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WIP: net: DHCP use the DNS servers option we request #1369

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WIP: net: DHCP use the DNS servers option we request #1369

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38 changes: 38 additions & 0 deletions subsys/net/ip/dhcpv4.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#include <net/udp.h>
#include "udp_internal.h"
#include <net/dhcpv4.h>
#include <net/dns_resolve.h>

struct dhcp_msg {
u8_t op; /* Message type, 1:BOOTREQUEST, 2:BOOTREPLY */
Expand Down Expand Up @@ -745,6 +746,43 @@ static enum net_verdict parse_options(struct net_if *iface,
net_if_ipv4_set_gw(iface, &router);
break;
}
case DHCPV4_OPTIONS_DNS_SERVER: {
struct in_addr dns;
char dns_string[NET_IPV4_ADDR_LEN];
const char *dns_servers[] = {dns_string, NULL};

/* DNS server option may present 1 or more
* addresses. Each 4 bytes in length. DNS
* servers should be listed in order
* of preference. Hence we choose the first
* and skip the rest.
*/
if (length % 4 != 0 || length < 4) {
NET_ERR("options_dns, bad length");
return NET_DROP;
}

frag = net_frag_read(frag, pos, &pos, 4, dns.s4_addr);
frag = net_frag_skip(frag, pos, &pos, length - 4);
if (!frag && pos) {
NET_ERR("options_dns, short packet");
return NET_DROP;
}

memset(dns_string, 0, sizeof(dns_string));
memcpy(dns_string, net_sprint_ipv4_addr(&dns),
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But this is what I don't like. Convert binary address to string, just for it to be converted back? Nope, we should allow to init resolver with struct in_addr.

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This definitely won't do, because net_sprint_ipv4_addr() is debugging func, available only when logging is enabled.

@pdxjohnny : I'm in the process of refactoring this patch already.

min(strlen(net_sprint_ipv4_addr(&dns)),
sizeof(dns_string) - 1));

NET_DBG("options_dns: %s", dns_servers[0]);

// TODO Change this to its own context
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Re: this TODO. I guess, for initial version of this feature it's not required.

if (dns_resolve_init(dns_resolve_get_default(), dns_servers) < 0) {
NET_DBG("options_dns, failed to set resolve address");
return NET_DROP;
}
break;
}
case DHCPV4_OPTIONS_LEASE_TIME:
if (length != 4) {
NET_ERR("options_lease_time, bad length");
Expand Down