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// Specific test for multiple IP resolution
// This uses a hostname that typically returns multiple IPs
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#ifndef _WIN32
#include <unistd.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
#else
#include <winsock2.h>
#include <ws2tcpip.h>
#endif
#define MAX_IP_RESULTS 10
static int
resolve_host(const char *hostname, char *ipaddr_list, int max_results,
int req_ai_family)
{
struct addrinfo hints;
struct addrinfo *result;
char ipaddr[INET6_ADDRSTRLEN];
int error;
// Truncate ipaddr_list to an empty string.
ipaddr_list[0] = '\0';
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = req_ai_family;
hints.ai_socktype = SOCK_STREAM;
error = getaddrinfo(hostname, NULL, &hints, &result);
if (error) return error;
int i = 0;
size_t offset = 0;
for(struct addrinfo *ai = result; ai != NULL && i < max_results; ai = ai->ai_next, i++) {
getnameinfo(ai->ai_addr, ai->ai_addrlen, ipaddr, sizeof(ipaddr), NULL, 0,
NI_NUMERICHOST);
if (offset > 0) {
ipaddr_list[offset++] = ';';
}
size_t len = strlen(ipaddr);
strcpy(ipaddr_list + offset, ipaddr);
offset += len;
}
freeaddrinfo(result);
return 0;
}
int main() {
char ipaddr_list[INET6_ADDRSTRLEN * MAX_IP_RESULTS + MAX_IP_RESULTS];
// Try multiple hostnames that might return multiple IPs
const char *hosts[] = {
"www.google.com", // Usually returns multiple IPs
"facebook.com", // Often returns multiple IPs
"amazon.com", // Usually returns multiple IPs
"cloudflare.com", // May return multiple IPs
};
printf("Testing multiple IP resolution:\n\n");
for (int h = 0; h < 4; h++) {
printf("--- Testing: %s ---\n", hosts[h]);
// Test with AF_UNSPEC which may return both IPv4 and IPv6
int result = resolve_host(hosts[h], ipaddr_list, 10, AF_UNSPEC);
if (result != 0) {
printf("Failed to resolve: %s\n\n", gai_strerror(result));
continue;
}
printf("Results: %s\n", ipaddr_list);
// Count IPs
int count = 1;
for (char *p = ipaddr_list; *p; p++) {
if (*p == ';') count++;
}
printf("Number of IPs: %d\n", count);
if (count > 1) {
printf("✓ Multiple IPs returned! Testing semicolon separation:\n");
// Parse and display each IP
char *copy = strdup(ipaddr_list);
char *token = strtok(copy, ";");
int idx = 1;
while (token) {
printf(" IP %d: %s\n", idx++, token);
token = strtok(NULL, ";");
}
free(copy);
// Verify format
if (ipaddr_list[0] == ';') {
printf("✗ ERROR: Starts with semicolon\n");
} else {
printf("✓ Doesn't start with semicolon\n");
}
size_t len = strlen(ipaddr_list);
if (len > 0 && ipaddr_list[len-1] == ';') {
printf("✗ ERROR: Ends with semicolon\n");
} else {
printf("✓ Doesn't end with semicolon\n");
}
if (strstr(ipaddr_list, ";;")) {
printf("✗ ERROR: Contains double semicolons\n");
} else {
printf("✓ No double semicolons\n");
}
printf("\n** SUCCESSFULLY TESTED MULTIPLE IP CASE **\n");
break; // Found a multi-IP case, we're done
}
printf("\n");
}
// Test max_results limiting
printf("\n--- Testing max_results limiting ---\n");
for (int max = 1; max <= 5; max++) {
int result = resolve_host("www.google.com", ipaddr_list, max, AF_UNSPEC);
if (result == 0) {
int count = 1;
for (char *p = ipaddr_list; *p; p++) {
if (*p == ';') count++;
}
printf("max_results=%d: got %d IPs\n", max, count);
if (count > max) {
printf("✗ ERROR: Returned more IPs than max_results!\n");
} else {
printf("✓ Correctly limited to %d\n", count);
}
}
}
return 0;
}
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