mutalk.c

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <errno.h>
#include "mutalk.h"

#define MUTALK_HASH_BASE 16777215 
#define MUTALK_PORT 51268
static const uint32_t UTALK_BEGIN_ADDR = 4009754625;
/*
  Name  : CRC-32
  Poly  : 0x04C11DB7    x^32 + x^26 + x^23 + x^22 + x^16 + x^12 + x^11 
                       + x^10 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1
  Init  : 0xFFFFFFFF
  Revert: true
  XorOut: 0xFFFFFFFF
  Check : 0xCBF43926 ("123456789")
  MaxLen: 268 435 455 bytes (2 147 483 647 bit)
 * 
 * This is simple CRC32 hash table. 
 * It could be extended or changed to something else
 */

const static uint_least32_t Crc32Table[256] = {
    0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA,
    0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
    0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
    0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
    0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
    0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
    0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC,
    0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
    0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
    0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
    0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940,
    0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
    0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116,
    0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
    0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
    0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
    0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A,
    0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
    0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818,
    0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
    0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
    0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
    0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C,
    0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
    0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
    0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
    0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
    0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
    0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086,
    0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
    0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4,
    0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
    0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
    0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
    0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
    0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
    0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE,
    0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
    0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
    0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
    0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252,
    0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
    0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60,
    0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
    0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
    0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
    0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04,
    0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
    0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A,
    0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
    0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
    0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
    0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E,
    0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
    0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
    0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
    0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
    0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
    0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0,
    0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
    0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6,
    0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
    0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
    0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
};

static uint32_t mutalk_hash(const char* name);

mutref mutalk_create(size_t buffer_size) {
    mutref talk;
    int efd;
    int fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (fd < 0) {
        perror("Create socket");
        return NULL;
    }
    efd = epoll_create1(0);
    if (efd < 0) {
        perror("Create epoll");
        close(fd);
        return NULL;
    }
    talk = (mutref) malloc(sizeof (mutalk_t));
    talk->cache_data = (char*) malloc(buffer_size);
    talk->cache_size = buffer_size;
    talk->groups = NULL;
    talk->epoll_fd = efd;
    talk->sender_fd = fd;
    return talk;
}

void mutalk_destroy(mutref talk) {
    mutalk_group_t *nxt;
    mutalk_group_t *pt = talk->groups;
    while (pt != NULL) {
        nxt = pt->next;
        close(pt->fd);
        free(pt->name);
        free(pt);
        pt = nxt;
    }
    close(talk->sender_fd);
    close(talk->epoll_fd);
    free(talk->cache_data);
    free(talk);
}

bool mutalk_group_add(mutref talk, const char* name) {
    mutalk_group_t *pt = talk->groups, *add;
    struct ip_mreq mreq;
    struct in_addr addr;
    struct sockaddr_in sin;
    struct epoll_event event;
    const int optval = 1;
    int fd;
    while (talk->groups != NULL && pt->next != NULL) {
        if (strcmp(pt->name, name) == 0)return true;
        pt = pt->next;
    }
    fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (fd < 0) {
        perror("Create socket");
        return false;
    }
    addr.s_addr = htonl(UTALK_BEGIN_ADDR + mutalk_hash(name));
    sin.sin_family = AF_INET;
    sin.sin_port = htons(MUTALK_PORT);
    sin.sin_addr.s_addr = addr.s_addr;
    mreq.imr_multiaddr = addr;
    mreq.imr_interface.s_addr = htonl(INADDR_ANY);
    setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &optval, sizeof (optval));
    if (bind(fd, (struct sockaddr *) &sin, sizeof (struct sockaddr_in)) < 0) {
        perror("Bind");
        return false;
    }
    if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof (mreq)) < 0) {
        perror("Join");
        return false;
    }
    add = (mutalk_group_t *) malloc(sizeof (mutalk_group_t));
    add->name_size = strlen(name);
    add->name = (char*) malloc(add->name_size);
    add->prev = pt;
    add->next = NULL;
    add->fd = fd;
    strcpy(add->name, name);
    if (talk->groups == NULL) {
        talk->groups = pt;
    } else {
        pt->next = add;
    }
    event.data.ptr = add;
    event.events = EPOLLIN;
    if (epoll_ctl(talk->epoll_fd, EPOLL_CTL_ADD, fd, &event) < 0) {
        mutalk_group_remove(talk, name);
        return false;
    }
    return true;
}

void mutalk_group_remove(mutref talk, const char* name) {
    if (talk->groups == NULL) return;
    mutalk_group_t *pt = talk->groups;
    while (strcmp(pt->name, name) != 0) {
        pt = pt->next;
        if (pt == NULL)return;
    }
    free(pt->name);
    epoll_ctl(talk->epoll_fd, EPOLL_CTL_DEL, pt->fd, NULL);
    close(pt->fd);
    if (pt->prev != NULL) (pt->prev)->next = pt->next;
    if (pt->next != NULL) (pt->next)->prev = pt->prev;
    free(pt);

}

void mutalk_send(mutref talk, const char *subject, const char * data, size_t size) {
    size_t slen = strlen(subject);
    char *buffer = (char*) malloc(size + slen + 1);
    unsigned int addr_v = UTALK_BEGIN_ADDR + mutalk_hash(subject);
    struct sockaddr_in addr;
    memcpy(buffer, subject, slen);
    buffer[slen] = ' ';
    memcpy(&buffer[slen + 1], data, size);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(MUTALK_PORT);
    addr.sin_addr.s_addr = htonl(addr_v);
    sendto(talk->sender_fd, buffer, size + slen + 1, 0,
            (struct sockaddr*) &addr, sizeof (addr));
    free(buffer);
}

mutalk_msg_t mutalk_wait(mutref talk, void *buffer, size_t buf_size, int32_t timeout_ms) {
    struct epoll_event event;
    struct sockaddr_in addr;
    socklen_t len = sizeof (struct sockaddr_in);
    mutalk_msg_t msg;
    size_t size;
    msg.error = false;
    while (!msg.error) {
        if (epoll_wait(talk->epoll_fd, &event, 1, timeout_ms) <= 0) {
            perror("epoll");
            msg.error = true;
        } else {
            msg.stream = (struct mutalk_group_t*) event.data.ptr;
            msg.count = recvfrom(msg.stream->fd, talk->cache_data, talk->cache_size, 0, (struct sockaddr *) &addr, &len);

            if (msg.count > 0) {
                sscanf(talk->cache_data, "%s", talk->cache_name);
                if (strncmp(talk->cache_name, msg.stream->name, msg.stream->name_size) == 0) {
                    size = msg.count - (msg.stream->name_size) - 1;
                    size = size > buf_size ? buf_size : size;
                    memcpy(buffer, talk->cache_data + (msg.stream->name_size) + 1, size);
                    msg.source_port = ntohs(addr.sin_port);
                    msg.source_ip = addr.sin_addr;
                    msg.error = false;
                    msg.count = size;
                    break;
                }
            } else {
                perror("recv");
                fflush(stderr);
                msg.error = true;
            }
        }
    }
    return msg;
}

static uint32_t mutalk_hash(const char* name) {
    // This is CRC32 hash
    uint64_t len = strlen(name);
    uint_least32_t crc = 0xFFFFFFFF;
    const char *buf = name;
    while (len--)
        crc = (crc >> 8) ^ Crc32Table[(crc ^ *buf++) & 0xFF];
    return (crc ^ 0xFFFFFFFF) % MUTALK_HASH_BASE;
}