dns: use compile time initialization for structs, remove unnecessary call to inet_aton

Also avoids excessive stack utilization for buffer

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

diff --git a/dns.c b/dns.c
index ecfaa63..75e739d 100644 (file)
--- a/dns.c
+++ b/dns.c
@@ -30,6 +30,7 @@
 
 #include <libubox/uloop.h>
 #include <libubox/usock.h>
+#include <libubox/utils.h>
 
 #include "announce.h"
 #include "util.h"
@@ -67,58 +68,62 @@ dns_type_string(uint16_t type)
 void
 dns_send_question(struct uloop_fd *u, char *question, int type)
 {
-       size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
-       unsigned char buffer[MAX_NAME_LEN];
-       struct dns_header h = { 0 };
-       struct dns_question q = { 0 };
-       struct msghdr m = { 0 };
-       struct iovec iov[3] = { {0}, {0}, {0} };
-       struct sockaddr_in a = { 0 };
+       static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
+       static unsigned char buffer[MAX_NAME_LEN];
+       static struct dns_header h = {
+               .questions = cpu_to_be16(1),
+       };
+       static struct dns_question q = {
+               .class = cpu_to_be16(1),
+       };
+       static struct iovec iov[] = {
+               {
+                       .iov_base = &h,
+                       .iov_len = sizeof(h),
+               },
+               {
+                       .iov_base = buffer,
+               },
+               {
+                       .iov_base = &q,
+                       .iov_len = sizeof(q),
+               }
+       };
+       static struct sockaddr_in a = {
+               .sin_family = AF_INET,
+               .sin_port = htons(MCAST_PORT),
+       };
+       static struct msghdr m = {
+               .msg_name = (struct sockaddr *) &a,
+               .msg_namelen = sizeof(a),
+               .msg_iov = iov,
+               .msg_iovlen = ARRAY_SIZE(iov),
+               .msg_control = cmsg_data,
+               .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)),
+       };
        struct in_pktinfo *pkti;
        struct cmsghdr *cmsg;
-       struct in_addr in;
        int len;
 
-       a.sin_family = AF_INET;
        a.sin_addr.s_addr = inet_addr(MCAST_ADDR);
-       a.sin_port = htons(MCAST_PORT);
-
-       h.questions = __cpu_to_be16(1);
        q.type = __cpu_to_be16(type);
-       q.class = __cpu_to_be16(1);
 
        len = dn_comp(question, buffer, MAX_NAME_LEN, NULL, NULL);
        if (len < 1)
                return;
 
-       m.msg_name = &a;
-       m.msg_namelen = sizeof(struct sockaddr_in);
-       m.msg_iov = iov;
-       m.msg_iovlen = 3;
+       iov[1].iov_len = len;
 
        memset(cmsg_data, 0, sizeof(cmsg_data));
-       m.msg_control = cmsg_data;
-       m.msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo));
 
        cmsg = CMSG_FIRSTHDR(&m);
        cmsg->cmsg_len = m.msg_controllen;
        cmsg->cmsg_level = IPPROTO_IP;
        cmsg->cmsg_type = IP_PKTINFO;
 
-       inet_aton(iface_ip, &in);
-
        pkti = (struct in_pktinfo*) CMSG_DATA(cmsg);
        pkti->ipi_ifindex = iface_index;
 
-       iov[0].iov_base = &h;
-       iov[0].iov_len = sizeof(struct dns_header);
-
-       iov[1].iov_base = buffer;
-       iov[1].iov_len = len;
-
-       iov[2].iov_base = &q;
-       iov[2].iov_len = sizeof(struct dns_question);
-
        if (sendmsg(u->fd, &m, 0) < 0)
                fprintf(stderr, "failed to send question\n");
        else