1991/0330/port/deviproute.c (diff list | history)

port/deviproute.c on 1991/0330
1991/0330		#include <u.h> #include <libc.h> typedef struct Iproute Iproute; typedef struct Iprtab Iprtab; enum { Nroutes= 256, }; /* * Standard ip masks for the 3 classes */ uchar classmask[4][4] = { 0xff, 0, 0, 0, 0xff, 0, 0, 0, 0xff, 0xff, 0, 0, 0xff, 0xff, 0xff, 0, }; #define CLASSMASK(x) classmask[(*x>>6) & 3] /* * routes */ struct Iproute { uchar dst[4]; uchar gate[4]; uchar mask[4]; Iproute *next; int inuse; }; struct Iprtab { /* Lock; */ Iproute *first; Iproute r[Nroutes]; /* routings */ }; Iprtab iprtab; #define lock(x) #define unlock(x) void printroute(void) { Iproute *r; print("\n"); for(r = iprtab.first; r; r = r->next) print("%d.%d.%d.%d %d.%d.%d.%d %d.%d.%d.%d\n", r->dst[0], r->dst[1], r->dst[2], r->dst[3], r->mask[0], r->mask[1], r->mask[2], r->mask[3], r->gate[0], r->gate[1], r->gate[2], r->gate[3]); print("\n"); } /* * The chosen route is the one obeys the constraint * r->mask[x] & dst[x] == r->dst[x] for x in 0 1 2 3 * * If there are several matches, the one whose mask has the most * leading ones (and hence is the most specific) wins. * * If there is no match, the default gateway is chosen. */ void iproute(uchar *dst, uchar *gate) { Iproute *r; /* * first check routes */ lock(&iprtab); for(r = iprtab.first; r; r = r->next){ if((r->mask[0]&dst[0]) == r->dst[0] && (r->mask[1]&dst[1]) == r->dst[1] && (r->mask[2]&dst[2]) == r->dst[2] && (r->mask[3]&dst[3]) == r->dst[3]){ memmove(gate, r->gate, 4); unlock(&iprtab); return; } } unlock(&iprtab); /* * else just return what we got */ memmove(gate, dst, 4); } /* * Compares 2 subnet masks and returns an integer less than, equal to, * or greater than 0, according as m1 is numericly less than, * equal to, or greater than m2. */ ipmaskcmp(uchar *m1, uchar *m2) { int a, i; for(i = 0; i < 4; i++){ if(a = *m1++ - *m2++) return a; } return 0; } /* * Add a route, create a mask if the first mask is 0. * * All routes are stored sorted by the length of leading * ones in the mask. * * NOTE: A default route has an all zeroes mask and dst. */ void ipaddroute(uchar *dst, uchar *mask, uchar *gate) { Iproute *r, *e, *free; int i; if(mask==0) mask = CLASSMASK(dst); /* * filter out impossible requests */ for(i = 0; i < 4; i++) if((dst[i]&mask[i]) != dst[i]) return; /* * see if we already have a route for * the destination */ lock(&iprtab); free = 0; for(r = iprtab.r; r < &iprtab.r[Nroutes]; r++){ if(r->inuse == 0){ free = r; continue; } if(memcmp(dst, r->dst, 4)==0 && memcmp(mask, r->mask, 4)==0){ memmove(r->gate, gate, 4); unlock(&iprtab); return; } } /* * add the new route in sorted order */ memmove(free->dst, dst, 4); memmove(free->mask, mask, 4); memmove(free->gate, gate, 4); free->inuse = 1; for(r = iprtab.first; r; r = r->next){ if(ipmaskcmp(free->mask, r->mask) > 0) break; e = r; } free->next = r; if(r == iprtab.first) iprtab.first = free; else e->next = free; unlock(&iprtab); } /* * remove a route */ void ipremroute(uchar *dst, uchar *mask) { Iproute *r, *e; lock(&iprtab); for(r = iprtab.first; r; r = r->next){ if(memcmp(dst, r->dst, 4)==0 && memcmp(mask, r->mask, 4)==0){ if(r == iprtab.first) iprtab.first = r->next; else e->next = r->next; r->inuse = 0; break; } e = r; } unlock(&iprtab); } /* * remove all routes */ void ipflushroute(void) { Iproute *r; lock(&iprtab); for(r = iprtab.first; r; r = r->next) r->inuse = 0; iprtab.first = 0; unlock(&iprtab); }