| 1 | /* Simple implementation of tracefilter that demonstrates the use of the |
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| 2 | * filter creation and application functions |
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| 3 | */ |
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| 4 | #include "libtrace.h" |
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| 5 | #include <stdio.h> |
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| 6 | #include <inttypes.h> |
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| 7 | #include <assert.h> |
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| 8 | #include <getopt.h> |
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| 9 | |
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| 10 | static int per_packet(libtrace_out_t *output, libtrace_packet_t *packet, |
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| 11 | libtrace_filter_t *filter) |
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| 12 | { |
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| 13 | int ret; |
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| 14 | |
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| 15 | /* Apply the filter to the packet */ |
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| 16 | ret = trace_apply_filter(filter, packet); |
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| 17 | |
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| 18 | /* Check for any errors that occur during the filtering process */ |
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| 19 | if (ret == -1) { |
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| 20 | fprintf(stderr, "Error applying filter\n"); |
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| 21 | return -1; |
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| 22 | } |
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| 23 | |
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| 24 | /* If we get a return value of zero, the packet did not match the |
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| 25 | * filter so we want to return immediately |
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| 26 | */ |
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| 27 | if (ret == 0) |
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| 28 | return 0; |
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| 29 | |
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| 30 | /* Otherwise, the packet matched our filter so we should write it to |
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| 31 | * our output trace */ |
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| 32 | if (trace_write_packet(output, packet) == -1) { |
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| 33 | trace_perror_output(output, "Writing packet"); |
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| 34 | return -1; |
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| 35 | } |
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| 36 | |
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| 37 | return 0; |
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| 38 | } |
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| 39 | |
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| 40 | /* The cleanup function has now been extended to destroy the filter and |
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| 41 | * output trace as well */ |
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| 42 | static void libtrace_cleanup(libtrace_t *trace, libtrace_out_t *output, |
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| 43 | libtrace_packet_t *packet, libtrace_filter_t *filter) { |
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| 44 | |
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| 45 | /* It's very important to ensure that we aren't trying to destroy |
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| 46 | * a NULL structure, so each of the destroy calls will only occur |
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| 47 | * if the structure exists */ |
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| 48 | if (trace) |
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| 49 | trace_destroy(trace); |
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| 50 | |
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| 51 | if (output) |
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| 52 | trace_destroy_output(output); |
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| 53 | |
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| 54 | if (packet) |
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| 55 | trace_destroy_packet(packet); |
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| 56 | |
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| 57 | if (filter) |
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| 58 | trace_destroy_filter(filter); |
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| 59 | |
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| 60 | } |
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| 61 | |
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| 62 | int main(int argc, char *argv[]) |
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| 63 | { |
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| 64 | /* Unlike most of the other example programs, this is not a copy and |
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| 65 | * paste job from readdemo.c as we now also have to initalise and |
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| 66 | * start an output trace too */ |
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| 67 | |
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| 68 | /* On top of that, we now have to manage a filter as well */ |
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| 69 | |
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| 70 | libtrace_t *trace = NULL; |
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| 71 | libtrace_packet_t *packet = NULL; |
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| 72 | libtrace_out_t *output = NULL; |
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| 73 | libtrace_filter_t *filter = NULL; |
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| 74 | |
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| 75 | /* Check that we have all the required command line arguments */ |
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| 76 | if (argc < 4) { |
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| 77 | fprintf(stderr, "Usage: %s inputURI bpffilter outputURI\n", |
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| 78 | argv[0]); |
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| 79 | return 1; |
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| 80 | } |
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| 81 | |
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| 82 | /* Creating the packet structure */ |
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| 83 | packet = trace_create_packet(); |
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| 84 | |
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| 85 | if (packet == NULL) { |
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| 86 | perror("Creating libtrace packet"); |
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| 87 | libtrace_cleanup(trace, output, packet, filter); |
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| 88 | return 1; |
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| 89 | } |
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| 90 | |
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| 91 | /* Creating and starting the INPUT trace */ |
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| 92 | trace = trace_create(argv[1]); |
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| 93 | |
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| 94 | if (trace_is_err(trace)) { |
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| 95 | trace_perror(trace,"Opening trace file"); |
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| 96 | libtrace_cleanup(trace, output, packet, filter); |
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| 97 | return 1; |
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| 98 | } |
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| 99 | |
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| 100 | if (trace_start(trace) == -1) { |
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| 101 | trace_perror(trace,"Starting trace"); |
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| 102 | libtrace_cleanup(trace, output, packet, filter); |
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| 103 | return 1; |
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| 104 | } |
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| 105 | |
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| 106 | /* Creating the filter */ |
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| 107 | filter = trace_create_filter(argv[2]); |
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| 108 | if (filter == NULL) { |
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| 109 | fprintf(stderr, "Failed to create filter (%s)\n", argv[2]); |
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| 110 | libtrace_cleanup(trace, output, packet, filter); |
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| 111 | return 1; |
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| 112 | } |
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| 113 | |
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| 114 | /* Creating and starting the OUTPUT trace */ |
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| 115 | output = trace_create_output(argv[3]); |
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| 116 | |
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| 117 | if (trace_is_err_output(output)) { |
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| 118 | trace_perror_output(output,"Opening output trace file"); |
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| 119 | libtrace_cleanup(trace, output, packet, filter); |
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| 120 | return 1; |
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| 121 | } |
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| 122 | |
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| 123 | if (trace_start_output(output) == -1) { |
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| 124 | trace_perror_output(output,"Starting output trace"); |
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| 125 | libtrace_cleanup(trace, output, packet, filter); |
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| 126 | return 1; |
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| 127 | } |
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| 128 | |
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| 129 | while (trace_read_packet(trace,packet)>0) { |
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| 130 | |
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| 131 | /* If something goes wrong when writing packets, we need to |
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| 132 | * catch that error, tidy up and exit */ |
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| 133 | if (per_packet(output, packet, filter) == -1) { |
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| 134 | libtrace_cleanup(trace, output, packet, filter); |
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| 135 | return 1; |
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| 136 | } |
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| 137 | } |
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| 138 | |
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| 139 | /* Checking for any errors that might have occurred while reading the |
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| 140 | * input trace */ |
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| 141 | if (trace_is_err(trace)) { |
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| 142 | trace_perror(trace,"Reading packets"); |
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| 143 | libtrace_cleanup(trace, output, packet, filter); |
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| 144 | return 1; |
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| 145 | } |
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| 146 | |
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| 147 | libtrace_cleanup(trace, output, packet, filter); |
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| 148 | return 0; |
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| 149 | } |
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| 150 | |
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