recvmmsg(2) - wariua/manpages-ko GitHub Wiki

#define _GNU_SOURCE         /* feature_test_macros(7) 참고 */
#include <sys/socket.h>

int recvmmsg(int sockfd, struct mmsghdr *msgvec, unsigned int vlen,
             int flags, struct timespec *timeout);

struct mmsghdr {
    struct msghdr msg_hdr;  /* 메시지 헤더 */
    unsigned int  msg_len;  /* 수신한 바이트 수 */
};

#define _GNU_SOURCE
#include <netinet/ip.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>

int
main(void)
{
#define VLEN 10
#define BUFSIZE 200
#define TIMEOUT 1
    int sockfd, retval, i;
    struct sockaddr_in addr;
    struct mmsghdr msgs[VLEN];
    struct iovec iovecs[VLEN];
    char bufs[VLEN][BUFSIZE+1];
    struct timespec timeout;

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd == -1) {
        perror("socket()");
        exit(EXIT_FAILURE);
    }

    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    addr.sin_port = htons(1234);
    if (bind(sockfd, (struct sockaddr *) &addr, sizeof(addr)) == -1) {
        perror("bind()");
        exit(EXIT_FAILURE);
    }

    memset(msgs, 0, sizeof(msgs));
    for (i = 0; i < VLEN; i++) {
        iovecs[i].iov_base         = bufs[i];
        iovecs[i].iov_len          = BUFSIZE;
        msgs[i].msg_hdr.msg_iov    = &iovecs[i];
        msgs[i].msg_hdr.msg_iovlen = 1;
    }

    timeout.tv_sec = TIMEOUT;
    timeout.tv_nsec = 0;

    retval = recvmmsg(sockfd, msgs, VLEN, 0, &timeout);
    if (retval == -1) {
        perror("recvmmsg()");
        exit(EXIT_FAILURE);
    }

    printf("%d messages received\n", retval);
    for (i = 0; i < retval; i++) {
        bufs[i][msgs[i].msg_len] = 0;
        printf("%d %s", i+1, bufs[i]);
    }
    exit(EXIT_SUCCESS);
}