+#include "netutils.h"
+#include <arpa/inet.h>
+#undef _GNU_SOURCE
+
+/* build ipv4 socket address from ipstr and portno */
+void build_ipv4_addr(skaddr4_t *addr, const char *ipstr, portno_t portno) {
+    addr->sin_family = AF_INET;
+    inet_pton(AF_INET, ipstr, &addr->sin_addr);
+    addr->sin_port = htons(portno);
+}
+
+/* build ipv6 socket address from ipstr and portno */
+void build_ipv6_addr(skaddr6_t *addr, const char *ipstr, portno_t portno) {
+    addr->sin6_family = AF_INET6;
+    inet_pton(AF_INET6, ipstr, &addr->sin6_addr);
+    addr->sin6_port = htons(portno);
+}
+
+/* parse ipstr and portno from ipv4 socket address */
+void parse_ipv4_addr(const skaddr4_t *addr, char *ipstr, portno_t *portno) {
+    inet_ntop(AF_INET, &addr->sin_addr, ipstr, IP4STRLEN);
+    *portno = ntohs(addr->sin_port);
+}
+
+/* parse ipstr and portno from ipv6 socket address */
+void parse_ipv6_addr(const skaddr6_t *addr, char *ipstr, portno_t *portno) {
+    inet_ntop(AF_INET6, &addr->sin6_addr, ipstr, IP6STRLEN);
+    *portno = ntohs(addr->sin6_port);
+}
+
+/* AF_INET or AF_INET6 or -1(invalid ip string) */
+int get_ipstr_family(const char *ipstr) {
+    if (!ipstr) return -1;
+    uint8_t ipaddr[16]; /* save ipv4/ipv6 addr */
+    if (inet_pton(AF_INET, ipstr, &ipaddr) == 1) {
+        return AF_INET;
+    } else if (inet_pton(AF_INET6, ipstr, &ipaddr) == 1) {
+        return AF_INET6;
+    } else {
+        return -1;
+    }
+}
diff --git a/netutils.h b/netutils.h
new file mode 100644
index 0000000..1645701
--- /dev/null
+++ b/netutils.h
@@ -0,0 +1,38 @@
+#ifndef DNS2TCP_NETUTILS_H
+#define DNS2TCP_NETUTILS_H
+
+#define _GNU_SOURCE
+#include <stdint.h>
+#include <netinet/in.h>
+#undef _GNU_SOURCE
+
+/* ipaddr string len */
+#define IP4STRLEN INET_ADDRSTRLEN
+#define IP6STRLEN INET6_ADDRSTRLEN
+
+/* portno string len */
+#define PORTSTRLEN 6
+
+/* port number typedef */
+typedef uint16_t portno_t;
+
+/* sockaddr type alias */
+typedef struct sockaddr_in  skaddr4_t;
+typedef struct sockaddr_in6 skaddr6_t;
+
+/* build ipv4 socket address from ipstr and portno */
+void build_ipv4_addr(skaddr4_t *addr, const char *ipstr, portno_t portno);
+
+/* build ipv6 socket address from ipstr and portno */
+void build_ipv6_addr(skaddr6_t *addr, const char *ipstr, portno_t portno);
+
+/* parse ipstr and portno from ipv4 socket address */
+void parse_ipv4_addr(const skaddr4_t *addr, char *ipstr, portno_t *portno);
+
+/* parse ipstr and portno from ipv6 socket address */
+void parse_ipv6_addr(const skaddr6_t *addr, char *ipstr, portno_t *portno);
+
+/* AF_INET or AF_INET6 or -1(invalid ip string) */
+int get_ipstr_family(const char *ipstr);
+
+#endif
-- 
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