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ipv6: reuse the existing socket for further lookups 

This reduces network overhead if you do not run a local caching
nameserver.
This commit is contained in:
Michael Stapelberg 2010-01-01 22:01:57 +01:00
parent 998109a653
commit 37882cee88
1 changed files with 36 additions and 24 deletions
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60
src/print_ipv6_addr.c
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@ -8,15 +8,46 @@
#include <string.h>
#include <arpa/inet.h>
static void print_sockname(int fd) {
static char buf[INET6_ADDRSTRLEN+1];
struct sockaddr_storage local;
int ret;
socklen_t local_len = sizeof(struct sockaddr_storage);
if (getsockname(fd, (struct sockaddr*)&local, &local_len) == -1) {
perror("getsockname()");
(void)close(fd);
printf("no IPv6");
return;
}
memset(buf, 0, INET6_ADDRSTRLEN + 1);
if ((ret = getnameinfo((struct sockaddr*)&local, local_len,
buf, sizeof(buf), NULL, 0,
NI_NUMERICHOST)) != 0) {
fprintf(stderr, "getnameinfo(): %s\n", gai_strerror(ret));
printf("no IPv6");
return;
}
printf("%s", buf);
}
/*
* Returns the IPv6 address with which you have connectivity at the moment.
*
*/
static void print_ipv6_addr() {
static char buf[INET6_ADDRSTRLEN+1];
struct addrinfo hints;
struct addrinfo *result, *resp;
int fd;
static int fd = -1;
/* To save dns lookups (if they are not cached locally) and creating
* sockets, we save the fd and keep it open. */
if (fd > -1) {
print_sockname(fd);
return;
}
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = AF_INET6;
@ -52,29 +83,10 @@ static void print_ipv6_addr() {
continue;
}
struct sockaddr_storage local;
socklen_t local_len = sizeof(struct sockaddr_storage);
if (getsockname(fd, (struct sockaddr*)&local, &local_len) == -1) {
perror("getsockname()");
(void)close(fd);
printf("no IPv6");
return;
}
(void)close(fd);
memset(buf, 0, INET6_ADDRSTRLEN + 1);
int ret;
if ((ret = getnameinfo((struct sockaddr*)&local, local_len,
buf, sizeof(buf), NULL, 0,
NI_NUMERICHOST)) != 0) {
fprintf(stderr, "getnameinfo(): %s\n", gai_strerror(ret));
printf("no IPv6");
return;
}
free(result);
printf("%s", buf);
print_sockname(fd);
return;
}