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esp-open-rtos/extras/mdnsresponder/mdnsresponder.c
Our Air Quality 85338ee672 mDNS-responder: ipv6 support and fixes 
* Adds ipv6 support. Compiles with ipv6 enabled and then accepts ipv6
  connections and answers AAAA questions.

* Fixes a few overflows of the reply buffer. Reduce the default reply buffer
  size, name it MDNS_RESPONDER_REPLY_SIZE, and allow overriding.

* Fix mdns_add_TXT.

* Prefer malloc to large stack buffers, to control stack sizes, and try to
  malloc only the buffer size needed where known in advance.

* Determine the IP addresses when responding, eliminating the update function
  and the update task.

* Allow use in SoftAP and StationAP mode too.

* Fix to compile without the debug output.

* Slightly better integration with lwip.

* Accept a NULL TXT entry.

* Some code style changes, not comprehensive.
2017-12-12 11:34:21 +11:00

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/*
* Basic multicast DNS responder
*
* Advertises the IP address, port, and characteristics of a service to other
* devices using multicast DNS on the same LAN, so they can find devices with
* addresses dynamically allocated by DHCP. See avahi, Bonjour, etc. See
* RFC6762, RFC6763
*
* This sample code is in the public domain.
*
* by M J A Hamel 2016
*/
#include <espressif/esp_common.h>
#include <espressif/esp_wifi.h>
#include <string.h>
#include <stdio.h>
#include <FreeRTOS.h>
#include <task.h>
#include <lwip/err.h>
#include <lwip/sockets.h>
#include <lwip/sys.h>
#include <lwip/netdb.h>
#include <lwip/dns.h>
#include <lwip/prot/dns.h>
#include <lwip/prot/iana.h>
#include <lwip/udp.h>
#include <lwip/igmp.h>
#include <lwip/netif.h>
#include "mdnsresponder.h"
#if !LWIP_IGMP
#error "LWIP_IGMP needs to be defined in lwipopts.h"
#endif
#define qDebugLog // Log activity generally
#define qLogIncoming // Log all arriving multicast packets
#define qLogAllTraffic // Log and decode all mDNS packets
//-------------------------------------------------------------------
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/bpstruct.h"
#endif
PACK_STRUCT_BEGIN
/** DNS message header */
struct mdns_hdr {
PACK_STRUCT_FIELD(u16_t id);
PACK_STRUCT_FIELD(u8_t flags1);
PACK_STRUCT_FIELD(u8_t flags2);
PACK_STRUCT_FIELD(u16_t numquestions);
PACK_STRUCT_FIELD(u16_t numanswers);
PACK_STRUCT_FIELD(u16_t numauthrr);
PACK_STRUCT_FIELD(u16_t numextrarr);
}PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#define SIZEOF_DNS_HDR 12
PACK_STRUCT_BEGIN
/** MDNS query message structure */
struct mdns_query {
/* MDNS query record starts with either a domain name or a pointer
to a name already present somewhere in the packet. */
PACK_STRUCT_FIELD(u16_t type);
PACK_STRUCT_FIELD(u16_t class);
}PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#define SIZEOF_DNS_QUERY 4
PACK_STRUCT_BEGIN
/** MDNS answer message structure */
struct mdns_answer {
/* MDNS answer record starts with either a domain name or a pointer
to a name already present somewhere in the packet. */
PACK_STRUCT_FIELD(u16_t type);
PACK_STRUCT_FIELD(u16_t class);
