diff options
Diffstat (limited to 'src/network/getifaddrs.c')
| -rw-r--r-- | src/network/getifaddrs.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/src/network/getifaddrs.c b/src/network/getifaddrs.c new file mode 100644 index 00000000..d96d1094 --- /dev/null +++ b/src/network/getifaddrs.c @@ -0,0 +1,191 @@ +/* (C) 2013 John Spencer. released under musl's standard MIT license. */ +#undef _GNU_SOURCE +#define _GNU_SOURCE +#include <ifaddrs.h> +#include <stdlib.h> +#include <net/if.h> /* IFNAMSIZ, ifreq, ifconf */ +#include <stdio.h> +#include <ctype.h> +#include <string.h> +#include <errno.h> +#include <arpa/inet.h> /* inet_pton */ +#include <unistd.h> +#include <sys/ioctl.h> + +static struct ifaddrs* list_add(struct ifaddrs** list, struct ifaddrs** head, char* ifname) +{ + struct ifaddrs* curr = calloc(1, sizeof(struct ifaddrs)); + if(curr) { + curr->ifa_name = strdup(ifname); + if(!curr->ifa_name) { + free(curr); + curr = 0; + goto out; + } + if(*head) (*head)->ifa_next = curr; + *head = curr; + if(!*list) *list = curr; + } + out: + return curr; +} + +void freeifaddrs(struct ifaddrs *ifp) +{ + struct ifaddrs *head = ifp; + while(head) { + free(head->ifa_name); + free(head->ifa_addr); + free(head->ifa_netmask); + free(head->ifa_ifu.ifu_dstaddr); + free(head->ifa_data); + void *p = head; + head = head->ifa_next; + free(p); + } +} + +static struct sockaddr *sockaddr_in_dup(struct sockaddr_in *src) +{ + struct sockaddr_in *nu = malloc(sizeof(struct sockaddr_in)); + if(nu) *nu = *src; + return (struct sockaddr*) nu; +} + +static struct sockaddr *sockaddr_in6_dup(struct sockaddr_in6 *src) +{ + struct sockaddr_in6 *nu = malloc(sizeof(struct sockaddr_in6)); + if(nu) *nu = *src; + return (struct sockaddr*) nu; +} + +static void ipv6netmask(unsigned prefix_length, struct sockaddr_in6 *sa) +{ + // FIXME: left for bit-wizard rich + memset(&sa->sin6_addr, -1, sizeof(sa->sin6_addr)); +} + +static void dealwithipv6(struct ifaddrs **list, struct ifaddrs** head) +{ + FILE* f = fopen("/proc/net/if_inet6", "r"); + /* 00000000000000000000000000000001 01 80 10 80 lo + A B C D E F + all numbers in hex + A = addr B=netlink device#, C=prefix length, + D = scope value (ipv6.h) E = interface flags (rnetlink.h, addrconf.c) + F = if name */ + char v6conv[32 + 7 + 1], *v6; + char *line, linebuf[512]; + if(!f) return; + while((line = fgets(linebuf, sizeof linebuf, f))) { + v6 = v6conv; + size_t i = 0; + for(; i < 8; i++) { + memcpy(v6, line, 4); + v6+=4; + *v6++=':'; + line+=4; + } + --v6; *v6 = 0; + line++; + unsigned b, c, d, e; + char name[IFNAMSIZ+1]; + if(5 == sscanf(line, "%x %x %x %x %s", &b, &c, &d, &e, name)) { + struct sockaddr_in6 sa = {0}; + if(1 == inet_pton(AF_INET6, v6conv, &sa.sin6_addr)) { + sa.sin6_family = AF_INET6; + struct ifaddrs* curr = list_add(list, head, name); + if(!curr) goto out; + curr->ifa_addr = sockaddr_in6_dup(&sa); + ipv6netmask(c, &sa); + curr->ifa_netmask = sockaddr_in6_dup(&sa); + /* find ipv4 struct with the same interface name to copy flags */ + struct ifaddrs* scan = *list; + for(;scan && strcmp(name, scan->ifa_name);scan=scan->ifa_next); + if(scan) curr->ifa_flags=scan->ifa_flags; + else curr->ifa_flags = 0; + } else errno = 0; + } + } + out: + fclose(f); +} + +int getifaddrs(struct ifaddrs **ifap) +{ + FILE* f = fopen("/proc/net/dev", "r"); + /* the alternative to parsing /proc.. seems to be iterating + through the interfaces using an index number in ifreq.ifr_ifindex + until we get some error code back. the kernel will fill ifr_name field + for valid ifindices (SIOCGIFINDEX) */ + if(!f) return -1; + struct ifaddrs *list = 0, *head = 0; + + char* line; char linebuf[512]; + while((line = fgets(linebuf, sizeof linebuf, f))) { + while(isspace(*line) && *line) line++; + char* start = line; + while(*line && isalnum(*line)) line++; + if(line > start && *line == ':') { + // found interface + *line = 0; + struct ifaddrs* curr = list_add(&list, &head, start); + if(!curr) { + fclose(f); + goto err2; + } + } + } + fclose(f); + + int sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); + if(sock == -1) goto err2; + struct ifreq reqs[32]; /* arbitrary chosen boundary */ + struct ifconf conf = {.ifc_len = sizeof reqs, .ifc_req = reqs}; + if(-1 == ioctl(sock, SIOCGIFCONF, &conf)) goto err; + else { + size_t reqitems = conf.ifc_len / sizeof(struct ifreq); + for(head = list; head; head=head->ifa_next) { + size_t i; + for(i = 0; i < reqitems; i++) { + // get SIOCGIFADDR of active interfaces. + if(!strcmp(reqs[i].ifr_name, head->ifa_name)) { + head->ifa_addr = sockaddr_in_dup((struct sockaddr_in*) &reqs[i].ifr_addr); + break; + } + } + struct ifreq req; + snprintf(req.ifr_name, sizeof req.ifr_name, "%s", head->ifa_name); + if(-1 == ioctl(sock, SIOCGIFFLAGS, &req)) goto err; + + head->ifa_flags = req.ifr_flags; + if(head->ifa_addr) { + /* or'ing flags with IFF_LOWER_UP on active interfaces to mimic glibc */ + head->ifa_flags |= IFF_LOWER_UP; + if(-1 == ioctl(sock, SIOCGIFNETMASK, &req)) goto err; + head->ifa_netmask = sockaddr_in_dup((struct sockaddr_in*) &req.ifr_netmask); + + if(head->ifa_flags & IFF_POINTOPOINT) { + if(-1 == ioctl(sock, SIOCGIFDSTADDR, &req)) goto err; + head->ifa_ifu.ifu_dstaddr = sockaddr_in_dup((struct sockaddr_in*) &req.ifr_dstaddr); + } else { + if(-1 == ioctl(sock, SIOCGIFBRDADDR, &req)) goto err; + head->ifa_ifu.ifu_broadaddr = sockaddr_in_dup((struct sockaddr_in*) &req.ifr_broadaddr); + } + } + } + } + close(sock); + void* last = 0; + for(head = list; head; head=head->ifa_next) last=head; + head = last; + dealwithipv6(&list, &head); + *ifap = list; + return 0; + err: + close(sock); + err2: + freeifaddrs(list); + return -1; +} + |