Yes, according to the source code https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/net/ipv4/udp.c?id=refs/tags/v3.19 -rc6 , udp_destroy_sock() (~ line 2028) clears any deferred frames and frees a socket that frees the address.
You can demonstrate this with a simple example. You will need netcat , client and server. One of the servers, run this code:
#include <arpa/inet.h> #include <netinet/in.h> #include <sys/types.h> #include <sys/socket.h> #include <stdio.h> #include <string.h> int main() { struct sockaddr_in me; int sock; if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) { perror("socket error:"); return -1; } memset(&me, 0, sizeof(me)); me.sin_family = AF_INET; me.sin_port = htons(60000); me.sin_addr.s_addr = htonl(INADDR_ANY); if (bind(sock, (struct sockaddr*)&me, sizeof(me)) == -1) { perror("bind error: "); return -1; } printf("On client execute:\n"); printf(" nc -u {servers ip address} 60000\n\n"); printf("type: hello world<enter>\n"); printf("Hit enter when you've done this..."); getchar(); printf("\nNow check the input queue on this server\n"); printf(" netstat -an|grep 60000\n"); printf("Notice that we have buffered data we have not read\n"); printf("(probably about 360 bytes)\n"); printf("Hit enter to continue..."); getchar(); printf("\nI'm going to end. After I do, run netstat -an again\n"); printf("and you'll notice port 60000 is gone.\n\n"); printf("Re-run this program on server again and see you\n"); printf("have no problem re-acquiring the UDP port.\n"); return 0; }