PACK_STRUCT_FIELD(u32_t ttl);
PACK_STRUCT_FIELD(u16_t len);
}PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#define SIZEOF_DNS_ANSWER 10
PACK_STRUCT_BEGIN
struct mdns_rr_srv {
/* RR SRV */
PACK_STRUCT_FIELD(u16_t prio);
PACK_STRUCT_FIELD(u16_t weight);
PACK_STRUCT_FIELD(u16_t port);
}PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#define SIZEOF_DNS_RR_SRV 6
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/epstruct.h"
#endif
#define vTaskDelayMs(ms) vTaskDelay((ms)/portTICK_PERIOD_MS)
#define UNUSED_ARG(x) (void)x
#define kDummyDataSize 8 // arbitrary, dynamically resized
#define kMaxNameSize 64
#define kMaxQStr 128 // max incoming question key handled
typedef struct mdns_rsrc {
struct mdns_rsrc* rNext;
u16_t rType;
u32_t rTTL;
u16_t rKeySize;
u16_t rDataSize;
char rData[kDummyDataSize]; // Key, as C str with . seperators, followed by data in network-ready form
// at rData[rKeySize]
} mdns_rsrc;
static struct udp_pcb* gMDNS_pcb = NULL;
static const ip_addr_t gMulticastV4Addr = DNS_MQUERY_IPV4_GROUP_INIT;
#if LWIP_IPV6
#include "lwip/mld6.h"
static const ip_addr_t gMulticastV6Addr = DNS_MQUERY_IPV6_GROUP_INIT;
#endif
static mdns_rsrc* gDictP = NULL; // RR database, linked list
//---------------------- Debug/logging utilities -------------------------
// DNS field TYPE used for "Resource Records", some additions
#define DNS_RRTYPE_AAAA 28 /* IPv6 host address */
#define DNS_RRTYPE_SRV 33 /* Service record */
#define DNS_RRTYPE_OPT 41 /* EDNS0 OPT record */
#define DNS_RRTYPE_NSEC 47 /* NSEC record */
#define DNS_RRTYPE_TSIG 250 /* Transaction Signature */
#define DNS_RRTYPE_ANY 255 /* Not a DNS type, but a DNS query type, meaning "all types"*/
// DNS field CLASS used for "Resource Records"
#define DNS_RRCLASS_ANY 255 /* Any class (q) */
#define DNS_FLAG1_RESP 0x80
#define DNS_FLAG1_OPMASK 0x78
#define DNS_FLAG1_AUTH 0x04
#define DNS_FLAG1_TRUNC 0x02
#define DNS_FLAG1_RD 0x01
#define DNS_FLAG2_RA 0x80
#define DNS_FLAG2_RESMASK 0x0F
#ifdef qDebugLog
static char qstr[12];
static char* mdns_qrtype(uint16_t typ)
{
switch(typ) {
case DNS_RRTYPE_A : return ("A");
case DNS_RRTYPE_NS : return ("NS");
case DNS_RRTYPE_PTR : return ("PTR");
case DNS_RRTYPE_TXT : return ("TXT ");
case DNS_RRTYPE_AAAA : return ("AAAA");
case DNS_RRTYPE_SRV : return ("SRV ");
case DNS_RRTYPE_NSEC : return ("NSEC ");
case DNS_RRTYPE_ANY : return ("ANY");
}
sprintf(qstr, "type %d", typ);
return qstr;
}
#ifdef qLogAllTraffic
static void mdns_printhex(u8_t* p, int n)
{
int i;
for (i=0; i<n; i++) {
printf("%02X ",*p++);
if ((i % 32) == 31) printf("\n");
}
printf("\n");
}
static void mdns_print_pstr(u8_t* p)
{
int i, n;
char* cp;
n = *p++;
cp = (char*)p;
for (i = 0; i < n; i++) {
putchar(*cp++);
}
}
static char cstr[16];
static char* mdns_qclass(uint16_t cls)
{
switch(cls) {
case DNS_RRCLASS_IN : return ("In");
case DNS_RRCLASS_ANY : return ("ANY");
}
sprintf(cstr,"class %d",cls);
return cstr;
}
// Sequence of Pascal strings, terminated by zero-length string
// Handles compression, returns ptr to next item
static u8_t* mdns_print_name(u8_t* p, struct mdns_hdr* hp)
{
char* cp = (char*)p;
int i, n;
