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Make DNS engine RFC 5452 compliant (#1324) 

The original code did not deal with UDP binding failures, this new code does one random port attempt and then sets port to 0 to get 'OS default' behaviour, and ASSERTs that that has to work.

Patch also moves the local UDP port range definition to udp.h from udp.c.
This commit is contained in:
bert hubert 2016-08-20 22:04:35 +02:00 committed by Marcel Stör
parent 98d3b46e2c
commit 6e25b74781
3 changed files with 13 additions and 6 deletions
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5
app/include/lwip/udp.h
View File

@ -156,6 +156,11 @@ void udp_input (struct pbuf *p, struct netif *inp)ICACHE_FLASH_
#define udp_init() /* Compatibility define, not init needed. */ #define udp_init() /* Compatibility define, not init needed. */
#ifndef UDP_LOCAL_PORT_RANGE_START
#define UDP_LOCAL_PORT_RANGE_START 4096
#define UDP_LOCAL_PORT_RANGE_END 0x7fff
#endif
#if UDP_DEBUG #if UDP_DEBUG
void udp_debug_print(struct udp_hdr *udphdr)ICACHE_FLASH_ATTR; void udp_debug_print(struct udp_hdr *udphdr)ICACHE_FLASH_ATTR;
#else #else

10
app/lwip/core/dns.c
View File

@ -254,8 +254,14 @@ dns_init()
LWIP_ASSERT("For implicit initialization to work, DNS_STATE_UNUSED needs to be 0", LWIP_ASSERT("For implicit initialization to work, DNS_STATE_UNUSED needs to be 0",
DNS_STATE_UNUSED == 0); DNS_STATE_UNUSED == 0);
/* initialize DNS client */ /* initialize DNS client, try to get RFC 5452 random source port */
udp_bind(dns_pcb, IP_ADDR_ANY, 0); u16_t port = UDP_LOCAL_PORT_RANGE_START + (os_random() % (UDP_LOCAL_PORT_RANGE_END - UDP_LOCAL_PORT_RANGE_START));
for(;;) {
if(udp_bind(dns_pcb, IP_ADDR_ANY, port) == ERR_OK)
break;
LWIP_ASSERT("Unable to get a PCB for DNS", port != 0);
port=0; // try again with random source
}
udp_recv(dns_pcb, dns_recv, NULL); udp_recv(dns_pcb, dns_recv, NULL);
/* initialize default DNS primary server */ /* initialize default DNS primary server */

4
app/lwip/core/udp.c
View File

@ -758,10 +758,6 @@ udp_bind(struct udp_pcb *pcb, ip_addr_t *ipaddr, u16_t port)
/* no port specified? */ /* no port specified? */
if (port == 0) { if (port == 0) {
#ifndef UDP_LOCAL_PORT_RANGE_START
#define UDP_LOCAL_PORT_RANGE_START 4096
#define UDP_LOCAL_PORT_RANGE_END 0x7fff
#endif
port = UDP_LOCAL_PORT_RANGE_START; port = UDP_LOCAL_PORT_RANGE_START;
ipcb = udp_pcbs; ipcb = udp_pcbs;
while ((ipcb != NULL) && (port != UDP_LOCAL_PORT_RANGE_END)) { while ((ipcb != NULL) && (port != UDP_LOCAL_PORT_RANGE_END)) {