udp.rar_V2

/* @(#)udp.c 1.1 92/07/30 SMI */ /* * Stand-alone UDP */ #include "../lib/common/saio.h" #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <net/if.h> #include <netinet/in_systm.h> #include <netinet/if_ether.h> #include <netinet/ip_var.h> #include <netinet/ip.h> #include <netinet/udp.h> #include <netinet/udp_var.h> #include "../lib/common/sainet.h" #define ETHER_OFFSET (sizeof(struct ether_header)) #define IP_OFFSET (ETHER_OFFSET + sizeof(struct ip)) #define UDP_OFFSET (IP_OFFSET + sizeof(struct udphdr)) struct saioreq ether_si; struct sainet ether_sain; int random; /* * Receive udp packet */ udp_input(sin, ether, myport, recvpacket, recvsize) struct sockaddr_in *sin; struct ether_addr *ether; u_short myport; char *recvpacket; int recvsize; { struct sainet sain; struct ip *ip; struct udphdr *uh; int len; sain = ether_sain; if (ip_input(&ether_si, recvpacket, &sain) <= 0) { return(0); } ip = (struct ip *) (recvpacket + ETHER_OFFSET); if (ntohs(ip->ip_p) != IPPROTO_UDP) { return(-1); } uh = (struct udphdr *) (recvpacket + IP_OFFSET); if (ntohs(uh->uh_dport) != myport) { return(-1); } len = ntohs(uh->uh_ulen) - sizeof(struct udphdr); if (len > recvsize) { return(-1); } *ether = sain.sain_hisether; sin->sin_addr = ip->ip_src; sin->sin_port = uh->uh_sport; return(len); } /* * Send udp packet */ udp_output(sin, ether, myport, sendpacket, sendsize) struct sockaddr_in *sin; struct ether_addr *ether; u_short myport; char *sendpacket; int sendsize; { struct udphdr *uh; struct ip *ip; struct sainet sain; sain = ether_sain; sain.sain_hisether = *ether; sain.sain_hisaddr = sin->sin_addr; uh = (struct udphdr *) (sendpacket + IP_OFFSET); uh->uh_sport = htons(myport); uh->uh_dport = htons(sin->sin_port); uh->uh_ulen = htons(sendsize + sizeof(struct udphdr)); uh->uh_sum = 0; ip = (struct ip *) (sendpacket + ETHER_OFFSET); ip->ip_v = IPVERSION; ip->ip_hl = sizeof(struct ip) >> 2; ip->ip_tos = 0; ip->ip_len = htons(sendsize + sizeof(struct udphdr) + sizeof(struct ip)); ip->ip_id = random++; ip->ip_off = 0; ip->ip_ttl = ~0; ip->ip_p = htons(IPPROTO_UDP); ip->ip_src = sain.sain_myaddr; ip->ip_dst = sain.sain_hisaddr; return(ip_output(&ether_si, sendpacket, sendsize + UDP_OFFSET, &sain, 0)); }