do {
n = *cp++;
if ((n & 0xC0) == 0xC0) {
n = (n & 0x3F) << 8;
n |= (u8_t)*cp++;
mdns_print_name((u8_t*)hp + n, hp);
n = 0;
} else if (n & 0xC0) {
printf("<label $%X?>",n);
n = 0;
} else {
for (i = 0; i < n; i++)
putchar(*cp++);
if (n != 0) putchar('.');
}
} while (n > 0);
return (u8_t*)cp;
}
static u8_t* mdns_print_header(struct mdns_hdr* hdr)
{
if (hdr->flags1 & DNS_FLAG1_RESP) {
printf("Response, ID $%X %s ", htons(hdr->id), (hdr->flags1 & DNS_FLAG1_AUTH) ? "Auth " : "Non-auth ");
if (hdr->flags2 & DNS_FLAG2_RA) printf("RA ");
if ((hdr->flags2 & DNS_FLAG2_RESMASK) == 0) printf("noerr");
else printf("err %d", hdr->flags2 & DNS_FLAG2_RESMASK);
} else {
printf("Query, ID $%X op %d", htons(hdr->id), (hdr->flags1 >> 4) & 0x7 );
}
if (hdr->flags1 & DNS_FLAG1_RD) printf("RD ");
if (hdr->flags1 & DNS_FLAG1_TRUNC) printf("[TRUNC] ");
printf(": %d questions", htons(hdr->numquestions) );
if (hdr->numanswers != 0)
printf(", %d answers",htons(hdr->numanswers));
if (hdr->numauthrr != 0)
printf(", %d auth RR",htons(hdr->numauthrr));
if (hdr->numextrarr != 0)
printf(", %d extra RR",htons(hdr->numextrarr));
putchar('\n');
return (u8_t*)hdr + SIZEOF_DNS_HDR;
}
// Copy needed because it may be misaligned
static u8_t* mdns_print_query(u8_t* p)
{
struct mdns_query q;
uint16_t c;
memcpy(&q, p, SIZEOF_DNS_QUERY);
c = htons(q.class);
printf(" %s %s", mdns_qrtype(htons(q.type)), mdns_qclass(c & 0x7FFF) );
if (c & 0x8000) printf(" unicast-req");
printf("\n");
return p + SIZEOF_DNS_QUERY;
}
// Copy needed because it may be misaligned
static u8_t* mdns_print_answer(u8_t* p, struct mdns_hdr* hp)
{
struct mdns_answer ans;
u16_t rrlen, atype, rrClass;;
memcpy(&ans,p,SIZEOF_DNS_ANSWER);
atype = htons(ans.type);
rrlen = htons(ans.len);
rrClass = htons(ans.class);
printf(" %s %s TTL %d ", mdns_qrtype(atype), mdns_qclass(rrClass & 0x7FFF), htonl(ans.ttl));
if (rrClass & 0x8000)
printf("cache-flush ");
if (rrlen > 0) {
u8_t* rp = p + SIZEOF_DNS_ANSWER;
if (atype == DNS_RRTYPE_A && rrlen == 4) {
printf("%d.%d.%d.%d\n",rp[0],rp[1],rp[2],rp[3]);
} else if (atype == DNS_RRTYPE_PTR) {
mdns_print_name(rp, hp);
printf("\n");
} else if (atype == DNS_RRTYPE_TXT) {
mdns_print_pstr(rp);
printf("\n");
} else if (atype == DNS_RRTYPE_SRV && rrlen > SIZEOF_DNS_RR_SRV) {
struct mdns_rr_srv srvRR;
memcpy(&srvRR, rp, SIZEOF_DNS_RR_SRV);
printf("prio %d, weight %d, port %d, target ", srvRR.prio, srvRR.weight, ntohs(srvRR.port));
mdns_print_name(rp + SIZEOF_DNS_RR_SRV, hp);
printf("\n");
} else {
printf("%db:", rrlen);
mdns_printhex(rp, rrlen);
}
} else
printf("\n");
return p + SIZEOF_DNS_ANSWER + rrlen;
}
static int mdns_print_msg(u8_t* msgP, int msgLen)
{
int i;
u8_t *tp;
u8_t *limP = msgP + msgLen;
struct mdns_hdr* hdr;
hdr = (struct mdns_hdr*) msgP;
tp = mdns_print_header(hdr);
for (i = 0; i < htons(hdr->numquestions); i++) {
printf(" Q%d: ", i + 1);
tp = mdns_print_name(tp, hdr);
tp = mdns_print_query(tp);
if (tp > limP) return 0;
}
for (i = 0; i < htons(hdr->numanswers); i++) {
printf(" A%d: ", i + 1);
tp = mdns_print_name(tp, hdr);
tp = mdns_print_answer(tp, hdr);
if (tp > limP) return 0;
}
