Add captdns to extras
Ported from Sprite_tm's libesphttpd, upstream at http://git.spritesserver.nl/libesphttpd.git/
This commit is contained in:
Sakari Kapanen
parent
9523e872f8
commit
1336a6c309
3 changed files with 316 additions and 0 deletions
305
extras/captdns/captdns.c
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305
extras/captdns/captdns.c
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/*
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* ----------------------------------------------------------------------------
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* "THE BEER-WARE LICENSE" (Revision 42):
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* Jeroen Domburg <jeroen@spritesmods.com> wrote this file. As long as you retain
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* this notice you can do whatever you want with this stuff. If we meet some day,
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* and you think this stuff is worth it, you can buy me a beer in return.
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* ----------------------------------------------------------------------------
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*/
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/* July 25 2017: ported to esp-open-rtos by Sakari Kapanen (flannelhead) */
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/*
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This is a 'captive portal' DNS server: it basically replies with a fixed IP (in this case:
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the one of the SoftAP interface of this ESP module) for any and all DNS queries. This can
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be used to send mobile phones, tablets etc which connect to the ESP in AP mode directly to
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the internal webserver.
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*/
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#include <espressif/esp_wifi.h>
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#include <FreeRTOS.h>
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#include <FreeRTOSConfig.h>
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#include <task.h>
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#include <queue.h>
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#include <string.h>
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#include <lwip/sockets.h>
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#include <lwip/err.h>
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static int sockFd;
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#ifdef LWIP_DEBUG
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#define httpd_printf printf
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#else
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#define httpd_printf(...)
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#endif
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#define DNS_LEN 512
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typedef struct __attribute__ ((packed)) {
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uint16_t id;
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uint8_t flags;
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uint8_t rcode;
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uint16_t qdcount;
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uint16_t ancount;
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uint16_t nscount;
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uint16_t arcount;
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} DnsHeader;
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typedef struct __attribute__ ((packed)) {
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uint8_t len;
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uint8_t data;
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} DnsLabel;
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typedef struct __attribute__ ((packed)) {
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//before: label
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uint16_t type;
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uint16_t class;
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} DnsQuestionFooter;
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typedef struct __attribute__ ((packed)) {
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//before: label
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uint16_t type;
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uint16_t class;
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uint32_t ttl;
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uint16_t rdlength;
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//after: rdata
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} DnsResourceFooter;
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typedef struct __attribute__ ((packed)) {
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uint16_t prio;
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uint16_t weight;
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} DnsUriHdr;
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#define FLAG_QR (1<<7)
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#define FLAG_AA (1<<2)
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#define FLAG_TC (1<<1)
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#define FLAG_RD (1<<0)
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#define QTYPE_A 1
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#define QTYPE_NS 2
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#define QTYPE_CNAME 5
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#define QTYPE_SOA 6
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#define QTYPE_WKS 11
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#define QTYPE_PTR 12
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#define QTYPE_HINFO 13
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#define QTYPE_MINFO 14
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#define QTYPE_MX 15
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#define QTYPE_TXT 16
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#define QTYPE_URI 256
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#define QCLASS_IN 1
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#define QCLASS_ANY 255
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#define QCLASS_URI 256
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//Function to put unaligned 16-bit network values
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static void setn16(void *pp, int16_t n) {
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char *p=pp;
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*p++=(n>>8);
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*p++=(n&0xff);
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}
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//Function to put unaligned 32-bit network values
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static void setn32(void *pp, int32_t n) {
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char *p=pp;
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*p++=(n>>24)&0xff;
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*p++=(n>>16)&0xff;
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*p++=(n>>8)&0xff;
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*p++=(n&0xff);
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}
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static uint16_t my_ntohs(uint16_t *in) {
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char *p=(char*)in;
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return ((p[0]<<8)&0xff00)|(p[1]&0xff);
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}
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//Parses a label into a C-string containing a dotted
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//Returns pointer to start of next fields in packet
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static char* labelToStr(char *packet, char *labelPtr, int packetSz, char *res, int resMaxLen) {
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int i, j, k;
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char *endPtr=NULL;
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i=0;
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do {
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if ((*labelPtr&0xC0)==0) {
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j=*labelPtr++; //skip past length
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//Add separator period if there already is data in res
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if (i<resMaxLen && i!=0) res[i++]='.';
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//Copy label to res
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for (k=0; k<j; k++) {
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if ((labelPtr-packet)>packetSz) return NULL;
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if (i<resMaxLen) res[i++]=*labelPtr++;
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}
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} else if ((*labelPtr&0xC0)==0xC0) {
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//Compressed label pointer
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endPtr=labelPtr+2;
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int offset=my_ntohs(((uint16_t *)labelPtr))&0x3FFF;
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//Check if offset points to somewhere outside of the packet
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if (offset>packetSz) return NULL;
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labelPtr=&packet[offset];
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}
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//check for out-of-bound-ness
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if ((labelPtr-packet)>packetSz) return NULL;
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} while (*labelPtr!=0);
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res[i]=0; //zero-terminate
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if (endPtr==NULL) endPtr=labelPtr+1;
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return endPtr;
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}
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//Converts a dotted hostname to the weird label form dns uses.
