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server: reply udp packet with original route path

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This commit is contained in:
Nick Peng
2022-11-03 20:44:04 +08:00
parent 7b8ff57773
commit 91ee65231e
1 changed files with 46 additions and 0 deletions
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46
src/dns_server.c
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@@ -905,10 +905,56 @@ static int _dns_server_reply_udp(struct dns_request *request, struct dns_server_
unsigned char *inpacket, int inpacket_len)
{
int send_len = 0;
struct iovec iovec[1];
struct msghdr msg;
struct cmsghdr *cmsg;
char msg_control[256];
if (atomic_read(&server.run) == 0 || inpacket == NULL || inpacket_len <= 0) {
return -1;
}
iovec[0].iov_base = inpacket;
iovec[0].iov_len = inpacket_len;
msg.msg_iov = iovec;
msg.msg_iovlen = 1;
msg.msg_control = msg_control;
msg.msg_controllen = sizeof(msg_control);
msg.msg_flags = 0;
msg.msg_name = &request->addr;
msg.msg_namelen = request->addr_len;
cmsg = CMSG_FIRSTHDR(&msg);
if (request->localaddr.ss_family == AF_INET) {
struct sockaddr_in *s4 = (struct sockaddr_in *)&request->localaddr;
cmsg->cmsg_level = SOL_IP;
cmsg->cmsg_type = IP_PKTINFO;
cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
msg.msg_controllen = CMSG_SPACE(sizeof(struct in_pktinfo));
struct in_pktinfo *pktinfo = (struct in_pktinfo *)CMSG_DATA(cmsg);
memset(pktinfo, 0, sizeof(*pktinfo));
pktinfo->ipi_spec_dst = s4->sin_addr;
} else if (request->localaddr.ss_family == AF_INET6) {
struct sockaddr_in6 *s6 = (struct sockaddr_in6 *)&request->localaddr;
cmsg->cmsg_level = IPPROTO_IPV6;
cmsg->cmsg_type = IPV6_PKTINFO;
cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
msg.msg_controllen = CMSG_SPACE(sizeof(struct in6_pktinfo));
struct in6_pktinfo *pktinfo = (struct in6_pktinfo *)CMSG_DATA(cmsg);
memset(pktinfo, 0, sizeof(*pktinfo));
pktinfo->ipi6_addr = s6->sin6_addr;
} else {
goto use_send;
}
send_len = sendmsg(udpserver->head.fd, &msg, 0);
if (send_len == inpacket_len) {
return 0;
}
use_send:
send_len = sendto(udpserver->head.fd, inpacket, inpacket_len, 0, &request->addr, request->addr_len);
if (send_len != inpacket_len) {
tlog(TLOG_ERROR, "send failed, %s", strerror(errno));