for (i = 0; i < htons(hdr->numauthrr); i++) {
printf(" AuRR%d: ", i + 1);
tp = mdns_print_name(tp, hdr);
tp = mdns_print_answer(tp, hdr);
if (tp > limP) return 0;
}
for (i = 0; i < htons(hdr->numextrarr); i++) {
printf(" ExRR%d: ", i + 1);
tp = mdns_print_name(tp, hdr);
tp = mdns_print_answer(tp, hdr);
if (tp > limP) return 0;
}
return 1;
}
#endif // qLogAllTraffic
#endif // qDebugLog
//---------------------------------------------------------------------------
// Convert a DNS domain name label sequence into C string with . seperators
// Handles compression
static u8_t* mdns_labels2str(u8_t* hdrP, u8_t* p, char* qStr)
{
int i, n;
do {
n = *p++;
if ((n & 0xC0) == 0xC0) {
n = (n & 0x3F) << 8;
n |= (u8_t)*p++;
mdns_labels2str( hdrP, hdrP + n, qStr);
return p;
} else if (n & 0xC0) {
printf(">>> mdns_labels2str,label $%X?",n);
return p;
} else {
for (i = 0; i < n; i++)
*qStr++ = *p++;
if (n == 0) *qStr++ = 0;
else *qStr++ = '.';
}
} while (n>0);
return p;
}
// Encode a <string>.<string>.<string> as a sequence of labels, return length
static int mdns_str2labels(const char* name, u8_t* lseq, int max)
{
int i, n, sdx, idx = 0;
int lc = 0;
do {
sdx = idx;
while (name[idx] != '.' && name[idx] != 0) idx++;
n = idx - sdx;
if (lc + 1 + n > max) {
printf(">>> mdns_str2labels: oversize (%d)\n", lc + 1 + n);
return 0;
}
*lseq++ = n;
lc++;
for (i = 0; i < n; i++)
*lseq++ = name[sdx + i];
lc += n;
if (name[idx] == '.')
idx++;
} while (n > 0);
return lc;
}
// Unpack a DNS question RR at qp, return pointer to next RR
static u8_t* mdns_get_question(u8_t* hdrP, u8_t* qp, char* qStr, uint16_t* qClass, uint16_t* qType, u8_t* qUnicast)
{
struct mdns_query qr;
uint16_t cls;
qp = mdns_labels2str(hdrP, qp, qStr);
memcpy(&qr, qp, SIZEOF_DNS_QUERY);
*qType = htons(qr.type);
cls = htons(qr.class);
*qUnicast = cls >> 15;
*qClass = cls & 0x7FFF;
return qp + SIZEOF_DNS_QUERY;
}
//---------------------------------------------------------------------------
// Add a record to the RR database list
static void mdns_add_response(const char* vKey, u16_t vType, u32_t ttl, const void* dataP, u16_t vDataSize)
{
mdns_rsrc* rsrcP;
int keyLen, recSize;
keyLen = strlen(vKey) + 1;
recSize = sizeof(mdns_rsrc) - kDummyDataSize + keyLen + vDataSize;
rsrcP = (mdns_rsrc*)malloc(recSize);
if (rsrcP == NULL) {
printf(">>> mdns_add_response: couldn't alloc %d\n",recSize);
} else {
rsrcP->rType = vType;
rsrcP->rTTL = ttl;
rsrcP->rKeySize = keyLen;
rsrcP->rDataSize = vDataSize;
memcpy(rsrcP->rData, vKey, keyLen);
memcpy(&rsrcP->rData[keyLen], dataP, vDataSize);
rsrcP->rNext = gDictP;
gDictP = rsrcP;
#ifdef qDebugLog
printf("mDNS added RR '%s' %s, %d bytes\n", vKey, mdns_qrtype(vType), vDataSize);
#endif
}
}
void mdns_add_PTR(const char* rKey, u32_t ttl, const char* nmStr)
{
size_t nl;
u8_t lBuff[kMaxNameSize];
nl = mdns_str2labels(nmStr, lBuff, sizeof(lBuff));
if (nl > 0) {
mdns_add_response(rKey, DNS_RRTYPE_PTR, ttl, lBuff, nl);
}
}
void mdns_add_SRV(const char* rKey, u32_t ttl, u16_t rPort, const char* targName)
{
typedef struct SrvRec {
struct mdns_rr_srv srvRR;
u8_t lBuff[kMaxNameSize];
} __attribute__((packed)) SrvRec;
int nl;