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static char *strToLabel(char *str, char *label, int maxLen) {
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char *len=label; //ptr to len byte
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char *p=label+1; //ptr to next label byte to be written
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while (1) {
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if (*str=='.' || *str==0) {
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*len=((p-len)-1); //write len of label bit
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len=p; //pos of len for next part
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p++; //data ptr is one past len
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if (*str==0) break; //done
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str++;
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} else {
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*p++=*str++; //copy byte
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// if ((p-label)>maxLen) return NULL; //check out of bounds
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}
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}
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*len=0;
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return p; //ptr to first free byte in resp
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}
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//Receive a DNS packet and maybe send a response back
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static void captdnsRecv(struct sockaddr_in *premote_addr, char *pusrdata, unsigned short length) {
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char buff[DNS_LEN];
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char reply[DNS_LEN];
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int i;
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char *rend=&reply[length];
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char *p=pusrdata;
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DnsHeader *hdr=(DnsHeader*)p;
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DnsHeader *rhdr=(DnsHeader*)&reply[0];
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p+=sizeof(DnsHeader);
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// httpd_printf("DNS packet: id 0x%X flags 0x%X rcode 0x%X qcnt %d ancnt %d nscount %d arcount %d len %d\n",
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// my_ntohs(&hdr->id), hdr->flags, hdr->rcode, my_ntohs(&hdr->qdcount), my_ntohs(&hdr->ancount), my_ntohs(&hdr->nscount), my_ntohs(&hdr->arcount), length);
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//Some sanity checks:
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if (length>DNS_LEN) return; //Packet is longer than DNS implementation allows
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if (length<sizeof(DnsHeader)) return; //Packet is too short
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if (hdr->ancount || hdr->nscount || hdr->arcount) return; //this is a reply, don't know what to do with it
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if (hdr->flags&FLAG_TC) return; //truncated, can't use this
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//Reply is basically the request plus the needed data
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memcpy(reply, pusrdata, length);
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rhdr->flags|=FLAG_QR;
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for (i=0; i<my_ntohs(&hdr->qdcount); i++) {
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//Grab the labels in the q string
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p=labelToStr(pusrdata, p, length, buff, sizeof(buff));
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if (p==NULL) return;
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DnsQuestionFooter *qf=(DnsQuestionFooter*)p;
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p+=sizeof(DnsQuestionFooter);
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httpd_printf("DNS: Q (type 0x%X class 0x%X) for %s\n", my_ntohs(&qf->type), my_ntohs(&qf->class), buff);
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if (my_ntohs(&qf->type)==QTYPE_A) {
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//They want to know the IPv4 address of something.
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//Build the response.
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rend=strToLabel(buff, rend, sizeof(reply)-(rend-reply)); //Add the label
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if (rend==NULL) return;
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DnsResourceFooter *rf=(DnsResourceFooter *)rend;
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rend+=sizeof(DnsResourceFooter);
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setn16(&rf->type, QTYPE_A);
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setn16(&rf->class, QCLASS_IN);
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setn32(&rf->ttl, 0);
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setn16(&rf->rdlength, 4); //IPv4 addr is 4 bytes;
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//Grab the current IP of the softap interface
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struct ip_info info;
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sdk_wifi_get_ip_info(SOFTAP_IF, &info);
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*rend++=ip4_addr1(&info.ip);
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*rend++=ip4_addr2(&info.ip);
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*rend++=ip4_addr3(&info.ip);
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*rend++=ip4_addr4(&info.ip);
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setn16(&rhdr->ancount, my_ntohs(&rhdr->ancount)+1);
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// httpd_printf("Added A rec to resp. Resp len is %d\n", (rend-reply));
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} else if (my_ntohs(&qf->type)==QTYPE_NS) {
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//Give ns server. Basically can be whatever we want because it'll get resolved to our IP later anyway.
