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fix #12 make the default route discovery work again.
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vastly simpler.
create release 2.1.0.
also fix #9 as a release is made.
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@karlkleinpaste
karlkleinpaste committed May 24, 2020
1 parent b16df42 commit 339ddfb
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Showing 3 changed files with 51 additions and 167 deletions.
2 changes: 1 addition & 1 deletion CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
# - INCLUDEDIR (default "CMAKE_INSTALL_PREFIX/include") - set to directory where header files should be installed
# - BIBLESYNC_SOVERSION (defaults to BIBLESYNC_VERSION) - Manually set the SOVERSION of the installed file
PROJECT(libbiblesync CXX)
SET(BIBLESYNC_VERSION 2.0.1)
SET(BIBLESYNC_VERSION 2.1.0)
# A required CMake line
CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
# Where our custom Find* files are located
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5 changes: 1 addition & 4 deletions include/biblesync.hh
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Expand Up @@ -380,10 +380,7 @@ private:

#ifdef linux
// network self-analysis, borrowed from the net.
int get_default_if_name(char *name, socklen_t size);
int parseRoutes(struct nlmsghdr *nlHdr, struct route_info *rtInfo);
int readNlSock(int sockFd, char *bufPtr, size_t buf_size,
unsigned int seqNum, unsigned int pId);
int get_default_if_name(char *name);
#else
// no other support routines needed for Windows/Solaris/BSD.
#endif /* linux */
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211 changes: 49 additions & 162 deletions src/biblesync.cc
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Expand Up @@ -956,178 +956,61 @@ void BibleSync::clearSpeakers()

#ifdef linux

// routines below imported from the net as workable examples.
// in order to do multicast setup, we require the address
// of the interface that has our default route. code below
// finds the name of that interface. then getifaddrs(3)
// code (taken from its man page) lets us match that name
// against an entry that has the address we need.
// of the interface that has our default route.
// get_default_if_name() reads /proc/net/route to find that interface.
// then getifaddrs(3) code (taken from its man page) lets us
// match that name against an entry that has the address we need.
// this entire methodology is 100 times simpler than the former
// rtnetlink-driven nightmare

// extra includes needed only for the
// route & gateway discovery code below.
// lines in /proc/net/route consist of
// IFACE \t DESTINATION \t GATEWAY \t FLAGS \t ...
// DESTINATION is an 8-byte hex value (string), so look for \t00000000\t.

#include <net/if.h>
#include <linux/rtnetlink.h>

struct route_info
{
struct in_addr dstAddr;
struct in_addr srcAddr;
struct in_addr gateWay;
char ifName[IF_NAMESIZE];
};

int BibleSync::readNlSock(int sockFd,
char *bufPtr,
size_t buf_size,
unsigned int seqNum,
unsigned int pId)
{
struct nlmsghdr *nlHdr;
int readLen = 0, msgLen = 0;

do
{
if((readLen = recv(sockFd, bufPtr, buf_size - msgLen, 0)) < 0)
{
return -1;
}

nlHdr = (struct nlmsghdr *)bufPtr;

if((NLMSG_OK(nlHdr, readLen) == 0) || (nlHdr->nlmsg_type == NLMSG_ERROR))
{
return -1;
}

/* check if last message */
if(nlHdr->nlmsg_type == NLMSG_DONE)
{
break;
}
else
{
/* else move pointer to buffer appropriately */
bufPtr += readLen;
msgLen += readLen;
}

/* check if multi part message */
if((nlHdr->nlmsg_flags & NLM_F_MULTI) == 0)
{
/* return if its not */
break;
}
}
while((nlHdr->nlmsg_seq != seqNum) || (nlHdr->nlmsg_pid != pId));

return msgLen;
}

int BibleSync::parseRoutes(struct nlmsghdr *nlHdr, struct route_info *rtInfo)
{
struct rtmsg *rtMsg;
struct rtattr *rtAttr;
int rtLen;

rtMsg = (struct rtmsg *)NLMSG_DATA(nlHdr);

/* if route is not AF_INET or not in main table, return. */
if((rtMsg->rtm_family != AF_INET) || (rtMsg->rtm_table != RT_TABLE_MAIN))
return -1;

rtAttr = (struct rtattr *)RTM_RTA(rtMsg);
rtLen = RTM_PAYLOAD(nlHdr);

for(; RTA_OK(rtAttr,rtLen); rtAttr = RTA_NEXT(rtAttr,rtLen))
{
switch(rtAttr->rta_type)
{
case RTA_OIF:
if_indextoname(*(int *)RTA_DATA(rtAttr), rtInfo->ifName);
break;

case RTA_GATEWAY:
memcpy(&rtInfo->gateWay, RTA_DATA(rtAttr), sizeof(rtInfo->gateWay));
break;
#define PROC_ROUTE "/proc/net/route"

case RTA_PREFSRC:
memcpy(&rtInfo->srcAddr, RTA_DATA(rtAttr), sizeof(rtInfo->srcAddr));
break;

case RTA_DST:
memcpy(&rtInfo->dstAddr, RTA_DATA(rtAttr), sizeof(rtInfo->dstAddr));
break;
}
}

return 0;
}
#include <net/if.h>
#include <netdb.h>
#include <ifaddrs.h>

int BibleSync::get_default_if_name(char *name, socklen_t size)
int BibleSync::get_default_if_name(char *name)
{
int found_default = 0;

struct nlmsghdr *nlMsg;
//struct rtmsg *rtMsg;
struct route_info route_info;
char msgBuf[4096];

int sock, len, msgSeq = 0;
int found = 0;
char line[256], *field;
FILE *proc_route;

name[1] = '\0'; // pre-set, in case of error.