SrvRec temp;
temp.srvRR.prio = 0;
temp.srvRR.weight = 0;
temp.srvRR.port = htons(rPort);
nl = mdns_str2labels(targName, temp.lBuff, sizeof(temp.lBuff));
if (nl > 0)
mdns_add_response(rKey, DNS_RRTYPE_SRV, ttl, &temp, SIZEOF_DNS_RR_SRV + nl);
}
// Single TXT str, can be concatenated
void mdns_add_TXT(const char* rKey, u32_t ttl, const char* txStr)
{
u16_t n = strlen(txStr);
if (n > 255) {
printf(">>> mdns_add_TXT oversize (%d)\n",n);
return;
}
char *pstr = malloc(n + 1);
pstr[0] = n;
memcpy(&pstr[1], txStr, n);
mdns_add_response(rKey, DNS_RRTYPE_TXT, ttl, pstr, n + 1);
free(pstr);
}
void mdns_add_A(const char* rKey, u32_t ttl, const ip4_addr_t *addr)
{
mdns_add_response(rKey, DNS_RRTYPE_A, ttl, addr, sizeof(ip4_addr_t));
}
#if LWIP_IPV6
void mdns_add_AAAA(const char* rKey, u32_t ttl, const ip6_addr_t *addr)
{
mdns_add_response(rKey, DNS_RRTYPE_AAAA, ttl, addr, sizeof(addr->addr));
}
#endif
void mdns_add_facility( const char* instanceName, // Friendly name, need not be unique
const char* serviceName, // Must be "_name", e.g. "_hap" or "_http"
const char* addText, // Must be <key>=<value>
mdns_flags flags, // TCP or UDP
u16_t onPort, // port number
u32_t ttl // seconds
)
{
size_t key_len = strlen(serviceName) + 12;
char *key = malloc(key_len + 1);
size_t full_name_len = strlen(instanceName) + 1 + key_len;
char *fullName = malloc(full_name_len + 1);
size_t dev_name_len = strlen(instanceName) + 7;
char *devName = malloc(dev_name_len + 1);
#ifdef qDebugLog
printf("\nmDNS advertising instance %s protocol %s", instanceName, serviceName);
if (addText) {
printf(" text %s", addText);
}
printf(" on port %d %s TTL %d secs\n", onPort, (flags & mdns_UDP) ? "UDP" : "TCP", ttl);
#endif
snprintf(key, key_len + 1, "%s.%s.local.", serviceName, (flags & mdns_UDP) ? "_udp" :"_tcp");
snprintf(fullName, full_name_len + 1, "%s.%s", instanceName, key);
snprintf(devName, dev_name_len + 1, "%s.local.", instanceName);
// Order has significance for extraRR feature
if (addText) {
mdns_add_TXT(fullName, ttl, addText);
}
#if LWIP_IPV6
const ip6_addr_t addr6 = { {0ul, 0ul, 0ul, 0ul} };
mdns_add_AAAA(devName, ttl, &addr6);
#endif
const ip4_addr_t addr4 = { 0 };
mdns_add_A(devName, ttl, &addr4);
mdns_add_SRV(fullName, ttl, onPort, devName);
mdns_add_PTR(key, ttl, fullName);
// Optional, makes us browsable
if (flags & mdns_Browsable) {
mdns_add_PTR("_services._dns-sd._udp.local.", ttl, key);
}
free(key);
free(fullName);
free(devName);
}
static mdns_rsrc* mdns_match(const char* qstr, u16_t qType)
{
mdns_rsrc* rp = gDictP;
while (rp != NULL) {
if (rp->rType == qType || qType == DNS_RRTYPE_ANY) {
if (strcasecmp(rp->rData, qstr) == 0) {
#ifdef qDebugLog
printf(" - matched '%s' %s\n", qstr, mdns_qrtype(rp->rType));
#endif
break;
}
}
rp = rp->rNext;
}
return rp;
}
// Create answer RR and append to resp[respLen], return new length
static int mdns_add_to_answer(mdns_rsrc* rsrcP, u8_t* resp, int respLen)
{
// Key is stored as C str, convert to labels
size_t rem = MDNS_RESPONDER_REPLY_SIZE - respLen;
size_t len = mdns_str2labels(rsrcP->rData, &resp[respLen], rem);
if (len == 0) {
// Overflow, skip this answer.