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rend=strToLabel(buff, rend, sizeof(reply)-(rend-reply)); //Add the label
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DnsResourceFooter *rf=(DnsResourceFooter *)rend;
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rend+=sizeof(DnsResourceFooter);
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setn16(&rf->type, QTYPE_NS);
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setn16(&rf->class, QCLASS_IN);
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setn16(&rf->ttl, 0);
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setn16(&rf->rdlength, 4);
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*rend++=2;
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*rend++='n';
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*rend++='s';
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*rend++=0;
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setn16(&rhdr->ancount, my_ntohs(&rhdr->ancount)+1);
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// httpd_printf("Added NS rec to resp. Resp len is %d\n", (rend-reply));
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} else if (my_ntohs(&qf->type)==QTYPE_URI) {
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//Give uri to us
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rend=strToLabel(buff, rend, sizeof(reply)-(rend-reply)); //Add the label
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DnsResourceFooter *rf=(DnsResourceFooter *)rend;
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rend+=sizeof(DnsResourceFooter);
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DnsUriHdr *uh=(DnsUriHdr *)rend;
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rend+=sizeof(DnsUriHdr);
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setn16(&rf->type, QTYPE_URI);
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setn16(&rf->class, QCLASS_URI);
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setn16(&rf->ttl, 0);
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setn16(&rf->rdlength, 4+16);
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setn16(&uh->prio, 10);
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setn16(&uh->weight, 1);
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memcpy(rend, "http://esp.nonet", 16);
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rend+=16;
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setn16(&rhdr->ancount, my_ntohs(&rhdr->ancount)+1);
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// httpd_printf("Added NS rec to resp. Resp len is %d\n", (rend-reply));
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}
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}
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//Send the response
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sendto(sockFd,(uint8_t*)reply, rend-reply, 0, (struct sockaddr *)premote_addr, sizeof(struct sockaddr_in));
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}
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static void captdnsTask(void *pvParameters) {
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struct sockaddr_in server_addr;
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int32_t ret;
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struct sockaddr_in from;
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socklen_t fromlen;
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char udp_msg[DNS_LEN];
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memset(&server_addr, 0, sizeof(server_addr));
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server_addr.sin_family = AF_INET;
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server_addr.sin_addr.s_addr = INADDR_ANY;
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server_addr.sin_port = PP_HTONS(53);
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server_addr.sin_len = sizeof(server_addr);
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do {
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sockFd=socket(AF_INET, SOCK_DGRAM, 0);
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if (sockFd==-1) {
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httpd_printf("captdns_task failed to create sock!\n");
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vTaskDelay(1000/portTICK_PERIOD_MS);
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}
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} while (sockFd==-1);
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do {
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ret=bind(sockFd, (struct sockaddr *)&server_addr, sizeof(server_addr));
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if (ret!=0) {
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httpd_printf("captdns_task failed to bind sock!\n");
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vTaskDelay(1000/portTICK_PERIOD_MS);
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}
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} while (ret!=0);
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httpd_printf("CaptDNS inited.\n");
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while(1) {
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memset(&from, 0, sizeof(from));
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fromlen=sizeof(struct sockaddr_in);
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ret=recvfrom(sockFd, (uint8_t *)udp_msg, DNS_LEN, 0,(struct sockaddr *)&from,(socklen_t *)&fromlen);
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if (ret>0) captdnsRecv(&from,udp_msg,ret);
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}
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close(sockFd);
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vTaskDelete(NULL);
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}
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void captdnsInit(void) {
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xTaskCreate(captdnsTask, (const char *)"captdns_task", 1200, NULL, 2, NULL);
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}
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3
extras/captdns/captdns.h
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3
extras/captdns/captdns.h
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@ -0,0 +1,3 @@
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#pragma once
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void captdnsInit(void);
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8
extras/captdns/component.mk
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8
extras/captdns/component.mk
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# Component makefile for extras/captdns
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INC_DIRS += $(captdns_ROOT)
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# args for passing into compile rule generation
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captdns_SRC_DIR = $(captdns_ROOT)
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$(eval $(call component_compile_rules,captdns))
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