if((sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0)
if ((proc_route = fopen(PROC_ROUTE, "r")) == NULL)
{
name[0] = 'x';
return -1;
}

memset(msgBuf, 0, sizeof(msgBuf));

nlMsg = (struct nlmsghdr *)msgBuf;
//rtMsg = (struct rtmsg *)NLMSG_DATA(nlMsg);

nlMsg->nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
nlMsg->nlmsg_type = RTM_GETROUTE;

nlMsg->nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
nlMsg->nlmsg_seq = msgSeq++;
nlMsg->nlmsg_pid = getpid();

if(send(sock, nlMsg, nlMsg->nlmsg_len, 0) < 0)
while (fgets(line, 255, proc_route) != NULL)
{
name[0] = 'y';
return -1;
}
if ((field = strchr(line, '\t')) == NULL)
continue; // invalid line?

if((len = readNlSock(sock, msgBuf, sizeof(msgBuf), msgSeq, getpid())) < 0)
{
name[0] = 'z';
return -1;
}

for(; NLMSG_OK(nlMsg,len); nlMsg = NLMSG_NEXT(nlMsg,len))
{
memset(&route_info, 0, sizeof(route_info));
if ( parseRoutes(nlMsg, &route_info) < 0 )
continue; // don't check: not set up

if (strstr((char *)inet_ntoa(route_info.dstAddr), "0.0.0.0"))
if (strncmp(field, "\t00000000\t", 10) == 0)
{
// copy it over
strcpy(name, route_info.ifName);
found_default = 1;
found = 1;
*field = '\0';
strcpy(name, line);
break;
}
}
fclose(proc_route);

close(sock);
return found_default;
}
if (!found)
{
// no default route? fallback: we're holding a valid last line.
// so we arbitrarily choose whatever was found there.
*field = '\0';
strcpy(name, line);
}

#include <netdb.h>
#include <ifaddrs.h>
return 0;
}

void BibleSync::InterfaceAddress()
{
Expand All @@ -1137,7 +1020,7 @@ void BibleSync::InterfaceAddress()

char gw_if[IF_NAMESIZE]; // default gateway interface.

(void)get_default_if_name(gw_if, 100);
(void)get_default_if_name(gw_if);

// if no error, search the interface list for that address.
if (gw_if[0] != '\0')
Expand Down Expand Up @@ -1169,19 +1052,23 @@ void BibleSync::InterfaceAddress()

// Solaris & BSD.

//
// this seeming grotesqueness is in fact the most general command
// that could be found which finds the interface holding the default
// route and then collects that interface's address. handles both
// solaris and bsd. in fact, it suffices for linux as well, but
// we're leaving the existing code above in place for linux, if for
// no other reason than that it's more likely that someone will
// foolishly screw up ifconfig output format in the linux world.
//
#define ADDRESS "PATH=/sbin:/usr/sbin:/bin:/usr/bin " \
"ifconfig \"`netstat -rn | egrep '^0\\.0\\.0\\.0|^default' | " \
"tr ' ' '\\n' | sed -e '/^$/d' | tail -1`\" | grep 'inet ' | " \
// solaris and bsd. also an instance for linux using "ip", in case
// whoever builds this doesn't like depending on /proc/net/route.

#ifdef linux
#define ADDRESS "PATH=/sbin:/usr/sbin:/bin:/usr/bin " \
"ip address show dev `ip route | egrep '^(default|0\\.0\\.0\\.0)' | " \
"head -1 | sed 's/dev /DEV-/' | tr ' ' '\\n' | grep DEV | sed s/DEV-//` | " \
"grep 'inet ' | tr '/ ' '\\n\\n' | grep '^[0-9.][0-9.]*' | head -1 | tr -d '\\n'"
#else
#define ADDRESS "PATH=/sbin:/usr/sbin:/bin:/usr/bin " \
"ifconfig \"`netstat -rn | egrep '^0\\.0\\.0\\.0|^default' | " \
"tr ' ' '\\n' | sed -e '/^$/d' | tail -1`\" | grep 'inet ' | " \
"tr ' ' '\\n' | grep '^[0-9.][0-9.]*$' | head -1 | tr -d '\\n'"
#endif

void BibleSync::InterfaceAddress()
{
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