return respLen;
}
if ((len + SIZEOF_DNS_ANSWER + rsrcP->rDataSize) > rem) {
// Overflow, skip this answer.
printf(">>> mdns_add_to_answer: oversize (%d)\n", len + SIZEOF_DNS_ANSWER + rsrcP->rDataSize);
return respLen;
}
respLen += len;
// Answer fields: may be misaligned, so build and memcpy
struct mdns_answer ans;
ans.type = htons(rsrcP->rType);
ans.class = htons(DNS_RRCLASS_IN);
ans.ttl = htonl(rsrcP->rTTL);
ans.len = htons(rsrcP->rDataSize);
memcpy(&resp[respLen], &ans, SIZEOF_DNS_ANSWER);
respLen += SIZEOF_DNS_ANSWER;
// Data for this key
memcpy(&resp[respLen], &rsrcP->rData[rsrcP->rKeySize], rsrcP->rDataSize);
respLen += rsrcP->rDataSize;
return respLen;
}
//---------------------------------------------------------------------------
// Send UDP to multicast address
static void mdns_send_mcast(const ip_addr_t *addr, u8_t* msgP, int nBytes)
{
struct pbuf* p;
err_t err;
#ifdef qLogAllTraffic
mdns_print_msg(msgP, nBytes);
#endif
p = pbuf_alloc(PBUF_TRANSPORT, nBytes, PBUF_RAM);
if (p) {
memcpy(p->payload, msgP, nBytes);
const ip_addr_t *dest_addr;
if (IP_IS_V6_VAL(*addr)) {
#if LWIP_IPV6
dest_addr = &gMulticastV6Addr;
#endif
} else {
dest_addr = &gMulticastV4Addr;
}
struct netif *netif = ip_current_input_netif();
err = udp_sendto_if(gMDNS_pcb, p, dest_addr, LWIP_IANA_PORT_MDNS, netif);
if (err == ERR_OK) {
#ifdef qDebugLog
printf(" - responded with %d bytes err %d\n", nBytes, err);
#endif
} else
printf(">>> mdns_send failed %d\n", err);
pbuf_free(p);
} else {
printf(">>> mdns_send: alloc failed[%d]\n", nBytes);
}
}
// Message has passed tests, may want to send an answer
static void mdns_reply(const ip_addr_t *addr, struct mdns_hdr* hdrP)
{
int i, nquestions, respLen;
struct mdns_hdr* rHdr;
mdns_rsrc* extra;
u8_t* qBase = (u8_t*)hdrP;
u8_t* qp;
u8_t* mdns_response;
mdns_response = malloc(MDNS_RESPONDER_REPLY_SIZE);
if (mdns_response == NULL) {
printf(">>> mdns_reply could not alloc %d\n", MDNS_RESPONDER_REPLY_SIZE);
return;
}
// Build response header
rHdr = (struct mdns_hdr*) mdns_response;
rHdr->id = hdrP->id;
rHdr->flags1 = DNS_FLAG1_RESP + DNS_FLAG1_AUTH;
rHdr->flags2 = 0;
rHdr->numquestions = 0;
rHdr->numanswers = 0;
rHdr->numauthrr = 0;
rHdr->numextrarr = 0;
respLen = SIZEOF_DNS_HDR;
extra = NULL;
qp = qBase + SIZEOF_DNS_HDR;
nquestions = htons(hdrP->numquestions);
for (i = 0; i < nquestions; i++) {
char qStr[kMaxQStr];
u16_t qClass, qType;
u8_t qUnicast;
mdns_rsrc* rsrcP;
qp = mdns_get_question(qBase, qp, qStr, &qClass, &qType, &qUnicast);
if (qClass == DNS_RRCLASS_IN || qClass == DNS_RRCLASS_ANY) {
rsrcP = mdns_match(qStr, qType);
if (rsrcP) {
#if LWIP_IPV6
if (rsrcP->rType == DNS_RRTYPE_AAAA) {
// Emit an answer for each ipv6 address.
