最近調試openwrt，發現低版本的ulibc不支持recv/send mmsg API,故簡單寫個實現一個測試程序，直接貼代碼吧！，這里的程序可能兼容新版版本的ulibc出現問題，所以使用wrap_簡單封裝一下。

#define _GNU_SOURCE #include <netinet/ip.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/socket.h>#include <linux/unistd.h> #include <unistd.h>/* Support recvmmsg/sendmmsg as uClib not support*/ #ifndef MSG_WAITFORONE #define MSG_WAITFORONE 0x10000 /* recvmmsg(): block until 1+ packets avail */ #endifstruct mmsghdr {struct msghdr msg_hdr;unsigned msg_len; };static inline int recvmmsg(int fd, struct mmsghdr *mmsg,unsigned vlen, unsigned flags, struct timespec *timeout) {return syscall(__NR_recvmmsg, fd, mmsg, vlen, flags, timeout); }static inline int sendmmsg(int fd, struct mmsghdr *mmsg,unsigned vlen, unsigned flags) {return syscall(__NR_sendmmsg, fd, mmsg, vlen, flags); }int main(void) { #define VLEN 10 #define BUFSIZE 200 #define TIMEOUT 3int sockfd, retval, i;struct sockaddr_in sa;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);}sa.sin_family = AF_INET;sa.sin_addr.s_addr = htonl(INADDR_ANY);sa.sin_port = htons(12345);if (bind(sockfd, (struct sockaddr *) &sa, sizeof(sa)) == -1) {perror("bind()");exit(EXIT_FAILURE);}LOOP: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, MSG_WAITFORONE, NULL);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]);}/* delay */for(i = 0; i < 10000000; i++)memset(msgs, 0, sizeof(msgs));goto LOOP;exit(EXIT_SUCCESS); }

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