struct netif *netif = ip_current_input_netif();
for (int i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i))) {
const ip6_addr_t *addr6 = netif_ip6_addr(netif, i);
#ifdef qDebugLog
char addr6_str[IP6ADDR_STRLEN_MAX];
ip6addr_ntoa_r(addr6, addr6_str, IP6ADDR_STRLEN_MAX);
printf("Updating AAAA record for '%s' to %s\n", rsrcP->rData, addr6_str);
#endif
memcpy(&rsrcP->rData[rsrcP->rKeySize], addr6, sizeof(addr6->addr));
size_t new_len = mdns_add_to_answer(rsrcP, mdns_response, respLen);
if (new_len > respLen) {
rHdr->numanswers = htons(htons(rHdr->numanswers) + 1);
respLen = new_len;
}
}
}
continue;
}
#endif
if (rsrcP->rType == DNS_RRTYPE_A) {
struct netif *netif = ip_current_input_netif();
#ifdef qDebugLog
char addr4_str[IP4ADDR_STRLEN_MAX];
ip4addr_ntoa_r(netif_ip4_addr(netif), addr4_str, IP4ADDR_STRLEN_MAX);
printf("Updating A record for '%s' to %s\n", rsrcP->rData, addr4_str);
#endif
memcpy(&rsrcP->rData[rsrcP->rKeySize], netif_ip4_addr(netif), sizeof(ip4_addr_t));
}
size_t new_len = mdns_add_to_answer(rsrcP, mdns_response, respLen);
if (new_len > respLen) {
rHdr->numanswers = htons(htons(rHdr->numanswers) + 1);
respLen = new_len;
}
// Extra RR logic: if SRV follows PTR, or A follows SRV, volunteer it in extraRR
// Not required, but could do more here, see RFC6763 s12
if (qType == DNS_RRTYPE_PTR) {
if (rsrcP->rNext && rsrcP->rNext->rType == DNS_RRTYPE_SRV)
extra = rsrcP->rNext;
} else if (qType == DNS_RRTYPE_SRV) {
if (rsrcP->rNext && rsrcP->rNext->rType == DNS_RRTYPE_A)
extra = rsrcP->rNext;
}
}
}
} // for nQuestions
if (respLen > SIZEOF_DNS_HDR) {
if (extra) {
if (extra->rType == DNS_RRTYPE_A) {
struct netif *netif = ip_current_input_netif();
#ifdef qDebugLog
char addr4_str[IP4ADDR_STRLEN_MAX];
ip4addr_ntoa_r(netif_ip4_addr(netif), addr4_str, IP4ADDR_STRLEN_MAX);
printf("Updating A record for '%s' to %s\n", extra->rData, addr4_str);
#endif
memcpy(&extra->rData[extra->rKeySize], netif_ip4_addr(netif), sizeof(ip4_addr_t));
}
size_t new_len = mdns_add_to_answer(extra, mdns_response, respLen);
if (new_len > respLen) {
rHdr->numextrarr = htons(htons(rHdr->numextrarr) + 1);
respLen = new_len;
}
}
mdns_send_mcast(addr, mdns_response, respLen);
}
free(mdns_response);
}
// Callback from udp_recv
static void mdns_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port)
{
UNUSED_ARG(pcb);
UNUSED_ARG(port);
u8_t* mdns_payload;
int plen;
plen = p->tot_len;
#ifdef qLogIncoming
char addr_str[IPADDR_STRLEN_MAX];
ipaddr_ntoa_r(addr, addr_str, IPADDR_STRLEN_MAX);
printf("\n\nmDNS IPv%d got %d bytes from %s\n", IP_IS_V6(addr) ? 6 : 4, plen, addr_str);
#endif
// Sanity checks on size
if (plen > MDNS_RESPONDER_REPLY_SIZE) {
printf(">>> mdns_recv: pbuf too big\n");
} else if (plen < (SIZEOF_DNS_HDR + SIZEOF_DNS_QUERY + 1 + SIZEOF_DNS_ANSWER + 1)) {
printf(">>> mdns_recv: pbuf too small\n");
} else {
mdns_payload = malloc(plen);
if (!mdns_payload) {
printf(">>> mdns_recv, could not alloc %d\n",plen);
} else {
if (pbuf_copy_partial(p, mdns_payload, plen, 0) == plen) {
struct mdns_hdr* hdrP = (struct mdns_hdr*) mdns_payload;
#ifdef qLogAllTraffic
mdns_print_msg(mdns_payload, plen);
#endif
if ( (hdrP->flags1 & (DNS_FLAG1_RESP + DNS_FLAG1_OPMASK + DNS_FLAG1_TRUNC) ) == 0
&& hdrP->numquestions > 0 )
mdns_reply(addr, hdrP);
}
free(mdns_payload);
}
}
pbuf_free(p);
}
// If we are in station mode and have an IP address, start a multicast UDP receive
void mdns_init()
{
err_t err;
struct netif *station_netif = sdk_system_get_netif(STATION_IF);
if (station_netif) {
// Start IGMP on the netif for our interface: this isn't done for us
if (!(station_netif->flags & NETIF_FLAG_IGMP)) {
station_netif->flags |= NETIF_FLAG_IGMP;
err = igmp_start(station_netif);
if (err != ERR_OK) {
printf(">>> mDNS_init: igmp_start on %c%c failed %d\n", station_netif->name[0], station_netif->name[1],err);
return;
}
}
if ((err = igmp_joingroup_netif(station_netif, ip_2_ip4(&gMulticastV4Addr))) != ERR_OK) {
printf(">>> mDNS_init: igmp_join failed %d\n",err);
return;
}
#if LWIP_IPV6
if ((err = mld6_joingroup_netif(station_netif, ip_2_ip6(&gMulticastV6Addr))) != ERR_OK) {
printf(">>> mDNS_init: igmp_join failed %d\n",err);
return;
}
#endif
}
struct netif *softap_netif = sdk_system_get_netif(SOFTAP_IF);
if (softap_netif) {
if (softap_netif == NULL) {
printf(">>> mDNS_init: wifi opmode not softap\n");
return;
}
// Start IGMP on the netif for our interface: this isn't done for us
if (!(softap_netif->flags & NETIF_FLAG_IGMP)) {
softap_netif->flags |= NETIF_FLAG_IGMP;
err = igmp_start(softap_netif);
if (err != ERR_OK) {
printf(">>> mDNS_init: igmp_start on %c%c failed %d\n", softap_netif->name[0], softap_netif->name[1],err);
return;
}
}
if ((err = igmp_joingroup_netif(softap_netif, ip_2_ip4(&gMulticastV4Addr))) != ERR_OK) {
printf(">>> mDNS_init: igmp_join failed %d\n",err);
return;
}
#if LWIP_IPV6
if ((err = mld6_joingroup_netif(softap_netif, ip_2_ip6(&gMulticastV6Addr))) != ERR_OK) {
printf(">>> mDNS_init: igmp_join failed %d\n",err);
return;
}
#endif
}
if (station_netif == NULL && softap_netif == NULL) {
printf(">>> mDNS_init: wifi opmode none\n");
return;
}
gMDNS_pcb = udp_new_ip_type(IPADDR_TYPE_ANY);
if (!gMDNS_pcb) {
printf(">>> mDNS_init: udp_new failed\n");
return;
}
if ((err = udp_bind(gMDNS_pcb, IP_ANY_TYPE, LWIP_IANA_PORT_MDNS)) != ERR_OK) {
printf(">>> mDNS_init: udp_bind failed %d\n",err);
return;
}
udp_recv(gMDNS_pcb, mdns_recv, NULL);
}
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